mirror of
https://gitlab.com/sortix/sortix.git
synced 2023-02-13 20:55:38 -05:00
2afe9d1fd6
This commit got completely out of control. Added the fork(), getpid(), getppid(), sleep(), usleep() system calls, and aliases in the Maxsi:: namespace. Fixed a bug where zero-byte allocation would fail. Worked on the DescriptorTable class which now works and can fork. Got rid of some massive print-registers statements and replaced them with the portable InterruptRegisters::LogRegisters() function. Removed the SysExecuteOld function and replaced it with Process::Execute(). Rewrote the boot sequence in kernel.cpp such that it now loads the system idle process 'idle' as PID 0, and the initization process 'init' as PID 1. Rewrote the SIGINT hack. Processes now maintain a family-tree structure and keep track of their threads. PIDs are now allocated using a simple hack. Virtual memory per-process can now be allocated using a simple hack. Processes can now be forked. Fixed the Process::Execute function such that it now resets the stack pointer to where the stack actually is - not just a magic value. Removed the old and ugly Process::_endcodesection hack. Rewrote the scheduler into a much cleaner and faster version. Debug code is now moved to designated functions. The noop kernel-thread has been replaced by a simple user-space infinite-loop program 'idle'. The Thread class has been seperated from the Scheduler except in Scheduler- related code. Thread::{Save,Load}Registers has been improved and has been moved to $(CPU)/thread.cpp. Threads can now be forked. A new CreateThread function creates threads properly and portably. Added a MicrosecondsSinceBoot() function. Fixed a crucial bug in MemoryManagement::Fork(). Added an 'idle' user-space program that is a noop infinite loop, which is used by the scheduler when there is nothing to do. Rewrote the 'init' program such that it now forks off a shell, instead of becoming the shell. Added the $$ (current PID) and $PPID (parent PPID) variables to the shell.
291 lines
7.9 KiB
C++
291 lines
7.9 KiB
C++
/******************************************************************************
|
|
|
|
COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
|
|
|
|
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/>.
|
|
|
|
scheduler.cpp
|
|
Handles context switching between tasks and deciding when to execute what.
|
|
|
|
******************************************************************************/
|
|
|
|
#include "platform.h"
|
|
#include "panic.h"
|
|
#include "thread.h"
|
|
#include "process.h"
|
|
#include "time.h"
|
|
#include "scheduler.h"
|
|
#include "memorymanagement.h"
|
|
#include "syscall.h"
|
|
|
|
namespace Sortix
|
|
{
|
|
// Internal forward-declarations.
|
|
namespace Scheduler
|
|
{
|
|
void InitCPU();
|
|
Thread* PopNextThread();
|
|
void WakeSleeping();
|
|
void LogBeginContextSwitch(Thread* current, const CPU::InterruptRegisters* state);
|
|
void LogContextSwitch(Thread* current, Thread* next);
|
|
void LogEndContextSwitch(Thread* current, const CPU::InterruptRegisters* state);
|
|
void SysSleep(size_t secs);
|
|
void SysUSleep(size_t usecs);
|
|
void HandleSigIntHack(CPU::InterruptRegisters* regs);
|
|
}
|
|
|
|
namespace Scheduler
|
|
{
|
|
byte dummythreaddata[sizeof(Thread)];
|
|
Thread* dummythread = (Thread*) &dummythreaddata;
|
|
Thread* currentthread;
|
|
Thread* idlethread;
|
|
Thread* firstrunnablethread;
|
|
Thread* firstsleepingthread;
|
|
bool hacksigintpending = false;
|
|
|
|
void Init()
|
|
{
|
|
// We use a dummy so that the first context switch won't crash when
|
|
// currentthread is accessed. This lets us avoid checking whether
|
|
// currentthread is NULL (which it only will be once) which gives
|
|
// simpler code.
|
|
currentthread = dummythread;
|
|
firstrunnablethread = NULL;
|
|
idlethread = NULL;
|
|
hacksigintpending = false;
|
|
|
|
Syscall::Register(SYSCALL_SLEEP, (void*) SysSleep);
|
|
Syscall::Register(SYSCALL_USLEEP, (void*) SysUSleep);
|
|
|
|
InitCPU();
|
|
}
|
|
|
|
// The no operating thread is a thread stuck in an infinite loop that
|
|
// executes absolutely nothing, which is only run when the system has
|
|
// nothing to do.
|
|
void SetIdleThread(Thread* thread)
|
|
{
|
|
ASSERT(idlethread == NULL);
|
|
idlethread = thread;
|
|
SetThreadState(thread, Thread::State::NONE);
|
|
}
|
|
|
|
void SetDummyThreadOwner(Process* process)
|
|
{
|
|
dummythread->process = process;
|
|
}
|
|
|
|
void SetInitialProcess(Process* init)
|
|
{
|
|
dummythread->process = init;
|
|
}
|
|
|
|
void MainLoop()
|
|
{
|
|
// Wait for the first hardware interrupt to trigger a context switch
|
|
// into the first task! Then the init process should gracefully
|
|
// start executing.
|
|
while(true);
|
|
}
|
|
|
|
void Switch(CPU::InterruptRegisters* regs)
|
|
{
|
|
LogBeginContextSwitch(currentthread, regs);
|
|
|
|
if ( hacksigintpending ) { HandleSigIntHack(regs); }
|
|
|
|
WakeSleeping();
|
|
|
|
Thread* nextthread = PopNextThread();
|
|
if ( !nextthread ) { Panic("had no thread to switch to"); }
|
|
|
|
LogContextSwitch(currentthread, nextthread);
|
|
if ( nextthread == currentthread ) { return; }
|
|
|
|
currentthread->SaveRegisters(regs);
|
|
nextthread->LoadRegisters(regs);
|
|
|
|
addr_t newaddrspace = nextthread->process->addrspace;
|
|
Memory::SwitchAddressSpace(newaddrspace);
|
|
currentthread = nextthread;
|
|
|
|
LogEndContextSwitch(currentthread, regs);
|
|
}
|
|
|
|
const bool DEBUG_BEGINCTXSWITCH = false;
|
|
const bool DEBUG_CTXSWITCH = false;
|
|
const bool DEBUG_ENDCTXSWITCH = false;
|
|
|
|
void LogBeginContextSwitch(Thread* current, const CPU::InterruptRegisters* state)
|
|
{
|
|
if ( DEBUG_BEGINCTXSWITCH && current->process->pid != 0 )
|
|
{
|
|
Log::PrintF("Switching from 0x%p", current);
|
|
state->LogRegisters();
|
|
Log::Print("\n");
|
|
}
|
|
}
|
|
|
|
void LogContextSwitch(Thread* current, Thread* next)
|
|
{
|
|
if ( DEBUG_CTXSWITCH && current != next )
|
|
{
|
|
Log::PrintF("switching from %u:%u (0x%p) to %u:%u (0x%p) \n",
|
|
current->process->pid, 0, current,
|
|
next->process->pid, 0, next);
|
|
}
|
|
}
|
|
|
|
void LogEndContextSwitch(Thread* current, const CPU::InterruptRegisters* state)
|
|
{
|
|
if ( DEBUG_ENDCTXSWITCH && current->process->pid != 0 )
|
|
{
|
|
Log::PrintF("Switched to 0x%p", current);
|
|
state->LogRegisters();
|
|
Log::Print("\n");
|
|
}
|
|
}
|
|
|
|
Thread* PopNextThread()
|
|
{
|
|
if ( !firstrunnablethread ) { return idlethread; }
|
|
Thread* result = firstrunnablethread;
|
|
firstrunnablethread = firstrunnablethread->schedulerlistnext;
|
|
return result;
|
|
}
|
|
|
|
void SetThreadState(Thread* thread, Thread::State state)
|
|
{
|
|
if ( thread->state == state ) { return; }
|
|
|
|
if ( thread->state == Thread::State::RUNNABLE )
|
|
{
|
|
if ( thread == firstrunnablethread ) { firstrunnablethread = thread->schedulerlistnext; }
|
|
if ( thread == firstrunnablethread ) { firstrunnablethread = NULL; }
|
|
thread->schedulerlistprev->schedulerlistnext = thread->schedulerlistnext;
|
|
thread->schedulerlistnext->schedulerlistprev = thread->schedulerlistprev;
|
|
thread->schedulerlistprev = NULL;
|
|
thread->schedulerlistnext = NULL;
|
|
}
|
|
|
|
// Insert the thread into the scheduler's carousel linked list.
|
|
if ( state == Thread::State::RUNNABLE )
|
|
{
|
|
if ( firstrunnablethread == NULL ) { firstrunnablethread = thread; }
|
|
thread->schedulerlistprev = firstrunnablethread->schedulerlistprev;
|
|
thread->schedulerlistnext = firstrunnablethread;
|
|
firstrunnablethread->schedulerlistprev = thread;
|
|
thread->schedulerlistprev->schedulerlistnext = thread;
|
|
}
|
|
|
|
thread->state = state;
|
|
}
|
|
|
|
Thread::State GetThreadState(Thread* thread)
|
|
{
|
|
return thread->state;
|
|
}
|
|
|
|
void PutThreadToSleep(Thread* thread, uintmax_t usecs)
|
|
{
|
|
SetThreadState(thread, Thread::State::BLOCKING);
|
|
thread->sleepuntil = Time::MicrosecondsSinceBoot() + usecs;
|
|
|
|
// We use a simple linked linked list sorted after wake-up time to
|
|
// keep track of the threads that are sleeping.
|
|
|
|
if ( firstsleepingthread == NULL )
|
|
{
|
|
thread->nextsleepingthread = NULL;
|
|
firstsleepingthread = thread;
|
|
return;
|
|
}
|
|
|
|
if ( thread->sleepuntil < firstsleepingthread->sleepuntil )
|
|
{
|
|
thread->nextsleepingthread = firstsleepingthread;
|
|
firstsleepingthread = thread;
|
|
return;
|
|
}
|
|
|
|
for ( Thread* tmp = firstsleepingthread; tmp != NULL; tmp = tmp->nextsleepingthread )
|
|
{
|
|
if ( tmp->nextsleepingthread == NULL ||
|
|
thread->sleepuntil < tmp->nextsleepingthread->sleepuntil )
|
|
{
|
|
thread->nextsleepingthread = tmp->nextsleepingthread;
|
|
tmp->nextsleepingthread = thread;
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
void WakeSleeping()
|
|
{
|
|
uintmax_t now = Time::MicrosecondsSinceBoot();
|
|
|
|
while ( firstsleepingthread && firstsleepingthread->sleepuntil < now )
|
|
{
|
|
SetThreadState(firstsleepingthread, Thread::State::RUNNABLE);
|
|
firstsleepingthread = firstsleepingthread->nextsleepingthread;
|
|
}
|
|
}
|
|
|
|
void HandleSigIntHack(CPU::InterruptRegisters* regs)
|
|
{
|
|
if ( currentthread == idlethread ) { return; }
|
|
|
|
hacksigintpending = false;
|
|
Log::PrintF("^C\n");
|
|
|
|
Process::Execute("sh", regs);
|
|
}
|
|
|
|
void SigIntHack()
|
|
{
|
|
hacksigintpending = true;
|
|
}
|
|
|
|
void SysSleep(size_t secs)
|
|
{
|
|
Thread* thread = currentthread;
|
|
uintmax_t timetosleep = ((uintmax_t) secs) * 1000ULL * 1000ULL;
|
|
if ( timetosleep == 0 ) { return; }
|
|
PutThreadToSleep(thread, timetosleep);
|
|
Syscall::Incomplete();
|
|
}
|
|
|
|
void SysUSleep(size_t usecs)
|
|
{
|
|
Thread* thread = currentthread;
|
|
uintmax_t timetosleep = usecs;
|
|
if ( timetosleep == 0 ) { return; }
|
|
PutThreadToSleep(thread, timetosleep);
|
|
Syscall::Incomplete();
|
|
}
|
|
}
|
|
|
|
Thread* CurrentThread()
|
|
{
|
|
return Scheduler::currentthread;
|
|
}
|
|
|
|
Process* CurrentProcess()
|
|
{
|
|
return Scheduler::currentthread->process;
|
|
}
|
|
}
|