Commit 661c8019 authored Nov 20, 2013 by H. Peter Anvin

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>

parent f4cb1cc1

arch/x86/lib/copy_user_64.S

+2 −2

Original line number	Diff line number	Diff line
		@@ -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