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
7 #ifdef CONFIG_OBJTOOL
8
9 #include <asm/asm.h>
10
11 #ifndef __ASSEMBLY__
12
13 #define UNWIND_HINT(type, sp_reg, sp_offset, signal) \
14 "987: \n\t" \
15 ".pushsection .discard.unwind_hints\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 ANNOTATE_NOENDBR \
49 "986: \n\t" \
50 ".pushsection .discard.noendbr\n\t" \
51 ".long 986b\n\t" \
52 ".popsection\n\t"
53
54 #define ASM_REACHABLE \
55 "998:\n\t" \
56 ".pushsection .discard.reachable\n\t" \
57 ".long 998b\n\t" \
58 ".popsection\n\t"
59
60 #else /* __ASSEMBLY__ */
61
62 /*
63 * This macro indicates that the following intra-function call is valid.
64 * Any non-annotated intra-function call will cause objtool to issue a warning.
65 */
66 #define ANNOTATE_INTRA_FUNCTION_CALL \
67 999: \
68 .pushsection .discard.intra_function_calls; \
69 .long 999b; \
70 .popsection;
71
72 /*
73 * In asm, there are two kinds of code: normal C-type callable functions and
74 * the rest. The normal callable functions can be called by other code, and
75 * don't do anything unusual with the stack. Such normal callable functions
76 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
77 * category. In this case, no special debugging annotations are needed because
78 * objtool can automatically generate the ORC data for the ORC unwinder to read
79 * at runtime.
80 *
81 * Anything which doesn't fall into the above category, such as syscall and
82 * interrupt handlers, tends to not be called directly by other functions, and
83 * often does unusual non-C-function-type things with the stack pointer. Such
84 * code needs to be annotated such that objtool can understand it. The
85 * following CFI hint macros are for this type of code.
86 *
87 * These macros provide hints to objtool about the state of the stack at each
88 * instruction. Objtool starts from the hints and follows the code flow,
89 * making automatic CFI adjustments when it sees pushes and pops, filling out
90 * the debuginfo as necessary. It will also warn if it sees any
91 * inconsistencies.
92 */
93 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
94 .Lhere_\@:
95 .pushsection .discard.unwind_hints
96 /* struct unwind_hint */
97 .long .Lhere_\@ - .
98 .short \sp_offset
99 .byte \sp_reg
100 .byte \type
101 .byte \signal
102 .balign 4
103 .popsection
104 .endm
105
106 .macro STACK_FRAME_NON_STANDARD func:req
107 .pushsection .discard.func_stack_frame_non_standard, "aw"
108 .long \func - .
109 .popsection
110 .endm
111
112 .macro STACK_FRAME_NON_STANDARD_FP func:req
113 #ifdef CONFIG_FRAME_POINTER
114 STACK_FRAME_NON_STANDARD \func
115 #endif
116 .endm
117
118 .macro ANNOTATE_NOENDBR
119 .Lhere_\@:
120 .pushsection .discard.noendbr
121 .long .Lhere_\@
122 .popsection
123 .endm
124
125 /*
126 * Use objtool to validate the entry requirement that all code paths do
127 * VALIDATE_UNRET_END before RET.
128 *
129 * NOTE: The macro must be used at the beginning of a global symbol, otherwise
130 * it will be ignored.
131 */
132 .macro VALIDATE_UNRET_BEGIN
133 #if defined(CONFIG_NOINSTR_VALIDATION) && \
134 (defined(CONFIG_MITIGATION_UNRET_ENTRY) || defined(CONFIG_MITIGATION_SRSO))
135 .Lhere_\@:
136 .pushsection .discard.validate_unret
137 .long .Lhere_\@ - .
138 .popsection
139 #endif
140 .endm
141
142 .macro REACHABLE
143 .Lhere_\@:
144 .pushsection .discard.reachable
145 .long .Lhere_\@
146 .popsection
147 .endm
148
149 #endif /* __ASSEMBLY__ */
150
151 #else /* !CONFIG_OBJTOOL */
152
153 #ifndef __ASSEMBLY__
154
155 #define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t"
156 #define STACK_FRAME_NON_STANDARD(func)
157 #define STACK_FRAME_NON_STANDARD_FP(func)
158 #define ANNOTATE_NOENDBR
159 #define ASM_REACHABLE
160 #else
161 #define ANNOTATE_INTRA_FUNCTION_CALL
162 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
163 .endm
164 .macro STACK_FRAME_NON_STANDARD func:req
165 .endm
166 .macro ANNOTATE_NOENDBR
167 .endm
168 .macro REACHABLE
169 .endm
170 #endif
171
172 #endif /* CONFIG_OBJTOOL */
173
174 #endif /* _LINUX_OBJTOOL_H */
175
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