1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_OBJTOOL_H
3 #define _LINUX_OBJTOOL_H
7 #include <linux/types.h>
10 * This struct is used by asm and inline asm code to manually annotate the
11 * location of registers on the stack.
23 * UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
24 * (the caller's SP right before it made the call). Used for all callable
25 * functions, i.e. all C code and all callable asm functions.
27 * UNWIND_HINT_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset
28 * points to a fully populated pt_regs from a syscall, interrupt, or exception.
30 * UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
31 * sp_reg+sp_offset points to the iret return frame.
33 * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
34 * Useful for code which doesn't have an ELF function annotation.
36 #define UNWIND_HINT_TYPE_CALL 0
37 #define UNWIND_HINT_TYPE_REGS 1
38 #define UNWIND_HINT_TYPE_REGS_PARTIAL 2
39 #define UNWIND_HINT_TYPE_FUNC 3
47 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \
49 ".pushsection .discard.unwind_hints\n\t" \
50 /* struct unwind_hint */ \
51 ".long 987b - .\n\t" \
52 ".short " __stringify(sp_offset) "\n\t" \
53 ".byte " __stringify(sp_reg) "\n\t" \
54 ".byte " __stringify(type) "\n\t" \
55 ".byte " __stringify(end) "\n\t" \
60 * This macro marks the given function's stack frame as "non-standard", which
61 * tells objtool to ignore the function when doing stack metadata validation.
62 * It should only be used in special cases where you're 100% sure it won't
63 * affect the reliability of frame pointers and kernel stack traces.
65 * For more information, see tools/objtool/Documentation/stack-validation.txt.
67 #define STACK_FRAME_NON_STANDARD(func) \
68 static void __used __section(".discard.func_stack_frame_non_standard") \
69 *__func_stack_frame_non_standard_##func = func
72 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
73 * for the case where a function is intentionally missing frame pointer setup,
74 * but otherwise needs objtool/ORC coverage when frame pointers are disabled.
76 #ifdef CONFIG_FRAME_POINTER
77 #define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
79 #define STACK_FRAME_NON_STANDARD_FP(func)
82 #define ANNOTATE_NOENDBR \
84 ".pushsection .discard.noendbr\n\t" \
85 _ASM_PTR " 986b\n\t" \
88 #define ASM_REACHABLE \
90 ".pushsection .discard.reachable\n\t" \
91 ".long 998b - .\n\t" \
94 #else /* __ASSEMBLY__ */
97 * This macro indicates that the following intra-function call is valid.
98 * Any non-annotated intra-function call will cause objtool to issue a warning.
100 #define ANNOTATE_INTRA_FUNCTION_CALL \
102 .pushsection .discard.intra_function_calls; \
107 * In asm, there are two kinds of code: normal C-type callable functions and
108 * the rest. The normal callable functions can be called by other code, and
109 * don't do anything unusual with the stack. Such normal callable functions
110 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
111 * category. In this case, no special debugging annotations are needed because
112 * objtool can automatically generate the ORC data for the ORC unwinder to read
115 * Anything which doesn't fall into the above category, such as syscall and
116 * interrupt handlers, tends to not be called directly by other functions, and
117 * often does unusual non-C-function-type things with the stack pointer. Such
118 * code needs to be annotated such that objtool can understand it. The
119 * following CFI hint macros are for this type of code.
121 * These macros provide hints to objtool about the state of the stack at each
122 * instruction. Objtool starts from the hints and follows the code flow,
123 * making automatic CFI adjustments when it sees pushes and pops, filling out
124 * the debuginfo as necessary. It will also warn if it sees any
127 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
129 .pushsection .discard.unwind_hints
130 /* struct unwind_hint */
131 .long .Lunwind_hint_ip_\@ - .
140 .macro STACK_FRAME_NON_STANDARD func:req
141 .pushsection .discard.func_stack_frame_non_standard, "aw"
146 .macro STACK_FRAME_NON_STANDARD_FP func:req
147 #ifdef CONFIG_FRAME_POINTER
148 STACK_FRAME_NON_STANDARD \func
152 .macro ANNOTATE_NOENDBR
154 .pushsection .discard.noendbr
161 .pushsection .discard.reachable
166 #endif /* __ASSEMBLY__ */
168 #else /* !CONFIG_OBJTOOL */
172 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \
174 #define STACK_FRAME_NON_STANDARD(func)
175 #define STACK_FRAME_NON_STANDARD_FP(func)
176 #define ANNOTATE_NOENDBR
177 #define ASM_REACHABLE
179 #define ANNOTATE_INTRA_FUNCTION_CALL
180 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
182 .macro STACK_FRAME_NON_STANDARD func:req
184 .macro ANNOTATE_NOENDBR
190 #endif /* CONFIG_OBJTOOL */
192 #endif /* _LINUX_OBJTOOL_H */