From patchwork Thu Feb 11 21:24:17 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kani, Toshi" X-Patchwork-Id: 8284891 Return-Path: X-Original-To: patchwork-linux-nvdimm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id E7772BEEE5 for ; Thu, 11 Feb 2016 20:31:23 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id F390C20380 for ; Thu, 11 Feb 2016 20:31:22 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 10D6E20364 for ; Thu, 11 Feb 2016 20:31:22 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 068621A1DF4; Thu, 11 Feb 2016 12:31:22 -0800 (PST) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received: from g9t5008.houston.hp.com (g9t5008.houston.hp.com [15.240.92.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id DEDAD1A1DF5 for ; Thu, 11 Feb 2016 12:31:18 -0800 (PST) Received: from g9t2301.houston.hp.com (g9t2301.houston.hp.com [16.216.185.78]) by g9t5008.houston.hp.com (Postfix) with ESMTP id C79A84E; Thu, 11 Feb 2016 20:31:17 +0000 (UTC) Received: from misato.fc.hp.com (misato.fc.hp.com [16.78.168.61]) by g9t2301.houston.hp.com (Postfix) with ESMTP id D03DA50; Thu, 11 Feb 2016 20:31:16 +0000 (UTC) From: Toshi Kani To: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, bp@suse.de, dan.j.williams@intel.com Subject: [PATCH v3 2/2] x86/lib/copy_user_64.S: Handle 4-byte nocache copy Date: Thu, 11 Feb 2016 14:24:17 -0700 Message-Id: <1455225857-12039-3-git-send-email-toshi.kani@hpe.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1455225857-12039-1-git-send-email-toshi.kani@hpe.com> References: <1455225857-12039-1-git-send-email-toshi.kani@hpe.com> Cc: linux-nvdimm@lists.01.org, x86@kernel.org, linux-kernel@vger.kernel.org, micah.parrish@hpe.com, brian.boylston@hpe.com X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Data corruption issues were observed in tests which initiated a system crash/reset while accessing BTT devices. This problem is reproducible. The BTT driver calls pmem_rw_bytes() to update data in pmem devices. This interface calls __copy_user_nocache(), which uses non-temporal stores so that the stores to pmem are persistent. __copy_user_nocache() uses non-temporal stores when a request size is 8 bytes or larger (and is aligned by 8 bytes). The BTT driver updates the BTT map table, which entry size is 4 bytes. Therefore, updates to the map table entries remain cached, and are not written to pmem after a crash. Change __copy_user_nocache() to use non-temporal store when a request size is 4 bytes. The change extends the current byte-copy path for a less-than-8-bytes request, and does not add any overhead to the regular path. Reported-and-tested-by: Micah Parrish Reported-and-tested-by: Brian Boylston Signed-off-by: Toshi Kani Cc: Thomas Gleixner Cc: Ingo Molnar Cc: H. Peter Anvin Cc: Borislav Petkov Cc: Dan Williams Cc: Ross Zwisler Cc: Vishal Verma --- arch/x86/lib/copy_user_64.S | 36 ++++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-) diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S index 23042ff..9228ce6 100644 --- a/arch/x86/lib/copy_user_64.S +++ b/arch/x86/lib/copy_user_64.S @@ -237,13 +237,14 @@ ENDPROC(copy_user_enhanced_fast_string) * Note: Cached memory copy is used when destination or size is not * naturally aligned. That is: * - Require 8-byte alignment when size is 8 bytes or larger. + * - Require 4-byte alignment when size is 4 bytes. */ ENTRY(__copy_user_nocache) ASM_STAC - /* If size is less than 8 bytes, goto byte copy */ + /* If size is less than 8 bytes, goto 4-byte copy */ cmpl $8,%edx - jb .Lcun_1b_cache_copy_entry + jb .Lcun_4b_nocache_copy_entry /* If destination is not 8-byte aligned, "cache" copy to align it */ ALIGN_DESTINATION @@ -282,7 +283,7 @@ ENTRY(__copy_user_nocache) movl %edx,%ecx andl $7,%edx shrl $3,%ecx - jz .Lcun_1b_cache_copy_entry /* jump if count is 0 */ + jz .Lcun_4b_nocache_copy_entry /* jump if count is 0 */ /* Perform 8-byte nocache loop-copy */ .Lcun_8b_nocache_copy_loop: @@ -294,11 +295,33 @@ ENTRY(__copy_user_nocache) jnz .Lcun_8b_nocache_copy_loop /* If no byte left, we're done */ -.Lcun_1b_cache_copy_entry: +.Lcun_4b_nocache_copy_entry: + andl %edx,%edx + jz .Lcun_finish_copy + + /* If destination is not 4-byte aligned, goto byte copy */ + movl %edi,%ecx + andl $3,%ecx + jnz .Lcun_1b_cache_copy_entry + + /* Set 4-byte copy count (1 or 0) and remainder */ + movl %edx,%ecx + andl $3,%edx + shrl $2,%ecx + jz .Lcun_1b_cache_copy_entry /* jump if count is 0 */ + + /* Perform 4-byte nocache copy */ +30: movl (%rsi),%r8d +31: movnti %r8d,(%rdi) + leaq 4(%rsi),%rsi + leaq 4(%rdi),%rdi + + /* If no byte left, we're done */ andl %edx,%edx jz .Lcun_finish_copy /* Perform byte "cache" loop-copy for the remainder */ +.Lcun_1b_cache_copy_entry: movl %edx,%ecx .Lcun_1b_cache_copy_loop: 40: movb (%rsi),%al @@ -323,6 +346,9 @@ ENTRY(__copy_user_nocache) .Lcun_fixup_8b_copy: lea (%rdx,%rcx,8),%rdx jmp .Lcun_fixup_handle_tail +.Lcun_fixup_4b_copy: + lea (%rdx,%rcx,4),%rdx + jmp .Lcun_fixup_handle_tail .Lcun_fixup_1b_copy: movl %ecx,%edx .Lcun_fixup_handle_tail: @@ -348,6 +374,8 @@ ENTRY(__copy_user_nocache) _ASM_EXTABLE(16b,.Lcun_fixup_4x8b_copy) _ASM_EXTABLE(20b,.Lcun_fixup_8b_copy) _ASM_EXTABLE(21b,.Lcun_fixup_8b_copy) + _ASM_EXTABLE(30b,.Lcun_fixup_4b_copy) + _ASM_EXTABLE(31b,.Lcun_fixup_4b_copy) _ASM_EXTABLE(40b,.Lcun_fixup_1b_copy) _ASM_EXTABLE(41b,.Lcun_fixup_1b_copy) ENDPROC(__copy_user_nocache)