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 ASM_REACHABLE \ 49 "998:\n\t" \ 50 ".pushsection .discard.reachable\n\t" \ 51 ".long 998b\n\t" \ 52 ".popsection\n\t" 53 54 #define __ASM_BREF(label) label ## b 55 56 #define __ASM_ANNOTATE(label, type) \ 57 ".pushsection .discard.annotate_insn,\"M\",@progbits,8\n\t" \ 58 ".long " __stringify(label) " - .\n\t" \ 59 ".long " __stringify(type) "\n\t" \ 60 ".popsection\n\t" 61 62 #define ASM_ANNOTATE(type) \ 63 "911:\n\t" \ 64 __ASM_ANNOTATE(911b, type) 65 66 #define ANNOTATE_NOENDBR ASM_ANNOTATE(ANNOTYPE_NOENDBR) 67 68 #else /* __ASSEMBLY__ */ 69 70 /* 71 * This macro indicates that the following intra-function call is valid. 72 * Any non-annotated intra-function call will cause objtool to issue a warning. 73 */ 74 #define ANNOTATE_INTRA_FUNCTION_CALL \ 75 999: \ 76 .pushsection .discard.intra_function_calls; \ 77 .long 999b; \ 78 .popsection; 79 80 /* 81 * In asm, there are two kinds of code: normal C-type callable functions and 82 * the rest. The normal callable functions can be called by other code, and 83 * don't do anything unusual with the stack. Such normal callable functions 84 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this 85 * category. In this case, no special debugging annotations are needed because 86 * objtool can automatically generate the ORC data for the ORC unwinder to read 87 * at runtime. 88 * 89 * Anything which doesn't fall into the above category, such as syscall and 90 * interrupt handlers, tends to not be called directly by other functions, and 91 * often does unusual non-C-function-type things with the stack pointer. Such 92 * code needs to be annotated such that objtool can understand it. The 93 * following CFI hint macros are for this type of code. 94 * 95 * These macros provide hints to objtool about the state of the stack at each 96 * instruction. Objtool starts from the hints and follows the code flow, 97 * making automatic CFI adjustments when it sees pushes and pops, filling out 98 * the debuginfo as necessary. It will also warn if it sees any 99 * inconsistencies. 100 */ 101 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 102 .Lhere_\@: 103 .pushsection .discard.unwind_hints 104 /* struct unwind_hint */ 105 .long .Lhere_\@ - . 106 .short \sp_offset 107 .byte \sp_reg 108 .byte \type 109 .byte \signal 110 .balign 4 111 .popsection 112 .endm 113 114 .macro STACK_FRAME_NON_STANDARD func:req 115 .pushsection .discard.func_stack_frame_non_standard, "aw" 116 .long \func - . 117 .popsection 118 .endm 119 120 .macro STACK_FRAME_NON_STANDARD_FP func:req 121 #ifdef CONFIG_FRAME_POINTER 122 STACK_FRAME_NON_STANDARD \func 123 #endif 124 .endm 125 126 /* 127 * Use objtool to validate the entry requirement that all code paths do 128 * VALIDATE_UNRET_END before RET. 129 * 130 * NOTE: The macro must be used at the beginning of a global symbol, otherwise 131 * it will be ignored. 132 */ 133 #if defined(CONFIG_NOINSTR_VALIDATION) && \ 134 (defined(CONFIG_MITIGATION_UNRET_ENTRY) || defined(CONFIG_MITIGATION_SRSO)) 135 #define VALIDATE_UNRET_BEGIN ANNOTATE type=ANNOTYPE_UNRET_BEGIN 136 #else 137 #define VALIDATE_UNRET_BEGIN 138 #endif 139 140 .macro REACHABLE 141 .Lhere_\@: 142 .pushsection .discard.reachable 143 .long .Lhere_\@ 144 .popsection 145 .endm 146 147 .macro ANNOTATE type:req 148 .Lhere_\@: 149 .pushsection .discard.annotate_insn,"M",@progbits,8 150 .long .Lhere_\@ - . 151 .long \type 152 .popsection 153 .endm 154 155 #define ANNOTATE_NOENDBR ANNOTATE type=ANNOTYPE_NOENDBR 156 157 #endif /* __ASSEMBLY__ */ 158 159 #else /* !CONFIG_OBJTOOL */ 160 161 #ifndef __ASSEMBLY__ 162 163 #define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t" 164 #define STACK_FRAME_NON_STANDARD(func) 165 #define STACK_FRAME_NON_STANDARD_FP(func) 166 #define __ASM_ANNOTATE(label, type) 167 #define ASM_ANNOTATE(type) 168 #define ANNOTATE_NOENDBR 169 #define ASM_REACHABLE 170 #else 171 #define ANNOTATE_INTRA_FUNCTION_CALL 172 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 173 .endm 174 .macro STACK_FRAME_NON_STANDARD func:req 175 .endm 176 .macro ANNOTATE_NOENDBR 177 .endm 178 .macro REACHABLE 179 .endm 180 .macro ANNOTATE type:req 181 .endm 182 #endif 183 184 #endif /* CONFIG_OBJTOOL */ 185 186 #endif /* _LINUX_OBJTOOL_H */ 187