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_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_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