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 end; 19 }; 20 #endif 21 22 /* 23 * UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP 24 * (the caller's SP right before it made the call). Used for all callable 25 * functions, i.e. all C code and all callable asm functions. 26 * 27 * UNWIND_HINT_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset 28 * points to a fully populated pt_regs from a syscall, interrupt, or exception. 29 * 30 * UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that 31 * sp_reg+sp_offset points to the iret return frame. 32 * 33 * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function. 34 * Useful for code which doesn't have an ELF function annotation. 35 */ 36 #define UNWIND_HINT_TYPE_CALL 0 37 #define UNWIND_HINT_TYPE_REGS 1 38 #define UNWIND_HINT_TYPE_REGS_PARTIAL 2 39 #define UNWIND_HINT_TYPE_FUNC 3 40 41 #ifdef CONFIG_STACK_VALIDATION 42 43 #ifndef __ASSEMBLY__ 44 45 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \ 46 "987: \n\t" \ 47 ".pushsection .discard.unwind_hints\n\t" \ 48 /* struct unwind_hint */ \ 49 ".long 987b - .\n\t" \ 50 ".short " __stringify(sp_offset) "\n\t" \ 51 ".byte " __stringify(sp_reg) "\n\t" \ 52 ".byte " __stringify(type) "\n\t" \ 53 ".byte " __stringify(end) "\n\t" \ 54 ".balign 4 \n\t" \ 55 ".popsection\n\t" 56 57 /* 58 * This macro marks the given function's stack frame as "non-standard", which 59 * tells objtool to ignore the function when doing stack metadata validation. 60 * It should only be used in special cases where you're 100% sure it won't 61 * affect the reliability of frame pointers and kernel stack traces. 62 * 63 * For more information, see tools/objtool/Documentation/stack-validation.txt. 64 */ 65 #define STACK_FRAME_NON_STANDARD(func) \ 66 static void __used __section(".discard.func_stack_frame_non_standard") \ 67 *__func_stack_frame_non_standard_##func = func 68 69 /* 70 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore 71 * for the case where a function is intentionally missing frame pointer setup, 72 * but otherwise needs objtool/ORC coverage when frame pointers are disabled. 73 */ 74 #ifdef CONFIG_FRAME_POINTER 75 #define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func) 76 #else 77 #define STACK_FRAME_NON_STANDARD_FP(func) 78 #endif 79 80 #define ANNOTATE_NOENDBR \ 81 "986: \n\t" \ 82 ".pushsection .discard.noendbr\n\t" \ 83 _ASM_PTR " 986b\n\t" \ 84 ".popsection\n\t" 85 86 #define ASM_REACHABLE \ 87 "998:\n\t" \ 88 ".pushsection .discard.reachable\n\t" \ 89 ".long 998b - .\n\t" \ 90 ".popsection\n\t" 91 92 #else /* __ASSEMBLY__ */ 93 94 /* 95 * This macro indicates that the following intra-function call is valid. 96 * Any non-annotated intra-function call will cause objtool to issue a warning. 97 */ 98 #define ANNOTATE_INTRA_FUNCTION_CALL \ 99 999: \ 100 .pushsection .discard.intra_function_calls; \ 101 .long 999b; \ 102 .popsection; 103 104 /* 105 * In asm, there are two kinds of code: normal C-type callable functions and 106 * the rest. The normal callable functions can be called by other code, and 107 * don't do anything unusual with the stack. Such normal callable functions 108 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this 109 * category. In this case, no special debugging annotations are needed because 110 * objtool can automatically generate the ORC data for the ORC unwinder to read 111 * at runtime. 112 * 113 * Anything which doesn't fall into the above category, such as syscall and 114 * interrupt handlers, tends to not be called directly by other functions, and 115 * often does unusual non-C-function-type things with the stack pointer. Such 116 * code needs to be annotated such that objtool can understand it. The 117 * following CFI hint macros are for this type of code. 118 * 119 * These macros provide hints to objtool about the state of the stack at each 120 * instruction. Objtool starts from the hints and follows the code flow, 121 * making automatic CFI adjustments when it sees pushes and pops, filling out 122 * the debuginfo as necessary. It will also warn if it sees any 123 * inconsistencies. 124 */ 125 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0 126 .Lunwind_hint_ip_\@: 127 .pushsection .discard.unwind_hints 128 /* struct unwind_hint */ 129 .long .Lunwind_hint_ip_\@ - . 130 .short \sp_offset 131 .byte \sp_reg 132 .byte \type 133 .byte \end 134 .balign 4 135 .popsection 136 .endm 137 138 .macro STACK_FRAME_NON_STANDARD func:req 139 .pushsection .discard.func_stack_frame_non_standard, "aw" 140 .long \func - . 141 .popsection 142 .endm 143 144 .macro ANNOTATE_NOENDBR 145 .Lhere_\@: 146 .pushsection .discard.noendbr 147 .quad .Lhere_\@ 148 .popsection 149 .endm 150 151 .macro REACHABLE 152 .Lhere_\@: 153 .pushsection .discard.reachable 154 .long .Lhere_\@ - . 155 .popsection 156 .endm 157 158 #endif /* __ASSEMBLY__ */ 159 160 #else /* !CONFIG_STACK_VALIDATION */ 161 162 #ifndef __ASSEMBLY__ 163 164 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \ 165 "\n\t" 166 #define STACK_FRAME_NON_STANDARD(func) 167 #define STACK_FRAME_NON_STANDARD_FP(func) 168 #define ANNOTATE_NOENDBR 169 #define ASM_REACHABLE 170 #else 171 #define ANNOTATE_INTRA_FUNCTION_CALL 172 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=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 #endif 181 182 #endif /* CONFIG_STACK_VALIDATION */ 183 184 #endif /* _LINUX_OBJTOOL_H */ 185