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