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 * UNWIND_HINT_ENTRY: machine entry without stack, SYSCALL/SYSENTER etc.
38 #define UNWIND_HINT_TYPE_CALL 0
39 #define UNWIND_HINT_TYPE_REGS 1
40 #define UNWIND_HINT_TYPE_REGS_PARTIAL 2
41 #define UNWIND_HINT_TYPE_FUNC 3
42 #define UNWIND_HINT_TYPE_ENTRY 4
43 #define UNWIND_HINT_TYPE_SAVE 5
44 #define UNWIND_HINT_TYPE_RESTORE 6
46 #ifdef CONFIG_STACK_VALIDATION
50 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \
52 ".pushsection .discard.unwind_hints\n\t" \
53 /* struct unwind_hint */ \
54 ".long 987b - .\n\t" \
55 ".short " __stringify(sp_offset) "\n\t" \
56 ".byte " __stringify(sp_reg) "\n\t" \
57 ".byte " __stringify(type) "\n\t" \
58 ".byte " __stringify(end) "\n\t" \
63 * This macro marks the given function's stack frame as "non-standard", which
64 * tells objtool to ignore the function when doing stack metadata validation.
65 * It should only be used in special cases where you're 100% sure it won't
66 * affect the reliability of frame pointers and kernel stack traces.
68 * For more information, see tools/objtool/Documentation/stack-validation.txt.
70 #define STACK_FRAME_NON_STANDARD(func) \
71 static void __used __section(".discard.func_stack_frame_non_standard") \
72 *__func_stack_frame_non_standard_##func = func
74 #else /* __ASSEMBLY__ */
77 * This macro indicates that the following intra-function call is valid.
78 * Any non-annotated intra-function call will cause objtool to issue a warning.
80 #define ANNOTATE_INTRA_FUNCTION_CALL \
82 .pushsection .discard.intra_function_calls; \
87 * In asm, there are two kinds of code: normal C-type callable functions and
88 * the rest. The normal callable functions can be called by other code, and
89 * don't do anything unusual with the stack. Such normal callable functions
90 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
91 * category. In this case, no special debugging annotations are needed because
92 * objtool can automatically generate the ORC data for the ORC unwinder to read
95 * Anything which doesn't fall into the above category, such as syscall and
96 * interrupt handlers, tends to not be called directly by other functions, and
97 * often does unusual non-C-function-type things with the stack pointer. Such
98 * code needs to be annotated such that objtool can understand it. The
99 * following CFI hint macros are for this type of code.
101 * These macros provide hints to objtool about the state of the stack at each
102 * instruction. Objtool starts from the hints and follows the code flow,
103 * making automatic CFI adjustments when it sees pushes and pops, filling out
104 * the debuginfo as necessary. It will also warn if it sees any
107 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
109 .pushsection .discard.unwind_hints
110 /* struct unwind_hint */
111 .long .Lunwind_hint_ip_\@ - .
120 .macro STACK_FRAME_NON_STANDARD func:req
121 .pushsection .discard.func_stack_frame_non_standard, "aw"
126 #endif /* __ASSEMBLY__ */
128 #else /* !CONFIG_STACK_VALIDATION */
132 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \
134 #define STACK_FRAME_NON_STANDARD(func)
136 #define ANNOTATE_INTRA_FUNCTION_CALL
137 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
139 .macro STACK_FRAME_NON_STANDARD func:req
143 #endif /* CONFIG_STACK_VALIDATION */
145 #endif /* _LINUX_OBJTOOL_H */