From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752859Ab2AZPtq (ORCPT ); Thu, 26 Jan 2012 10:49:46 -0500 Received: from nat28.tlf.novell.com ([130.57.49.28]:28697 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752326Ab2AZPtp convert rfc822-to-8bit (ORCPT ); Thu, 26 Jan 2012 10:49:45 -0500 Message-Id: <4F21846F020000780006F3FA@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.0 Date: Thu, 26 Jan 2012 15:50:55 +0000 From: "Jan Beulich" To: , , Cc: Subject: [PATCH] x86-64: fix memcpy() to support sizes of 4Gb and above Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 /*