From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELvLEoIrYLeQkl9uKsRwe2kGuH4/zkqrxugyhUr300MJgWxVYth91KOhgL710TxK5tUHUJPU ARC-Seal: i=1; a=rsa-sha256; t=1520824085; cv=none; d=google.com; s=arc-20160816; b=VN63dGWw3Qh+Ty1nx43jzLiTugMb0kuknO6zEgvWbJ2L6aeDqMZ5WRjfR8ARYZCbYZ 2SYCbMuwlLUsLp7YB64DLeM7RV4kUNJWvAV96PqGkudzHPKTr8ArH8hRIrFtImPts3uv UiS3NiOzUb9B2Co7iE1YSlr3OzmqNw6BD8q9b5hLRTKjAsvPs8EYKGS3O+Iv78Up/PYo 2GRjz02DdgI0q5gPJKP14BSqQXnTE8bPZWN7Pf/zM3sU1HWcUTnsq2E8kIPqS/bWch1l r4SUuO6TZGy8bvKDdb5p+vE1WjbSMgl74tqHVAYtfMtg79vw9mEnDiT7WWPWPO5t+8YA mxsA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=in-reply-to:subject:message-id:date:cc:to:from:mime-version :content-transfer-encoding:content-disposition :arc-authentication-results; bh=VWxbIVjHBvwyiyTFNd6DAJSue2Us/F4zZ6OD2+GjjC8=; b=jWVt5x2HtsH4zhlC7BTXj8UtgGT5wj4NkTmjVlyVw/QDfJpizOgnkhxQcRqg8KQwF8 5Zwjxf0jyEm0DjG1xNc9YNkjkHBI1DrYpFuyTRjnEhgmG7fnSF41MEtXXL2/GysopzmM rNRC1xIq6jPJIQ9Er5Nb7UNgy8qeXHCXosVnoeYgSNARREBt0wrQNAIZ09QvQSz8/rdv WRKzPFqVo/9ZMfH5+5+Rss+efQoDQ/2a6+gIISyBIxRkx/EZnCsAez8WUX41x5p3taPJ c221ZufxYqxZocNa0frPgMFkKDS+6bReY0m0Kr3bIbR+ycIVam63vsKH+KShPv/yTJau BbZA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of ben@decadent.org.uk designates 88.96.1.126 as permitted sender) smtp.mailfrom=ben@decadent.org.uk Authentication-Results: mx.google.com; spf=pass (google.com: domain of ben@decadent.org.uk designates 88.96.1.126 as permitted sender) smtp.mailfrom=ben@decadent.org.uk Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, linux-arch@vger.kernel.org, "Al Viro" , "Ingo Molnar" , "Thomas Gleixner" , gregkh@linuxfoundation.org, "Tom Lendacky" , "Linus Torvalds" , kernel-hardening@lists.openwall.com, "Andi Kleen" , "Dan Williams" , "Kees Cook" , alan@linux.intel.com Date: Mon, 12 Mar 2018 03:03:34 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 085/104] x86: Introduce barrier_nospec In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594699636153002589?= X-GMAIL-MSGID: =?utf-8?q?1594699636153002589?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 3.2.101-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams commit b3d7ad85b80bbc404635dca80f5b129f6242bc7a upstream. Rename the open coded form of this instruction sequence from rdtsc_ordered() into a generic barrier primitive, barrier_nospec(). One of the mitigations for Spectre variant1 vulnerabilities is to fence speculative execution after successfully validating a bounds check. I.e. force the result of a bounds check to resolve in the instruction pipeline to ensure speculative execution honors that result before potentially operating on out-of-bounds data. No functional changes. Suggested-by: Linus Torvalds Suggested-by: Andi Kleen Suggested-by: Ingo Molnar Signed-off-by: Dan Williams Signed-off-by: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: Tom Lendacky Cc: Kees Cook Cc: kernel-hardening@lists.openwall.com Cc: gregkh@linuxfoundation.org Cc: Al Viro Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727415361.33451.9049453007262764675.stgit@dwillia2-desk3.amr.corp.intel.com [bwh: Backported to 3.2: update rdtsc_barrier() instead of rdtsc_ordered()] Signed-off-by: Ben Hutchings --- --- a/arch/x86/include/asm/system.h +++ b/arch/x86/include/asm/system.h @@ -478,6 +478,10 @@ static inline unsigned long array_index_ /* Override the default implementation from linux/nospec.h. */ #define array_index_mask_nospec array_index_mask_nospec +/* Prevent speculative execution past this barrier. */ +#define barrier_nospec() alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC, \ + "lfence", X86_FEATURE_LFENCE_RDTSC) + /** * read_barrier_depends - Flush all pending reads that subsequents reads * depend on. @@ -563,8 +567,7 @@ static inline unsigned long array_index_ */ static __always_inline void rdtsc_barrier(void) { - alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC); - alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC); + barrier_nospec(); } /*