add context switch in thread

This commit is contained in:
Mathieu Maret 2021-11-02 21:24:12 +01:00
parent 814d38bc97
commit 98db8b8962
7 changed files with 157 additions and 11 deletions

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@ -310,6 +310,43 @@ int cpu_kstate_init(struct cpu_state **ctxt, cpu_kstate_function_arg1_t *start_f
return 0;
}
int cpu_ustate_init(struct cpu_state **ctx, uaddr_t startPC, uint32_t arg1, uint32_t arg2,
uaddr_t startSP, vaddr_t kernelStackBottom, size_t kernelStackSize)
{
// The user context is stacked above the usual cpu state by the CPU on context switch.
// So store it when the cpu expect it (See cpu_kstate_init for more details)
struct cpu_ustate *uctx =
(struct cpu_ustate *)(kernelStackBottom + kernelStackSize - sizeof(struct cpu_ustate));
/* If needed, poison the stack */
#ifdef CPU_STATE_DETECT_UNINIT_KERNEL_VARS
memset((void *)kernelStackBottom, CPU_STATE_STACK_POISON, kernelStackSize);
#elif defined(CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW)
cpu_state_prepare_detect_kernel_stack_overflow(stack_bottom, stack_size);
#endif
memset(uctx, 0, sizeof(struct cpu_ustate));
uctx->regs.eip = startPC;
uctx->regs.eax = arg1;
uctx->regs.ebx = arg2;
uctx->regs.cs = BUILD_SEGMENT_REG_VALUE(3, FALSE, SEG_UCODE); // Code
uctx->regs.ds = BUILD_SEGMENT_REG_VALUE(3, FALSE, SEG_UDATA); // Data
uctx->regs.es = BUILD_SEGMENT_REG_VALUE(3, FALSE, SEG_UDATA); // Data
uctx->regs.cpl0_ss = BUILD_SEGMENT_REG_VALUE(3, FALSE, SEG_UDATA); // Kernel Stack
uctx->cpl3_ss = BUILD_SEGMENT_REG_VALUE(3, FALSE, SEG_UDATA); // User Stack
uctx->cpl3_esp = startSP;
/* The newly created context is initially interruptible */
uctx->regs.eflags = (1 << 9); /* set IF bit */
*ctx = (struct cpu_state *)uctx;
return 0;
}
#if defined(CPU_STATE_DETECT_KERNEL_STACK_OVERFLOW)
void cpu_state_prepare_detect_kernel_stack_overflow(const struct cpu_state *ctxt,
vaddr_t stack_bottom, size_t stack_size)

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@ -1,3 +1,5 @@
#define ASM_SOURCE 1
#include "segment.h"
.file "irq_pit.S"
.text
@ -22,6 +24,13 @@ pit_handler: // already got eflags, cs and eip on stack thanks to CPU
pushw %fs // esp+2
pushw %gs // esp
/* Set correct kernel segment descriptors' value */
movw $BUILD_SEGMENT_REG_VALUE(0, 0, SEG_KDATA), %di
pushw %di ; popw %ds
pushw %di ; popw %es
pushw %di ; popw %fs
pushw %di ; popw %gs
/* Send EOI to PIC */
movb $0x20, %al
outb %al, $0x20

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@ -161,3 +161,8 @@ int processSetName(struct process *proc, char *name)
return 0;
}
struct mmu_context *processGetMMUContext(struct process *proc)
{
return proc->context;
}

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@ -14,3 +14,4 @@ int processUnref(struct process *proc);
int processSetName(struct process *proc, char *name);
int processAddThread(struct process *proc, struct thread *th);
int processRemoveThread(struct thread *th);
struct mmu_context *processGetMMUContext(struct process *th);

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@ -4,12 +4,15 @@
#include "irq.h"
#include "klibc.h"
#include "list.h"
#include "mmuContext.h"
#include "time.h"
#include "vga.h"
static struct thread *currentThread;
static struct thread *threadWithTimeout;
static void threadPrepareContext(struct thread *th);
void threadExit()
{
uint32_t flags;
@ -55,7 +58,7 @@ struct thread *threadCreate(const char *name, cpu_kstate_function_arg1_t func, v
return NULL;
thread->stackAddr = (vaddr_t)malloc(THREAD_DEFAULT_STACK_SIZE);
if(!thread->stackAddr)
if (!thread->stackAddr)
return NULL;
#ifdef DEBUG
printf("Alloc stack at 0x%x struct at 0x%x\n", thread->stackAddr, thread);
@ -92,13 +95,19 @@ void threadDelete(struct thread *thread)
uint32_t flags;
disable_IRQs(flags);
list_delete(currentThread, thread);
restore_IRQs(flags);
if (thread->squattedContext) {
threadChangeCurrentContext(NULL);
}
if (thread->process)
processRemoveThread(thread);
#ifdef DEBUG
printf("Free stack at 0x%x struct at 0x%x\n", thread->stackAddr, thread);
#endif
free((void *)thread->stackAddr);
free((void *)thread);
restore_IRQs(flags);
}
struct thread *threadSelectNext()
@ -187,6 +196,7 @@ int threadWait(struct thread *current, struct thread *next, unsigned long msec)
currentThread = next;
currentThread->state = RUNNING;
threadPrepareContext(next);
cpu_context_switch(&current->cpuState, next->cpuState);
return current->sleepHaveTimeouted;
@ -213,6 +223,7 @@ int threadYield()
currentThread = next;
currentThread->state = RUNNING;
threadPrepareContext(next);
cpu_context_switch(&current->cpuState, next->cpuState);
restore_IRQs(flags);
@ -240,6 +251,7 @@ int threadMsleep(unsigned long msec)
currentThread = next;
currentThread->state = RUNNING;
threadPrepareContext(next);
cpu_context_switch(&current->cpuState, next->cpuState);
restore_IRQs(flags);
return current->sleepHaveTimeouted == 1;
@ -261,17 +273,61 @@ int threadAddThread(struct thread *th)
return 0;
}
void threadPrepareSyscallSwitchBack(struct cpu_state *cpu_state){
(void)cpu_state;
return;
static void threadPrepareContext(struct thread *th)
{
if (cpu_context_is_in_user_mode(th->cpuState)) {
assert(th->process != NULL);
assert(th->squattedContext == NULL);
mmuContextSwitch(processGetMMUContext(th->process));
} else if (th->squattedContext) {
mmuContextSwitch(th->squattedContext);
}
}
void threadPrepareExceptionSwitchBack(struct cpu_state *cpu_state){
(void)cpu_state;
return;
int threadChangeCurrentContext(struct mmu_context *ctx)
{
uint32_t flags;
struct mmu_context *prev = currentThread->squattedContext;
if (ctx != NULL) {
assert(prev == NULL);
} else {
assert(prev != NULL);
}
disable_IRQs(flags);
currentThread->squattedContext = ctx;
if (ctx != NULL) {
mmuContextRef(ctx);
mmuContextSwitch(ctx);
} else {
mmuContextUnref(prev);
}
restore_IRQs(flags);
return 0;
}
void threadPrepareIrqSwitchBack(struct cpu_state *cpu_state){
(void)cpu_state;
return;
void threadPrepareSyscallSwitchBack(struct cpu_state *cpuState)
{
currentThread->cpuState = cpuState;
threadPrepareContext(currentThread);
}
void threadPrepareExceptionSwitchBack(struct cpu_state *cpuState)
{
currentThread->cpuState = cpuState;
threadPrepareContext(currentThread);
}
void threadPrepareIrqServicing(struct cpu_state *cpuState)
{
currentThread->cpuState = cpuState;
}
void threadPrepareIrqSwitchBack(struct cpu_state *cpuState)
{
currentThread->cpuState = cpuState;
threadPrepareContext(currentThread);
}

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@ -32,6 +32,40 @@ struct thread {
// For User thread only
struct thread *nextInProcess, *prevInProcess;
struct process *process;
/**
* Address space currently "squatted" by the thread, or used to be
* active when the thread was interrupted/preempted. This is the MMU
* configuration expected before the cpu_state of the thread is
* restored on CPU.
* - For kernel threads: should normally be NULL, meaning that the
* thread will squat the current mm_context currently set in the
* MMU. Might be NON NULL when a kernel thread squats a given
* process to manipulate its address space.
* - For user threads: should normally be NULL. More precisely:
* - in user mode: the thread->process.mm_context is ALWAYS
* set on MMU. squatted_mm_context is ALWAYS NULL in this
* situation, meaning that the thread in user mode uses its
* process-space as expected
* - in kernel mode: NULL means that we keep on using the
* mm_context currently set on MMU, which might be the
* mm_context of another process. This is natural since a
* thread in kernel mode normally only uses data in kernel
* space. BTW, this limits the number of TLB flushes. However,
* there are exceptions where this squatted_mm_context will
* NOT be NULL. One is the copy_from/to_user API, which can
* force the effective mm_context so that the MMU will be
* (re)configured upon every context to the thread to match
* the squatted_mm_context. Another exception is when a parent
* thread creates the address space of a child process, in
* which case the parent thread might temporarilly decide to
* switch to the child's process space.
*
* This is the SOS/matos implementation of the Linux "Lazy TLB" and
* address-space loaning.
*/
struct mmu_context *squattedContext;
};
int threadSetup(vaddr_t mainStack, size_t mainStackSize);
@ -50,3 +84,4 @@ int threadMsleep(unsigned long msec);
int threadOnJieffiesTick();
struct thread *getCurrentThread();
int threadAddThread(struct thread *th);
int threadChangeCurrentContext(struct mmu_context *ctx);

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@ -33,3 +33,6 @@ typedef unsigned long vaddr_t;
// Physical address
typedef unsigned long paddr_t;
// Userspace vaddr
typedef unsigned long uaddr_t;