1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_LINKAGE_H
3 #define _ASM_X86_LINKAGE_H
4
5 #include <linux/stringify.h>
6 #include <asm/ibt.h>
7
8 #undef notrace
9 #define notrace __attribute__((no_instrument_function))
10
11 #ifdef CONFIG_64BIT
12 /*
13 * The generic version tends to create spurious ENDBR instructions under
14 * certain conditions.
15 */
16 #define _THIS_IP_ ({ unsigned long __here; asm ("lea 0(%%rip), %0" : "=r" (__here)); __here; })
17 #endif
18
19 #ifdef CONFIG_X86_32
20 #define asmlinkage CPP_ASMLINKAGE __attribute__((regparm(0)))
21 #endif /* CONFIG_X86_32 */
22
23 #define __ALIGN .balign CONFIG_FUNCTION_ALIGNMENT, 0x90;
24 #define __ALIGN_STR __stringify(__ALIGN)
25
26 #if defined(CONFIG_CALL_PADDING) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
27 #define FUNCTION_PADDING .skip CONFIG_FUNCTION_ALIGNMENT, 0x90;
28 #else
29 #define FUNCTION_PADDING
30 #endif
31
32 #if (CONFIG_FUNCTION_ALIGNMENT > 8) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
33 # define __FUNC_ALIGN __ALIGN; FUNCTION_PADDING
34 #else
35 # define __FUNC_ALIGN __ALIGN
36 #endif
37
38 #define ASM_FUNC_ALIGN __stringify(__FUNC_ALIGN)
39 #define SYM_F_ALIGN __FUNC_ALIGN
40
41 #ifdef __ASSEMBLY__
42
43 #if defined(CONFIG_MITIGATION_RETHUNK) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
44 #define RET jmp __x86_return_thunk
45 #else /* CONFIG_MITIGATION_RETPOLINE */
46 #ifdef CONFIG_MITIGATION_SLS
47 #define RET ret; int3
48 #else
49 #define RET ret
50 #endif
51 #endif /* CONFIG_MITIGATION_RETPOLINE */
52
53 #else /* __ASSEMBLY__ */
54
55 #if defined(CONFIG_MITIGATION_RETHUNK) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
56 #define ASM_RET "jmp __x86_return_thunk\n\t"
57 #else /* CONFIG_MITIGATION_RETPOLINE */
58 #ifdef CONFIG_MITIGATION_SLS
59 #define ASM_RET "ret; int3\n\t"
60 #else
61 #define ASM_RET "ret\n\t"
62 #endif
63 #endif /* CONFIG_MITIGATION_RETPOLINE */
64
65 #endif /* __ASSEMBLY__ */
66
67 /*
68 * Depending on -fpatchable-function-entry=N,N usage (CONFIG_CALL_PADDING) the
69 * CFI symbol layout changes.
70 *
71 * Without CALL_THUNKS:
72 *
73 * .align FUNCTION_ALIGNMENT
74 * __cfi_##name:
75 * .skip FUNCTION_PADDING, 0x90
76 * .byte 0xb8
77 * .long __kcfi_typeid_##name
78 * name:
79 *
80 * With CALL_THUNKS:
81 *
82 * .align FUNCTION_ALIGNMENT
83 * __cfi_##name:
84 * .byte 0xb8
85 * .long __kcfi_typeid_##name
86 * .skip FUNCTION_PADDING, 0x90
87 * name:
88 *
89 * In both cases the whole thing is FUNCTION_ALIGNMENT aligned and sized.
90 */
91
92 #ifdef CONFIG_CALL_PADDING
93 #define CFI_PRE_PADDING
94 #define CFI_POST_PADDING .skip CONFIG_FUNCTION_PADDING_BYTES, 0x90;
95 #else
96 #define CFI_PRE_PADDING .skip CONFIG_FUNCTION_PADDING_BYTES, 0x90;
97 #define CFI_POST_PADDING
98 #endif
99
100 #define __CFI_TYPE(name) \
101 SYM_START(__cfi_##name, SYM_L_LOCAL, SYM_A_NONE) \
102 CFI_PRE_PADDING \
103 .byte 0xb8 ASM_NL \
104 .long __kcfi_typeid_##name ASM_NL \
105 CFI_POST_PADDING \
106 SYM_FUNC_END(__cfi_##name)
107
108 /* UML needs to be able to override memcpy() and friends for KASAN. */
109 #ifdef CONFIG_UML
110 # define SYM_FUNC_ALIAS_MEMFUNC SYM_FUNC_ALIAS_WEAK
111 #else
112 # define SYM_FUNC_ALIAS_MEMFUNC SYM_FUNC_ALIAS
113 #endif
114
115 /* SYM_TYPED_FUNC_START -- use for indirectly called globals, w/ CFI type */
116 #define SYM_TYPED_FUNC_START(name) \
117 SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_F_ALIGN) \
118 ENDBR
119
120 /* SYM_FUNC_START -- use for global functions */
121 #define SYM_FUNC_START(name) \
122 SYM_START(name, SYM_L_GLOBAL, SYM_F_ALIGN) \
123 ENDBR
124
125 /* SYM_FUNC_START_NOALIGN -- use for global functions, w/o alignment */
126 #define SYM_FUNC_START_NOALIGN(name) \
127 SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE) \
128 ENDBR
129
130 /* SYM_FUNC_START_LOCAL -- use for local functions */
131 #define SYM_FUNC_START_LOCAL(name) \
132 SYM_START(name, SYM_L_LOCAL, SYM_F_ALIGN) \
133 ENDBR
134
135 /* SYM_FUNC_START_LOCAL_NOALIGN -- use for local functions, w/o alignment */
136 #define SYM_FUNC_START_LOCAL_NOALIGN(name) \
137 SYM_START(name, SYM_L_LOCAL, SYM_A_NONE) \
138 ENDBR
139
140 /* SYM_FUNC_START_WEAK -- use for weak functions */
141 #define SYM_FUNC_START_WEAK(name) \
142 SYM_START(name, SYM_L_WEAK, SYM_F_ALIGN) \
143 ENDBR
144
145 /* SYM_FUNC_START_WEAK_NOALIGN -- use for weak functions, w/o alignment */
146 #define SYM_FUNC_START_WEAK_NOALIGN(name) \
147 SYM_START(name, SYM_L_WEAK, SYM_A_NONE) \
148 ENDBR
149
150 #endif /* _ASM_X86_LINKAGE_H */
151
152
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