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1a338ac32c
Remove the bloat of the C calling convention out of the
preempt_enable() sites by creating an ASM wrapper which allows us to
do an asm("call ___preempt_schedule") instead.
calling.h bits by Andi Kleen
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-tk7xdi1cvvxewixzke8t8le1@git.kernel.org
[ Fixed build error. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
245 lines
5.9 KiB
C
245 lines
5.9 KiB
C
/*
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x86 function call convention, 64-bit:
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-------------------------------------
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arguments | callee-saved | extra caller-saved | return
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[callee-clobbered] | | [callee-clobbered] |
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---------------------------------------------------------------------------
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rdi rsi rdx rcx r8-9 | rbx rbp [*] r12-15 | r10-11 | rax, rdx [**]
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( rsp is obviously invariant across normal function calls. (gcc can 'merge'
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functions when it sees tail-call optimization possibilities) rflags is
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clobbered. Leftover arguments are passed over the stack frame.)
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[*] In the frame-pointers case rbp is fixed to the stack frame.
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[**] for struct return values wider than 64 bits the return convention is a
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bit more complex: up to 128 bits width we return small structures
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straight in rax, rdx. For structures larger than that (3 words or
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larger) the caller puts a pointer to an on-stack return struct
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[allocated in the caller's stack frame] into the first argument - i.e.
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into rdi. All other arguments shift up by one in this case.
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Fortunately this case is rare in the kernel.
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For 32-bit we have the following conventions - kernel is built with
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-mregparm=3 and -freg-struct-return:
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x86 function calling convention, 32-bit:
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----------------------------------------
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arguments | callee-saved | extra caller-saved | return
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[callee-clobbered] | | [callee-clobbered] |
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-------------------------------------------------------------------------
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eax edx ecx | ebx edi esi ebp [*] | <none> | eax, edx [**]
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( here too esp is obviously invariant across normal function calls. eflags
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is clobbered. Leftover arguments are passed over the stack frame. )
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[*] In the frame-pointers case ebp is fixed to the stack frame.
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[**] We build with -freg-struct-return, which on 32-bit means similar
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semantics as on 64-bit: edx can be used for a second return value
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(i.e. covering integer and structure sizes up to 64 bits) - after that
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it gets more complex and more expensive: 3-word or larger struct returns
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get done in the caller's frame and the pointer to the return struct goes
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into regparm0, i.e. eax - the other arguments shift up and the
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function's register parameters degenerate to regparm=2 in essence.
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*/
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#include <asm/dwarf2.h>
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#ifdef CONFIG_X86_64
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/*
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* 64-bit system call stack frame layout defines and helpers,
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* for assembly code:
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*/
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#define R15 0
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#define R14 8
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#define R13 16
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#define R12 24
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#define RBP 32
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#define RBX 40
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/* arguments: interrupts/non tracing syscalls only save up to here: */
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#define R11 48
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#define R10 56
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#define R9 64
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#define R8 72
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#define RAX 80
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#define RCX 88
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#define RDX 96
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#define RSI 104
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#define RDI 112
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#define ORIG_RAX 120 /* + error_code */
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/* end of arguments */
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/* cpu exception frame or undefined in case of fast syscall: */
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#define RIP 128
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#define CS 136
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#define EFLAGS 144
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#define RSP 152
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#define SS 160
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#define ARGOFFSET R11
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#define SWFRAME ORIG_RAX
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.macro SAVE_ARGS addskip=0, save_rcx=1, save_r891011=1
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subq $9*8+\addskip, %rsp
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CFI_ADJUST_CFA_OFFSET 9*8+\addskip
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movq_cfi rdi, 8*8
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movq_cfi rsi, 7*8
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movq_cfi rdx, 6*8
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.if \save_rcx
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movq_cfi rcx, 5*8
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.endif
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movq_cfi rax, 4*8
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.if \save_r891011
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movq_cfi r8, 3*8
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movq_cfi r9, 2*8
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movq_cfi r10, 1*8
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movq_cfi r11, 0*8
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.endif
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.endm
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#define ARG_SKIP (9*8)
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.macro RESTORE_ARGS rstor_rax=1, addskip=0, rstor_rcx=1, rstor_r11=1, \
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rstor_r8910=1, rstor_rdx=1
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.if \rstor_r11
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movq_cfi_restore 0*8, r11
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.endif
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.if \rstor_r8910
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movq_cfi_restore 1*8, r10
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movq_cfi_restore 2*8, r9
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movq_cfi_restore 3*8, r8
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.endif
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.if \rstor_rax
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movq_cfi_restore 4*8, rax
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.endif
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.if \rstor_rcx
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movq_cfi_restore 5*8, rcx
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.endif
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.if \rstor_rdx
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movq_cfi_restore 6*8, rdx
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.endif
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movq_cfi_restore 7*8, rsi
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movq_cfi_restore 8*8, rdi
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.if ARG_SKIP+\addskip > 0
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addq $ARG_SKIP+\addskip, %rsp
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CFI_ADJUST_CFA_OFFSET -(ARG_SKIP+\addskip)
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.endif
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.endm
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.macro LOAD_ARGS offset, skiprax=0
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movq \offset(%rsp), %r11
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movq \offset+8(%rsp), %r10
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movq \offset+16(%rsp), %r9
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movq \offset+24(%rsp), %r8
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movq \offset+40(%rsp), %rcx
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movq \offset+48(%rsp), %rdx
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movq \offset+56(%rsp), %rsi
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movq \offset+64(%rsp), %rdi
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.if \skiprax
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.else
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movq \offset+72(%rsp), %rax
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.endif
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.endm
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#define REST_SKIP (6*8)
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.macro SAVE_REST
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subq $REST_SKIP, %rsp
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CFI_ADJUST_CFA_OFFSET REST_SKIP
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movq_cfi rbx, 5*8
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movq_cfi rbp, 4*8
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movq_cfi r12, 3*8
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movq_cfi r13, 2*8
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movq_cfi r14, 1*8
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movq_cfi r15, 0*8
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.endm
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.macro RESTORE_REST
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movq_cfi_restore 0*8, r15
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movq_cfi_restore 1*8, r14
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movq_cfi_restore 2*8, r13
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movq_cfi_restore 3*8, r12
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movq_cfi_restore 4*8, rbp
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movq_cfi_restore 5*8, rbx
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addq $REST_SKIP, %rsp
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CFI_ADJUST_CFA_OFFSET -(REST_SKIP)
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.endm
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.macro SAVE_ALL
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SAVE_ARGS
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SAVE_REST
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.endm
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.macro RESTORE_ALL addskip=0
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RESTORE_REST
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RESTORE_ARGS 1, \addskip
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.endm
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.macro icebp
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.byte 0xf1
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.endm
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#else /* CONFIG_X86_64 */
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/*
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* For 32bit only simplified versions of SAVE_ALL/RESTORE_ALL. These
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* are different from the entry_32.S versions in not changing the segment
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* registers. So only suitable for in kernel use, not when transitioning
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* from or to user space. The resulting stack frame is not a standard
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* pt_regs frame. The main use case is calling C code from assembler
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* when all the registers need to be preserved.
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*/
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.macro SAVE_ALL
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pushl_cfi %eax
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CFI_REL_OFFSET eax, 0
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pushl_cfi %ebp
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CFI_REL_OFFSET ebp, 0
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pushl_cfi %edi
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CFI_REL_OFFSET edi, 0
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pushl_cfi %esi
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CFI_REL_OFFSET esi, 0
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pushl_cfi %edx
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CFI_REL_OFFSET edx, 0
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pushl_cfi %ecx
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CFI_REL_OFFSET ecx, 0
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pushl_cfi %ebx
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CFI_REL_OFFSET ebx, 0
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.endm
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.macro RESTORE_ALL
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popl_cfi %ebx
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CFI_RESTORE ebx
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popl_cfi %ecx
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CFI_RESTORE ecx
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popl_cfi %edx
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CFI_RESTORE edx
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popl_cfi %esi
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CFI_RESTORE esi
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popl_cfi %edi
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CFI_RESTORE edi
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popl_cfi %ebp
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CFI_RESTORE ebp
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popl_cfi %eax
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CFI_RESTORE eax
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.endm
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#endif /* CONFIG_X86_64 */
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