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 681F8235C17; Thu, 26 Jun 2025 23:56:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750982211; cv=none; b=EqTIf8ibMAAaqI4WLaHwEnKgSfonmmqAA5SIJGuGLasNVWn5EL5SfK1t3NUbL8cNxP/uA1pYy68XAbLqucQwTKO1KtuogjrVpHPzBWskpmYGYJ/iwjN/rNI8z0176yBi0JTOOFQtKgFOI7aDEGuqnqK5G6mk1Z81ud3K6ZaIMnk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750982211; c=relaxed/simple; bh=VXqwGELhvBppXS9Y+OxD5QQxGhtLxEoBSvtvok1uXGA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QV9eRa3L2X9XS6qxCxgQftoLHUmn8deMYZ6cx+d+OFZhQJ6pJDSdDF/EeH29FEmNNJcH5rT7FRiX7YTO3Pru2bw0ONbsETnw49UW8rilhAWg3p/xtY/va09Y8MoOrgOPWNyZwoEr8GbPmOYN3oDgxw1hExZ+okH0ZPT/9odEQxg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qT1bGcem; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qT1bGcem" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60BA4C4CEEF; Thu, 26 Jun 2025 23:56:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750982210; bh=VXqwGELhvBppXS9Y+OxD5QQxGhtLxEoBSvtvok1uXGA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qT1bGcem2MtfnMm9my/N6Fl/CQ5+ysGv2qlaOkHZhNGN+r2ji8zpMZ2uWroEU9OeX RKMAPN/ek5gk3q/HGhuAjKEX5D0qOwzCuPLiGvC4B3ChYOKzXZZHxXbpzUNy82z5my DHddDeYaZxSfA5S9zbHMnar/vI/wRjliLg0P9suHS5M3wAhMgqQVWQyxF9bqIDmgoW hAk5xSTb2rqkN+PUXFLYs4tLFsP6i+Ng8lyuuv4ZjguzctYKBRkkLvExGH9/OtAgNn xESJwqqLKynAfgU0SSLduvwG7yWN6BTbiAHUGvlWR9O6TR3BV6Ku2Ww7iaezuacI6g tTK+NXEwqX+wA== From: Josh Poimboeuf To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Petr Mladek , Miroslav Benes , Joe Lawrence , live-patching@vger.kernel.org, Song Liu , laokz , Jiri Kosina , Marcos Paulo de Souza , Weinan Liu , Fazla Mehrab , Chen Zhongjin , Puranjay Mohan , Dylan Hatch Subject: [PATCH v3 56/64] objtool: Add base objtool support for livepatch modules Date: Thu, 26 Jun 2025 16:55:43 -0700 Message-ID: <55fe04b73123ef5029beeabebf14028d153467a1.1750980517.git.jpoimboe@kernel.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: live-patching@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In preparation for klp-build, enable "classic" objtool to work on livepatch modules: - Avoid duplicate symbol/section warnings for prefix symbols and the .static_call_sites and __mcount_loc sections which may have already been extracted by klp diff. - Add __klp_funcs to the IBT function pointer section whitelist. - Prevent KLP symbols from getting incorrectly classified as cold subfunctions. Signed-off-by: Josh Poimboeuf --- tools/objtool/check.c | 48 +++++++++++++++++++++---- tools/objtool/elf.c | 5 ++- tools/objtool/include/objtool/elf.h | 1 + tools/objtool/include/objtool/objtool.h | 2 +- 4 files changed, 48 insertions(+), 8 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index c6c99e3fb76f..1eb6489ae459 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3,6 +3,7 @@ * Copyright (C) 2015-2017 Josh Poimboeuf */ +#define _GNU_SOURCE /* memmem() */ #include #include #include @@ -610,6 +611,20 @@ static int init_pv_ops(struct objtool_file *file) return 0; } +static bool is_livepatch_module(struct objtool_file *file) +{ + struct section *sec; + + if (!opts.module) + return false; + + sec = find_section_by_name(file->elf, ".modinfo"); + if (!sec) + return false; + + return memmem(sec->data->d_buf, sec_size(sec), "\0livepatch=Y", 12); +} + static int create_static_call_sections(struct objtool_file *file) { struct static_call_site *site; @@ -621,7 +636,14 @@ static int create_static_call_sections(struct objtool_file *file) sec = find_section_by_name(file->elf, ".static_call_sites"); if (sec) { - WARN("file already has .static_call_sites section, skipping"); + /* + * Livepatch modules may have already extracted the static call + * site entries to take advantage of vmlinux static call + * privileges. + */ + if (!file->klp) + WARN("file already has .static_call_sites section, skipping"); + return 0; } @@ -672,7 +694,7 @@ static int create_static_call_sections(struct objtool_file *file) key_sym = find_symbol_by_name(file->elf, tmp); if (!key_sym) { - if (!opts.module) { + if (!opts.module || file->klp) { ERROR("static_call: can't find static_call_key symbol: %s", tmp); return -1; } @@ -891,7 +913,13 @@ static int create_mcount_loc_sections(struct objtool_file *file) sec = find_section_by_name(file->elf, "__mcount_loc"); if (sec) { - WARN("file already has __mcount_loc section, skipping"); + /* + * Livepatch modules have already extracted their __mcount_loc + * entries to cover the !CONFIG_FTRACE_MCOUNT_USE_OBJTOOL case. + */ + if (!file->klp) + WARN("file already has __mcount_loc section, skipping"); + return 0; } @@ -2575,6 +2603,8 @@ static bool validate_branch_enabled(void) static int decode_sections(struct objtool_file *file) { + file->klp = is_livepatch_module(file); + mark_rodata(file); if (init_pv_ops(file)) @@ -4235,8 +4265,13 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func) if (offset < opts.prefix) continue; + /* + * Ignore attempts to make duplicate symbols in livepatch + * modules. They've already extracted the prefix symbols + * except for the newly compiled init.c. + */ sym_pfx = elf_create_prefix_symbol(file->elf, func, opts.prefix); - if (!sym_pfx) { + if (!sym_pfx && !file->klp) { WARN("duplicate prefix symbol for %s\n", func->name); return -1; } @@ -4571,6 +4606,7 @@ static int validate_ibt(struct objtool_file *file) !strncmp(sec->name, ".debug", 6) || !strcmp(sec->name, ".altinstructions") || !strcmp(sec->name, ".ibt_endbr_seal") || + !strcmp(sec->name, ".kcfi_traps") || !strcmp(sec->name, ".orc_unwind_ip") || !strcmp(sec->name, ".retpoline_sites") || !strcmp(sec->name, ".smp_locks") || @@ -4580,12 +4616,12 @@ static int validate_ibt(struct objtool_file *file) !strcmp(sec->name, "__bug_table") || !strcmp(sec->name, "__ex_table") || !strcmp(sec->name, "__jump_table") || + !strcmp(sec->name, "__klp_funcs") || !strcmp(sec->name, "__mcount_loc") || - !strcmp(sec->name, ".kcfi_traps") || !strcmp(sec->name, ".llvm.call-graph-profile") || !strcmp(sec->name, ".llvm_bb_addr_map") || !strcmp(sec->name, "__tracepoints") || - strstr(sec->name, "__patchable_function_entries")) + !strcmp(sec->name, "__patchable_function_entries")) continue; for_each_reloc(sec->rsec, reloc) diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 383183e9cf2d..f9eed5d50de5 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -496,7 +496,10 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym) (strstarts(sym->name, "__pfx_") || strstarts(sym->name, "__cfi_"))) sym->prefix = 1; - if (is_func_sym(sym) && strstr(sym->name, ".cold")) + if (strstarts(sym->name, ".klp.sym")) + sym->klp = 1; + + if (!sym->klp && is_func_sym(sym) && strstr(sym->name, ".cold")) sym->cold = 1; sym->pfunc = sym->cfunc = sym; diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index c2a744afd5d5..1212f81f40e0 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -84,6 +84,7 @@ struct symbol { u8 debug_checksum : 1; u8 changed : 1; u8 included : 1; + u8 klp : 1; struct list_head pv_target; struct reloc *relocs; struct section *group_sec; diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h index 37e9fe4492d6..731965a742e9 100644 --- a/tools/objtool/include/objtool/objtool.h +++ b/tools/objtool/include/objtool/objtool.h @@ -30,7 +30,7 @@ struct objtool_file { struct list_head mcount_loc_list; struct list_head endbr_list; struct list_head call_list; - bool ignore_unreachables, hints, rodata; + bool ignore_unreachables, hints, rodata, klp; unsigned int nr_endbr; unsigned int nr_endbr_int; -- 2.49.0