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_CLANG 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_CLANG */ 33 34 #define SYM_TYPED_START(name, linkage, align...) \ 35 SYM_START(name, linkage, align) 36 37 #endif /* CONFIG_CFI_CLANG */ 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_CLANG 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 = __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 */ 69