objtool.h (5595B)
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 */ 13struct 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_OBJTOOL 42 43#include <asm/asm.h> 44 45#ifndef __ASSEMBLY__ 46 47#define UNWIND_HINT(sp_reg, sp_offset, type, end) \ 48 "987: \n\t" \ 49 ".pushsection .discard.unwind_hints\n\t" \ 50 /* struct unwind_hint */ \ 51 ".long 987b - .\n\t" \ 52 ".short " __stringify(sp_offset) "\n\t" \ 53 ".byte " __stringify(sp_reg) "\n\t" \ 54 ".byte " __stringify(type) "\n\t" \ 55 ".byte " __stringify(end) "\n\t" \ 56 ".balign 4 \n\t" \ 57 ".popsection\n\t" 58 59/* 60 * This macro marks the given function's stack frame as "non-standard", which 61 * tells objtool to ignore the function when doing stack metadata validation. 62 * It should only be used in special cases where you're 100% sure it won't 63 * affect the reliability of frame pointers and kernel stack traces. 64 * 65 * For more information, see tools/objtool/Documentation/stack-validation.txt. 66 */ 67#define STACK_FRAME_NON_STANDARD(func) \ 68 static void __used __section(".discard.func_stack_frame_non_standard") \ 69 *__func_stack_frame_non_standard_##func = func 70 71/* 72 * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore 73 * for the case where a function is intentionally missing frame pointer setup, 74 * but otherwise needs objtool/ORC coverage when frame pointers are disabled. 75 */ 76#ifdef CONFIG_FRAME_POINTER 77#define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func) 78#else 79#define STACK_FRAME_NON_STANDARD_FP(func) 80#endif 81 82#define ANNOTATE_NOENDBR \ 83 "986: \n\t" \ 84 ".pushsection .discard.noendbr\n\t" \ 85 _ASM_PTR " 986b\n\t" \ 86 ".popsection\n\t" 87 88#define ASM_REACHABLE \ 89 "998:\n\t" \ 90 ".pushsection .discard.reachable\n\t" \ 91 ".long 998b - .\n\t" \ 92 ".popsection\n\t" 93 94#else /* __ASSEMBLY__ */ 95 96/* 97 * This macro indicates that the following intra-function call is valid. 98 * Any non-annotated intra-function call will cause objtool to issue a warning. 99 */ 100#define ANNOTATE_INTRA_FUNCTION_CALL \ 101 999: \ 102 .pushsection .discard.intra_function_calls; \ 103 .long 999b; \ 104 .popsection; 105 106/* 107 * In asm, there are two kinds of code: normal C-type callable functions and 108 * the rest. The normal callable functions can be called by other code, and 109 * don't do anything unusual with the stack. Such normal callable functions 110 * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this 111 * category. In this case, no special debugging annotations are needed because 112 * objtool can automatically generate the ORC data for the ORC unwinder to read 113 * at runtime. 114 * 115 * Anything which doesn't fall into the above category, such as syscall and 116 * interrupt handlers, tends to not be called directly by other functions, and 117 * often does unusual non-C-function-type things with the stack pointer. Such 118 * code needs to be annotated such that objtool can understand it. The 119 * following CFI hint macros are for this type of code. 120 * 121 * These macros provide hints to objtool about the state of the stack at each 122 * instruction. Objtool starts from the hints and follows the code flow, 123 * making automatic CFI adjustments when it sees pushes and pops, filling out 124 * the debuginfo as necessary. It will also warn if it sees any 125 * inconsistencies. 126 */ 127.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0 128.Lunwind_hint_ip_\@: 129 .pushsection .discard.unwind_hints 130 /* struct unwind_hint */ 131 .long .Lunwind_hint_ip_\@ - . 132 .short \sp_offset 133 .byte \sp_reg 134 .byte \type 135 .byte \end 136 .balign 4 137 .popsection 138.endm 139 140.macro STACK_FRAME_NON_STANDARD func:req 141 .pushsection .discard.func_stack_frame_non_standard, "aw" 142 _ASM_PTR \func 143 .popsection 144.endm 145 146.macro STACK_FRAME_NON_STANDARD_FP func:req 147#ifdef CONFIG_FRAME_POINTER 148 STACK_FRAME_NON_STANDARD \func 149#endif 150.endm 151 152.macro ANNOTATE_NOENDBR 153.Lhere_\@: 154 .pushsection .discard.noendbr 155 .quad .Lhere_\@ 156 .popsection 157.endm 158 159.macro REACHABLE 160.Lhere_\@: 161 .pushsection .discard.reachable 162 .long .Lhere_\@ - . 163 .popsection 164.endm 165 166#endif /* __ASSEMBLY__ */ 167 168#else /* !CONFIG_OBJTOOL */ 169 170#ifndef __ASSEMBLY__ 171 172#define UNWIND_HINT(sp_reg, sp_offset, type, end) \ 173 "\n\t" 174#define STACK_FRAME_NON_STANDARD(func) 175#define STACK_FRAME_NON_STANDARD_FP(func) 176#define ANNOTATE_NOENDBR 177#define ASM_REACHABLE 178#else 179#define ANNOTATE_INTRA_FUNCTION_CALL 180.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0 181.endm 182.macro STACK_FRAME_NON_STANDARD func:req 183.endm 184.macro ANNOTATE_NOENDBR 185.endm 186.macro REACHABLE 187.endm 188#endif 189 190#endif /* CONFIG_OBJTOOL */ 191 192#endif /* _LINUX_OBJTOOL_H */