arch/x86/include/asm/bug.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_BUG_H
   3 #define _ASM_X86_BUG_H
   4
   5 #include <linux/stringify.h>
   6
   7 /*
   8  * Since some emulators terminate on UD2, we cannot use it for WARN.
   9  * Since various instruction decoders disagree on the length of UD1,
  10  * we cannot use it either. So use UD0 for WARN.
  11  *
  12  * (binutils knows about "ud1" but {en,de}codes it as 2 bytes, whereas
  13  *  our kernel decoder thinks it takes a ModRM byte, which seems consistent
  14  *  with various things like the Intel SDM instruction encoding rules)
  15  */
  16
  17 #define ASM_UD0         ".byte 0x0f, 0xff"
  18 #define ASM_UD1         ".byte 0x0f, 0xb9" /* + ModRM */
  19 #define ASM_UD2         ".byte 0x0f, 0x0b"
  20
  21 #define INSN_UD0        0xff0f
  22 #define INSN_UD2        0x0b0f
  23
  24 #define LEN_UD0         2
  25
  26 #ifdef CONFIG_GENERIC_BUG
  27
  28 #ifdef CONFIG_X86_32
  29 # define __BUG_REL(val) ".long " __stringify(val)
  30 #else
  31 # define __BUG_REL(val) ".long " __stringify(val) " - 2b"
  32 #endif
  33
  34 #ifdef CONFIG_DEBUG_BUGVERBOSE
  35
  36 #define _BUG_FLAGS(ins, flags)                                          \
  37 do {                                                                    \
  38         asm volatile("1:\t" ins "\n"                                    \
  39                      ".pushsection __bug_table,\"aw\"\n"                \
  40                      "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"   \
  41                      "\t"  __BUG_REL(%c0) "\t# bug_entry::file\n"       \
  42                      "\t.word %c1"        "\t# bug_entry::line\n"       \
  43                      "\t.word %c2"        "\t# bug_entry::flags\n"      \
  44                      "\t.org 2b+%c3\n"                                  \
  45                      ".popsection"                                      \
  46                      : : "i" (__FILE__), "i" (__LINE__),                \
  47                          "i" (flags),                                   \
  48                          "i" (sizeof(struct bug_entry)));               \
  49 } while (0)
  50
  51 #else /* !CONFIG_DEBUG_BUGVERBOSE */
  52
  53 #define _BUG_FLAGS(ins, flags)                                          \
  54 do {                                                                    \
  55         asm volatile("1:\t" ins "\n"                                    \
  56                      ".pushsection __bug_table,\"aw\"\n"                \
  57                      "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"   \
  58                      "\t.word %c0"        "\t# bug_entry::flags\n"      \
  59                      "\t.org 2b+%c1\n"                                  \
  60                      ".popsection"                                      \
  61                      : : "i" (flags),                                   \
  62                          "i" (sizeof(struct bug_entry)));               \
  63 } while (0)
  64
  65 #endif /* CONFIG_DEBUG_BUGVERBOSE */
  66
  67 #else
  68
  69 #define _BUG_FLAGS(ins, flags)  asm volatile(ins)
  70
  71 #endif /* CONFIG_GENERIC_BUG */
  72
  73 #define HAVE_ARCH_BUG
  74 #define BUG()                                                   \
  75 do {                                                            \
  76         _BUG_FLAGS(ASM_UD2, 0);                                 \
  77         unreachable();                                          \
  78 } while (0)
  79
  80 #define __WARN_FLAGS(flags)     _BUG_FLAGS(ASM_UD0, BUGFLAG_WARNING|(flags))
  81
  82 #include <asm-generic/bug.h>
  83
  84 #endif /* _ASM_X86_BUG_H */