x86-64: Fix memcpy() to support sizes of 4Gb and above
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>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/4F21846F020000780006F3FA@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index efbf2a0..1235b04 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/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 @@
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 @@
*/
cmp %dil, %sil
jl .Lcopy_backward
- subl $0x20, %edx
+ subq $0x20, %rdx
.Lcopy_forward_loop:
subq $0x20, %rdx
@@ -91,7 +86,7 @@
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 @@
/*
* 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 @@
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 @@
retq
.p2align 4
.Lless_8bytes:
- cmpq $4, %rdx
+ cmpl $4, %edx
jb .Lless_3bytes
/*
