matos/arch/x86/exception.c

#include "exception.h"
#include "cpu_context.h"
#include "idt.h"
#include "interrupt.h"
#include "irq.h"
#include "klibc.h"
#include "process.h"
#include "thread.h"
#include "types.h"
#include "uaddrspace.h"
#include "vga.h"

exception_handler exception_handler_array[EXCEPTION_NUM] = {
    NULL,
};

extern vaddr_t exception_handler_wrapper_array[EXCEPTION_NUM];

void exception_handler_wrap(int intr, struct cpu_state *frame)
{
    if (0 > intr || EXCEPTION_NUM <= intr) {
        pr_err("Trying to handle unknow exception %d\n", intr);
        return;
    }

    if (exception_handler_array[intr] != NULL)
        exception_handler_array[intr](frame, intr);
}

int exceptionSetRoutine(int exception, exception_handler handler)
{
    uint32_t flags;
    if ((exception < 0) || exception >= EXCEPTION_NUM)
        return -1;

    disable_IRQs(flags);

    exception_handler_array[exception] = handler;

    idt_set_handler(EXCEPTION_INTERRUPT_BASE_ADDRESS + exception,
                    (unsigned int)exception_handler_wrapper_array[exception], 0);
    restore_IRQs(flags);
    return 0;
}

void print_handler(struct cpu_state *frame, ulong intr)
{
    VGAPrintf(RED, BLACK, 0, VGA_HEIGHT - 1, "EXCEPTION %lu", intr);
    printf("Exception %lu at 0x%p\n", intr, (void *)cpu_context_get_PC(frame));

    asm("hlt");
}

void pagefault_handler(struct cpu_state *frame, ulong intr)
{
    // PAGE_FAULT is a interrupt with an error code (see exception_wrapper.S)
    uint32_t error_code = cpu_context_get_EX_err(frame);
    struct thread *current = getCurrentThread();

    if (cpu_context_is_in_user_mode(current->cpuState)) {
        assert(frame == current->cpuState); // pagefault in kernel not supported ATM

        struct uAddrSpace *as = processGetAddrSpace(current->process);
        vaddr_t faultAddr     = cpu_context_get_EX_faulting_vaddr(frame);
        int needMMUSetup =
            (uAddrSpaceGetMMUContext(as) != getCurrentThread()->squattedContext);

        if (needMMUSetup) {
            threadChangeCurrentContext(uAddrSpaceGetMMUContext(as));
        }

        if (!uAddrSpaceHeapCheckNAlloc(as, faultAddr))
            goto release_context;

        int ret             = uAddrSpaceSolvePageFault(as, faultAddr, error_code & 0x2);

        if (!ret)
            goto release_context;

        printf(
            "page fault while in thread [%s] at 0x%p when trying to access 0x%p err_code 0x%x ressource ret %d\n",
            current->name, (void *)cpu_context_get_PC(frame), (void *)faultAddr, error_code,
            ret);
        printf("Killing User Thread\n");
        threadExit();

    release_context:
        if (needMMUSetup)
            threadChangeCurrentContext(NULL);

        return;
    }

    VGAPrintf(RED, BLACK, 0, VGA_HEIGHT - 1, "PAGE FAULT %d", intr);
    for (;;)
        continue;
}

int exceptionSetup()
{
    for (int i = 0; i < EXCEPTION_NUM; i++) {
        exceptionSetRoutine(i, print_handler);
    }
    exceptionSetRoutine(EXCEPTION_PAGE_FAULT, pagefault_handler);

    return 0;
}