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 #define UNWIND_HINT_TYPE_CALL 0 34 #define UNWIND_HINT_TYPE_REGS 1 35 #define UNWIND_HINT_TYPE_REGS_PARTIAL 2 36 #define UNWIND_HINT_TYPE_RET_OFFSET 3 37 38 #ifdef CONFIG_STACK_VALIDATION 39 40 #ifndef __ASSEMBLY__ 41 42 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \ 43 "987: \n\t" \ 44 ".pushsection .discard.unwind_hints\n\t" \ 45 /* struct unwind_hint */ \ 46 ".long 987b - .\n\t" \ 47 ".short " __stringify(sp_offset) "\n\t" \ 48 ".byte " __stringify(sp_reg) "\n\t" \ 49 ".byte " __stringify(type) "\n\t" \ 50 ".byte " __stringify(end) "\n\t" \ 51 ".balign 4 \n\t" \ 52 ".popsection\n\t" 53 54 /* 55 * This macro marks the given function's stack frame as "non-standard", which 56 * tells objtool to ignore the function when doing stack metadata validation. 57 * It should only be used in special cases where you're 100% sure it won't 58 * affect the reliability of frame pointers and kernel stack traces. 59 * 60 * For more information, see tools/objtool/Documentation/stack-validation.txt. 61 */ 62 #define STACK_FRAME_NON_STANDARD(func) \ 63 static void __used __section(".discard.func_stack_frame_non_standard") \ 64 *__func_stack_frame_non_standard_##func = func 65 66 #else /* __ASSEMBLY__ */ 67 68 /* 69 * This macro indicates that the following intra-function call is valid. 70 * Any non-annotated intra-function call will cause objtool to issue a warning. 71 */ 72 #define ANNOTATE_INTRA_FUNCTION_CALL \ 73 999: \ 74 .pushsection .discard.intra_function_calls; \ 75 .long 999b; \ 76 .popsection; 77 78 /* 79 * In asm, there are two kinds of code: normal C-type callable functions and 80 * the rest. The normal callable functions can be called by other code, and 81 * don't do anything unusual with the stack. Such normal callable functions 82 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this 83 * category. In this case, no special debugging annotations are needed because 84 * objtool can automatically generate the ORC data for the ORC unwinder to read 85 * at runtime. 86 * 87 * Anything which doesn't fall into the above category, such as syscall and 88 * interrupt handlers, tends to not be called directly by other functions, and 89 * often does unusual non-C-function-type things with the stack pointer. Such 90 * code needs to be annotated such that objtool can understand it. The 91 * following CFI hint macros are for this type of code. 92 * 93 * These macros provide hints to objtool about the state of the stack at each 94 * instruction. Objtool starts from the hints and follows the code flow, 95 * making automatic CFI adjustments when it sees pushes and pops, filling out 96 * the debuginfo as necessary. It will also warn if it sees any 97 * inconsistencies. 98 */ 99 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0 100 .Lunwind_hint_ip_\@: 101 .pushsection .discard.unwind_hints 102 /* struct unwind_hint */ 103 .long .Lunwind_hint_ip_\@ - . 104 .short \sp_offset 105 .byte \sp_reg 106 .byte \type 107 .byte \end 108 .balign 4 109 .popsection 110 .endm 111 112 #endif /* __ASSEMBLY__ */ 113 114 #else /* !CONFIG_STACK_VALIDATION */ 115 116 #ifndef __ASSEMBLY__ 117 118 #define UNWIND_HINT(sp_reg, sp_offset, type, end) \ 119 "\n\t" 120 #define STACK_FRAME_NON_STANDARD(func) 121 #else 122 #define ANNOTATE_INTRA_FUNCTION_CALL 123 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0 124 .endm 125 #endif 126 127 #endif /* CONFIG_STACK_VALIDATION */ 128 129 #endif /* _LINUX_OBJTOOL_H */ 130
