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 #include <linux/instrumentation.h>
   7
   8 /*
   9  * Despite that some emulators terminate on UD2, we use it for WARN().
  10  *
  11  * Since various instruction decoders/specs disagree on the encoding of
  12  * UD0/UD1.
  13  */
  14
  15 #define ASM_UD0         ".byte 0x0f, 0xff" /* + ModRM (for Intel) */
  16 #define ASM_UD1         ".byte 0x0f, 0xb9" /* + ModRM */
  17 #define ASM_UD2         ".byte 0x0f, 0x0b"
  18
  19 #define INSN_UD0        0xff0f
  20 #define INSN_UD2        0x0b0f
  21
  22 #define LEN_UD2         2
  23
  24 #ifdef CONFIG_GENERIC_BUG
  25
  26 #ifdef CONFIG_X86_32
  27 # define __BUG_REL(val) ".long " __stringify(val)
  28 #else
  29 # define __BUG_REL(val) ".long " __stringify(val) " - 2b"
  30 #endif
  31
  32 #ifdef CONFIG_DEBUG_BUGVERBOSE
  33
  34 #define _BUG_FLAGS(ins, flags)                                          \
  35 do {                                                                    \
  36         asm_inline volatile("1:\t" ins "\n"                             \
  37                      ".pushsection __bug_table,\"aw\"\n"                \
  38                      "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"   \
  39                      "\t"  __BUG_REL(%c0) "\t# bug_entry::file\n"       \
  40                      "\t.word %c1"        "\t# bug_entry::line\n"       \
  41                      "\t.word %c2"        "\t# bug_entry::flags\n"      \
  42                      "\t.org 2b+%c3\n"                                  \
  43                      ".popsection"                                      \
  44                      : : "i" (__FILE__), "i" (__LINE__),                \
  45                          "i" (flags),                                   \
  46                          "i" (sizeof(struct bug_entry)));               \
  47 } while (0)
  48
  49 #else /* !CONFIG_DEBUG_BUGVERBOSE */
  50
  51 #define _BUG_FLAGS(ins, flags)                                          \
  52 do {                                                                    \
  53         asm_inline volatile("1:\t" ins "\n"                             \
  54                      ".pushsection __bug_table,\"aw\"\n"                \
  55                      "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"   \
  56                      "\t.word %c0"        "\t# bug_entry::flags\n"      \
  57                      "\t.org 2b+%c1\n"                                  \
  58                      ".popsection"                                      \
  59                      : : "i" (flags),                                   \
  60                          "i" (sizeof(struct bug_entry)));               \
  61 } while (0)
  62
  63 #endif /* CONFIG_DEBUG_BUGVERBOSE */
  64
  65 #else
  66
  67 #define _BUG_FLAGS(ins, flags)  asm volatile(ins)
  68
  69 #endif /* CONFIG_GENERIC_BUG */
  70
  71 #define HAVE_ARCH_BUG
  72 #define BUG()                                                   \
  73 do {                                                            \
  74         instrumentation_begin();                                \
  75         _BUG_FLAGS(ASM_UD2, 0);                                 \
  76         unreachable();                                          \
  77 } while (0)
  78
  79 /*
  80  * This instrumentation_begin() is strictly speaking incorrect; but it
  81  * suppresses the complaints from WARN()s in noinstr code. If such a WARN()
  82  * were to trigger, we'd rather wreck the machine in an attempt to get the
  83  * message out than not know about it.
  84  */
  85 #define __WARN_FLAGS(flags)                                     \
  86 do {                                                            \
  87         instrumentation_begin();                                \
  88         _BUG_FLAGS(ASM_UD2, BUGFLAG_WARNING|(flags));           \
  89         annotate_reachable();                                   \
  90         instrumentation_end();                                  \
  91 } while (0)
  92
  93 #include <asm-generic/bug.h>
  94
  95 #endif /* _ASM_X86_BUG_H */