arch/x86/include/asm/frame.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_FRAME_H
   3 #define _ASM_X86_FRAME_H
   4
   5 #include <asm/asm.h>
   6
   7 /*
   8  * These are stack frame creation macros.  They should be used by every
   9  * callable non-leaf asm function to make kernel stack traces more reliable.
  10  */
  11
  12 #ifdef CONFIG_FRAME_POINTER
  13
  14 #ifdef __ASSEMBLY__
  15
  16 .macro FRAME_BEGIN
  17         push %_ASM_BP
  18         _ASM_MOV %_ASM_SP, %_ASM_BP
  19 .endm
  20
  21 .macro FRAME_END
  22         pop %_ASM_BP
  23 .endm
  24
  25 #ifdef CONFIG_X86_64
  26 /*
  27  * This is a sneaky trick to help the unwinder find pt_regs on the stack.  The
  28  * frame pointer is replaced with an encoded pointer to pt_regs.  The encoding
  29  * is just setting the LSB, which makes it an invalid stack address and is also
  30  * a signal to the unwinder that it's a pt_regs pointer in disguise.
  31  *
  32  * NOTE: This macro must be used *after* PUSH_AND_CLEAR_REGS because it corrupts
  33  * the original rbp.
  34  */
  35 .macro ENCODE_FRAME_POINTER ptregs_offset=0
  36         leaq 1+\ptregs_offset(%rsp), %rbp
  37 .endm
  38 #else /* !CONFIG_X86_64 */
  39 /*
  40  * This is a sneaky trick to help the unwinder find pt_regs on the stack.  The
  41  * frame pointer is replaced with an encoded pointer to pt_regs.  The encoding
  42  * is just clearing the MSB, which makes it an invalid stack address and is also
  43  * a signal to the unwinder that it's a pt_regs pointer in disguise.
  44  *
  45  * NOTE: This macro must be used *after* SAVE_ALL because it corrupts the
  46  * original ebp.
  47  */
  48 .macro ENCODE_FRAME_POINTER
  49         mov %esp, %ebp
  50         andl $0x7fffffff, %ebp
  51 .endm
  52 #endif /* CONFIG_X86_64 */
  53
  54 #else /* !__ASSEMBLY__ */
  55
  56 #define FRAME_BEGIN                             \
  57         "push %" _ASM_BP "\n"                   \
  58         _ASM_MOV "%" _ASM_SP ", %" _ASM_BP "\n"
  59
  60 #define FRAME_END "pop %" _ASM_BP "\n"
  61
  62 #ifdef CONFIG_X86_64
  63
  64 #define ENCODE_FRAME_POINTER                    \
  65         "lea 1(%rsp), %rbp\n\t"
  66
  67 static inline unsigned long encode_frame_pointer(struct pt_regs *regs)
  68 {
  69         return (unsigned long)regs + 1;
  70 }
  71
  72 #else /* !CONFIG_X86_64 */
  73
  74 #define ENCODE_FRAME_POINTER                    \
  75         "movl %esp, %ebp\n\t"                   \
  76         "andl $0x7fffffff, %ebp\n\t"
  77
  78 static inline unsigned long encode_frame_pointer(struct pt_regs *regs)
  79 {
  80         return (unsigned long)regs & 0x7fffffff;
  81 }
  82
  83 #endif /* CONFIG_X86_64 */
  84
  85 #endif /* __ASSEMBLY__ */
  86
  87 #define FRAME_OFFSET __ASM_SEL(4, 8)
  88
  89 #else /* !CONFIG_FRAME_POINTER */
  90
  91 #ifdef __ASSEMBLY__
  92
  93 .macro ENCODE_FRAME_POINTER ptregs_offset=0
  94 .endm
  95
  96 #else /* !__ASSEMBLY */
  97
  98 #define ENCODE_FRAME_POINTER
  99
 100 static inline unsigned long encode_frame_pointer(struct pt_regs *regs)
 101 {
 102         return 0;
 103 }
 104
 105 #endif
 106
 107 #define FRAME_BEGIN
 108 #define FRAME_END
 109 #define FRAME_OFFSET 0
 110
 111 #endif /* CONFIG_FRAME_POINTER */
 112
 113 #endif /* _ASM_X86_FRAME_H */