Linux kernel mirror (for testing)
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linux
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) \
37do { \
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) \
54do { \
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() \
75do { \
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 */