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 #else /* __ASSEMBLY__ */ 67 68 /* 69 * In asm, there are two kinds of code: normal C-type callable functions and 70 * the rest. The normal callable functions can be called by other code, and 71 * don't do anything unusual with the stack. Such normal callable functions 72 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this 73 * category. In this case, no special debugging annotations are needed because 74 * objtool can automatically generate the ORC data for the ORC unwinder to read 75 * at runtime. 76 * 77 * Anything which doesn't fall into the above category, such as syscall and 78 * interrupt handlers, tends to not be called directly by other functions, and 79 * often does unusual non-C-function-type things with the stack pointer. Such 80 * code needs to be annotated such that objtool can understand it. The 81 * following CFI hint macros are for this type of code. 82 * 83 * These macros provide hints to objtool about the state of the stack at each 84 * instruction. Objtool starts from the hints and follows the code flow, 85 * making automatic CFI adjustments when it sees pushes and pops, filling out 86 * the debuginfo as necessary. It will also warn if it sees any 87 * inconsistencies. 88 */ 89 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 90 .Lhere_\@: 91 .pushsection .discard.unwind_hints 92 /* struct unwind_hint */ 93 .long .Lhere_\@ - . 94 .short \sp_offset 95 .byte \sp_reg 96 .byte \type 97 .byte \signal 98 .balign 4 99 .popsection 100 .endm 101 102 .macro STACK_FRAME_NON_STANDARD func:req 103 .pushsection .discard.func_stack_frame_non_standard, "aw" 104 .long \func - . 105 .popsection 106 .endm 107 108 .macro STACK_FRAME_NON_STANDARD_FP func:req 109 #ifdef CONFIG_FRAME_POINTER 110 STACK_FRAME_NON_STANDARD \func 111 #endif 112 .endm 113 114 .macro ANNOTATE type:req 115 .Lhere_\@: 116 .pushsection .discard.annotate_insn,"M",@progbits,8 117 .long .Lhere_\@ - . 118 .long \type 119 .popsection 120 .endm 121 122 #endif /* __ASSEMBLY__ */ 123 124 #else /* !CONFIG_OBJTOOL */ 125 126 #ifndef __ASSEMBLY__ 127 128 #define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t" 129 #define STACK_FRAME_NON_STANDARD(func) 130 #define STACK_FRAME_NON_STANDARD_FP(func) 131 #define __ASM_ANNOTATE(label, type) 132 #define ASM_ANNOTATE(type) 133 #else 134 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 135 .endm 136 .macro STACK_FRAME_NON_STANDARD func:req 137 .endm 138 .macro ANNOTATE type:req 139 .endm 140 #endif 141 142 #endif /* CONFIG_OBJTOOL */ 143 144 #ifndef __ASSEMBLY__ 145 /* 146 * Annotate away the various 'relocation to !ENDBR` complaints; knowing that 147 * these relocations will never be used for indirect calls. 148 */ 149 #define ANNOTATE_NOENDBR ASM_ANNOTATE(ANNOTYPE_NOENDBR) 150 /* 151 * This should be used immediately before an indirect jump/call. It tells 152 * objtool the subsequent indirect jump/call is vouched safe for retpoline 153 * builds. 154 */ 155 #define ANNOTATE_RETPOLINE_SAFE ASM_ANNOTATE(ANNOTYPE_RETPOLINE_SAFE) 156 /* 157 * See linux/instrumentation.h 158 */ 159 #define ANNOTATE_INSTR_BEGIN(label) __ASM_ANNOTATE(label, ANNOTYPE_INSTR_BEGIN) 160 #define ANNOTATE_INSTR_END(label) __ASM_ANNOTATE(label, ANNOTYPE_INSTR_END) 161 /* 162 * objtool annotation to ignore the alternatives and only consider the original 163 * instruction(s). 164 */ 165 #define ANNOTATE_IGNORE_ALTERNATIVE ASM_ANNOTATE(ANNOTYPE_IGNORE_ALTS) 166 /* 167 * This macro indicates that the following intra-function call is valid. 168 * Any non-annotated intra-function call will cause objtool to issue a warning. 169 */ 170 #define ANNOTATE_INTRA_FUNCTION_CALL ASM_ANNOTATE(ANNOTYPE_INTRA_FUNCTION_CALL) 171 /* 172 * Use objtool to validate the entry requirement that all code paths do 173 * VALIDATE_UNRET_END before RET. 174 * 175 * NOTE: The macro must be used at the beginning of a global symbol, otherwise 176 * it will be ignored. 177 */ 178 #define ANNOTATE_UNRET_BEGIN ASM_ANNOTATE(ANNOTYPE_UNRET_BEGIN) 179 /* 180 * This should be used to refer to an instruction that is considered 181 * terminating, like a noreturn CALL or UD2 when we know they are not -- eg 182 * WARN using UD2. 183 */ 184 #define ANNOTATE_REACHABLE(label) __ASM_ANNOTATE(label, ANNOTYPE_REACHABLE) 185 186 #else 187 #define ANNOTATE_NOENDBR ANNOTATE type=ANNOTYPE_NOENDBR 188 #define ANNOTATE_RETPOLINE_SAFE ANNOTATE type=ANNOTYPE_RETPOLINE_SAFE 189 /* ANNOTATE_INSTR_BEGIN ANNOTATE type=ANNOTYPE_INSTR_BEGIN */ 190 /* ANNOTATE_INSTR_END ANNOTATE type=ANNOTYPE_INSTR_END */ 191 #define ANNOTATE_IGNORE_ALTERNATIVE ANNOTATE type=ANNOTYPE_IGNORE_ALTS 192 #define ANNOTATE_INTRA_FUNCTION_CALL ANNOTATE type=ANNOTYPE_INTRA_FUNCTION_CALL 193 #define ANNOTATE_UNRET_BEGIN ANNOTATE type=ANNOTYPE_UNRET_BEGIN 194 #define ANNOTATE_REACHABLE ANNOTATE type=ANNOTYPE_REACHABLE 195 #endif 196 197 #if defined(CONFIG_NOINSTR_VALIDATION) && \ 198 (defined(CONFIG_MITIGATION_UNRET_ENTRY) || defined(CONFIG_MITIGATION_SRSO)) 199 #define VALIDATE_UNRET_BEGIN ANNOTATE_UNRET_BEGIN 200 #else 201 #define VALIDATE_UNRET_BEGIN 202 #endif 203 204 #endif /* _LINUX_OBJTOOL_H */ 205