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 7C3AD3321A2; Fri, 1 May 2026 04:08:58 +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=1777608539; cv=none; b=pM9v52AmQ/3BfsYpshZBrtKo5V+0Y5uXkZR18i9b9tzyoCK5Kml2sWEW3mcYVs2Z661ZumIY1tokxPQAZAjURd+MymjzbieiNEhWHfdsyjVe2ufOrV63WoKklsIgeGaxv7bP/ZCI9e6wNflCswdxD5XoYv+K6sn67mPPIEe3tbU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777608539; c=relaxed/simple; bh=XjTMzGfi8bZF7bQaM0dm87pbnohW8womDStrdD8mTyA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aNBgTN9JLFX9cPo1Wu+jChITu2WJuLkfaWtQ8+a+6kUSUCN8zaTya11ZudXf4KY+SZVuSl+/wgQgcX6YfS05zmuL5jriDNwVjBvFmdb4MUxE8yes9cjGrpK/KjwBkd1O8YCixQq3esjVA8L3ZC+H170Csw/wwOtJsMgDvSEHoQk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eeYeQbLY; 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="eeYeQbLY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C3C4C2BCC6; Fri, 1 May 2026 04:08:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777608538; bh=XjTMzGfi8bZF7bQaM0dm87pbnohW8womDStrdD8mTyA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eeYeQbLYVHzIAYgoVCJFcHqKXLQjZ6IERnz0WUlH5bXoZhf45SEI0y2gpegqMRtfb 4PUy5c33fyEAPpM6X2pSz+1NoEyEsBontSQ7yWehuik01iZmHfQspmZW2zwKpah0wN T7ErI20WADNcoo4RvoSI6bbs1o8xsRUzA7TN8uZw4rGKha+l/qrsDqASzpzU8iO9GP YXSEvx5LGWwFVXEpolCGE4WJG0cgmurInRrlJRy+qseO+NigbwzuxnCwjZoFtrvgWE lFxOtKhFBmrTOKPnD8HYTvdH46reddefPyLkCgsBRl9xgaZ/VhEupkVl7SkW4mM/c9 macECQx4QKxfQ== From: Josh Poimboeuf To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, Peter Zijlstra , Joe Lawrence , Song Liu , Miroslav Benes , Petr Mladek Subject: [PATCH v2 18/53] objtool/klp: Simplify reloc symbol conversion Date: Thu, 30 Apr 2026 21:08:06 -0700 Message-ID: <9572b2e15500e5ed8dcbaac78c966557d3000d85.1777575752.git.jpoimboe@kernel.org> X-Mailer: git-send-email 2.53.0 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 Inline section_reference_needed() and is_reloc_allowed() into convert_reloc_sym() and remove the redundant is_reloc_allowed() check in clone_reloc(). Move the is_sec_sym() checks into the convert callees so they become no-ops when the reloc is already in the right format. This allows convert_reloc_sym() to unconditionally dispatch to the right converter based on section type. Signed-off-by: Josh Poimboeuf --- tools/objtool/klp-diff.c | 76 +++++++++++++++------------------------- 1 file changed, 28 insertions(+), 48 deletions(-) diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c index 19bc811db396..78633c9b68eb 100644 --- a/tools/objtool/klp-diff.c +++ b/tools/objtool/klp-diff.c @@ -838,39 +838,6 @@ static int clone_included_functions(struct elfs *e) return 0; } -/* - * Determine whether a relocation should reference the section rather than the - * underlying symbol. - */ -static bool section_reference_needed(struct section *sec) -{ - /* - * String symbols are zero-length and uncorrelated. It's easier to - * deal with them as section symbols. - */ - if (is_string_sec(sec)) - return true; - - /* - * .rodata has mostly anonymous data so there's no way to determine the - * length of a needed reference. just copy the whole section if needed. - */ - if (strstarts(sec->name, ".rodata")) - return true; - - /* UBSAN anonymous data */ - if (strstarts(sec->name, ".data..Lubsan") || /* GCC */ - strstarts(sec->name, ".data..L__unnamed_")) /* Clang */ - return true; - - return false; -} - -static bool is_reloc_allowed(struct reloc *reloc) -{ - return section_reference_needed(reloc->sym->sec) == is_sec_sym(reloc->sym); -} - static struct export *find_export(struct symbol *sym) { struct export *export; @@ -979,11 +946,15 @@ static bool klp_reloc_needed(struct reloc *patched_reloc) return true; } +/* Return -1 error, 0 success, 1 skip */ static int convert_reloc_sym_to_secsym(struct elf *elf, struct reloc *reloc) { struct symbol *sym = reloc->sym; struct section *sec = sym->sec; + if (is_sec_sym(sym)) + return 0; + if (!sec->sym && !elf_create_section_symbol(elf, sec)) return -1; @@ -993,11 +964,15 @@ static int convert_reloc_sym_to_secsym(struct elf *elf, struct reloc *reloc) return 0; } +/* Return -1 error, 0 success, 1 skip */ static int convert_reloc_secsym_to_sym(struct elf *elf, struct reloc *reloc) { struct symbol *sym = reloc->sym; struct section *sec = sym->sec; + if (!is_sec_sym(sym)) + return 0; + /* If the symbol has a dedicated section, it's easy to find */ sym = find_symbol_by_offset(sec, 0); if (sym && sym->len == sec_size(sec)) @@ -1027,22 +1002,34 @@ static int convert_reloc_secsym_to_sym(struct elf *elf, struct reloc *reloc) return 0; } +/* + * Sections with anonymous or uncorrelated data (strings, UBSAN data) + * need section symbol references. + */ +static bool is_uncorrelated_section(struct section *sec) +{ + return is_string_sec(sec) || + strstarts(sec->name, ".rodata") || + strstarts(sec->name, ".data..Lubsan") || /* GCC */ + strstarts(sec->name, ".data..L__unnamed_"); /* Clang */ +} + /* * Convert a relocation symbol reference to the needed format: either a section - * symbol or the underlying symbol itself. + * symbol or the underlying symbol itself. Return -1 error, 0 success, 1 skip. */ static int convert_reloc_sym(struct elf *elf, struct reloc *reloc) { + struct section *sec = reloc->sym->sec; + if (reloc_type(reloc) == R_NONE) return 1; - if (is_reloc_allowed(reloc)) - return 0; - - if (section_reference_needed(reloc->sym->sec)) + if (is_uncorrelated_section(sec)) return convert_reloc_sym_to_secsym(elf, reloc); - else - return convert_reloc_secsym_to_sym(elf, reloc); + + /* Everything else: references should use named symbols. */ + return convert_reloc_secsym_to_sym(elf, reloc); } /* @@ -1187,13 +1174,6 @@ static int clone_reloc(struct elfs *e, struct reloc *patched_reloc, struct symbol *out_sym; bool klp; - if (!is_reloc_allowed(patched_reloc)) { - ERROR_FUNC(patched_reloc->sec->base, reloc_offset(patched_reloc), - "missing symbol for reference to %s+%ld", - patched_sym->name, addend); - return -1; - } - klp = klp_reloc_needed(patched_reloc); dbg_clone_reloc(sec, offset, patched_sym, addend, export, klp); @@ -1223,7 +1203,7 @@ static int clone_reloc(struct elfs *e, struct reloc *patched_reloc, /* * For strings, all references use section symbols, thanks to - * section_reference_needed(). clone_symbol() has cloned an empty + * convert_reloc_sym(). clone_symbol() has cloned an empty * version of the string section. Now copy the string itself. */ if (is_string_sec(patched_sym->sec)) { -- 2.53.0