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/* Copyright 2002 Andi Kleen, SuSE Labs.
* Subject to the GNU Public License v2.
*
* Functions to copy from and to user space.
*/
#include <asm/current.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
/* Standard copy_to_user with segment limit checking */
.globl copy_to_user
.p2align 4
copy_to_user:
GET_THREAD_INFO(%rax)
movq %rdi,%rcx
addq %rdx,%rcx
jc bad_to_user
cmpq threadinfo_addr_limit(%rax),%rcx
jae bad_to_user
jmp copy_user_generic
/* Standard copy_from_user with segment limit checking */
.globl copy_from_user
.p2align 4
copy_from_user:
GET_THREAD_INFO(%rax)
movq %rsi,%rcx
addq %rdx,%rcx
jc bad_from_user
cmpq threadinfo_addr_limit(%rax),%rcx
jae bad_from_user
/* FALL THROUGH to copy_user_generic */
.section .fixup,"ax"
/* must zero dest */
bad_from_user:
movl %edx,%ecx
xorl %eax,%eax
rep
stosb
bad_to_user:
movl %edx,%eax
ret
.previous
/*
* copy_user_generic - memory copy with exception handling.
*
* Input:
* rdi destination
* rsi source
* rdx count
*
* Only 4GB of copy is supported. This shouldn't be a problem
* because the kernel normally only writes from/to page sized chunks
* even if user space passed a longer buffer.
* And more would be dangerous because both Intel and AMD have
* errata with rep movsq > 4GB. If someone feels the need to fix
* this please consider this.
*
* Output:
* eax uncopied bytes or 0 if successful.
*/
.globl copy_user_generic
copy_user_generic:
movl %edx,%ecx
shrl $3,%ecx
andl $7,%edx
jz 5f
1: rep
movsq
movl %edx,%ecx
xor %eax,%eax
2: rep
movsb
ret
/* align here? */
5: xorl %eax,%eax
6: rep movsq
ret
.section .fixup,"ax"
3: lea (%rdx,%rcx,8),%rax
ret
4: movl %ecx,%eax
ret
.previous
.section __ex_table,"a"
.quad 1b,3b
.quad 2b,4b
.quad 6b,4b
.previous
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