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