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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Clang Control Flow Integrity (CFI) type definitions.
4 */
5#ifndef _LINUX_CFI_TYPES_H
6#define _LINUX_CFI_TYPES_H
7
8#ifdef __ASSEMBLY__
9#include <linux/linkage.h>
10
11#ifdef CONFIG_CFI
12/*
13 * Use the __kcfi_typeid_<function> type identifier symbol to
14 * annotate indirectly called assembly functions. The compiler emits
15 * these symbols for all address-taken function declarations in C
16 * code.
17 */
18#ifndef __CFI_TYPE
19#define __CFI_TYPE(name) \
20 .4byte __kcfi_typeid_##name
21#endif
22
23#define SYM_TYPED_ENTRY(name, linkage, align...) \
24 linkage(name) ASM_NL \
25 align ASM_NL \
26 __CFI_TYPE(name) ASM_NL \
27 name:
28
29#define SYM_TYPED_START(name, linkage, align...) \
30 SYM_TYPED_ENTRY(name, linkage, align)
31
32#else /* CONFIG_CFI */
33
34#define SYM_TYPED_START(name, linkage, align...) \
35 SYM_START(name, linkage, align)
36
37#endif /* CONFIG_CFI */
38
39#ifndef SYM_TYPED_FUNC_START
40#define SYM_TYPED_FUNC_START(name) \
41 SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)
42#endif
43
44#else /* __ASSEMBLY__ */
45
46#ifdef CONFIG_CFI
47#define DEFINE_CFI_TYPE(name, func) \
48 /* \
49 * Force a reference to the function so the compiler generates \
50 * __kcfi_typeid_<func>. \
51 */ \
52 __ADDRESSABLE(func); \
53 /* u32 name __ro_after_init = __kcfi_typeid_<func> */ \
54 extern u32 name; \
55 asm ( \
56 " .pushsection .data..ro_after_init,\"aw\",\%progbits \n" \
57 " .type " #name ",\%object \n" \
58 " .globl " #name " \n" \
59 " .p2align 2, 0x0 \n" \
60 #name ": \n" \
61 " .4byte __kcfi_typeid_" #func " \n" \
62 " .size " #name ", 4 \n" \
63 " .popsection \n" \
64 );
65#endif
66
67#endif /* __ASSEMBLY__ */
68#endif /* _LINUX_CFI_TYPES_H */