x86自定义OS启动时initialize_paging()触发崩溃问题排查

问题概述 #

从零开始用C语言和GAS汇编编写x86操作系统，当前可正常启动，完成GDT、IDT及中断处理器初始化，但按照James Molloy的实现方式初始化分页时，执行到switch_page_directory()函数会导致QEMU中的OS崩溃并反复重启。

相关代码 #

kernel_main函数 #

void kernel_main(void) 
{   
    clear_screen();

    // Initialise all the ISRs and segmentation
    gdt_init();
    idt_init();

    initialize_paging(); // 问题出在此函数内

    nanos_printf("Hello, paging world!\n");

    uint32_t *ptr = (uint32_t*)0xA0000000;
    uint32_t do_page_fault = *ptr;

    return 0;
}

initialize_paging函数 #

void initialize_paging()
{
    uint32_t mem_end_page = 0x1000000;
    
    nframes = mem_end_page / 0x1000;
    frames = (uint32_t*)kmalloc(INDEX_FROM_BIT(nframes));
    memset(frames, 0, INDEX_FROM_BIT(nframes));
    
    kernel_directory = (page_directory_t*)kmalloc_a(sizeof(page_directory_t));
    current_directory = kernel_directory;

    int i = 0;
    while (i < placement_address)
    {
        alloc_frame( get_page(i, 1, kernel_directory), 0, 0);
        i += 0x1000;
    }
    register_interrupt_handler(14, page_fault);

    switch_page_directory(kernel_directory); // 问题触发点
    
}

switch_page_directory函数 #

void switch_page_directory(page_directory_t *dir)
{
    if (dir == NULL) {
        // Handle null pointer case
        return;
    }

    current_directory = dir;

    asm volatile("mov %0, %%cr3":: "r"(&dir->tablesPhysical));

    uint32_t cr0;
    asm volatile("mov %%cr0, %0": "=r"(cr0));
    cr0 |= 0x80000000; // 设置分页位
    asm volatile("mov %0, %%cr0":: "r"(cr0));
}

链接脚本 #

ENTRY(_start)
 
SECTIONS
{
    . = 1M;
 
    .text BLOCK(4K) : ALIGN(4K)
    {
        *(.multiboot)
        *(.text)
    }
 
    .rodata BLOCK(4K) : ALIGN(4K)
    {
        *(.rodata)
    }

    .data BLOCK(4K) : ALIGN(4K)
    {
        *(.data)
    }
 
    .bss BLOCK(4K) : ALIGN(4K)
    {
        *(COMMON)
        *(.bss)
    }
 
    /DISCARD/ : {
        *(.comment)
        *(.eh_frame)
        *(.note*)
        *(.iplt)
        *(.igot)
    }

    end = .; _end = .; __end = .;
}

已尝试的解决措施 #

曾修改链接脚本为James Molloy的版本，问题未解决，已恢复原脚本。

内容的提问来源于stack exchange，提问作者user21223662