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_STACK_VALIDATION 47 48 #ifndef __ASSEMBLY__ 49 50 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \ 51 "987: \n\t" \ 52 ".pushsection .discard.unwind_hints\n\t" \ 53 /* struct unwind_hint */ \ 54 ".long 987b - .\n\t" \ 55 ".short " __stringify(sp_offset) "\n\t" \ 56 ".byte " __stringify(sp_reg) "\n\t" \ 57 ".byte " __stringify(type) "\n\t" \ 58 ".byte " __stringify(end) "\n\t" \ 59 ".balign 4 \n\t" \ 60 ".popsection\n\t" 61 62 /* 63 * This macro marks the given function's stack frame as "non-standard", which 64 * tells objtool to ignore the function when doing stack metadata validation. 65 * It should only be used in special cases where you're 100% sure it won't 66 * affect the reliability of frame pointers and kernel stack traces. 67 * 68 * For more information, see tools/objtool/Documentation/stack-validation.txt. 69 */ 70 #define STACK_FRAME_NON_STANDARD(func) \ 71 static void __used __section(".discard.func_stack_frame_non_standard") \ 72 *__func_stack_frame_non_standard_##func = func 73 74 /* 75 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore 76 * for the case where a function is intentionally missing frame pointer setup, 77 * but otherwise needs objtool/ORC coverage when frame pointers are disabled. 78 */ 79 #ifdef CONFIG_FRAME_POINTER 80 #define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func) 81 #else 82 #define STACK_FRAME_NON_STANDARD_FP(func) 83 #endif 84 85 #define ANNOTATE_NOENDBR \ 86 "986: \n\t" \ 87 ".pushsection .discard.noendbr\n\t" \ 88 _ASM_PTR " 986b\n\t" \ 89 ".popsection\n\t" 90 91 #else /* __ASSEMBLY__ */ 92 93 /* 94 * This macro indicates that the following intra-function call is valid. 95 * Any non-annotated intra-function call will cause objtool to issue a warning. 96 */ 97 #define ANNOTATE_INTRA_FUNCTION_CALL \ 98 999: \ 99 .pushsection .discard.intra_function_calls; \ 100 .long 999b; \ 101 .popsection; 102 103 /* 104 * In asm, there are two kinds of code: normal C-type callable functions and 105 * the rest. The normal callable functions can be called by other code, and 106 * don't do anything unusual with the stack. Such normal callable functions 107 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this 108 * category. In this case, no special debugging annotations are needed because 109 * objtool can automatically generate the ORC data for the ORC unwinder to read 110 * at runtime. 111 * 112 * Anything which doesn't fall into the above category, such as syscall and 113 * interrupt handlers, tends to not be called directly by other functions, and 114 * often does unusual non-C-function-type things with the stack pointer. Such 115 * code needs to be annotated such that objtool can understand it. The 116 * following CFI hint macros are for this type of code. 117 * 118 * These macros provide hints to objtool about the state of the stack at each 119 * instruction. Objtool starts from the hints and follows the code flow, 120 * making automatic CFI adjustments when it sees pushes and pops, filling out 121 * the debuginfo as necessary. It will also warn if it sees any 122 * inconsistencies. 123 */ 124 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0 125 .Lunwind_hint_ip_\@: 126 .pushsection .discard.unwind_hints 127 /* struct unwind_hint */ 128 .long .Lunwind_hint_ip_\@ - . 129 .short \sp_offset 130 .byte \sp_reg 131 .byte \type 132 .byte \end 133 .balign 4 134 .popsection 135 .endm 136 137 .macro STACK_FRAME_NON_STANDARD func:req 138 .pushsection .discard.func_stack_frame_non_standard, "aw" 139 .long \func - . 140 .popsection 141 .endm 142 143 .macro ANNOTATE_NOENDBR 144 .Lhere_\@: 145 .pushsection .discard.noendbr 146 .quad .Lhere_\@ 147 .popsection 148 .endm 149 150 #endif /* __ASSEMBLY__ */ 151 152 #else /* !CONFIG_STACK_VALIDATION */ 153 154 #ifndef __ASSEMBLY__ 155 156 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \ 157 "\n\t" 158 #define STACK_FRAME_NON_STANDARD(func) 159 #define STACK_FRAME_NON_STANDARD_FP(func) 160 #define ANNOTATE_NOENDBR 161 #else 162 #define ANNOTATE_INTRA_FUNCTION_CALL 163 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0 164 .endm 165 .macro STACK_FRAME_NON_STANDARD func:req 166 .endm 167 .macro ANNOTATE_NOENDBR 168 .endm 169 #endif 170 171 #endif /* CONFIG_STACK_VALIDATION */ 172 173 #endif /* _LINUX_OBJTOOL_H */ 174