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x86: change testing logic in putuser_64.S.

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Instead of operating over a register we need to put back
into normal state afterwards (the memory position), just
sub from rbx, which is trashed anyway. We can save a few instructions.

Also, this is the i386 way.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Glauber Costa 2008-06-24 16:51:59 -03:00 committed by Ingo Molnar
parent 0ada316403
commit 663aa96df3
1 changed files with 12 additions and 21 deletions
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33
arch/x86/lib/putuser_64.S
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@ -46,48 +46,39 @@ ENDPROC(__put_user_1)
ENTRY(__put_user_2)
CFI_STARTPROC
GET_THREAD_INFO(%rbx)
addq $1,%rcx
jc 20f
cmpq TI_addr_limit(%rbx),%rcx
jae 20f
decq %rcx
mov TI_addr_limit(%rbx),%rbx
sub $1, %rbx
cmpq %rbx ,%rcx
jae bad_put_user
2: movw %ax,(%rcx)
xorl %eax,%eax
ret
20: decq %rcx
jmp bad_put_user
CFI_ENDPROC
ENDPROC(__put_user_2)
ENTRY(__put_user_4)
CFI_STARTPROC
GET_THREAD_INFO(%rbx)
addq $3,%rcx
jc 30f
cmpq TI_addr_limit(%rbx),%rcx
jae 30f
subq $3,%rcx
mov TI_addr_limit(%rbx),%rbx
sub $3, %rbx
cmp %rbx, %rcx
jae bad_put_user
3: movl %eax,(%rcx)
xorl %eax,%eax
ret
30: subq $3,%rcx
jmp bad_put_user
CFI_ENDPROC
ENDPROC(__put_user_4)
ENTRY(__put_user_8)
CFI_STARTPROC
GET_THREAD_INFO(%rbx)
addq $7,%rcx
jc 40f
cmpq TI_addr_limit(%rbx),%rcx
jae 40f
subq $7,%rcx
mov TI_addr_limit(%rbx),%rbx
sub $7, %rbx
cmp %rbx, %rcx
jae bad_put_user
4: movq %rax,(%rcx)
xorl %eax,%eax
ret
40: subq $7,%rcx
jmp bad_put_user
CFI_ENDPROC
ENDPROC(__put_user_8)