From 2ab560911a427fdc73bfd3a7d2944d8ee0ca6db8 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 26 Jan 2012 15:50:55 +0000 Subject: [PATCH] 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 Cc: Linus Torvalds Link: http://lkml.kernel.org/r/4F21846F020000780006F3FA@nat28.tlf.novell.com Signed-off-by: Ingo Molnar --- arch/x86/lib/memcpy_64.S | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) 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 @@ 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 /* -- 2.7.4