From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-23.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43569C49EA5 for ; Tue, 8 Jun 2021 18:49:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D1B86194A for ; Tue, 8 Jun 2021 18:49:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235348AbhFHSu6 (ORCPT ); Tue, 8 Jun 2021 14:50:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:44090 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235665AbhFHSsv (ORCPT ); Tue, 8 Jun 2021 14:48:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 906576145C; Tue, 8 Jun 2021 18:38:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623177523; bh=pf9sCuH6qSJr5Mi5BzRuDjVWH5L/CQHBf01+mlBKuJ0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S3ycZzcBaGqoxalpt3+CGi6e3o4bST+STK01yng9jaTGtmXSFD7GaEDxNCJ3TtOZ4 73HgJKoxFqdeK6MXEaksjJ5dIfgiwGM43chfkRbo2Ful5QowI+WVxf68fxBKEiFod0 OHpzfZ9gWrfnHoRoBrWN+dESoMm3dvNVKx8xA9lk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Gao Xiang , Nick Terrell , Yann Collet , Miao Xie , Chao Yu , Li Guifu , Guo Xuenan , Andrew Morton , Linus Torvalds , Gao Xiang Subject: [PATCH 5.4 75/78] lib/lz4: explicitly support in-place decompression Date: Tue, 8 Jun 2021 20:27:44 +0200 Message-Id: <20210608175937.795560094@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210608175935.254388043@linuxfoundation.org> References: <20210608175935.254388043@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Gao Xiang commit 89b158635ad79574bde8e94d45dad33f8cf09549 upstream. LZ4 final literal copy could be overlapped when doing in-place decompression, so it's unsafe to just use memcpy() on an optimized memcpy approach but memmove() instead. Upstream LZ4 has updated this years ago [1] (and the impact is non-sensible [2] plus only a few bytes remain), this commit just synchronizes LZ4 upstream code to the kernel side as well. It can be observed as EROFS in-place decompression failure on specific files when X86_FEATURE_ERMS is unsupported, memcpy() optimization of commit 59daa706fbec ("x86, mem: Optimize memcpy by avoiding memory false dependece") will be enabled then. Currently most modern x86-CPUs support ERMS, these CPUs just use "rep movsb" approach so no problem at all. However, it can still be verified with forcely disabling ERMS feature... arch/x86/lib/memcpy_64.S: ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \ - "jmp memcpy_erms", X86_FEATURE_ERMS + "jmp memcpy_orig", X86_FEATURE_ERMS We didn't observe any strange on arm64/arm/x86 platform before since most memcpy() would behave in an increasing address order ("copy upwards" [3]) and it's the correct order of in-place decompression but it really needs an update to memmove() for sure considering it's an undefined behavior according to the standard and some unique optimization already exists in the kernel. [1] https://github.com/lz4/lz4/commit/33cb8518ac385835cc17be9a770b27b40cd0e15b [2] https://github.com/lz4/lz4/pull/717#issuecomment-497818921 [3] https://sourceware.org/bugzilla/show_bug.cgi?id=12518 Link: https://lkml.kernel.org/r/20201122030749.2698994-1-hsiangkao@redhat.com Signed-off-by: Gao Xiang Reviewed-by: Nick Terrell Cc: Yann Collet Cc: Miao Xie Cc: Chao Yu Cc: Li Guifu Cc: Guo Xuenan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Gao Xiang Signed-off-by: Greg Kroah-Hartman --- lib/lz4/lz4_decompress.c | 6 +++++- lib/lz4/lz4defs.h | 2 ++ 2 files changed, 7 insertions(+), 1 deletion(-) --- a/lib/lz4/lz4_decompress.c +++ b/lib/lz4/lz4_decompress.c @@ -260,7 +260,11 @@ static FORCE_INLINE int LZ4_decompress_g } } - memcpy(op, ip, length); + /* + * supports overlapping memory regions; only matters + * for in-place decompression scenarios + */ + LZ4_memmove(op, ip, length); ip += length; op += length; --- a/lib/lz4/lz4defs.h +++ b/lib/lz4/lz4defs.h @@ -137,6 +137,8 @@ static FORCE_INLINE void LZ4_writeLE16(v return put_unaligned_le16(value, memPtr); } +#define LZ4_memmove(dst, src, size) __builtin_memmove(dst, src, size) + static FORCE_INLINE void LZ4_copy8(void *dst, const void *src) { #if LZ4_ARCH64