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.
24 * UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
25 * (the caller's SP right before it made the call). Used for all callable
26 * functions, i.e. all C code and all callable asm functions.
28 * UNWIND_HINT_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset
29 * points to a fully populated pt_regs from a syscall, interrupt, or exception.
31 * UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
32 * sp_reg+sp_offset points to the iret return frame.
34 * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
35 * Useful for code which doesn't have an ELF function annotation.
37 * UNWIND_HINT_ENTRY: machine entry without stack, SYSCALL/SYSENTER etc.
39 #define UNWIND_HINT_TYPE_CALL 0
40 #define UNWIND_HINT_TYPE_REGS 1
41 #define UNWIND_HINT_TYPE_REGS_PARTIAL 2
42 #define UNWIND_HINT_TYPE_FUNC 3
43 #define UNWIND_HINT_TYPE_ENTRY 4
44 #define UNWIND_HINT_TYPE_SAVE 5
45 #define UNWIND_HINT_TYPE_RESTORE 6
53 #define UNWIND_HINT(sp_reg, sp_offset, type, signal, end) \
55 ".pushsection .discard.unwind_hints\n\t" \
56 /* struct unwind_hint */ \
57 ".long 987b - .\n\t" \
58 ".short " __stringify(sp_offset) "\n\t" \
59 ".byte " __stringify(sp_reg) "\n\t" \
60 ".byte " __stringify(type) "\n\t" \
61 ".byte " __stringify(signal) "\n\t" \
62 ".byte " __stringify(end) "\n\t" \
67 * This macro marks the given function's stack frame as "non-standard", which
68 * tells objtool to ignore the function when doing stack metadata validation.
69 * It should only be used in special cases where you're 100% sure it won't
70 * affect the reliability of frame pointers and kernel stack traces.
72 * For more information, see tools/objtool/Documentation/objtool.txt.
74 #define STACK_FRAME_NON_STANDARD(func) \
75 static void __used __section(".discard.func_stack_frame_non_standard") \
76 *__func_stack_frame_non_standard_##func = func
79 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
80 * for the case where a function is intentionally missing frame pointer setup,
81 * but otherwise needs objtool/ORC coverage when frame pointers are disabled.
83 #ifdef CONFIG_FRAME_POINTER
84 #define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
86 #define STACK_FRAME_NON_STANDARD_FP(func)
89 #define ANNOTATE_NOENDBR \
91 ".pushsection .discard.noendbr\n\t" \
92 _ASM_PTR " 986b\n\t" \
95 #define ASM_REACHABLE \
97 ".pushsection .discard.reachable\n\t" \
98 ".long 998b - .\n\t" \
101 #else /* __ASSEMBLY__ */
104 * This macro indicates that the following intra-function call is valid.
105 * Any non-annotated intra-function call will cause objtool to issue a warning.
107 #define ANNOTATE_INTRA_FUNCTION_CALL \
109 .pushsection .discard.intra_function_calls; \
114 * In asm, there are two kinds of code: normal C-type callable functions and
115 * the rest. The normal callable functions can be called by other code, and
116 * don't do anything unusual with the stack. Such normal callable functions
117 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
118 * category. In this case, no special debugging annotations are needed because
119 * objtool can automatically generate the ORC data for the ORC unwinder to read
122 * Anything which doesn't fall into the above category, such as syscall and
123 * interrupt handlers, tends to not be called directly by other functions, and
124 * often does unusual non-C-function-type things with the stack pointer. Such
125 * code needs to be annotated such that objtool can understand it. The
126 * following CFI hint macros are for this type of code.
128 * These macros provide hints to objtool about the state of the stack at each
129 * instruction. Objtool starts from the hints and follows the code flow,
130 * making automatic CFI adjustments when it sees pushes and pops, filling out
131 * the debuginfo as necessary. It will also warn if it sees any
134 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
136 .pushsection .discard.unwind_hints
137 /* struct unwind_hint */
138 .long .Lunwind_hint_ip_\@ - .
148 .macro STACK_FRAME_NON_STANDARD func:req
149 .pushsection .discard.func_stack_frame_non_standard, "aw"
154 .macro STACK_FRAME_NON_STANDARD_FP func:req
155 #ifdef CONFIG_FRAME_POINTER
156 STACK_FRAME_NON_STANDARD \func
160 .macro ANNOTATE_NOENDBR
162 .pushsection .discard.noendbr
169 .pushsection .discard.reachable
174 #endif /* __ASSEMBLY__ */
176 #else /* !CONFIG_OBJTOOL */
180 #define UNWIND_HINT(sp_reg, sp_offset, type, signal, end) \
182 #define STACK_FRAME_NON_STANDARD(func)
183 #define STACK_FRAME_NON_STANDARD_FP(func)
184 #define ANNOTATE_NOENDBR
185 #define ASM_REACHABLE
187 #define ANNOTATE_INTRA_FUNCTION_CALL
188 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
190 .macro STACK_FRAME_NON_STANDARD func:req
192 .macro ANNOTATE_NOENDBR
198 #endif /* CONFIG_OBJTOOL */
200 #endif /* _LINUX_OBJTOOL_H */