arch/i386/kernel/doublefault.c

   1 #include <linux/mm.h>
   2 #include <linux/sched.h>
   3 #include <linux/init.h>
   4 #include <linux/init_task.h>
   5 #include <linux/fs.h>
   6
   7 #include <asm/uaccess.h>
   8 #include <asm/pgtable.h>
   9 #include <asm/processor.h>
  10 #include <asm/desc.h>
  11
  12 #define DOUBLEFAULT_STACKSIZE (1024)
  13 static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE];
  14 #define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE)
  15
  16 #define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + 0x1000000)
  17
  18 static void doublefault_fn(void)
  19 {
  20         struct Xgt_desc_struct gdt_desc = {0, 0};
  21         unsigned long gdt, tss;
  22
  23         __asm__ __volatile__("sgdt %0": "=m" (gdt_desc): :"memory");
  24         gdt = gdt_desc.address;
  25
  26         printk("double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size);
  27
  28         if (ptr_ok(gdt)) {
  29                 gdt += GDT_ENTRY_TSS << 3;
  30                 tss = *(u16 *)(gdt+2);
  31                 tss += *(u8 *)(gdt+4) << 16;
  32                 tss += *(u8 *)(gdt+7) << 24;
  33                 printk("double fault, tss at %08lx\n", tss);
  34
  35                 if (ptr_ok(tss)) {
  36                         struct tss_struct *t = (struct tss_struct *)tss;
  37
  38                         printk("eip = %08lx, esp = %08lx\n", t->eip, t->esp);
  39
  40                         printk("eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n",
  41                                 t->eax, t->ebx, t->ecx, t->edx);
  42                         printk("esi = %08lx, edi = %08lx\n",
  43                                 t->esi, t->edi);
  44                 }
  45         }
  46
  47         for (;;) /* nothing */;
  48 }
  49
  50 struct tss_struct doublefault_tss __cacheline_aligned = {
  51         .esp0           = STACK_START,
  52         .ss0            = __KERNEL_DS,
  53         .ldt            = 0,
  54         .io_bitmap_base = INVALID_IO_BITMAP_OFFSET,
  55
  56         .eip            = (unsigned long) doublefault_fn,
  57         .eflags         = X86_EFLAGS_SF | 0x2,  /* 0x2 bit is always set */
  58         .esp            = STACK_START,
  59         .es             = __USER_DS,
  60         .cs             = __KERNEL_CS,
  61         .ss             = __KERNEL_DS,
  62         .ds             = __USER_DS,
  63
  64         .__cr3          = __pa(swapper_pg_dir)
  65 };