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42fc6c6cb1
Andrey Konovalov reported the following warning while fuzzing the kernel with syzkaller: WARNING: kernel stack regs at ffff8800686869f8 in a.out:4933 has bad 'bp' value c3fc855a10167ec0 The unwinder dump revealed that RBP had a bad value when an interrupt occurred in csum_partial_copy_generic(). That function saves RBP on the stack and then overwrites it, using it as a scratch register. That's problematic because it breaks stack traces if an interrupt occurs in the middle of the function. Replace the usage of RBP with another callee-saved register (R15) so stack traces are no longer affected. Reported-by: Andrey Konovalov <andreyknvl@google.com> Tested-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: David S . Miller <davem@davemloft.net> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlad Yasevich <vyasevich@gmail.com> Cc: linux-sctp@vger.kernel.org Cc: netdev <netdev@vger.kernel.org> Cc: syzkaller <syzkaller@googlegroups.com> Link: http://lkml.kernel.org/r/4b03a961efda5ec9bfe46b7b9c9ad72d1efad343.1493909486.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
225 lines
3.7 KiB
ArmAsm
225 lines
3.7 KiB
ArmAsm
/*
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* Copyright 2002, 2003 Andi Kleen, SuSE Labs.
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of this archive
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* for more details. No warranty for anything given at all.
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*/
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#include <linux/linkage.h>
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#include <asm/errno.h>
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#include <asm/asm.h>
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/*
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* Checksum copy with exception handling.
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* On exceptions src_err_ptr or dst_err_ptr is set to -EFAULT and the
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* destination is zeroed.
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*
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* Input
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* rdi source
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* rsi destination
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* edx len (32bit)
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* ecx sum (32bit)
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* r8 src_err_ptr (int)
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* r9 dst_err_ptr (int)
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*
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* Output
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* eax 64bit sum. undefined in case of exception.
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*
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* Wrappers need to take care of valid exception sum and zeroing.
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* They also should align source or destination to 8 bytes.
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*/
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.macro source
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10:
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_ASM_EXTABLE(10b, .Lbad_source)
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.endm
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.macro dest
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20:
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_ASM_EXTABLE(20b, .Lbad_dest)
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.endm
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.macro ignore L=.Lignore
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30:
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_ASM_EXTABLE(30b, \L)
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.endm
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ENTRY(csum_partial_copy_generic)
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cmpl $3*64, %edx
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jle .Lignore
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.Lignore:
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subq $7*8, %rsp
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movq %rbx, 2*8(%rsp)
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movq %r12, 3*8(%rsp)
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movq %r14, 4*8(%rsp)
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movq %r13, 5*8(%rsp)
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movq %r15, 6*8(%rsp)
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movq %r8, (%rsp)
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movq %r9, 1*8(%rsp)
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movl %ecx, %eax
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movl %edx, %ecx
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xorl %r9d, %r9d
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movq %rcx, %r12
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shrq $6, %r12
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jz .Lhandle_tail /* < 64 */
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clc
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/* main loop. clear in 64 byte blocks */
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/* r9: zero, r8: temp2, rbx: temp1, rax: sum, rcx: saved length */
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/* r11: temp3, rdx: temp4, r12 loopcnt */
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/* r10: temp5, r15: temp6, r14 temp7, r13 temp8 */
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.p2align 4
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.Lloop:
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source
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movq (%rdi), %rbx
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source
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movq 8(%rdi), %r8
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source
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movq 16(%rdi), %r11
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source
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movq 24(%rdi), %rdx
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source
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movq 32(%rdi), %r10
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source
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movq 40(%rdi), %r15
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source
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movq 48(%rdi), %r14
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source
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movq 56(%rdi), %r13
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ignore 2f
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prefetcht0 5*64(%rdi)
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2:
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adcq %rbx, %rax
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adcq %r8, %rax
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adcq %r11, %rax
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adcq %rdx, %rax
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adcq %r10, %rax
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adcq %r15, %rax
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adcq %r14, %rax
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adcq %r13, %rax
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decl %r12d
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dest
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movq %rbx, (%rsi)
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dest
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movq %r8, 8(%rsi)
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dest
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movq %r11, 16(%rsi)
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dest
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movq %rdx, 24(%rsi)
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dest
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movq %r10, 32(%rsi)
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dest
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movq %r15, 40(%rsi)
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dest
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movq %r14, 48(%rsi)
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dest
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movq %r13, 56(%rsi)
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3:
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leaq 64(%rdi), %rdi
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leaq 64(%rsi), %rsi
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jnz .Lloop
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adcq %r9, %rax
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/* do last up to 56 bytes */
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.Lhandle_tail:
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/* ecx: count */
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movl %ecx, %r10d
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andl $63, %ecx
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shrl $3, %ecx
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jz .Lfold
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clc
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.p2align 4
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.Lloop_8:
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source
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movq (%rdi), %rbx
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adcq %rbx, %rax
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decl %ecx
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dest
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movq %rbx, (%rsi)
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leaq 8(%rsi), %rsi /* preserve carry */
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leaq 8(%rdi), %rdi
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jnz .Lloop_8
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adcq %r9, %rax /* add in carry */
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.Lfold:
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/* reduce checksum to 32bits */
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movl %eax, %ebx
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shrq $32, %rax
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addl %ebx, %eax
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adcl %r9d, %eax
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/* do last up to 6 bytes */
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.Lhandle_7:
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movl %r10d, %ecx
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andl $7, %ecx
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shrl $1, %ecx
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jz .Lhandle_1
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movl $2, %edx
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xorl %ebx, %ebx
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clc
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.p2align 4
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.Lloop_1:
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source
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movw (%rdi), %bx
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adcl %ebx, %eax
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decl %ecx
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dest
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movw %bx, (%rsi)
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leaq 2(%rdi), %rdi
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leaq 2(%rsi), %rsi
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jnz .Lloop_1
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adcl %r9d, %eax /* add in carry */
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/* handle last odd byte */
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.Lhandle_1:
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testb $1, %r10b
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jz .Lende
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xorl %ebx, %ebx
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source
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movb (%rdi), %bl
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dest
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movb %bl, (%rsi)
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addl %ebx, %eax
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adcl %r9d, %eax /* carry */
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.Lende:
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movq 2*8(%rsp), %rbx
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movq 3*8(%rsp), %r12
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movq 4*8(%rsp), %r14
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movq 5*8(%rsp), %r13
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movq 6*8(%rsp), %r15
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addq $7*8, %rsp
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ret
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/* Exception handlers. Very simple, zeroing is done in the wrappers */
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.Lbad_source:
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movq (%rsp), %rax
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testq %rax, %rax
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jz .Lende
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movl $-EFAULT, (%rax)
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jmp .Lende
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.Lbad_dest:
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movq 8(%rsp), %rax
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testq %rax, %rax
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jz .Lende
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movl $-EFAULT, (%rax)
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jmp .Lende
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ENDPROC(csum_partial_copy_generic)
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