From patchwork Mon Mar 7 22:34:21 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 594155 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 24D06140C03; Wed, 9 Mar 2016 00:05:16 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1adHK4-0005NZ-M0; Tue, 08 Mar 2016 13:05:12 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1ad3jN-0007Aj-MR for kernel-team@lists.ubuntu.com; Mon, 07 Mar 2016 22:34:25 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1ad3jN-0007UP-1p; Mon, 07 Mar 2016 22:34:25 +0000 Received: from kamal by fourier with local (Exim 4.86) (envelope-from ) id 1ad3jK-0008S7-BG; Mon, 07 Mar 2016 14:34:22 -0800 From: Kamal Mostafa To: Toshi Kani Subject: [4.2.y-ckt stable] Patch "x86/uaccess/64: Handle the caching of 4-byte nocache copies properly in __copy_user_nocache()" has been added to the 4.2.y-ckt tree Date: Mon, 7 Mar 2016 14:34:21 -0800 Message-Id: <1457390061-32456-1-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.0 X-Extended-Stable: 4.2 X-Mailman-Approved-At: Tue, 08 Mar 2016 13:05:01 +0000 Cc: Thomas Gleixner , Denys Vlasenko , Ross Zwisler , linux-nvdimm@lists.01.org, Peter Zijlstra , Brian Gerst , "Luis R . Rodriguez" , Ingo Molnar , Kamal Mostafa , Andy Lutomirski , Vishal Verma , kernel-team@lists.ubuntu.com, Borislav Petkov , "H . Peter Anvin" , Toshi Kani , Andrew Morton , Borislav Petkov , Linus Torvalds , Dan Williams X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled x86/uaccess/64: Handle the caching of 4-byte nocache copies properly in __copy_user_nocache() to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt5. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From e1aa4f7fd1f243f280c9c3fde9d4cbe31e4cc492 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Thu, 11 Feb 2016 14:24:17 -0700 Subject: x86/uaccess/64: Handle the caching of 4-byte nocache copies properly in __copy_user_nocache() commit a82eee7424525e34e98d821dd059ce14560a1e35 upstream. 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: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Dan Williams Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Ross Zwisler Cc: Thomas Gleixner Cc: Toshi Kani Cc: Vishal Verma Cc: linux-nvdimm@lists.01.org Link: http://lkml.kernel.org/r/1455225857-12039-3-git-send-email-toshi.kani@hpe.com [ Small readability edits. ] Signed-off-by: Ingo Molnar Signed-off-by: Kamal Mostafa --- arch/x86/lib/copy_user_64.S | 36 ++++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-) -- 2.7.0 diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S index a644aad..27f89c7 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, go to byte copy */ + /* If size is less than 8 bytes, go to 4-byte copy */ cmpl $8,%edx - jb .L_1b_cache_copy_entry + jb .L_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 .L_1b_cache_copy_entry /* jump if count is 0 */ + jz .L_4b_nocache_copy_entry /* jump if count is 0 */ /* Perform 8-byte nocache loop-copy */ .L_8b_nocache_copy_loop: @@ -294,11 +295,33 @@ ENTRY(__copy_user_nocache) jnz .L_8b_nocache_copy_loop /* If no byte left, we're done */ -.L_1b_cache_copy_entry: +.L_4b_nocache_copy_entry: + andl %edx,%edx + jz .L_finish_copy + + /* If destination is not 4-byte aligned, go to byte copy: */ + movl %edi,%ecx + andl $3,%ecx + jnz .L_1b_cache_copy_entry + + /* Set 4-byte copy count (1 or 0) and remainder */ + movl %edx,%ecx + andl $3,%edx + shrl $2,%ecx + jz .L_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 bytes left, we're done: */ andl %edx,%edx jz .L_finish_copy /* Perform byte "cache" loop-copy for the remainder */ +.L_1b_cache_copy_entry: movl %edx,%ecx .L_1b_cache_copy_loop: 40: movb (%rsi),%al @@ -323,6 +346,9 @@ ENTRY(__copy_user_nocache) .L_fixup_8b_copy: lea (%rdx,%rcx,8),%rdx jmp .L_fixup_handle_tail +.L_fixup_4b_copy: + lea (%rdx,%rcx,4),%rdx + jmp .L_fixup_handle_tail .L_fixup_1b_copy: movl %ecx,%edx .L_fixup_handle_tail: @@ -348,6 +374,8 @@ ENTRY(__copy_user_nocache) _ASM_EXTABLE(16b,.L_fixup_4x8b_copy) _ASM_EXTABLE(20b,.L_fixup_8b_copy) _ASM_EXTABLE(21b,.L_fixup_8b_copy) + _ASM_EXTABLE(30b,.L_fixup_4b_copy) + _ASM_EXTABLE(31b,.L_fixup_4b_copy) _ASM_EXTABLE(40b,.L_fixup_1b_copy) _ASM_EXTABLE(41b,.L_fixup_1b_copy) ENDPROC(__copy_user_nocache)