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