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#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)
};
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