arch/x86/kernel/doublefault.c

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