1#include <linux/mm.h>
2#include <linux/sched.h>
3#include <linux/init_task.h>
4#include <linux/fs.h>
5
6#include <asm/uaccess.h>
7#include <asm/pgtable.h>
8#include <asm/processor.h>
9#include <asm/desc.h>
10
11#ifdef CONFIG_X86_32
12
13#define DOUBLEFAULT_STACKSIZE (1024)
14static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE];
15#define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE)
16
17#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + MAXMEM)
18
19static void doublefault_fn(void)
20{
21	struct desc_ptr gdt_desc = {0, 0};
22	unsigned long gdt, tss;
23
24	native_store_gdt(&gdt_desc);
25	gdt = gdt_desc.address;
26
27	printk(KERN_EMERG "PANIC: double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size);
28
29	if (ptr_ok(gdt)) {
30		gdt += GDT_ENTRY_TSS << 3;
31		tss = get_desc_base((struct desc_struct *)gdt);
32		printk(KERN_EMERG "double fault, tss at %08lx\n", tss);
33
34		if (ptr_ok(tss)) {
35			struct x86_hw_tss *t = (struct x86_hw_tss *)tss;
36
37			printk(KERN_EMERG "eip = %08lx, esp = %08lx\n",
38			       t->ip, t->sp);
39
40			printk(KERN_EMERG "eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n",
41				t->ax, t->bx, t->cx, t->dx);
42			printk(KERN_EMERG "esi = %08lx, edi = %08lx\n",
43				t->si, t->di);
44		}
45	}
46
47	for (;;)
48		cpu_relax();
49}
50
51struct tss_struct doublefault_tss __cacheline_aligned = {
52	.x86_tss = {
53		.sp0		= STACK_START,
54		.ss0		= __KERNEL_DS,
55		.ldt		= 0,
56		.io_bitmap_base	= INVALID_IO_BITMAP_OFFSET,
57
58		.ip		= (unsigned long) doublefault_fn,
59		/* 0x2 bit is always set */
60		.flags		= X86_EFLAGS_SF | 0x2,
61		.sp		= STACK_START,
62		.es		= __USER_DS,
63		.cs		= __KERNEL_CS,
64		.ss		= __KERNEL_DS,
65		.ds		= __USER_DS,
66		.fs		= __KERNEL_PERCPU,
67
68		.__cr3		= __pa_nodebug(swapper_pg_dir),
69	}
70};
71
72/* dummy for do_double_fault() call */
73void df_debug(struct pt_regs *regs, long error_code) {}
74
75#else /* !CONFIG_X86_32 */
76
77void df_debug(struct pt_regs *regs, long error_code)
78{
79	pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code);
80	show_regs(regs);
81	panic("Machine halted.");
82}
83#endif
84