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 #else /* __ASSEMBLY__ */ 70 71 /* 72 * This macro indicates that the following intra-function call is valid. 73 * Any non-annotated intra-function call will cause objtool to issue a warning. 74 */ 75 #define ANNOTATE_INTRA_FUNCTION_CALL \ 76 999: \ 77 .pushsection .discard.intra_function_calls; \ 78 .long 999b; \ 79 .popsection; 80 81 /* 82 * In asm, there are two kinds of code: normal C-type callable functions and 83 * the rest. The normal callable functions can be called by other code, and 84 * don't do anything unusual with the stack. Such normal callable functions 85 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this 86 * category. In this case, no special debugging annotations are needed because 87 * objtool can automatically generate the ORC data for the ORC unwinder to read 88 * at runtime. 89 * 90 * Anything which doesn't fall into the above category, such as syscall and 91 * interrupt handlers, tends to not be called directly by other functions, and 92 * often does unusual non-C-function-type things with the stack pointer. Such 93 * code needs to be annotated such that objtool can understand it. The 94 * following CFI hint macros are for this type of code. 95 * 96 * These macros provide hints to objtool about the state of the stack at each 97 * instruction. Objtool starts from the hints and follows the code flow, 98 * making automatic CFI adjustments when it sees pushes and pops, filling out 99 * the debuginfo as necessary. It will also warn if it sees any 100 * inconsistencies. 101 */ 102 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0 103 .Lunwind_hint_ip_\@: 104 .pushsection .discard.unwind_hints 105 /* struct unwind_hint */ 106 .long .Lunwind_hint_ip_\@ - . 107 .short \sp_offset 108 .byte \sp_reg 109 .byte \type 110 .byte \end 111 .balign 4 112 .popsection 113 .endm 114 115 .macro STACK_FRAME_NON_STANDARD func:req 116 .pushsection .discard.func_stack_frame_non_standard, "aw" 117 .long \func - . 118 .popsection 119 .endm 120 121 #endif /* __ASSEMBLY__ */ 122 123 #else /* !CONFIG_STACK_VALIDATION */ 124 125 #ifndef __ASSEMBLY__ 126 127 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \ 128 "\n\t" 129 #define STACK_FRAME_NON_STANDARD(func) 130 #else 131 #define ANNOTATE_INTRA_FUNCTION_CALL 132 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0 133 .endm 134 .macro STACK_FRAME_NON_STANDARD func:req 135 .endm 136 #endif 137 138 #endif /* CONFIG_STACK_VALIDATION */ 139 140 #endif /* _LINUX_OBJTOOL_H */ 141