1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_OBJTOOL_H 3 #define _LINUX_OBJTOOL_H 4 5 #ifndef __ASSEMBLY__ 6 7 #include <linux/types.h> 8 9 /* 10 * This struct is used by asm and inline asm code to manually annotate the 11 * location of registers on the stack. 12 */ 13 struct unwind_hint { 14 u32 ip; 15 s16 sp_offset; 16 u8 sp_reg; 17 u8 type; 18 u8 signal; 19 u8 end; 20 }; 21 #endif 22 23 /* 24 * UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP 25 * (the caller's SP right before it made the call). Used for all callable 26 * functions, i.e. all C code and all callable asm functions. 27 * 28 * UNWIND_HINT_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset 29 * points to a fully populated pt_regs from a syscall, interrupt, or exception. 30 * 31 * UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that 32 * sp_reg+sp_offset points to the iret return frame. 33 * 34 * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function. 35 * Useful for code which doesn't have an ELF function annotation. 36 * 37 * UNWIND_HINT_ENTRY: machine entry without stack, SYSCALL/SYSENTER etc. 38 */ 39 #define UNWIND_HINT_TYPE_CALL 0 40 #define UNWIND_HINT_TYPE_REGS 1 41 #define UNWIND_HINT_TYPE_REGS_PARTIAL 2 42 #define UNWIND_HINT_TYPE_FUNC 3 43 #define UNWIND_HINT_TYPE_ENTRY 4 44 #define UNWIND_HINT_TYPE_SAVE 5 45 #define UNWIND_HINT_TYPE_RESTORE 6 46 47 #ifdef CONFIG_OBJTOOL 48 49 #include <asm/asm.h> 50 51 #ifndef __ASSEMBLY__ 52 53 #define UNWIND_HINT(sp_reg, sp_offset, type, signal, end) \ 54 "987: \n\t" \ 55 ".pushsection .discard.unwind_hints\n\t" \ 56 /* struct unwind_hint */ \ 57 ".long 987b - .\n\t" \ 58 ".short " __stringify(sp_offset) "\n\t" \ 59 ".byte " __stringify(sp_reg) "\n\t" \ 60 ".byte " __stringify(type) "\n\t" \ 61 ".byte " __stringify(signal) "\n\t" \ 62 ".byte " __stringify(end) "\n\t" \ 63 ".balign 4 \n\t" \ 64 ".popsection\n\t" 65 66 /* 67 * This macro marks the given function's stack frame as "non-standard", which 68 * tells objtool to ignore the function when doing stack metadata validation. 69 * It should only be used in special cases where you're 100% sure it won't 70 * affect the reliability of frame pointers and kernel stack traces. 71 * 72 * For more information, see tools/objtool/Documentation/objtool.txt. 73 */ 74 #define STACK_FRAME_NON_STANDARD(func) \ 75 static void __used __section(".discard.func_stack_frame_non_standard") \ 76 *__func_stack_frame_non_standard_##func = func 77 78 /* 79 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore 80 * for the case where a function is intentionally missing frame pointer setup, 81 * but otherwise needs objtool/ORC coverage when frame pointers are disabled. 82 */ 83 #ifdef CONFIG_FRAME_POINTER 84 #define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func) 85 #else 86 #define STACK_FRAME_NON_STANDARD_FP(func) 87 #endif 88 89 #define ANNOTATE_NOENDBR \ 90 "986: \n\t" \ 91 ".pushsection .discard.noendbr\n\t" \ 92 _ASM_PTR " 986b\n\t" \ 93 ".popsection\n\t" 94 95 #define ASM_REACHABLE \ 96 "998:\n\t" \ 97 ".pushsection .discard.reachable\n\t" \ 98 ".long 998b - .\n\t" \ 99 ".popsection\n\t" 100 101 #else /* __ASSEMBLY__ */ 102 103 /* 104 * This macro indicates that the following intra-function call is valid. 105 * Any non-annotated intra-function call will cause objtool to issue a warning. 106 */ 107 #define ANNOTATE_INTRA_FUNCTION_CALL \ 108 999: \ 109 .pushsection .discard.intra_function_calls; \ 110 .long 999b; \ 111 .popsection; 112 113 /* 114 * In asm, there are two kinds of code: normal C-type callable functions and 115 * the rest. The normal callable functions can be called by other code, and 116 * don't do anything unusual with the stack. Such normal callable functions 117 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this 118 * category. In this case, no special debugging annotations are needed because 119 * objtool can automatically generate the ORC data for the ORC unwinder to read 120 * at runtime. 121 * 122 * Anything which doesn't fall into the above category, such as syscall and 123 * interrupt handlers, tends to not be called directly by other functions, and 124 * often does unusual non-C-function-type things with the stack pointer. Such 125 * code needs to be annotated such that objtool can understand it. The 126 * following CFI hint macros are for this type of code. 127 * 128 * These macros provide hints to objtool about the state of the stack at each 129 * instruction. Objtool starts from the hints and follows the code flow, 130 * making automatic CFI adjustments when it sees pushes and pops, filling out 131 * the debuginfo as necessary. It will also warn if it sees any 132 * inconsistencies. 133 */ 134 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0 135 .Lunwind_hint_ip_\@: 136 .pushsection .discard.unwind_hints 137 /* struct unwind_hint */ 138 .long .Lunwind_hint_ip_\@ - . 139 .short \sp_offset 140 .byte \sp_reg 141 .byte \type 142 .byte \signal 143 .byte \end 144 .balign 4 145 .popsection 146 .endm 147 148 .macro STACK_FRAME_NON_STANDARD func:req 149 .pushsection .discard.func_stack_frame_non_standard, "aw" 150 _ASM_PTR \func 151 .popsection 152 .endm 153 154 .macro STACK_FRAME_NON_STANDARD_FP func:req 155 #ifdef CONFIG_FRAME_POINTER 156 STACK_FRAME_NON_STANDARD \func 157 #endif 158 .endm 159 160 .macro ANNOTATE_NOENDBR 161 .Lhere_\@: 162 .pushsection .discard.noendbr 163 .quad .Lhere_\@ 164 .popsection 165 .endm 166 167 .macro REACHABLE 168 .Lhere_\@: 169 .pushsection .discard.reachable 170 .long .Lhere_\@ - . 171 .popsection 172 .endm 173 174 #endif /* __ASSEMBLY__ */ 175 176 #else /* !CONFIG_OBJTOOL */ 177 178 #ifndef __ASSEMBLY__ 179 180 #define UNWIND_HINT(sp_reg, sp_offset, type, signal, end) \ 181 "\n\t" 182 #define STACK_FRAME_NON_STANDARD(func) 183 #define STACK_FRAME_NON_STANDARD_FP(func) 184 #define ANNOTATE_NOENDBR 185 #define ASM_REACHABLE 186 #else 187 #define ANNOTATE_INTRA_FUNCTION_CALL 188 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0 189 .endm 190 .macro STACK_FRAME_NON_STANDARD func:req 191 .endm 192 .macro ANNOTATE_NOENDBR 193 .endm 194 .macro REACHABLE 195 .endm 196 #endif 197 198 #endif /* CONFIG_OBJTOOL */ 199 200 #endif /* _LINUX_OBJTOOL_H */ 201