LXR linux/include/linux/objtool.h

   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_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