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sortix--sortix/kernel/signal.cpp

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Update copyright headers of old files to the current format.
2013-07-10 09:26:01 -04:00
/*******************************************************************************
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Fix untimely delivery of signals during userfs reference count messages.
2015-08-14 12:24:40 -04:00
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013, 2014, 2015.
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Update copyright headers of old files to the current format.
2013-07-10 09:26:01 -04:00
This file is part of Sortix.
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Update copyright headers of old files to the current format.
2013-07-10 09:26:01 -04:00
Sortix is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Update copyright headers of old files to the current format.
2013-07-10 09:26:01 -04:00
Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Update copyright headers of old files to the current format.
2013-07-10 09:26:01 -04:00
You should have received a copy of the GNU General Public License along with
Sortix. If not, see <http://www.gnu.org/licenses/>.
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Update copyright headers of old files to the current format.
2013-07-10 09:26:01 -04:00
signal.cpp
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
Asynchronous user-space thread interruption.
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Update copyright headers of old files to the current format.
2013-07-10 09:26:01 -04:00
*******************************************************************************/
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#include <sys/types.h>
Remove <sortix/kernel/platform.h>.
2013-10-26 20:42:10 -04:00
#include <assert.h>
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#include <errno.h>
Remove <sortix/kernel/platform.h>.
2013-10-26 20:42:10 -04:00
#include <string.h>
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#include <stdint.h>
#include <signal.h>
Remove <sortix/kernel/platform.h>.
2013-10-26 20:42:10 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#include <sortix/sigaction.h>
Refactor kernel signal.h header.
2013-05-12 18:52:58 -04:00
#include <sortix/signal.h>
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#include <sortix/sigset.h>
#include <sortix/stack.h>
#include <sortix/ucontext.h>
Refactor kernel signal.h header.
2013-05-12 18:52:58 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#include <sortix/kernel/copy.h>
Refactor kernel interrupt API.
2013-01-09 17:30:36 -05:00
#include <sortix/kernel/interrupt.h>
Remove <sortix/kernel/platform.h>.
2013-10-26 20:42:10 -04:00
#include <sortix/kernel/kernel.h>
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#include <sortix/kernel/process.h>
Refactor process id allocation and accounting.
2014-03-19 18:34:09 -04:00
#include <sortix/kernel/ptable.h>
Refactor kernel signal.h header.
2013-05-12 18:52:58 -04:00
#include <sortix/kernel/signal.h>
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#include <sortix/kernel/syscall.h>
Refactor kernel process.h and thread.h headers.
2013-05-12 18:41:30 -04:00
#include <sortix/kernel/thread.h>
Refactor kernel interrupt API.
2013-01-09 17:30:36 -05:00
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
namespace Sortix {
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
sigset_t default_ignored_signals;
sigset_t default_stop_signals;
sigset_t unblockable_signals;
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
// A per-cpu value whether a signal is pending in the running task.
extern "C" { volatile unsigned long asm_signal_is_pending = 0; }
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
static
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
void UpdatePendingSignals(Thread* thread) // thread->process->signal_lock held
{
struct sigaction* signal_actions = thread->process->signal_actions;
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
// Determine which signals wouldn't be ignored if received.
sigset_t handled_signals;
sigemptyset(&handled_signals);
for ( int i = 1; i < SIG_MAX_NUM; i++ )
{
if ( signal_actions[i].sa_handler == SIG_IGN )
continue;
if ( signal_actions[i].sa_handler == SIG_DFL &&
sigismember(&default_ignored_signals, i) )
continue;
// TODO: A process that is a member of an orphaned process group shall
// not be allowed to stop in response to the SIGTSTP, SIGTTIN, or
// SIGTTOU signals. In cases where delivery of one of these
// signals would stop such a process, the signal shall be
// discarded.
if ( /* is member of an orphaned process group */ false &&
signal_actions[i].sa_handler == SIG_DFL &&
sigismember(&default_stop_signals, i) )
continue;
sigaddset(&handled_signals, i);
}
// TODO: Handle that signals can be pending process-wide!
// Discard all requested signals that would be ignored if delivered.
sigandset(&thread->signal_pending, &thread->signal_pending, &handled_signals);
// Determine which signals are not blocked.
sigset_t permitted_signals;
signotset(&permitted_signals, &thread->signal_mask);
sigorset(&permitted_signals, &permitted_signals, &unblockable_signals);
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
// Determine which signals can currently be delivered to this thread.
sigset_t deliverable_signals;
sigandset(&deliverable_signals, &permitted_signals, &thread->signal_pending);
// Determine whether any signals can be delivered.
unsigned long is_pending = !sigisemptyset(&deliverable_signals) ? 1 : 0;
Fix untimely delivery of signals during userfs reference count messages.
2015-08-14 12:24:40 -04:00
if ( thread->force_no_signals )
is_pending = 0;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
// Store whether a signal is pending in the virtual register.
if ( thread == CurrentThread() )
asm_signal_is_pending = is_pending;
else
thread->registers.signal_pending = is_pending;
}
Fix untimely delivery of signals during userfs reference count messages.
2015-08-14 12:24:40 -04:00
void Thread::DoUpdatePendingSignal()
{
ScopedLock lock(&process->signal_lock);
UpdatePendingSignals(this);
}
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
int sys_sigaction(int signum,
const struct sigaction* user_newact,
struct sigaction* user_oldact)
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
{
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
if ( signum < 0 || signum == 0 /* null signal */ || SIG_MAX_NUM <= signum )
return errno = EINVAL;
Process* process = CurrentProcess();
ScopedLock lock(&process->signal_lock);
struct sigaction* kact = &process->signal_actions[signum];
// Let the caller know the previous action.
if ( user_oldact )
{
if ( !CopyToUser(user_oldact, kact, sizeof(struct sigaction)) )
return -1;
}
// Retrieve and validate the new signal action.
if ( user_newact )
{
struct sigaction newact;
if ( !CopyFromUser(&newact, user_newact, sizeof(struct sigaction)) )
return -1;
if ( newact.sa_flags & ~__SA_SUPPORTED_FLAGS )
return errno = EINVAL, -1;
if ( newact.sa_handler == SIG_ERR )
return errno = EINVAL, -1;
memcpy(kact, &newact, sizeof(struct sigaction));
// Signals may become discarded because of the new handler.
ScopedLock threads_lock(&process->threadlock);
for ( Thread* t = process->firstthread; t; t = t->nextsibling )
UpdatePendingSignals(t);
}
return 0;
}
Initialize system call table at compile time.
2014-10-16 18:04:47 -04:00
int sys_sigaltstack(const stack_t* user_newstack, stack_t* user_oldstack)
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
Thread* thread = CurrentThread();
if ( user_oldstack )
{
if ( !CopyToUser(user_oldstack, &thread->signal_stack, sizeof(stack_t)) )
return -1;
}
if ( user_newstack )
{
stack_t newstack;
if ( !CopyFromUser(&newstack, user_newstack, sizeof(stack_t)) )
return -1;
if ( newstack.ss_flags & ~__SS_SUPPORTED_FLAGS )
return errno = EINVAL, -1;
memcpy(&thread->signal_stack, &newstack, sizeof(stack_t));
}
return 0;
}
Initialize system call table at compile time.
2014-10-16 18:04:47 -04:00
int sys_sigpending(sigset_t* set)
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
Process* process = CurrentProcess();
Thread* thread = CurrentThread();
ScopedLock lock(&process->signal_lock);
// TODO: What about process-wide signals?
return CopyToUser(set, &thread->signal_pending, sizeof(sigset_t)) ? 0 : -1;
}
int sys_sigprocmask(int how, const sigset_t* user_set, sigset_t* user_oldset)
{
Process* process = CurrentProcess();
Thread* thread = CurrentThread();
// TODO: Signal masks are a per-thread property, perhaps this should be
// locked in another manner?
ScopedLock lock(&process->signal_lock);
// Let the caller know the previous signal mask.
if ( user_oldset )
{
if ( !CopyToUser(user_oldset, &thread->signal_mask, sizeof(sigset_t)) )
return -1;
}
// Update the current signal mask according to how.
if ( user_set )
{
sigset_t set;
if ( !CopyFromUser(&set, user_set, sizeof(sigset_t)) )
return -1;
switch ( how )
{
case SIG_BLOCK:
sigorset(&thread->signal_mask, &thread->signal_mask, &set);
break;
case SIG_UNBLOCK:
signotset(&set, &set);
sigandset(&thread->signal_mask, &thread->signal_mask, &set);
break;
case SIG_SETMASK:
memcpy(&thread->signal_mask, &set, sizeof(sigset_t));
break;
default:
return errno = EINVAL, -1;
};
UpdatePendingSignals(thread);
}
return 0;
}
Initialize system call table at compile time.
2014-10-16 18:04:47 -04:00
int sys_sigsuspend(const sigset_t* set)
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
Process* process = CurrentProcess();
Thread* thread = CurrentThread();
Silence maybe initialized warning in sigsuspend.
2015-11-21 18:42:10 -05:00
sigset_t old_signal_mask; sigemptyset(&old_signal_mask);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
sigset_t new_signal_mask;
ScopedLock lock(&process->signal_lock);
// Only accept signals from the user-provided set if given.
if ( set )
{
if ( !CopyFromUser(&new_signal_mask, set, sizeof(sigset_t)) )
return -1;
memcpy(&old_signal_mask, &thread->signal_mask, sizeof(sigset_t));
memcpy(&thread->signal_mask, &new_signal_mask, sizeof(sigset_t));
UpdatePendingSignals(thread);
}
// Wait for a signal to happen or otherwise never halt.
kthread_cond_t never_triggered = KTHREAD_COND_INITIALIZER;
while ( !Signal::IsPending() )
kthread_cond_wait_signal(&never_triggered, &process->signal_lock);
// Restore the previous signal mask if the user gave its own set to wait on.
if ( set )
{
memcpy(&thread->signal_mask, &old_signal_mask, sizeof(sigset_t));
UpdatePendingSignals(thread);
}
// The system call never halts or it halts because a signal interrupted it.
return errno = EINTR, -1;
}
Initialize system call table at compile time.
2014-10-16 18:04:47 -04:00
int sys_kill(pid_t pid, int signum)
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
// Protect the kernel process.
if ( !pid )
return errno = EPERM, -1;
// TODO: Implement that pid == -1 means all processes!
bool process_group = pid < 0 ? (pid = -pid, true) : false;
// TODO: Race condition: The process could be deleted while we use it.
Refactor process id allocation and accounting.
2014-03-19 18:34:09 -04:00
Process* process = CurrentProcess()->GetPTable()->Get(pid);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
if ( !process )
return errno = ESRCH, -1;
// TODO: Protect init?
// TODO: Check for permission.
// TODO: Check for zombies.
if ( process_group )
{
if ( !process->DeliverGroupSignal(signum) && errno != ESIGPENDING )
return -1;
return errno = 0, 0;
}
if ( !process->DeliverSignal(signum) && errno != ESIGPENDING )
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
return -1;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
return errno = 0, 0;
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
}
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
bool Process::DeliverGroupSignal(int signum)
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
{
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
ScopedLock lock(&groupparentlock);
if ( !groupfirst )
return errno = ESRCH, false;
for ( Process* iter = groupfirst; iter; iter = iter->groupnext )
{
int saved_errno = errno;
if ( !iter->DeliverSignal(signum) && errno != ESIGPENDING )
{
// This is not currently an error condition.
}
errno = saved_errno;
}
return true;
}
bool Process::DeliverSignal(int signum)
{
ScopedLock lock(&threadlock);
if ( !firstthread )
return errno = EINIT, false;
// Broadcast particular signals to all the threads in the process.
if ( signum == SIGCONT || signum == SIGSTOP || signum == SIGKILL )
{
int saved_errno = errno;
for ( Thread* t = firstthread; t; t = t->nextsibling )
{
if ( !t->DeliverSignal(signum) && errno != ESIGPENDING )
{
// This is not currently an error condition.
}
}
errno = saved_errno;
return true;
}
// Route the signal to a suitable thread that accepts it.
// TODO: This isn't how signals should be routed to a particular thread.
if ( CurrentThread()->process == this )
return CurrentThread()->DeliverSignal(signum);
return firstthread->DeliverSignal(signum);
}
Initialize system call table at compile time.
2014-10-16 18:04:47 -04:00
int sys_raise(int signum)
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
if ( !CurrentThread()->DeliverSignal(signum) && errno != ESIGPENDING )
return -1;
return errno = 0, 0;
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
}
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
bool Thread::DeliverSignal(int signum)
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
{
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
ScopedLock lock(&process->signal_lock);
return DeliverSignalUnlocked(signum);
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
}
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
bool Thread::DeliverSignalUnlocked(int signum) // thread->process->signal_lock held
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
{
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
if ( signum <= 0 || SIG_MAX_NUM <= signum )
return errno = EINVAL, false;
// Discard the null signal, which does error checking, but doesn't actually
// deliver a signal to the process or thread.
if ( signum == 0 )
return true;
if ( sigismember(&signal_pending, signum) )
return errno = ESIGPENDING, false;
sigaddset(&signal_pending, signum);
if ( signum == SIGSTOP || signum == SIGTSTP ||
signum == SIGTTIN || signum == SIGTTOU )
sigdelset(&signal_pending, SIGCONT);
if ( signum == SIGCONT )
{
sigdelset(&signal_pending, SIGSTOP);
sigdelset(&signal_pending, SIGTSTP);
sigdelset(&signal_pending, SIGTTIN);
sigdelset(&signal_pending, SIGTTOU);
}
UpdatePendingSignals(this);
return true;
}
static int PickImportantSignal(const sigset_t* set)
{
if ( sigismember(set, SIGKILL) )
return SIGKILL;
if ( sigismember(set, SIGSTOP) )
return SIGSTOP;
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
for ( int i = 1; i < SIG_MAX_NUM; i++ )
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
if ( sigismember(set, i) )
return i;
return 0;
}
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
static void EncodeMachineContext(mcontext_t* mctx,
const struct thread_registers* regs,
const struct interrupt_context* intctx)
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
memset(mctx, 0, sizeof(*mctx));
#if defined(__i386__)
// TODO: REG_GS
// TODO: REG_FS
// TODO: REG_ES
// TODO: REG_DS
mctx->gregs[REG_EDI] = regs->edi;
mctx->gregs[REG_ESI] = regs->esi;
mctx->gregs[REG_EBP] = regs->ebp;
mctx->gregs[REG_ESP] = regs->esp;
mctx->gregs[REG_EBX] = regs->ebx;
mctx->gregs[REG_EDX] = regs->edx;
mctx->gregs[REG_ECX] = regs->ecx;
mctx->gregs[REG_EAX] = regs->eax;
mctx->gregs[REG_EIP] = regs->eip;
// TODO: REG_CS
mctx->gregs[REG_EFL] = regs->eflags & 0x0000FFFF;
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
mctx->gregs[REG_CR2] = intctx->cr2;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
// TODO: REG_SS
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
memcpy(mctx->fpuenv, regs->fpuenv, 512);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#elif defined(__x86_64__)
mctx->gregs[REG_R8] = regs->r8;
mctx->gregs[REG_R9] = regs->r9;
mctx->gregs[REG_R10] = regs->r10;
mctx->gregs[REG_R11] = regs->r11;
mctx->gregs[REG_R12] = regs->r12;
mctx->gregs[REG_R13] = regs->r13;
mctx->gregs[REG_R14] = regs->r14;
mctx->gregs[REG_R15] = regs->r15;
mctx->gregs[REG_RDI] = regs->rdi;
mctx->gregs[REG_RSI] = regs->rsi;
mctx->gregs[REG_RBP] = regs->rbp;
mctx->gregs[REG_RBX] = regs->rbx;
mctx->gregs[REG_RDX] = regs->rdx;
mctx->gregs[REG_RAX] = regs->rax;
mctx->gregs[REG_RCX] = regs->rcx;
mctx->gregs[REG_RSP] = regs->rsp;
mctx->gregs[REG_RIP] = regs->rip;
mctx->gregs[REG_EFL] = regs->rflags & 0x000000000000FFFF;
// TODO: REG_CSGSFS.
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
mctx->gregs[REG_CR2] = intctx->cr2;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
mctx->gregs[REG_FSBASE] = 0x0;
mctx->gregs[REG_GSBASE] = 0x0;
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
memcpy(mctx->fpuenv, regs->fpuenv, 512);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#else
#error "You need to implement conversion to mcontext"
#endif
}
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
static void DecodeMachineContext(const mcontext_t* mctx,
struct thread_registers* regs)
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
#if defined(__i386__) || defined(__x86_64__)
unsigned long user_flags = FLAGS_CARRY | FLAGS_PARITY | FLAGS_AUX
| FLAGS_ZERO | FLAGS_SIGN | FLAGS_DIRECTION
| FLAGS_OVERFLOW;
#endif
#if defined(__i386__)
regs->edi = mctx->gregs[REG_EDI];
regs->esi = mctx->gregs[REG_ESI];
regs->ebp = mctx->gregs[REG_EBP];
regs->esp = mctx->gregs[REG_ESP];
regs->ebx = mctx->gregs[REG_EBX];
regs->edx = mctx->gregs[REG_EDX];
regs->ecx = mctx->gregs[REG_ECX];
regs->eax = mctx->gregs[REG_EAX];
regs->eip = mctx->gregs[REG_EIP];
regs->eflags &= ~user_flags;
regs->eflags |= mctx->gregs[REG_EFL] & user_flags;
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
memcpy(regs->fpuenv, mctx->fpuenv, 512);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#elif defined(__x86_64__)
regs->r8 = mctx->gregs[REG_R8];
regs->r9 = mctx->gregs[REG_R9];
regs->r10 = mctx->gregs[REG_R10];
regs->r11 = mctx->gregs[REG_R11];
regs->r12 = mctx->gregs[REG_R12];
regs->r13 = mctx->gregs[REG_R13];
regs->r14 = mctx->gregs[REG_R14];
regs->r15 = mctx->gregs[REG_R15];
regs->rdi = mctx->gregs[REG_RDI];
regs->rsi = mctx->gregs[REG_RSI];
regs->rbp = mctx->gregs[REG_RBP];
regs->rbx = mctx->gregs[REG_RBX];
regs->rdx = mctx->gregs[REG_RDX];
regs->rax = mctx->gregs[REG_RAX];
regs->rcx = mctx->gregs[REG_RCX];
regs->rsp = mctx->gregs[REG_RSP];
regs->rip = mctx->gregs[REG_RIP];
regs->rflags &= ~user_flags;
regs->rflags |= mctx->gregs[REG_EFL] & user_flags;
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
memcpy(regs->fpuenv, mctx->fpuenv, 512);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#else
#error "You need to implement conversion to mcontext"
#endif
}
#if defined(__i386__)
struct stack_frame
{
unsigned long sigreturn;
int signum_param;
siginfo_t* siginfo_param;
ucontext_t* ucontext_param;
void* cookie_param;
siginfo_t siginfo;
ucontext_t ucontext;
};
#elif defined(__x86_64__)
struct stack_frame
{
unsigned long sigreturn;
siginfo_t siginfo;
ucontext_t ucontext;
};
#else
#error "You need to implement struct stack_frame"
#endif
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
void Thread::HandleSignal(struct interrupt_context* intctx)
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
assert(Interrupt::IsEnabled());
assert(this == CurrentThread());
ScopedLock lock(&process->signal_lock);
assert(process->sigreturn);
retry_another_signal:
// Determine which signals are not blocked.
sigset_t permitted_signals;
signotset(&permitted_signals, &signal_mask);
sigorset(&permitted_signals, &permitted_signals, &unblockable_signals);
// Determine which signals can currently be delivered to this thread.
sigset_t deliverable_signals;
sigandset(&deliverable_signals, &permitted_signals, &signal_pending);
// Decide which signal to deliver to the thread.
int signum = PickImportantSignal(&deliverable_signals);
if ( !signum )
return;
// Unmark the selected signal as pending.
sigdelset(&signal_pending, signum);
UpdatePendingSignals(this);
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
intctx->signal_pending = asm_signal_is_pending;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
// Destroy the current thread if the signal is critical.
if ( signum == SIGKILL )
{
lock.Reset();
kthread_exit();
}
struct sigaction* action = &process->signal_actions[signum];
// Stop the current thread upon receipt of a stop signal that isn't handled
// or cannot be handled (SIGSTOP).
if ( (action->sa_handler == SIG_DFL &&
sigismember(&default_stop_signals, signum) ) ||
signum == SIGSTOP )
{
Log::PrintF("%s:%u: `%s' FIXME SIGSTOP\n", __FILE__, __LINE__, __PRETTY_FUNCTION__);
// TODO: Stop the current process.
// TODO: Deliver SIGCHLD to the parent except if SA_NOCLDSTOP is set in
// the parent's SIGCHLD sigaction.
// TODO: SIGCHLD should not be delivered until all the threads in the
// process has received SIGSTOP and stopped?
// TODO: SIGKILL must still be deliverable to a stopped process.
}
// Resume the current thread upon receipt of SIGCONT.
if ( signum == SIGCONT )
{
Log::PrintF("%s:%u: `%s' FIXME SIGCONT\n", __FILE__, __LINE__, __PRETTY_FUNCTION__);
// TODO: Resume the current process.
// TODO: Can SIGCONT be masked?
// TODO: Can SIGCONT be handled?
// TODO: Can SIGCONT be ignored?
// TODO: Deliver SIGCHLD to the parent except if SA_NOCLDSTOP is set in
// the parent's SIGCHLD sigaction.
}
// Signals that would be ignored are already filtered away at this point.
assert(action->sa_handler != SIG_IGN);
assert(action->sa_handler != SIG_DFL || !sigismember(&default_ignored_signals, signum));
// The default action must be to terminate the process. Signals that are
// ignored by default got discarded earlier.
if ( action->sa_handler == SIG_DFL )
{
kthread_mutex_unlock(&process->signal_lock);
process->ExitThroughSignal(signum);
kthread_mutex_lock(&process->signal_lock);
goto retry_another_signal;
}
// At this point we have to attempt to invoke the user-space signal handler,
// which will then return control to us through sigreturn. However, we can't
// save the kernel state because 1) we can't trust the user-space stack 2)
// we can't rely on the kernel stack being intact as the signal handler may
// invoke system calls. For those reasons, we'll have to modify the saved
// registers so they restore a user-space state. We can do this because
// threads in the kernel cannot be delivered signals except when returning
// from a system call, so we'll simply save the state that would have been
// returned to user-space had no signal occured.
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
if ( !InUserspace(intctx) )
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
#if defined(__i386__)
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
uint32_t* params = (uint32_t*) intctx->ebx;
intctx->eip = params[0];
intctx->eflags = params[2];
intctx->esp = params[3];
intctx->cs = UCS | URPL;
intctx->ds = UDS | URPL;
intctx->ss = UDS | URPL;
Clear registers after system calls.
2015-05-16 13:22:46 -04:00
intctx->ebx = 0;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#elif defined(__x86_64__)
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
intctx->rip = intctx->rdi;
intctx->rflags = intctx->rsi;
intctx->rsp = intctx->r8;
intctx->cs = UCS | URPL;
intctx->ds = UDS | URPL;
intctx->ss = UDS | URPL;
Clear registers after system calls.
2015-05-16 13:22:46 -04:00
intctx->rdi = 0;
intctx->rsi = 0;
intctx->r8 = 0;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#else
#error "You may need to fix the registers"
#endif
}
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
struct thread_registers stopped_regs;
Scheduler::SaveInterruptedContext(intctx, &stopped_regs);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
sigset_t new_signal_mask;
memcpy(&new_signal_mask, &action->sa_mask, sizeof(sigset_t));
sigorset(&new_signal_mask, &new_signal_mask, &signal_mask);
// Prevent signals from interrupting themselves by default.
if ( !(action->sa_flags & SA_NODEFER) )
sigaddset(&new_signal_mask, signum);
// Determine whether we use an alternate signal stack.
bool signal_uses_altstack = action->sa_flags & SA_ONSTACK;
bool usable_altstack = !(signal_stack.ss_flags & (SS_DISABLE | SS_ONSTACK));
bool use_altstack = signal_uses_altstack && usable_altstack;
// Determine which signal stack to use and what to save.
stack_t old_signal_stack, new_signal_stack;
uintptr_t stack_location;
if ( use_altstack )
{
old_signal_stack = signal_stack;
new_signal_stack = signal_stack;
new_signal_stack.ss_flags |= SS_ONSTACK;
#if defined(__i386__) || defined(__x86_64__)
stack_location = (uintptr_t) signal_stack.ss_sp + signal_stack.ss_size;
#else
#error "You need to implement getting the alternate stack pointer"
#endif
}
else
{
old_signal_stack.ss_sp = NULL;
old_signal_stack.ss_flags = SS_DISABLE;
old_signal_stack.ss_size = 0;
new_signal_stack = signal_stack;
#if defined(__i386__)
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
stack_location = (uintptr_t) stopped_regs.esp;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#elif defined(__x86_64__)
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
stack_location = (uintptr_t) stopped_regs.rsp;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#else
#error "You need to implement getting the user-space stack pointer"
#endif
}
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
struct thread_registers handler_regs;
memcpy(&handler_regs, &stopped_regs, sizeof(handler_regs));
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
struct stack_frame stack_frame;
memset(&stack_frame, 0, sizeof(stack_frame));
void* handler_ptr = action->sa_flags & SA_COOKIE ?
(void*) action->sa_sigaction_cookie :
action->sa_flags & SA_SIGINFO ?
(void*) action->sa_sigaction :
(void*) action->sa_handler;
#if defined(__i386__)
stack_location -= sizeof(stack_frame);
stack_location &= ~(4UL-1UL);
struct stack_frame* stack = (struct stack_frame*) stack_location;
stack_frame.sigreturn = (unsigned long) process->sigreturn;
stack_frame.signum_param = signum;
stack_frame.siginfo_param = &stack->siginfo;
stack_frame.ucontext_param = &stack->ucontext;
stack_frame.cookie_param = action->sa_cookie;
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
handler_regs.esp = (unsigned long) stack;
handler_regs.eip = (unsigned long) handler_ptr;
handler_regs.eflags &= ~FLAGS_DIRECTION;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#elif defined(__x86_64__)
stack_location -= 128; /* Red zone. */
stack_location -= sizeof(stack_frame);
stack_location = ((stack_location - 8) & ~(16UL-1UL)) + 8;
struct stack_frame* stack = (struct stack_frame*) stack_location;
stack_frame.sigreturn = (unsigned long) process->sigreturn;
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
handler_regs.rdi = (unsigned long) signum;
handler_regs.rsi = (unsigned long) &stack->siginfo;
handler_regs.rdx = (unsigned long) &stack->ucontext;
handler_regs.rcx = (unsigned long) action->sa_cookie;
handler_regs.rsp = (unsigned long) stack;
handler_regs.rip = (unsigned long) handler_ptr;
handler_regs.rflags &= ~FLAGS_DIRECTION;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#else
#error "You need to format the stack frame"
#endif
// Format the siginfo into the stack frame.
stack_frame.siginfo.si_signo = signum;
#if defined(__i386__) || defined(__x86_64__)
// TODO: Is this cr2 value trustworthy? I don't think it is.
if ( signum == SIGSEGV )
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
stack_frame.siginfo.si_addr = (void*) intctx->cr2;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#else
#warning "You need to tell user-space where it crashed"
#endif
// Format the ucontext into the stack frame.
stack_frame.ucontext.uc_link = NULL;
memcpy(&stack_frame.ucontext.uc_sigmask, &signal_mask, sizeof(signal_mask));
memcpy(&stack_frame.ucontext.uc_stack, &signal_stack, sizeof(signal_stack));
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
EncodeMachineContext(&stack_frame.ucontext.uc_mcontext, &stopped_regs, intctx);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
if ( !CopyToUser(stack, &stack_frame, sizeof(stack_frame)) )
{
// Self-destruct if we crashed during delivering the crash signal.
if ( signum == SIGSEGV )
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
{
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
kthread_mutex_unlock(&process->signal_lock);
process->ExitThroughSignal(signum);
kthread_mutex_lock(&process->signal_lock);
goto retry_another_signal;
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
}
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
// Deliver SIGSEGV if we could not deliver the signal on the stack.
// TODO: Is it possible to block SIGSEGV here?
kthread_mutex_unlock(&process->signal_lock);
DeliverSignal(SIGSEGV);
kthread_mutex_lock(&process->signal_lock);
goto retry_another_signal;
}
// Update the current signal mask.
memcpy(&signal_mask, &new_signal_mask, sizeof(sigset_t));
// Update the current alternate signal stack.
signal_stack = new_signal_stack;
// Update the current registers.
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
Scheduler::LoadInterruptedContext(intctx, &handler_regs);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
Implement sigaction(2) SA_RESETHAND.
2015-08-19 08:54:19 -04:00
// Reset the signal handler if this signal handler is once only.
if ( action->sa_flags & SA_RESETHAND )
{
// POSIX mandates SA_RESETHAND is silently ignored for these signals.
if ( signum != SIGILL && signum != SIGTRAP )
{
action->sa_flags &= ~SA_RESETHAND;
action->sa_handler = SIG_DFL;
}
}
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
// Run the signal handler by returning to user-space.
return;
}
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
void Thread::HandleSigreturn(struct interrupt_context* intctx)
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
{
assert(Interrupt::IsEnabled());
assert(this == CurrentThread());
ScopedLock lock(&process->signal_lock);
struct stack_frame stack_frame;
const struct stack_frame* user_stack_frame;
#if defined(__i386__)
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
user_stack_frame = (const struct stack_frame*) (intctx->esp - 4);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#elif defined(__x86_64__)
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
user_stack_frame = (const struct stack_frame*) (intctx->rsp - 8);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
#else
#error "You need to locate the stack we passed the signal handler"
#endif
if ( CopyFromUser(&stack_frame, user_stack_frame, sizeof(stack_frame)) )
{
memcpy(&signal_mask, &stack_frame.ucontext.uc_sigmask, sizeof(signal_mask));
memcpy(&signal_stack, &stack_frame.ucontext.uc_stack, sizeof(signal_stack));
signal_stack.ss_flags &= __SS_SUPPORTED_FLAGS;
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
struct thread_registers resume_regs;
Scheduler::SaveInterruptedContext(intctx, &resume_regs);
DecodeMachineContext(&stack_frame.ucontext.uc_mcontext, &resume_regs);
Scheduler::LoadInterruptedContext(intctx, &resume_regs);
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
}
UpdatePendingSignals(this);
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
intctx->signal_pending = asm_signal_is_pending;
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
lock.Reset();
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
HandleSignal(intctx);
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
}
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
namespace Signal {
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
void DispatchHandler(struct interrupt_context* intctx, void* /*user*/)
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
{
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
return CurrentThread()->HandleSignal(intctx);
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
}
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
void ReturnHandler(struct interrupt_context* intctx, void* /*user*/)
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
{
Refactor kernel interrupt and thread register support.
2014-03-03 18:11:13 -05:00
return CurrentThread()->HandleSigreturn(intctx);
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
}
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
void Init()
{
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
sigemptyset(&default_ignored_signals);
sigaddset(&default_ignored_signals, SIGCHLD);
sigaddset(&default_ignored_signals, SIGURG);
sigaddset(&default_ignored_signals, SIGPWR);
sigaddset(&default_ignored_signals, SIGWINCH);
sigemptyset(&default_stop_signals);
sigaddset(&default_stop_signals, SIGTSTP);
sigaddset(&default_stop_signals, SIGTTIN);
sigaddset(&default_stop_signals, SIGTTOU);
sigemptyset(&unblockable_signals);
sigaddset(&unblockable_signals, SIGKILL);
sigaddset(&unblockable_signals, SIGSTOP);
Initial signal support. Please squash improvements into this commit.
2011-09-15 16:38:40 -04:00
}
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
} // namespace Signal
Implement signals. Note: This is an incompatible ABI change.
2013-08-04 14:24:59 -04:00
Multithreaded kernel and improvement of signal handling. Pardon the big ass-commit, this took months to develop and debug and the refactoring got so far that a clean merge became impossible. The good news is that this commit does quite a bit of cleaning up and generally improves the kernel quality. This makes the kernel fully pre-emptive and multithreaded. This was done by rewriting the interrupt code, the scheduler, introducing new threading primitives, and rewriting large parts of the kernel. During the past few commits the kernel has had its device drivers thread secured; this commit thread secures large parts of the core kernel. There still remains some parts of the kernel that is _not_ thread secured, but this is not a problem at this point. Each user-space thread has an associated kernel stack that it uses when it goes into kernel mode. This stack is by default 8 KiB since that value works for me and is also used by Linux. Strange things tends to happen on x86 in case of a stack overflow - there is no ideal way to catch such a situation right now. The system call conventions were changed, too. The %edx register is now used to provide the errno value of the call, instead of the kernel writing it into a registered global variable. The system call code has also been updated to better reflect the native calling conventions: not all registers have to be preserved. This makes system calls faster and simplifies the assembly. In the kernel, there is no longer the event.h header or the hacky method of 'resuming system calls' that closely resembles cooperative multitasking. If a system call wants to block, it should just block. The signal handling was also improved significantly. At this point, signals cannot interrupt kernel threads (but can always interrupt user-space threads if enabled), which introduces some problems with how a SIGINT could interrupt a blocking read, for instance. This commit introduces and uses a number of new primitives such as kthread_lock_mutex_signal() that attempts to get the lock but fails if a signal is pending. In this manner, the kernel is safer as kernel threads cannot be shut down inconveniently, but in return for complexity as blocking operations must check they if they should fail. Process exiting has also been refactored significantly. The _exit(2) system call sets the exit code and sends SIGKILL to all the threads in the process. Once all the threads have cleaned themselves up and exited, a worker thread calls the process's LastPrayer() method that unmaps memory, deletes the address space, notifies the parent, etc. This provides a very robust way to terminate processes as even half-constructed processes (during a failing fork for instance) can be gracefully terminated. I have introduced a number of kernel threads to help avoid threading problems and simplify kernel design. For instance, there is now a functional generic kernel worker thread that any kernel thread can schedule jobs for. Interrupt handlers run with interrupts off (hence they cannot call kthread_ functions as it may deadlock the system if another thread holds the lock) therefore they cannot use the standard kernel worker threads. Instead, they use a special purpose interrupt worker thread that works much like the generic one expect that interrupt handlers can safely queue work with interrupts off. Note that this also means that interrupt handlers cannot allocate memory or print to the kernel log/screen as such mechanisms uses locks. I'll introduce a lock free algorithm for such cases later on. The boot process has also changed. The original kernel init thread in kernel.cpp creates a new bootstrap thread and becomes the system idle thread. Note that pid=0 now means the kernel, as there is no longer a system idle process. The bootstrap thread launches all the kernel worker threads and then creates a new process and loads /bin/init into it and then creates a thread in pid=1, which starts the system. The bootstrap thread then quietly waits for pid=1 to exit after which it shuts down/reboots/panics the system. In general, the introduction of race conditions and dead locks have forced me to revise a lot of the design and make sure it was thread secure. Since early parts of the kernel was quite hacky, I had to refactor such code. So it seems that the risk of dead locks forces me to write better code. Note that a real preemptive multithreaded kernel simplifies the construction of blocking system calls. My hope is that this will trigger a clean up of the filesystem code that current is almost beyond repair. Almost all of the kernel was modified during this refactoring. To the extent possible, these changes have been backported to older non-multithreaded kernel, but many changes were tightly coupled and went into this commit. Of interest is the implementation of the kthread_ api based on the design of pthreads; this library allows easy synchronization mechanisms and includes C++-style scoped locks. This commit also introduces new worker threads and tested mechanisms for interrupt handlers to schedule work in a kernel worker thread. A lot of code have been rewritten from scratch and has become a lot more stable and correct. Share and enjoy!
2012-08-01 11:30:34 -04:00
} // namespace Sortix
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