From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4F68C8F5D for ; Thu, 31 Aug 2023 11:11:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9BF10C433C8; Thu, 31 Aug 2023 11:11:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1693480302; bh=rnFiiiFf6JkVS+r3sZqzuwn/lOreRNt0mGEyduogGGQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hxlLPH81h2zBMs3iPOFT2LoXCu2SCFs3de/PBBffva4JvPcIcCCKofWh0CkUSSNQy 5xo4qgzI0KSgtNLVyK6UPjHxEgvwrSU36wXGtVo84LAoRC1PgPUypEM811V8rQbPUI pWmlsA2k09kpGyJCRc/7tzNXVwBURLiBs6zH0yXA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, kernel test robot , Yonghong Song , Song Liu , Zhen Lei , Kees Cook Subject: [PATCH 6.5 8/8] kallsyms: Fix kallsyms_selftest failure Date: Thu, 31 Aug 2023 13:10:35 +0200 Message-ID: <20230831110831.131024174@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230831110830.817738361@linuxfoundation.org> References: <20230831110830.817738361@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yonghong Song commit 33f0467fe06934d5e4ea6e24ce2b9c65ce618e26 upstream. Kernel test robot reported a kallsyms_test failure when clang lto is enabled (thin or full) and CONFIG_KALLSYMS_SELFTEST is also enabled. I can reproduce in my local environment with the following error message with thin lto: [ 1.877897] kallsyms_selftest: Test for 1750th symbol failed: (tsc_cs_mark_unstable) addr=ffffffff81038090 [ 1.877901] kallsyms_selftest: abort It appears that commit 8cc32a9bbf29 ("kallsyms: strip LTO-only suffixes from promoted global functions") caused the failure. Commit 8cc32a9bbf29 changed cleanup_symbol_name() based on ".llvm." instead of '.' where ".llvm." is appended to a before-lto-optimization local symbol name. We need to propagate such knowledge in kallsyms_selftest.c as well. Further more, compare_symbol_name() in kallsyms.c needs change as well. In scripts/kallsyms.c, kallsyms_names and kallsyms_seqs_of_names are used to record symbol names themselves and index to symbol names respectively. For example: kallsyms_names: ... __amd_smn_rw._entry <== seq 1000 __amd_smn_rw._entry.5 <== seq 1001 __amd_smn_rw.llvm. <== seq 1002 ... kallsyms_seqs_of_names are sorted based on cleanup_symbol_name() through, so the order in kallsyms_seqs_of_names actually has index 1000: seq 1002 <== __amd_smn_rw.llvm. (actual symbol comparison using '__amd_smn_rw') index 1001: seq 1000 <== __amd_smn_rw._entry index 1002: seq 1001 <== __amd_smn_rw._entry.5 Let us say at a particular point, at index 1000, symbol '__amd_smn_rw.llvm.' is comparing to '__amd_smn_rw._entry' where '__amd_smn_rw._entry' is the one to search e.g., with function kallsyms_on_each_match_symbol(). The current implementation will find out '__amd_smn_rw._entry' is less than '__amd_smn_rw.llvm.' and then continue to search e.g., index 999 and never found a match although the actual index 1001 is a match. To fix this issue, let us do cleanup_symbol_name() first and then do comparison. In the above case, comparing '__amd_smn_rw' vs '__amd_smn_rw._entry' and '__amd_smn_rw._entry' being greater than '__amd_smn_rw', the next comparison will be > index 1000 and eventually index 1001 will be hit an a match is found. For any symbols not having '.llvm.' substr, there is no functionality change for compare_symbol_name(). Fixes: 8cc32a9bbf29 ("kallsyms: strip LTO-only suffixes from promoted global functions") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202308232200.1c932a90-oliver.sang@intel.com Signed-off-by: Yonghong Song Reviewed-by: Song Liu Reviewed-by: Zhen Lei Link: https://lore.kernel.org/r/20230825034659.1037627-1-yonghong.song@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman --- kernel/kallsyms.c | 17 +++++++---------- kernel/kallsyms_selftest.c | 23 +---------------------- 2 files changed, 8 insertions(+), 32 deletions(-) --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -188,16 +188,13 @@ static bool cleanup_symbol_name(char *s) static int compare_symbol_name(const char *name, char *namebuf) { - int ret; - - ret = strcmp(name, namebuf); - if (!ret) - return ret; - - if (cleanup_symbol_name(namebuf) && !strcmp(name, namebuf)) - return 0; - - return ret; + /* The kallsyms_seqs_of_names is sorted based on names after + * cleanup_symbol_name() (see scripts/kallsyms.c) if clang lto is enabled. + * To ensure correct bisection in kallsyms_lookup_names(), do + * cleanup_symbol_name(namebuf) before comparing name and namebuf. + */ + cleanup_symbol_name(namebuf); + return strcmp(name, namebuf); } static unsigned int get_symbol_seq(int index) --- a/kernel/kallsyms_selftest.c +++ b/kernel/kallsyms_selftest.c @@ -196,7 +196,7 @@ static bool match_cleanup_name(const cha if (!IS_ENABLED(CONFIG_LTO_CLANG)) return false; - p = strchr(s, '.'); + p = strstr(s, ".llvm."); if (!p) return false; @@ -344,27 +344,6 @@ static int test_kallsyms_basic_function( goto failed; } - /* - * The first '.' may be the initial letter, in which case the - * entire symbol name will be truncated to an empty string in - * cleanup_symbol_name(). Do not test these symbols. - * - * For example: - * cat /proc/kallsyms | awk '{print $3}' | grep -E "^\." | head - * .E_read_words - * .E_leading_bytes - * .E_trailing_bytes - * .E_write_words - * .E_copy - * .str.292.llvm.12122243386960820698 - * .str.24.llvm.12122243386960820698 - * .str.29.llvm.12122243386960820698 - * .str.75.llvm.12122243386960820698 - * .str.99.llvm.12122243386960820698 - */ - if (IS_ENABLED(CONFIG_LTO_CLANG) && !namebuf[0]) - continue; - lookup_addr = kallsyms_lookup_name(namebuf); memset(stat, 0, sizeof(*stat));