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Subject[tip:x86/asm] x86-64, copy_user: Use leal to produce 32-bit results
Commit-ID:  661c80192d21269c7fc566f1d547510b0c867677
Gitweb: http://git.kernel.org/tip/661c80192d21269c7fc566f1d547510b0c867677
Author: H. Peter Anvin <hpa@linux.intel.com>
AuthorDate: Wed, 20 Nov 2013 12:50:51 -0800
Committer: H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Wed, 20 Nov 2013 13:57:07 -0800

x86-64, copy_user: Use leal to produce 32-bit results

When we are using lea to produce a 32-bit result, we can use the leal
form, rather than using leaq and worry about truncation elsewhere.

Make the leal explicit, both to be more obvious and since that is what
gcc generates and thus is less likely to trigger obscure gas bugs.

Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1384634221-6006-1-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
arch/x86/lib/copy_user_64.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index ffe4eb9..dee945d 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -186,7 +186,7 @@ ENTRY(copy_user_generic_unrolled)
30: shll $6,%ecx
addl %ecx,%edx
jmp 60f
-40: lea (%rdx,%rcx,8),%rdx
+40: leal (%rdx,%rcx,8),%edx
jmp 60f
50: movl %ecx,%edx
60: jmp copy_user_handle_tail /* ecx is zerorest also */
@@ -252,7 +252,7 @@ ENTRY(copy_user_generic_string)
ret

.section .fixup,"ax"
-11: lea (%rdx,%rcx,8),%rcx
+11: leal (%rdx,%rcx,8),%ecx
12: movl %ecx,%edx /* ecx is zerorest also */
jmp copy_user_handle_tail
.previous

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