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