Olivier Deprez | 157378f | 2022-04-04 15:47:50 +0200 | [diff] [blame^] | 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 */ |