#include <linux/mm.h> #include <linux/sched.h> #include <linux/init.h> #include <linux/init_task.h> #include <linux/fs.h> #include <asm/uaccess.h> #include <asm/pgtable.h> #include <asm/processor.h> #include <asm/desc.h> #define DOUBLEFAULT_STACKSIZE (1024) static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE]; #define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE) #define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + 0x1000000) static void doublefault_fn(void) { struct Xgt_desc_struct gdt_desc = {0, 0}; unsigned long gdt, tss; __asm__ __volatile__("sgdt %0": "=m" (gdt_desc): :"memory"); gdt = gdt_desc.address; printk("double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size); if (ptr_ok(gdt)) { gdt += GDT_ENTRY_TSS << 3; tss = *(u16 *)(gdt+2); tss += *(u8 *)(gdt+4) << 16; tss += *(u8 *)(gdt+7) << 24; printk("double fault, tss at %08lx\n", tss); if (ptr_ok(tss)) { struct tss_struct *t = (struct tss_struct *)tss; printk("eip = %08lx, esp = %08lx\n", t->eip, t->esp); printk("eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n", t->eax, t->ebx, t->ecx, t->edx); printk("esi = %08lx, edi = %08lx\n", t->esi, t->edi); } } for (;;) /* nothing */; } struct tss_struct doublefault_tss __cacheline_aligned = { .esp0 = STACK_START, .ss0 = __KERNEL_DS, .ldt = 0, .io_bitmap_base = INVALID_IO_BITMAP_OFFSET, .eip = (unsigned long) doublefault_fn, .eflags = X86_EFLAGS_SF | 0x2, /* 0x2 bit is always set */ .esp = STACK_START, .es = __USER_DS, .cs = __KERNEL_CS, .ss = __KERNEL_DS, .ds = __USER_DS, .__cr3 = __pa(swapper_pg_dir) };