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scheduler: Fix page table switch for scheduler

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The userspace process may map pages where the kernel has allocated data and cause a crash.

This patch fixes this issue by having a separate IRQ handler which sets the kernel page table at the start of SchedulerInterruptHandler() and restores it in SchedulerHandlerStub() function.
This commit is contained in:
EnderIce2
2024-11-17 03:11:20 +02:00
parent 079055082a
commit 86a119ea51
9 changed files with 161 additions and 21 deletions
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67
arch/amd64/cpu/idt.cpp
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@ -29,6 +29,7 @@
#pragma GCC diagnostic ignored "-Wconversion"
extern "C" void MainInterruptHandler(void *Data);
extern "C" void SchedulerInterruptHandler(void *Data);
extern "C" void ExceptionHandler(void *Data);
#define __stub_handler \
@ -247,6 +248,62 @@ namespace InterruptDescriptorTable
"iretq"); // pop CS RIP RFLAGS SS RSP
}
extern "C" __stub_handler void SchedulerHandlerStub()
{
asm("cld\n"
"cli\n"
"pushq %rax\n"
"pushq %rbx\n"
"pushq %rcx\n"
"pushq %rdx\n"
"pushq %rsi\n"
"pushq %rdi\n"
"pushq %rbp\n"
"pushq %r8\n"
"pushq %r9\n"
"pushq %r10\n"
"pushq %r11\n"
"pushq %r12\n"
"pushq %r13\n"
"pushq %r14\n"
"pushq %r15\n"
/* TODO: Add advanced check so we won't update the cr3 when not needed */
"movq %cr3, %rax\n pushq %rax\n" /* Push opt */
"pushq %rax\n" /* Push ppt */
"movq %rsp, %rdi\n"
"call SchedulerInterruptHandler\n"
"popq %rax\n movq %rax, %cr3\n" /* Restore to ppt */
"popq %rax\n" /* Pop opt */
"popq %r15\n"
"popq %r14\n"
"popq %r13\n"
"popq %r12\n"
"popq %r11\n"
"popq %r10\n"
"popq %r9\n"
"popq %r8\n"
"popq %rbp\n"
"popq %rdi\n"
"popq %rsi\n"
"popq %rdx\n"
"popq %rcx\n"
"popq %rbx\n"
"popq %rax\n"
"addq $16, %rsp\n"
"sti\n"
"iretq"); // pop CS RIP RFLAGS SS RSP
}
#pragma region Interrupt Macros
#define EXCEPTION_HANDLER(num) \
@ -272,6 +329,14 @@ namespace InterruptDescriptorTable
"jmp InterruptHandlerStub\n"); \
}
#define SCHEDULER_HANDLER(num) \
__stub_handler void InterruptHandler_##num() \
{ \
asm("pushq $0\n" \
"pushq $" #num "\n" \
"jmp SchedulerHandlerStub\n"); \
}
/* ISR */
EXCEPTION_HANDLER(0x0);
@ -328,7 +393,7 @@ namespace InterruptDescriptorTable
/* Reserved by OS */
INTERRUPT_HANDLER(0x30)
SCHEDULER_HANDLER(0x30)
INTERRUPT_HANDLER(0x31)
INTERRUPT_HANDLER(0x32)
INTERRUPT_HANDLER(0x33)