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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_OBJTOOL_H
3#define _LINUX_OBJTOOL_H
4
5#ifndef __ASSEMBLY__
6
7#include <linux/types.h>
8
9/*
10 * This struct is used by asm and inline asm code to manually annotate the
11 * location of registers on the stack.
12 */
13struct unwind_hint {
14 u32 ip;
15 s16 sp_offset;
16 u8 sp_reg;
17 u8 type;
18 u8 signal;
19 u8 end;
20};
21#endif
22
23/*
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.
27 *
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.
30 *
31 * UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
32 * sp_reg+sp_offset points to the iret return frame.
33 *
34 * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
35 * Useful for code which doesn't have an ELF function annotation.
36 *
37 * UNWIND_HINT_ENTRY: machine entry without stack, SYSCALL/SYSENTER etc.
38 */
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
46
47#ifdef CONFIG_OBJTOOL
48
49#include <asm/asm.h>
50
51#ifndef __ASSEMBLY__
52
53#define UNWIND_HINT(sp_reg, sp_offset, type, signal, end) \
54 "987: \n\t" \
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" \
63 ".balign 4 \n\t" \
64 ".popsection\n\t"
65
66/*
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.
71 *
72 * For more information, see tools/objtool/Documentation/objtool.txt.
73 */
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
77
78/*
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.
82 */
83#ifdef CONFIG_FRAME_POINTER
84#define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
85#else
86#define STACK_FRAME_NON_STANDARD_FP(func)
87#endif
88
89#define ANNOTATE_NOENDBR \
90 "986: \n\t" \
91 ".pushsection .discard.noendbr\n\t" \
92 _ASM_PTR " 986b\n\t" \
93 ".popsection\n\t"
94
95#define ASM_REACHABLE \
96 "998:\n\t" \
97 ".pushsection .discard.reachable\n\t" \
98 ".long 998b - .\n\t" \
99 ".popsection\n\t"
100
101#else /* __ASSEMBLY__ */
102
103/*
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.
106 */
107#define ANNOTATE_INTRA_FUNCTION_CALL \
108 999: \
109 .pushsection .discard.intra_function_calls; \
110 .long 999b; \
111 .popsection;
112
113/*
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
120 * at runtime.
121 *
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.
127 *
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
132 * inconsistencies.
133 */
134.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
135.Lunwind_hint_ip_\@:
136 .pushsection .discard.unwind_hints
137 /* struct unwind_hint */
138 .long .Lunwind_hint_ip_\@ - .
139 .short \sp_offset
140 .byte \sp_reg
141 .byte \type
142 .byte \signal
143 .byte \end
144 .balign 4
145 .popsection
146.endm
147
148.macro STACK_FRAME_NON_STANDARD func:req
149 .pushsection .discard.func_stack_frame_non_standard, "aw"
150 _ASM_PTR \func
151 .popsection
152.endm
153
154.macro STACK_FRAME_NON_STANDARD_FP func:req
155#ifdef CONFIG_FRAME_POINTER
156 STACK_FRAME_NON_STANDARD \func
157#endif
158.endm
159
160.macro ANNOTATE_NOENDBR
161.Lhere_\@:
162 .pushsection .discard.noendbr
163 .quad .Lhere_\@
164 .popsection
165.endm
166
167.macro REACHABLE
168.Lhere_\@:
169 .pushsection .discard.reachable
170 .long .Lhere_\@ - .
171 .popsection
172.endm
173
174#endif /* __ASSEMBLY__ */
175
176#else /* !CONFIG_OBJTOOL */
177
178#ifndef __ASSEMBLY__
179
180#define UNWIND_HINT(sp_reg, sp_offset, type, signal, end) \
181 "\n\t"
182#define STACK_FRAME_NON_STANDARD(func)
183#define STACK_FRAME_NON_STANDARD_FP(func)
184#define ANNOTATE_NOENDBR
185#define ASM_REACHABLE
186#else
187#define ANNOTATE_INTRA_FUNCTION_CALL
188.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
189.endm
190.macro STACK_FRAME_NON_STANDARD func:req
191.endm
192.macro ANNOTATE_NOENDBR
193.endm
194.macro REACHABLE
195.endm
196#endif
197
198#endif /* CONFIG_OBJTOOL */
199
200#endif /* _LINUX_OBJTOOL_H */