Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 end;
19};
20#endif
21
22/*
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.
26 *
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.
29 *
30 * UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
31 * sp_reg+sp_offset points to the iret return frame.
32 *
33 * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
34 * Useful for code which doesn't have an ELF function annotation.
35 *
36 * UNWIND_HINT_ENTRY: machine entry without stack, SYSCALL/SYSENTER etc.
37 */
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
45
46#ifdef CONFIG_OBJTOOL
47
48#include <asm/asm.h>
49
50#ifndef __ASSEMBLY__
51
52#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
53 "987: \n\t" \
54 ".pushsection .discard.unwind_hints\n\t" \
55 /* struct unwind_hint */ \
56 ".long 987b - .\n\t" \
57 ".short " __stringify(sp_offset) "\n\t" \
58 ".byte " __stringify(sp_reg) "\n\t" \
59 ".byte " __stringify(type) "\n\t" \
60 ".byte " __stringify(end) "\n\t" \
61 ".balign 4 \n\t" \
62 ".popsection\n\t"
63
64/*
65 * This macro marks the given function's stack frame as "non-standard", which
66 * tells objtool to ignore the function when doing stack metadata validation.
67 * It should only be used in special cases where you're 100% sure it won't
68 * affect the reliability of frame pointers and kernel stack traces.
69 *
70 * For more information, see tools/objtool/Documentation/objtool.txt.
71 */
72#define STACK_FRAME_NON_STANDARD(func) \
73 static void __used __section(".discard.func_stack_frame_non_standard") \
74 *__func_stack_frame_non_standard_##func = func
75
76/*
77 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
78 * for the case where a function is intentionally missing frame pointer setup,
79 * but otherwise needs objtool/ORC coverage when frame pointers are disabled.
80 */
81#ifdef CONFIG_FRAME_POINTER
82#define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
83#else
84#define STACK_FRAME_NON_STANDARD_FP(func)
85#endif
86
87#define ANNOTATE_NOENDBR \
88 "986: \n\t" \
89 ".pushsection .discard.noendbr\n\t" \
90 _ASM_PTR " 986b\n\t" \
91 ".popsection\n\t"
92
93#define ASM_REACHABLE \
94 "998:\n\t" \
95 ".pushsection .discard.reachable\n\t" \
96 ".long 998b - .\n\t" \
97 ".popsection\n\t"
98
99#else /* __ASSEMBLY__ */
100
101/*
102 * This macro indicates that the following intra-function call is valid.
103 * Any non-annotated intra-function call will cause objtool to issue a warning.
104 */
105#define ANNOTATE_INTRA_FUNCTION_CALL \
106 999: \
107 .pushsection .discard.intra_function_calls; \
108 .long 999b; \
109 .popsection;
110
111/*
112 * In asm, there are two kinds of code: normal C-type callable functions and
113 * the rest. The normal callable functions can be called by other code, and
114 * don't do anything unusual with the stack. Such normal callable functions
115 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
116 * category. In this case, no special debugging annotations are needed because
117 * objtool can automatically generate the ORC data for the ORC unwinder to read
118 * at runtime.
119 *
120 * Anything which doesn't fall into the above category, such as syscall and
121 * interrupt handlers, tends to not be called directly by other functions, and
122 * often does unusual non-C-function-type things with the stack pointer. Such
123 * code needs to be annotated such that objtool can understand it. The
124 * following CFI hint macros are for this type of code.
125 *
126 * These macros provide hints to objtool about the state of the stack at each
127 * instruction. Objtool starts from the hints and follows the code flow,
128 * making automatic CFI adjustments when it sees pushes and pops, filling out
129 * the debuginfo as necessary. It will also warn if it sees any
130 * inconsistencies.
131 */
132.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
133.Lunwind_hint_ip_\@:
134 .pushsection .discard.unwind_hints
135 /* struct unwind_hint */
136 .long .Lunwind_hint_ip_\@ - .
137 .short \sp_offset
138 .byte \sp_reg
139 .byte \type
140 .byte \end
141 .balign 4
142 .popsection
143.endm
144
145.macro STACK_FRAME_NON_STANDARD func:req
146 .pushsection .discard.func_stack_frame_non_standard, "aw"
147 _ASM_PTR \func
148 .popsection
149.endm
150
151.macro STACK_FRAME_NON_STANDARD_FP func:req
152#ifdef CONFIG_FRAME_POINTER
153 STACK_FRAME_NON_STANDARD \func
154#endif
155.endm
156
157.macro ANNOTATE_NOENDBR
158.Lhere_\@:
159 .pushsection .discard.noendbr
160 .quad .Lhere_\@
161 .popsection
162.endm
163
164.macro REACHABLE
165.Lhere_\@:
166 .pushsection .discard.reachable
167 .long .Lhere_\@ - .
168 .popsection
169.endm
170
171#endif /* __ASSEMBLY__ */
172
173#else /* !CONFIG_OBJTOOL */
174
175#ifndef __ASSEMBLY__
176
177#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
178 "\n\t"
179#define STACK_FRAME_NON_STANDARD(func)
180#define STACK_FRAME_NON_STANDARD_FP(func)
181#define ANNOTATE_NOENDBR
182#define ASM_REACHABLE
183#else
184#define ANNOTATE_INTRA_FUNCTION_CALL
185.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
186.endm
187.macro STACK_FRAME_NON_STANDARD func:req
188.endm
189.macro ANNOTATE_NOENDBR
190.endm
191.macro REACHABLE
192.endm
193#endif
194
195#endif /* CONFIG_OBJTOOL */
196
197#endif /* _LINUX_OBJTOOL_H */