From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757745AbcBJMIe (ORCPT ); Wed, 10 Feb 2016 07:08:34 -0500 Received: from mail.skyhub.de ([78.46.96.112]:60871 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752813AbcBJMIc (ORCPT ); Wed, 10 Feb 2016 07:08:32 -0500 Date: Wed, 10 Feb 2016 13:08:27 +0100 From: Borislav Petkov To: mingo@kernel.org, luto@amacapital.net Cc: tglx@linutronix.de, oleg@redhat.com, brgerst@gmail.com, mcgrof@suse.com, dave.hansen@linux.intel.com, akpm@linux-foundation.org, dvlasenk@redhat.com, peterz@infradead.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, toshi.kani@hp.com, luto@kernel.org, aryabinin@virtuozzo.com, hpa@zytor.com, Michael Matz , linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/mm] x86/mm: Add INVPCID helpers Message-ID: <20160210120827.GA11832@pd.tnic> References: <8a62b23ad686888cee01da134c91409e22064db9.1454096309.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 09, 2016 at 08:07:31AM -0800, tip-bot for Andy Lutomirski wrote: > Commit-ID: 060a402a1ddb551455ee410de2eadd3349f2801b > Gitweb: http://git.kernel.org/tip/060a402a1ddb551455ee410de2eadd3349f2801b > Author: Andy Lutomirski > AuthorDate: Fri, 29 Jan 2016 11:42:57 -0800 > Committer: Ingo Molnar > CommitDate: Tue, 9 Feb 2016 13:36:10 +0100 > > x86/mm: Add INVPCID helpers > > This adds helpers for each of the four currently-specified INVPCID > modes. ... > +static inline void __invpcid(unsigned long pcid, unsigned long addr, > + unsigned long type) > +{ > + u64 desc[2] = { pcid, addr }; > + > + /* > + * The memory clobber is because the whole point is to invalidate > + * stale TLB entries and, especially if we're flushing global > + * mappings, we don't want the compiler to reorder any subsequent > + * memory accesses before the TLB flush. > + * > + * The hex opcode is invpcid (%ecx), %eax in 32-bit mode and > + * invpcid (%rcx), %rax in long mode. > + */ > + asm volatile (".byte 0x66, 0x0f, 0x38, 0x82, 0x01" > + : : "m" (desc), "a" (type), "c" (desc) : "memory"); --- From: Borislav Petkov Date: Wed, 10 Feb 2016 12:53:48 +0100 Subject: [PATCH] x86/mm: Fix INVPCID asm constraint MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit So we want to specify the dependency on both @pcid and @addr so that the compiler doesn't reorder accesses to them *before* the TLB flush. But for that to work, we need to express this properly in the inline asm and deref the whole desc array, not the pointer to it. See clwb() for an example. This fixes the build error on 32-bit: arch/x86/include/asm/tlbflush.h: In function ‘__invpcid’: arch/x86/include/asm/tlbflush.h:26:18: error: memory input 0 is not directly addressable which gcc4.7 caught but 5.x didn't. Which is strange. :-\ Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Michael Matz Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Toshi Kani Cc: linux-mm@kvack.org --- arch/x86/include/asm/tlbflush.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 6f9e27aa2aaf..c820b2a9e026 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -23,7 +23,7 @@ static inline void __invpcid(unsigned long pcid, unsigned long addr, * invpcid (%rcx), %rax in long mode. */ asm volatile (".byte 0x66, 0x0f, 0x38, 0x82, 0x01" - : : "m" (desc), "a" (type), "c" (desc) : "memory"); + : : "m" (*desc), "a" (type), "c" (desc) : "memory"); } #define INVPCID_TYPE_INDIV_ADDR 0 -- 2.3.5 -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply.