arch/x86/include/asm/unwind_hints.h

   1 #ifndef _ASM_X86_UNWIND_HINTS_H
   2 #define _ASM_X86_UNWIND_HINTS_H
   3
   4 #include "orc_types.h"
   5
   6 #ifdef __ASSEMBLY__
   7
   8 /*
   9  * In asm, there are two kinds of code: normal C-type callable functions and
  10  * the rest.  The normal callable functions can be called by other code, and
  11  * don't do anything unusual with the stack.  Such normal callable functions
  12  * are annotated with the ENTRY/ENDPROC macros.  Most asm code falls in this
  13  * category.  In this case, no special debugging annotations are needed because
  14  * objtool can automatically generate the ORC data for the ORC unwinder to read
  15  * at runtime.
  16  *
  17  * Anything which doesn't fall into the above category, such as syscall and
  18  * interrupt handlers, tends to not be called directly by other functions, and
  19  * often does unusual non-C-function-type things with the stack pointer.  Such
  20  * code needs to be annotated such that objtool can understand it.  The
  21  * following CFI hint macros are for this type of code.
  22  *
  23  * These macros provide hints to objtool about the state of the stack at each
  24  * instruction.  Objtool starts from the hints and follows the code flow,
  25  * making automatic CFI adjustments when it sees pushes and pops, filling out
  26  * the debuginfo as necessary.  It will also warn if it sees any
  27  * inconsistencies.
  28  */
  29 .macro UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=0 type=ORC_TYPE_CALL
  30 #ifdef CONFIG_STACK_VALIDATION
  31 .Lunwind_hint_ip_\@:
  32         .pushsection .discard.unwind_hints
  33                 /* struct unwind_hint */
  34                 .long .Lunwind_hint_ip_\@ - .
  35                 .short \sp_offset
  36                 .byte \sp_reg
  37                 .byte \type
  38         .popsection
  39 #endif
  40 .endm
  41
  42 .macro UNWIND_HINT_EMPTY
  43         UNWIND_HINT sp_reg=ORC_REG_UNDEFINED
  44 .endm
  45
  46 .macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 iret=0
  47         .if \base == %rsp
  48                 .if \indirect
  49                         .set sp_reg, ORC_REG_SP_INDIRECT
  50                 .else
  51                         .set sp_reg, ORC_REG_SP
  52                 .endif
  53         .elseif \base == %rbp
  54                 .set sp_reg, ORC_REG_BP
  55         .elseif \base == %rdi
  56                 .set sp_reg, ORC_REG_DI
  57         .elseif \base == %rdx
  58                 .set sp_reg, ORC_REG_DX
  59         .elseif \base == %r10
  60                 .set sp_reg, ORC_REG_R10
  61         .else
  62                 .error "UNWIND_HINT_REGS: bad base register"
  63         .endif
  64
  65         .set sp_offset, \offset
  66
  67         .if \iret
  68                 .set type, ORC_TYPE_REGS_IRET
  69         .elseif \extra == 0
  70                 .set type, ORC_TYPE_REGS_IRET
  71                 .set sp_offset, \offset + (16*8)
  72         .else
  73                 .set type, ORC_TYPE_REGS
  74         .endif
  75
  76         UNWIND_HINT sp_reg=sp_reg sp_offset=sp_offset type=type
  77 .endm
  78
  79 .macro UNWIND_HINT_IRET_REGS base=%rsp offset=0
  80         UNWIND_HINT_REGS base=\base offset=\offset iret=1
  81 .endm
  82
  83 .macro UNWIND_HINT_FUNC sp_offset=8
  84         UNWIND_HINT sp_offset=\sp_offset
  85 .endm
  86
  87 #else /* !__ASSEMBLY__ */
  88
  89 #define UNWIND_HINT(sp_reg, sp_offset, type)                    \
  90         "987: \n\t"                                             \
  91         ".pushsection .discard.unwind_hints\n\t"                \
  92         /* struct unwind_hint */                                \
  93         ".long 987b - .\n\t"                                    \
  94         ".short " __stringify(sp_offset) "\n\t"         \
  95         ".byte " __stringify(sp_reg) "\n\t"                     \
  96         ".byte " __stringify(type) "\n\t"                       \
  97         ".popsection\n\t"
  98
  99 #define UNWIND_HINT_SAVE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_SAVE)
 100
 101 #define UNWIND_HINT_RESTORE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_RESTORE)
 102
 103 #endif /* __ASSEMBLY__ */
 104
 105 #endif /* _ASM_X86_UNWIND_HINTS_H */