diff options
Diffstat (limited to 'arch/x86/entry/calling.h')
| -rw-r--r-- | arch/x86/entry/calling.h | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 9a9e5884066c..05ed3d393da7 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -90,8 +90,8 @@ For 32-bit we have the following conventions - kernel is built with #define SIZEOF_PTREGS 21*8 - .macro ALLOC_PT_GPREGS_ON_STACK addskip=0 - addq $-(15*8+\addskip), %rsp + .macro ALLOC_PT_GPREGS_ON_STACK + addq $-(15*8), %rsp .endm .macro SAVE_C_REGS_HELPER offset=0 rax=1 rcx=1 r8910=1 r11=1 @@ -147,15 +147,6 @@ For 32-bit we have the following conventions - kernel is built with movq 5*8+\offset(%rsp), %rbx .endm - .macro ZERO_EXTRA_REGS - xorl %r15d, %r15d - xorl %r14d, %r14d - xorl %r13d, %r13d - xorl %r12d, %r12d - xorl %ebp, %ebp - xorl %ebx, %ebx - .endm - .macro RESTORE_C_REGS_HELPER rstor_rax=1, rstor_rcx=1, rstor_r11=1, rstor_r8910=1, rstor_rdx=1 .if \rstor_r11 movq 6*8(%rsp), %r11 @@ -201,6 +192,26 @@ For 32-bit we have the following conventions - kernel is built with .byte 0xf1 .endm +/* + * This is a sneaky trick to help the unwinder find pt_regs on the stack. The + * frame pointer is replaced with an encoded pointer to pt_regs. The encoding + * is just setting the LSB, which makes it an invalid stack address and is also + * a signal to the unwinder that it's a pt_regs pointer in disguise. + * + * NOTE: This macro must be used *after* SAVE_EXTRA_REGS because it corrupts + * the original rbp. + */ +.macro ENCODE_FRAME_POINTER ptregs_offset=0 +#ifdef CONFIG_FRAME_POINTER + .if \ptregs_offset + leaq \ptregs_offset(%rsp), %rbp + .else + mov %rsp, %rbp + .endif + orq $0x1, %rbp +#endif +.endm + #endif /* CONFIG_X86_64 */ /* |