From: "Jan Beulich" <JBeulich@suse.com>
To: <mingo@elte.hu>, <tglx@linutronix.de>, <hpa@zytor.com>
Cc: <linux-kernel@vger.kernel.org>
Subject: [PATCH] x86-64: fix memcpy() to support sizes of 4Gb and above
Date: Thu, 26 Jan 2012 15:50:55 +0000 [thread overview]
Message-ID: <4F21846F020000780006F3FA@nat28.tlf.novell.com> (raw)
While currently there doesn't appear to be any reachable in-tree case
where such large memory blocks may be passed to memcpy(), we already
had hit the problem in our Xen kernels. Just like done recently for
mmeset(), rather than working around it, prevent others from falling
into the same trap by fixing this long standing limitation.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
arch/x86/lib/memcpy_64.S | 25 ++++++++++---------------
1 file changed, 10 insertions(+), 15 deletions(-)
--- 3.3-rc1/arch/x86/lib/memcpy_64.S
+++ 3.3-rc1-x86_64-memcpy/arch/x86/lib/memcpy_64.S
@@ -27,9 +27,8 @@
.section .altinstr_replacement, "ax", @progbits
.Lmemcpy_c:
movq %rdi, %rax
-
- movl %edx, %ecx
- shrl $3, %ecx
+ movq %rdx, %rcx
+ shrq $3, %rcx
andl $7, %edx
rep movsq
movl %edx, %ecx
@@ -48,8 +47,7 @@
.section .altinstr_replacement, "ax", @progbits
.Lmemcpy_c_e:
movq %rdi, %rax
-
- movl %edx, %ecx
+ movq %rdx, %rcx
rep movsb
ret
.Lmemcpy_e_e:
@@ -60,10 +58,7 @@ ENTRY(memcpy)
CFI_STARTPROC
movq %rdi, %rax
- /*
- * Use 32bit CMP here to avoid long NOP padding.
- */
- cmp $0x20, %edx
+ cmpq $0x20, %rdx
jb .Lhandle_tail
/*
@@ -72,7 +67,7 @@ ENTRY(memcpy)
*/
cmp %dil, %sil
jl .Lcopy_backward
- subl $0x20, %edx
+ subq $0x20, %rdx
.Lcopy_forward_loop:
subq $0x20, %rdx
@@ -91,7 +86,7 @@ ENTRY(memcpy)
movq %r11, 3*8(%rdi)
leaq 4*8(%rdi), %rdi
jae .Lcopy_forward_loop
- addq $0x20, %rdx
+ addl $0x20, %edx
jmp .Lhandle_tail
.Lcopy_backward:
@@ -123,11 +118,11 @@ ENTRY(memcpy)
/*
* Calculate copy position to head.
*/
- addq $0x20, %rdx
+ addl $0x20, %edx
subq %rdx, %rsi
subq %rdx, %rdi
.Lhandle_tail:
- cmpq $16, %rdx
+ cmpl $16, %edx
jb .Lless_16bytes
/*
@@ -144,7 +139,7 @@ ENTRY(memcpy)
retq
.p2align 4
.Lless_16bytes:
- cmpq $8, %rdx
+ cmpl $8, %edx
jb .Lless_8bytes
/*
* Move data from 8 bytes to 15 bytes.
@@ -156,7 +151,7 @@ ENTRY(memcpy)
retq
.p2align 4
.Lless_8bytes:
- cmpq $4, %rdx
+ cmpl $4, %edx
jb .Lless_3bytes
/*
next reply other threads:[~2012-01-26 15:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-26 15:50 Jan Beulich [this message]
2012-01-26 21:38 ` [tip:x86/asm] x86-64: Fix " tip-bot for Jan Beulich
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