1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_OBJTOOL_H 3 #define _LINUX_OBJTOOL_H 4 5 #include <linux/objtool_types.h> 6 7 #ifdef CONFIG_OBJTOOL 8 9 #include <asm/asm.h> 10 11 #ifndef __ASSEMBLY__ 12 13 #define UNWIND_HINT(type, sp_reg, sp_offset, signal) \ 14 "987: \n\t" \ 15 ".pushsection .discard.unwind_hints\n\t" \ 16 /* struct unwind_hint */ \ 17 ".long 987b - .\n\t" \ 18 ".short " __stringify(sp_offset) "\n\t" \ 19 ".byte " __stringify(sp_reg) "\n\t" \ 20 ".byte " __stringify(type) "\n\t" \ 21 ".byte " __stringify(signal) "\n\t" \ 22 ".balign 4 \n\t" \ 23 ".popsection\n\t" 24 25 /* 26 * This macro marks the given function's stack frame as "non-standard", which 27 * tells objtool to ignore the function when doing stack metadata validation. 28 * It should only be used in special cases where you're 100% sure it won't 29 * affect the reliability of frame pointers and kernel stack traces. 30 * 31 * For more information, see tools/objtool/Documentation/objtool.txt. 32 */ 33 #define STACK_FRAME_NON_STANDARD(func) \ 34 static void __used __section(".discard.func_stack_frame_non_standard") \ 35 *__func_stack_frame_non_standard_##func = func 36 37 /* 38 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore 39 * for the case where a function is intentionally missing frame pointer setup, 40 * but otherwise needs objtool/ORC coverage when frame pointers are disabled. 41 */ 42 #ifdef CONFIG_FRAME_POINTER 43 #define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func) 44 #else 45 #define STACK_FRAME_NON_STANDARD_FP(func) 46 #endif 47 48 #define ANNOTATE_NOENDBR \ 49 "986: \n\t" \ 50 ".pushsection .discard.noendbr\n\t" \ 51 ".long 986b\n\t" \ 52 ".popsection\n\t" 53 54 #define ASM_REACHABLE \ 55 "998:\n\t" \ 56 ".pushsection .discard.reachable\n\t" \ 57 ".long 998b\n\t" \ 58 ".popsection\n\t" 59 60 #else /* __ASSEMBLY__ */ 61 62 /* 63 * This macro indicates that the following intra-function call is valid. 64 * Any non-annotated intra-function call will cause objtool to issue a warning. 65 */ 66 #define ANNOTATE_INTRA_FUNCTION_CALL \ 67 999: \ 68 .pushsection .discard.intra_function_calls; \ 69 .long 999b; \ 70 .popsection; 71 72 /* 73 * In asm, there are two kinds of code: normal C-type callable functions and 74 * the rest. The normal callable functions can be called by other code, and 75 * don't do anything unusual with the stack. Such normal callable functions 76 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this 77 * category. In this case, no special debugging annotations are needed because 78 * objtool can automatically generate the ORC data for the ORC unwinder to read 79 * at runtime. 80 * 81 * Anything which doesn't fall into the above category, such as syscall and 82 * interrupt handlers, tends to not be called directly by other functions, and 83 * often does unusual non-C-function-type things with the stack pointer. Such 84 * code needs to be annotated such that objtool can understand it. The 85 * following CFI hint macros are for this type of code. 86 * 87 * These macros provide hints to objtool about the state of the stack at each 88 * instruction. Objtool starts from the hints and follows the code flow, 89 * making automatic CFI adjustments when it sees pushes and pops, filling out 90 * the debuginfo as necessary. It will also warn if it sees any 91 * inconsistencies. 92 */ 93 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 94 .Lhere_\@: 95 .pushsection .discard.unwind_hints 96 /* struct unwind_hint */ 97 .long .Lhere_\@ - . 98 .short \sp_offset 99 .byte \sp_reg 100 .byte \type 101 .byte \signal 102 .balign 4 103 .popsection 104 .endm 105 106 .macro STACK_FRAME_NON_STANDARD func:req 107 .pushsection .discard.func_stack_frame_non_standard, "aw" 108 .long \func - . 109 .popsection 110 .endm 111 112 .macro STACK_FRAME_NON_STANDARD_FP func:req 113 #ifdef CONFIG_FRAME_POINTER 114 STACK_FRAME_NON_STANDARD \func 115 #endif 116 .endm 117 118 .macro ANNOTATE_NOENDBR 119 .Lhere_\@: 120 .pushsection .discard.noendbr 121 .long .Lhere_\@ 122 .popsection 123 .endm 124 125 /* 126 * Use objtool to validate the entry requirement that all code paths do 127 * VALIDATE_UNRET_END before RET. 128 * 129 * NOTE: The macro must be used at the beginning of a global symbol, otherwise 130 * it will be ignored. 131 */ 132 .macro VALIDATE_UNRET_BEGIN 133 #if defined(CONFIG_NOINSTR_VALIDATION) && \ 134 (defined(CONFIG_MITIGATION_UNRET_ENTRY) || defined(CONFIG_MITIGATION_SRSO)) 135 .Lhere_\@: 136 .pushsection .discard.validate_unret 137 .long .Lhere_\@ - . 138 .popsection 139 #endif 140 .endm 141 142 .macro REACHABLE 143 .Lhere_\@: 144 .pushsection .discard.reachable 145 .long .Lhere_\@ 146 .popsection 147 .endm 148 149 #endif /* __ASSEMBLY__ */ 150 151 #else /* !CONFIG_OBJTOOL */ 152 153 #ifndef __ASSEMBLY__ 154 155 #define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t" 156 #define STACK_FRAME_NON_STANDARD(func) 157 #define STACK_FRAME_NON_STANDARD_FP(func) 158 #define ANNOTATE_NOENDBR 159 #define ASM_REACHABLE 160 #else 161 #define ANNOTATE_INTRA_FUNCTION_CALL 162 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 163 .endm 164 .macro STACK_FRAME_NON_STANDARD func:req 165 .endm 166 .macro ANNOTATE_NOENDBR 167 .endm 168 .macro REACHABLE 169 .endm 170 #endif 171 172 #endif /* CONFIG_OBJTOOL */ 173 174 #endif /* _LINUX_OBJTOOL_H */ 175