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