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Subject[PATCH 19/39] change testing logic in putuser_64.S
Date
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>
---
arch/x86/lib/putuser_64.S | 33 ++++++++++++---------------------
1 files changed, 12 insertions(+), 21 deletions(-)
diff --git a/arch/x86/lib/putuser_64.S b/arch/x86/lib/putuser_64.S
index ce5fcd5..a96bd8a 100644
--- a/arch/x86/lib/putuser_64.S
+++ b/arch/x86/lib/putuser_64.S
@@ -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)

--
1.5.5.1


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