1
0
Fork 0
mirror of https://gitlab.com/sortix/sortix.git synced 2023-02-13 20:55:38 -05:00
sortix--sortix/sortix/x64/interrupt.s
Jonas 'Sortie' Termansen 51e3de971c 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!
2012-09-08 18:45:41 +02:00

509 lines
9.1 KiB
ArmAsm

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
This file is part of Sortix.
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.
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.
You should have received a copy of the GNU General Public License along with
Sortix. If not, see <http://www.gnu.org/licenses/>.
x64/interrupt.s
Transfers control to interrupt handlers when interrupts happen.
*******************************************************************************/
.section .text
.global isr0
.type isr0, @function
isr0:
cli
pushq $0 # err_code
pushq $0 # int_no
jmp interrupt_handler_prepare
.global isr1
.type isr1, @function
isr1:
cli
pushq $0 # err_code
pushq $1 # int_no
jmp interrupt_handler_prepare
.global isr2
.type isr2, @function
isr2:
cli
pushq $0 # err_code
pushq $2 # int_no
jmp interrupt_handler_prepare
.global isr3
.type isr3, @function
isr3:
cli
pushq $0 # err_code
pushq $3 # int_no
jmp interrupt_handler_prepare
.global isr4
.type isr4, @function
isr4:
cli
pushq $0 # err_code
pushq $4 # int_no
jmp interrupt_handler_prepare
.global isr5
.type isr5, @function
isr5:
cli
pushq $0 # err_code
pushq $5 # int_no
jmp interrupt_handler_prepare
.global isr6
.type isr6, @function
isr6:
cli
pushq $0 # err_code
pushq $6 # int_no
jmp interrupt_handler_prepare
.global isr7
.type isr7, @function
isr7:
cli
pushq $0 # err_code
pushq $7 # int_no
jmp interrupt_handler_prepare
.global isr8
.type isr8, @function
isr8:
cli
# pushq $0 # err_code pushed by CPU
pushq $8 # int_no
jmp interrupt_handler_prepare
.global isr9
.type isr9, @function
isr9:
cli
pushq $0 # err_code
pushq $9 # int_no
jmp interrupt_handler_prepare
.global isr10
.type isr10, @function
isr10:
cli
# pushq $0 # err_code pushed by CPU
pushq $10 # int_no
jmp interrupt_handler_prepare
.global isr11
.type isr11, @function
isr11:
cli
# pushq $0 # err_code pushed by CPU
pushq $11 # int_no
jmp interrupt_handler_prepare
.global isr12
.type isr12, @function
isr12:
cli
# pushq $0 # err_code pushed by CPU
pushq $12 # int_no
jmp interrupt_handler_prepare
.global isr13
.type isr13, @function
isr13:
cli
# pushq $0 # err_code pushed by CPU
pushq $13 # int_no
jmp interrupt_handler_prepare
.global isr14
.type isr14, @function
isr14:
cli
# pushq $0 # err_code pushed by CPU
pushq $14 # int_no
jmp interrupt_handler_prepare
.global isr15
.type isr15, @function
isr15:
cli
pushq $0 # err_code
pushq $15 # int_no
jmp interrupt_handler_prepare
.global isr16
.type isr16, @function
isr16:
cli
pushq $0 # err_code
pushq $16 # int_no
jmp interrupt_handler_prepare
.global isr17
.type isr17, @function
isr17:
cli
pushq $0 # err_code
pushq $17 # int_no
jmp interrupt_handler_prepare
.global isr18
.type isr18, @function
isr18:
cli
pushq $0 # err_code
pushq $18 # int_no
jmp interrupt_handler_prepare
.global isr19
.type isr19, @function
isr19:
cli
pushq $0 # err_code
pushq $19 # int_no
jmp interrupt_handler_prepare
.global isr20
.type isr20, @function
isr20:
cli
pushq $0 # err_code
pushq $20 # int_no
jmp interrupt_handler_prepare
.global isr21
.type isr21, @function
isr21:
cli
pushq $0 # err_code
pushq $21 # int_no
jmp interrupt_handler_prepare
.global isr22
.type isr22, @function
isr22:
cli
pushq $0 # err_code
pushq $22 # int_no
jmp interrupt_handler_prepare
.global isr23
.type isr23, @function
isr23:
cli
pushq $0 # err_code
pushq $23 # int_no
jmp interrupt_handler_prepare
.global isr24
.type isr24, @function
isr24:
cli
pushq $0 # err_code
pushq $24 # int_no
jmp interrupt_handler_prepare
.global isr25
.type isr25, @function
isr25:
cli
pushq $0 # err_code
pushq $25 # int_no
jmp interrupt_handler_prepare
.global isr26
.type isr26, @function
isr26:
cli
pushq $0 # err_code
pushq $26 # int_no
jmp interrupt_handler_prepare
.global isr27
.type isr27, @function
isr27:
cli
pushq $0 # err_code
pushq $27 # int_no
jmp interrupt_handler_prepare
.global isr28
.type isr28, @function
isr28:
cli
pushq $0 # err_code
pushq $28 # int_no
jmp interrupt_handler_prepare
.global isr29
.type isr29, @function
isr29:
cli
pushq $0 # err_code
pushq $29 # int_no
jmp interrupt_handler_prepare
.global isr30
.type isr30, @function
isr30:
cli
pushq $0 # err_code
pushq $30 # int_no
jmp interrupt_handler_prepare
.global isr31
.type isr31, @function
isr31:
cli
pushq $0 # err_code
pushq $31 # int_no
jmp interrupt_handler_prepare
.global isr128
.type isr128, @function
isr128:
cli
pushq $0 # err_code
pushq $128 # int_no
jmp interrupt_handler_prepare
.global isr130
.type isr130, @function
isr130:
cli
pushq $0 # err_code
pushq $130 # int_no
jmp interrupt_handler_prepare
.global isr131
.type isr131, @function
isr131:
cli
pushq $0 # err_code
pushq $131 # int_no
jmp interrupt_handler_prepare
.global irq0
.type irq0, @function
irq0:
cli
pushq $0 # err_code
pushq $32 # int_no
jmp interrupt_handler_prepare
.global irq1
.type irq1, @function
irq1:
cli
pushq $0 # err_code
pushq $33 # int_no
jmp interrupt_handler_prepare
.global irq2
.type irq2, @function
irq2:
cli
pushq $0 # err_code
pushq $34 # int_no
jmp interrupt_handler_prepare
.global irq3
.type irq3, @function
irq3:
cli
pushq $0 # err_code
pushq $35 # int_no
jmp interrupt_handler_prepare
.global irq4
.type irq4, @function
irq4:
cli
pushq $0 # err_code
pushq $36 # int_no
jmp interrupt_handler_prepare
.global irq5
.type irq5, @function
irq5:
cli
pushq $0 # err_code
pushq $37 # int_no
jmp interrupt_handler_prepare
.global irq6
.type irq6, @function
irq6:
cli
pushq $0 # err_code
pushq $38 # int_no
jmp interrupt_handler_prepare
.global irq7
.type irq7, @function
irq7:
cli
pushq $0 # err_code
pushq $39 # int_no
jmp interrupt_handler_prepare
.global irq8
.type irq8, @function
irq8:
cli
pushq $0 # err_code
pushq $40 # int_no
jmp interrupt_handler_prepare
.global irq9
.type irq9, @function
irq9:
cli
pushq $0 # err_code
pushq $41 # int_no
jmp interrupt_handler_prepare
.global irq10
.type irq10, @function
irq10:
cli
pushq $0 # err_code
pushq $42 # int_no
jmp interrupt_handler_prepare
.global irq11
.type irq11, @function
irq11:
cli
pushq $0 # err_code
pushq $43 # int_no
jmp interrupt_handler_prepare
.global irq12
.type irq12, @function
irq12:
cli
pushq $0 # err_code
pushq $44 # int_no
jmp interrupt_handler_prepare
.global irq13
.type irq13, @function
irq13:
cli
pushq $0 # err_code
pushq $45 # int_no
jmp interrupt_handler_prepare
.global irq14
.type irq14, @function
irq14:
cli
pushq $0 # err_code
pushq $46 # int_no
jmp interrupt_handler_prepare
.global irq15
.type irq15, @function
irq15:
cli
pushq $0 # err_code
pushq $47 # int_no
jmp interrupt_handler_prepare
.global yield_cpu_handler
.type yield_cpu_handler, @function
yield_cpu_handler:
cli
pushq $0 # err_code
pushq $129 # int_no
jmp interrupt_handler_prepare
.global thread_exit_handler
.type thread_exit_handler, @function
thread_exit_handler:
cli
pushq $0 # err_code
pushq $132 # int_no
jmp interrupt_handler_prepare
interrupt_handler_prepare:
movq $1, asm_is_cpu_interrupted
pushq %r15
pushq %r14
pushq %r13
pushq %r12
pushq %r11
pushq %r10
pushq %r9
pushq %r8
pushq %rax
pushq %rcx
pushq %rdx
pushq %rbx
pushq %rsp
pushq %rbp
pushq %rsi
pushq %rdi
# Push the user-space data segment.
movl %ds, %ebp
pushq %rbp
# Load the kernel data segment.
movw $0x10, %bp
movl %ebp, %ds
movl %ebp, %es
movl %ebp, %fs
movl %ebp, %gs
# Push CR2 in case of page faults
movq %cr2, %rbp
pushq %rbp
# Push the current kernel errno value.
movl global_errno, %ebp
pushq %rbp
# Push whether a signal is pending.
movq asm_signal_is_pending, %rbp
pushq %rbp
# Now call the interrupt handler.
movq %rsp, %rdi
call interrupt_handler
load_interrupted_registers:
# Restore whether signals are pending.
popq %rbp
movq %rbp, asm_signal_is_pending
# Restore the previous kernel errno.
popq %rbp
movl %ebp, global_errno
# Remove CR2 from the stack.
addq $8, %rsp
# Restore the user-space data segment.
popq %rbp
movl %ebp, %ds
movl %ebp, %es
movl %ebp, %fs
movl %ebp, %gs
popq %rdi
popq %rsi
popq %rbp
addq $8, %rsp # Don't pop %rsp, may not be defined.
popq %rbx
popq %rdx
popq %rcx
popq %rax
popq %r8
popq %r9
popq %r10
popq %r11
popq %r12
popq %r13
popq %r14
popq %r15
# Remove int_no and err_code
addq $16, %rsp
movq $0, asm_is_cpu_interrupted
# Return to where we came from.
iretq
.global interrupt_handler_null
.type interrupt_handler_null, @function
interrupt_handler_null:
iretq
.global asm_interrupts_are_enabled
.type asm_interrupts_are_enabled, @function
asm_interrupts_are_enabled:
pushfq
popq %rax
andq $0x000200, %rax # FLAGS_INTERRUPT
retq
.global load_registers
.type load_registers, @function
load_registers:
# Let the register struct become our temporary stack
movq %rdi, %rsp
jmp load_interrupted_registers