From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-186.mta0.migadu.com (out-186.mta0.migadu.com [91.218.175.186]) (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 D0C243DD85E for ; Tue, 7 Jul 2026 07:23:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.186 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783408999; cv=none; b=KLm/iQznoXP9tfNhxS9Km08JsGTHj65GgkJvMZKH8gj5xb7MOLfO6DoJVO1xjqTMImWjVao/l6ptBLuLkU85A2CBoqOs6LL29QYP6EHMI+19c2gcUG1jHJJ5HlyzAIPy2qJs6o8bXrcUw+UBuL9BfW9BMB9n8Ru/QSvL1OPnB18= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783408999; c=relaxed/simple; bh=oJfRTd/YfCpRQIlHUU0EhRdn+cxmTArmqxlE5cFyjUE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=BTw4oi3kjv/Tc/d92Ez5Xh6Apsi5BWOyyHoZa7qB772txbne28X7L6EvPE5lF4qmhluaZ/mcm3rEaZm2bQGilwLKTOOW7trD9bVPeeAw5oMhGdZzmhfpxXFMMsx2p99RGe3NmNpP0uVid7SzYtdRqPBb5xWjUyhZZCyeaQwj1ds= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=fmAjCcjR; arc=none smtp.client-ip=91.218.175.186 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="fmAjCcjR" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1783408991; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=omd/IYAr8HFNM9DotDwvj76ZFJM2G5dGzr6lUjILi60=; b=fmAjCcjR9cbDf5NazGB/ImTERibPDSjn9Ub1+5xRAqpo43QWGh3HW0nVZWTuJG0Z5kfIwO y4lMf8IUDE1iyves59uzlfmsHwGZi16xNW0N86d3z81HmuWCMg7U0pIoDaGlpXbS+qMwWd tscN0Pw7zXDfVvLzjg5o0Qrj/tuOrN4= From: George Guo To: chenhuacai@kernel.org, jpoimboe@kernel.org, peterz@infradead.org, jikos@kernel.org, mbenes@suse.cz, pmladek@suse.com Cc: kernel@xen0n.name, joe.lawrence@redhat.com, rostedt@goodmis.org, ardb@kernel.org, nathan@kernel.org, nick.desaulniers+lkml@gmail.com, yangtiezhu@loongson.cn, jiaxun.yang@flygoat.com, liukexin@kylinos.cn, guodongtai@kylinos.cn, xry111@xry111.site, wangyuli@aosc.io, loongarch@lists.linux.dev, live-patching@vger.kernel.org, llvm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v3 10/12] objtool/klp: Convert local label references in special sections Date: Tue, 7 Jul 2026 15:20:29 +0800 Message-Id: <20260707072031.231066-11-dongtai.guo@linux.dev> In-Reply-To: <20260707072031.231066-1-dongtai.guo@linux.dev> References: <20260707072031.231066-1-dongtai.guo@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: George Guo GCC/GAS on LoongArch references special section entries (__ex_table, __bug_table, __jump_table, .altinstructions) through local text labels (.L*) instead of a section symbol plus offset. The assembler keeps the label because of linker relaxation: a "section + constant offset" reference would go stale when the linker deletes or shrinks instructions, while a symbol reference can be recomputed after relaxation. convert_reloc_secsym_to_sym() only handles the section symbol form and returns early for such label references. The label is never cloned into the livepatch object, so should_keep_special_sym() cannot correlate the entry with an included function and silently drops it: a GCC-built livepatch module ends up missing the patched function's __ex_table / __bug_table / __jump_table entries, with no error at build or load time. Redirect label references in text sections to the containing function symbol, mirroring the section symbol case. A label with no containing function symbol (e.g. hand-written asm in a plain .text section) can't be correlated; skip it rather than failing, since such entries belong to unchanged code and are dropped anyway. Reported-by: Joe Lawrence Suggested-by: Joe Lawrence Signed-off-by: George Guo --- tools/objtool/klp-diff.c | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c index b9624bd9439b..05fd70e24326 100644 --- a/tools/objtool/klp-diff.c +++ b/tools/objtool/klp-diff.c @@ -1423,8 +1423,41 @@ static int convert_reloc_secsym_to_sym(struct elf *elf, struct reloc *reloc) if (!strcmp(reloc->sec->name, ".rela__patchable_function_entries")) return convert_pfe_reloc(elf, reloc); - if (!is_sec_sym(sym)) + if (!is_sec_sym(sym)) { + /* + * Most toolchains reference special-section entries via the + * section symbol plus an offset. GCC/GAS on LoongArch instead + * references a local text label (.L*): LoongArch linker + * relaxation is the reason GAS keeps the label rather than + * reducing it to a section symbol reference. Such a label is + * never cloned into the livepatch object, so the entry would be + * silently dropped. Redirect the relocation to the containing + * function, mirroring the section-symbol case below. + */ + if (is_local_label(sym) && is_text_sec(sec)) { + unsigned long offset = sym->offset + reloc_addend(reloc); + + sym = find_symbol_containing_inclusive(sec, offset); + if (!sym) { + /* + * A local label with no containing function + * symbol (e.g. hand-written asm in a plain .text + * section). It can't be correlated to a function, + * so skip it rather than failing the build; such + * entries belong to unchanged code and are dropped + * anyway. + */ + return 1; + } + + reloc->sym = sym; + set_reloc_sym(elf, reloc, sym->idx); + set_reloc_addend(elf, reloc, offset - sym->offset); + return 0; + } + return 0; + } sym = find_symbol_containing_inclusive(sec, arch_adjusted_addend(reloc)); if (!sym) { -- 2.25.1