Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_OBJTOOL_H
3#define _LINUX_OBJTOOL_H
4
5#include <linux/objtool_types.h>
6#include <linux/annotate.h>
7
8#ifdef CONFIG_OBJTOOL
9
10#ifndef __ASSEMBLY__
11
12#define UNWIND_HINT(type, sp_reg, sp_offset, signal) \
13 "987: \n\t" \
14 ".pushsection .discard.unwind_hints\n\t" \
15 ANNOTATE_DATA_SPECIAL "\n\t" \
16 /* struct unwind_hint */ \
17 ".long 987b - .\n\t" \
18 ".short " __stringify(sp_offset) "\n\t" \
19 ".byte " __stringify(sp_reg) "\n\t" \
20 ".byte " __stringify(type) "\n\t" \
21 ".byte " __stringify(signal) "\n\t" \
22 ".balign 4 \n\t" \
23 ".popsection\n\t"
24
25/*
26 * This macro marks the given function's stack frame as "non-standard", which
27 * tells objtool to ignore the function when doing stack metadata validation.
28 * It should only be used in special cases where you're 100% sure it won't
29 * affect the reliability of frame pointers and kernel stack traces.
30 *
31 * For more information, see tools/objtool/Documentation/objtool.txt.
32 */
33#define STACK_FRAME_NON_STANDARD(func) \
34 static void __used __section(".discard.func_stack_frame_non_standard") \
35 *__func_stack_frame_non_standard_##func = func
36
37/*
38 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
39 * for the case where a function is intentionally missing frame pointer setup,
40 * but otherwise needs objtool/ORC coverage when frame pointers are disabled.
41 */
42#ifdef CONFIG_FRAME_POINTER
43#define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
44#else
45#define STACK_FRAME_NON_STANDARD_FP(func)
46#endif
47
48#define ASM_REACHABLE \
49 "998:\n\t" \
50 ".pushsection .discard.reachable\n\t" \
51 ".long 998b\n\t" \
52 ".popsection\n\t"
53
54#define __ASM_BREF(label) label ## b
55
56#else /* __ASSEMBLY__ */
57
58/*
59 * In asm, there are two kinds of code: normal C-type callable functions and
60 * the rest. The normal callable functions can be called by other code, and
61 * don't do anything unusual with the stack. Such normal callable functions
62 * are annotated with SYM_FUNC_{START,END}. Most asm code falls in this
63 * category. In this case, no special debugging annotations are needed because
64 * objtool can automatically generate the ORC data for the ORC unwinder to read
65 * at runtime.
66 *
67 * Anything which doesn't fall into the above category, such as syscall and
68 * interrupt handlers, tends to not be called directly by other functions, and
69 * often does unusual non-C-function-type things with the stack pointer. Such
70 * code needs to be annotated such that objtool can understand it. The
71 * following CFI hint macros are for this type of code.
72 *
73 * These macros provide hints to objtool about the state of the stack at each
74 * instruction. Objtool starts from the hints and follows the code flow,
75 * making automatic CFI adjustments when it sees pushes and pops, filling out
76 * the debuginfo as necessary. It will also warn if it sees any
77 * inconsistencies.
78 */
79.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
80.Lhere_\@:
81 .pushsection .discard.unwind_hints
82 ANNOTATE_DATA_SPECIAL
83 /* struct unwind_hint */
84 .long .Lhere_\@ - .
85 .short \sp_offset
86 .byte \sp_reg
87 .byte \type
88 .byte \signal
89 .balign 4
90 .popsection
91.endm
92
93.macro STACK_FRAME_NON_STANDARD func:req
94 .pushsection .discard.func_stack_frame_non_standard, "aw"
95 .quad \func
96 .popsection
97.endm
98
99.macro STACK_FRAME_NON_STANDARD_FP func:req
100#ifdef CONFIG_FRAME_POINTER
101 STACK_FRAME_NON_STANDARD \func
102#endif
103.endm
104
105#endif /* __ASSEMBLY__ */
106
107#else /* !CONFIG_OBJTOOL */
108
109#ifndef __ASSEMBLY__
110
111#define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t"
112#define STACK_FRAME_NON_STANDARD(func)
113#define STACK_FRAME_NON_STANDARD_FP(func)
114#else
115.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
116.endm
117.macro STACK_FRAME_NON_STANDARD func:req
118.endm
119#endif
120
121#endif /* CONFIG_OBJTOOL */
122
123#if defined(CONFIG_NOINSTR_VALIDATION) && \
124 (defined(CONFIG_MITIGATION_UNRET_ENTRY) || defined(CONFIG_MITIGATION_SRSO))
125#define VALIDATE_UNRET_BEGIN ANNOTATE_UNRET_BEGIN
126#else
127#define VALIDATE_UNRET_BEGIN
128#endif
129
130#endif /* _LINUX_OBJTOOL_H */