1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_FRAME_H
3 #define _ASM_X86_FRAME_H
4
5 #include <asm/asm.h>
6
7 /*
8 * These are stack frame creation macros. They should be used by every
9 * callable non-leaf asm function to make kernel stack traces more reliable.
10 */
11
12 #ifdef CONFIG_FRAME_POINTER
13
14 #ifdef __ASSEMBLY__
15
16 .macro FRAME_BEGIN
17 push %_ASM_BP
18 _ASM_MOV %_ASM_SP, %_ASM_BP
19 .endm
20
21 .macro FRAME_END
22 pop %_ASM_BP
23 .endm
24
25 #ifdef CONFIG_X86_64
26 /*
27 * This is a sneaky trick to help the unwinder find pt_regs on the stack. The
28 * frame pointer is replaced with an encoded pointer to pt_regs. The encoding
29 * is just setting the LSB, which makes it an invalid stack address and is also
30 * a signal to the unwinder that it's a pt_regs pointer in disguise.
31 *
32 * NOTE: This macro must be used *after* PUSH_AND_CLEAR_REGS because it corrupts
33 * the original rbp.
34 */
35 .macro ENCODE_FRAME_POINTER ptregs_offset=0
36 leaq 1+\ptregs_offset(%rsp), %rbp
37 .endm
38 #else /* !CONFIG_X86_64 */
39 /*
40 * This is a sneaky trick to help the unwinder find pt_regs on the stack. The
41 * frame pointer is replaced with an encoded pointer to pt_regs. The encoding
42 * is just clearing the MSB, which makes it an invalid stack address and is also
43 * a signal to the unwinder that it's a pt_regs pointer in disguise.
44 *
45 * NOTE: This macro must be used *after* SAVE_ALL because it corrupts the
46 * original ebp.
47 */
48 .macro ENCODE_FRAME_POINTER
49 mov %esp, %ebp
50 andl $0x7fffffff, %ebp
51 .endm
52 #endif /* CONFIG_X86_64 */
53
54 #else /* !__ASSEMBLY__ */
55
56 #define FRAME_BEGIN \
57 "push %" _ASM_BP "\n" \
58 _ASM_MOV "%" _ASM_SP ", %" _ASM_BP "\n"
59
60 #define FRAME_END "pop %" _ASM_BP "\n"
61
62 #ifdef CONFIG_X86_64
63
64 #define ENCODE_FRAME_POINTER \
65 "lea 1(%rsp), %rbp\n\t"
66
67 static inline unsigned long encode_frame_pointer(struct pt_regs *regs)
68 {
69 return (unsigned long)regs + 1;
70 }
71
72 #else /* !CONFIG_X86_64 */
73
74 #define ENCODE_FRAME_POINTER \
75 "movl %esp, %ebp\n\t" \
76 "andl $0x7fffffff, %ebp\n\t"
77
78 static inline unsigned long encode_frame_pointer(struct pt_regs *regs)
79 {
80 return (unsigned long)regs & 0x7fffffff;
81 }
82
83 #endif /* CONFIG_X86_64 */
84
85 #endif /* __ASSEMBLY__ */
86
87 #define FRAME_OFFSET __ASM_SEL(4, 8)
88
89 #else /* !CONFIG_FRAME_POINTER */
90
91 #ifdef __ASSEMBLY__
92
93 .macro ENCODE_FRAME_POINTER ptregs_offset=0
94 .endm
95
96 #else /* !__ASSEMBLY */
97
98 #define ENCODE_FRAME_POINTER
99
100 static inline unsigned long encode_frame_pointer(struct pt_regs *regs)
101 {
102 return 0;
103 }
104
105 #endif
106
107 #define FRAME_BEGIN
108 #define FRAME_END
109 #define FRAME_OFFSET 0
110
111 #endif /* CONFIG_FRAME_POINTER */
112
113 #endif /* _ASM_X86_FRAME_H */
114
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