From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-4056489-1516723194-2-14576486767157952418 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='com', MailFrom='org' X-Spam-charsets: X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-api-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1516723193; b=INu78gsQKYSdBRmGAj7DcEhEViDxZwh71ktL+6u9lIWOOLy +JlQkJbRjJtoVfMphVYhj1HeJyV/8+0k+O5xUWnhYlEBZF6OuVR8Qpu6q8A53erY S5w78rI28hrb8Gz5mWKQsavADj8Z9gXyfbCgX0Lj5ck0A4gf6I8lZbYOEI0/qnap LSVLxGwIj9578iqBoARjCmOj5+CwjRIk74REXrsEUMaYYR7i0IS0+O/oppDxS040 DIqca6q7XlCkjsaAKRCtkUHqjt006+DmyA0facmdkNcsuoXsTfecRfHixe0iw2BU 9i9fpIx9iWPYWbow1LtGwU1CyWPv3OHGY1Ukqgw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:sender:list-id; s=arctest; t=1516723193; bh=a6Zz+kgHOhtESJn3YyeCxd4nJGqtN2pxu9zpR/8BzQY=; b=nCBVRP41t58g 4kjYHxmZBBDE14smzu2d4dg8geanodd/EDYP2vohgib1lcl4PbyMH0KD1zyNxuZm DvRowUepD1N4/kXFeC55/k9KGiVaq2/mcXJf2ZgZiYoU3C1ero5BRTBiDpgOsGSH x+8YGSy4txS5dN9PSuTx2dLwIVwAc9U3Dr3R9REi6SKzJ/QmHwIrVl3/Z9uTzVRa Ma9h1cXfR+c4+HLb8WfcaUnmOVzWsMsYkO1i1naXsIoT7ngTlbTgaoEI+YuaKIxD jYW3acj4Q29rujhEsNCDS+yQnp3w2qMbblD1JZRyN3RLjcjs1Xx8hfVbyig3fJsw LkmJC2Ay6g== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=efficios.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=efficios.com header.result=pass header_is_org_domain=yes Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=efficios.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=efficios.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752326AbeAWP7W (ORCPT ); Tue, 23 Jan 2018 10:59:22 -0500 Received: from mail.efficios.com ([167.114.142.141]:34848 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752391AbeAWP6M (ORCPT ); Tue, 23 Jan 2018 10:58:12 -0500 From: Mathieu Desnoyers To: Ingo Molnar , Peter Zijlstra , Thomas Gleixner Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Andy Lutomirski , "Paul E . McKenney" , Boqun Feng , Andrew Hunter , Maged Michael , Avi Kivity , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Dave Watson , "H . Peter Anvin" , Andrea Parri , Russell King , Greg Hackmann , Will Deacon , David Sehr , Linus Torvalds , x86@kernel.org, Mathieu Desnoyers , linux-arch@vger.kernel.org Subject: [PATCH 09/11] membarrier: x86: Provide core serializing command (v4) Date: Tue, 23 Jan 2018 10:57:31 -0500 Message-Id: <20180123155733.3404-10-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180123155733.3404-1-mathieu.desnoyers@efficios.com> References: <20180123155733.3404-1-mathieu.desnoyers@efficios.com> Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: There are two places where core serialization is needed by membarrier: 1) When returning from the membarrier IPI, 2) After scheduler updates curr to a thread with a different mm, before going back to user-space, since the curr->mm is used by membarrier to check whether it needs to send an IPI to that CPU. x86-32 uses iret as return from interrupt, and both iret and sysexit to go back to user-space. The iret instruction is core serializing, but not sysexit. x86-64 uses iret as return from interrupt, which takes care of the IPI. However, it can return to user-space through either sysretl (compat code), sysretq, or iret. Given that sysret{l,q} is not core serializing, we rely instead on write_cr3() performed by switch_mm() to provide core serialization after changing the current mm, and deal with the special case of kthread -> uthread (temporarily keeping current mm into active_mm) by adding a sync_core() in that specific case. Use the new sync_core_before_usermode() to guarantee this. Signed-off-by: Mathieu Desnoyers CC: Peter Zijlstra CC: Andy Lutomirski CC: Paul E. McKenney CC: Boqun Feng CC: Andrew Hunter CC: Maged Michael CC: Avi Kivity CC: Benjamin Herrenschmidt CC: Paul Mackerras CC: Michael Ellerman CC: Dave Watson CC: Thomas Gleixner CC: Ingo Molnar CC: "H. Peter Anvin" CC: Andrea Parri CC: Russell King CC: Greg Hackmann CC: Will Deacon CC: David Sehr CC: x86@kernel.org CC: linux-arch@vger.kernel.org --- Changes since v1: - Use the newly introduced sync_core_before_usermode(). Move all state handling to generic code. - Add linux/processor.h include to include/linux/sched/mm.h. Changes since v2: - Fix use-after-free in membarrier_mm_sync_core_before_usermode. Changes since v3: - Move generic code into separate patch. --- arch/x86/Kconfig | 1 + arch/x86/entry/entry_32.S | 5 +++++ arch/x86/entry/entry_64.S | 4 ++++ arch/x86/mm/tlb.c | 7 ++++--- 4 files changed, 14 insertions(+), 3 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 0b44c8dd0e95..b5324f2e3162 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -54,6 +54,7 @@ config X86 select ARCH_HAS_FORTIFY_SOURCE select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_KCOV if X86_64 + select ARCH_HAS_MEMBARRIER_SYNC_CORE select ARCH_HAS_PMEM_API if X86_64 select ARCH_HAS_REFCOUNT select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64 diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 60c4c342316c..267d747a867f 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -565,6 +565,11 @@ restore_all: .Lrestore_nocheck: RESTORE_REGS 4 # skip orig_eax/error_code .Lirq_return: + /* + * ARCH_HAS_MEMBARRIER_SYNC_CORE rely on iret core serialization + * when returning from IPI handler and when returning from + * scheduler to user-space. + */ INTERRUPT_RETURN .section .fixup, "ax" diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index ff6f8022612c..52e20d37cdd3 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -803,6 +803,10 @@ GLOBAL(restore_regs_and_return_to_kernel) POP_EXTRA_REGS POP_C_REGS addq $8, %rsp /* skip regs->orig_ax */ + /* + * ARCH_HAS_MEMBARRIER_SYNC_CORE rely on iret core serialization + * when returning from IPI handler. + */ INTERRUPT_RETURN ENTRY(native_iret) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index c28cd5592b0d..df4e21371c89 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -201,9 +201,10 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, this_cpu_write(cpu_tlbstate.is_lazy, false); /* - * The membarrier system call requires a full memory barrier - * before returning to user-space, after storing to rq->curr. - * Writing to CR3 provides that full memory barrier. + * The membarrier system call requires a full memory barrier and + * core serialization before returning to user-space, after + * storing to rq->curr. Writing to CR3 provides that full + * memory barrier and core serializing instruction. */ if (real_prev == next) { VM_WARN_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) != -- 2.11.0