arch/x86/include/asm/bug.h

   1 #ifndef _ASM_X86_BUG_H
   2 #define _ASM_X86_BUG_H
   3
   4 #include <linux/stringify.h>
   5
   6 /*
   7  * Since some emulators terminate on UD2, we cannot use it for WARN.
   8  * Since various instruction decoders disagree on the length of UD1,
   9  * we cannot use it either. So use UD0 for WARN.
  10  *
  11  * (binutils knows about "ud1" but {en,de}codes it as 2 bytes, whereas
  12  *  our kernel decoder thinks it takes a ModRM byte, which seems consistent
  13  *  with various things like the Intel SDM instruction encoding rules)
  14  */
  15
  16 #define ASM_UD0         ".byte 0x0f, 0xff"
  17 #define ASM_UD1         ".byte 0x0f, 0xb9" /* + ModRM */
  18 #define ASM_UD2         ".byte 0x0f, 0x0b"
  19
  20 #define INSN_UD0        0xff0f
  21 #define INSN_UD2        0x0b0f
  22
  23 #define LEN_UD0         2
  24
  25 #ifdef CONFIG_GENERIC_BUG
  26
  27 #ifdef CONFIG_X86_32
  28 # define __BUG_REL(val) ".long " __stringify(val)
  29 #else
  30 # define __BUG_REL(val) ".long " __stringify(val) " - 2b"
  31 #endif
  32
  33 #ifdef CONFIG_DEBUG_BUGVERBOSE
  34
  35 #define _BUG_FLAGS(ins, flags)                                          \
  36 do {                                                                    \
  37         asm volatile("1:\t" ins "\n"                                    \
  38                      ".pushsection __bug_table,\"a\"\n"                 \
  39                      "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"   \
  40                      "\t"  __BUG_REL(%c0) "\t# bug_entry::file\n"       \
  41                      "\t.word %c1"        "\t# bug_entry::line\n"       \
  42                      "\t.word %c2"        "\t# bug_entry::flags\n"      \
  43                      "\t.org 2b+%c3\n"                                  \
  44                      ".popsection"                                      \
  45                      : : "i" (__FILE__), "i" (__LINE__),                \
  46                          "i" (flags),                                   \
  47                          "i" (sizeof(struct bug_entry)));               \
  48 } while (0)
  49
  50 #else /* !CONFIG_DEBUG_BUGVERBOSE */
  51
  52 #define _BUG_FLAGS(ins, flags)                                          \
  53 do {                                                                    \
  54         asm volatile("1:\t" ins "\n"                                    \
  55                      ".pushsection __bug_table,\"a\"\n"                 \
  56                      "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"   \
  57                      "\t.word %c0"        "\t# bug_entry::flags\n"      \
  58                      "\t.org 2b+%c1\n"                                  \
  59                      ".popsection"                                      \
  60                      : : "i" (flags),                                   \
  61                          "i" (sizeof(struct bug_entry)));               \
  62 } while (0)
  63
  64 #endif /* CONFIG_DEBUG_BUGVERBOSE */
  65
  66 #else
  67
  68 #define _BUG_FLAGS(ins, flags)  asm volatile(ins)
  69
  70 #endif /* CONFIG_GENERIC_BUG */
  71
  72 #define HAVE_ARCH_BUG
  73 #define BUG()                                                   \
  74 do {                                                            \
  75         _BUG_FLAGS(ASM_UD2, 0);                                 \
  76         unreachable();                                          \
  77 } while (0)
  78
  79 #define __WARN_FLAGS(flags)     _BUG_FLAGS(ASM_UD0, BUGFLAG_WARNING|(flags))
  80
  81 #include <asm-generic/bug.h>
  82
  83 #endif /* _ASM_X86_BUG_H */