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 #define ENCODE_FRAME_POINTER \ 64 "lea 1(%rsp), %rbp\n\t" 65 #else /* !CONFIG_X86_64 */ 66 #define ENCODE_FRAME_POINTER \ 67 "movl %esp, %ebp\n\t" \ 68 "andl $0x7fffffff, %ebp\n\t" 69 #endif /* CONFIG_X86_64 */ 70 71 #endif /* __ASSEMBLY__ */ 72 73 #define FRAME_OFFSET __ASM_SEL(4, 8) 74 75 #else /* !CONFIG_FRAME_POINTER */ 76 77 #ifdef __ASSEMBLY__ 78 79 .macro ENCODE_FRAME_POINTER ptregs_offset=0 80 .endm 81 82 #else /* !__ASSEMBLY */ 83 84 #define ENCODE_FRAME_POINTER 85 86 #endif 87 88 #define FRAME_BEGIN 89 #define FRAME_END 90 #define FRAME_OFFSET 0 91 92 #endif /* CONFIG_FRAME_POINTER */ 93 94 #endif /* _ASM_X86_FRAME_H */ 95