From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 896113E44F6 for ; Mon, 14 Sep 2026 06:27:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789367252; cv=none; b=FLpAFc9GX8u9Q4bPD+u+SVdeNvxN+Tbha+NzEksc6b6ogQ7pRvbAKpkXEhuqj8E/EtnA4tBLhVzfNpE+NcrQR1/P+2yDvetzdsDq9BnUFbJH1q3qSU6SJL9ceF3qdZVUkL2t5dNa2LUqjd7qui77yrBVM/RJ+UbrpImDL/UhM1s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789367252; c=relaxed/simple; bh=Hpc8eV9YUuJjcfTtf/++IRXFmsn3zz3LHYhT9H2rXV4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KGuGmrfhh7gLyg5mAMTnHm0W7lsJjU7ENKRuaIt7aUBDu7agpxrS39lbzrTf9aavZ/Wctir61sJVg17uCmJhgARyV7B035PKmWR0cfdsXkV5qdyztTFr/ycHDwR/DE8NEglHWOfMXnOlr4byMfB0eZIO4pb63BmDI/mSwEPF5nQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kdd4zAej; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kdd4zAej" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96D331F000FF; Mon, 14 Sep 2026 06:27:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789367246; bh=hA0hZsrt0/jr18TQlcGZGo0x/XtImYu+Pw3jl/+a/3E=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=kdd4zAejB9vhTLncsfQNa2cWClGZRezTWnzs/TAk1V3kByBy8nMy1SlpxbS59kBbs +H/bZOqfT+cFDYelfL6AHtvhDbb6+3v1HX7TbMgV88RmOu8l2OXzHf2XDV3wP3FtYY rkBn922iG0yPWhRotasY7Si1Dx0Td/yehM0txDfy/H8MhUvUm8WyQ+BbBVcsACKuxK ZyOFkcdPmO8KCldDPMDQ98wlccVmcZcGiKMev+w1rE5qRKkCF1B3q1OvvFdrgZ2ymg Y+GtilE5yWroNa3wsHs0JHtd5pMyhO3nihAaIVufsyiNom/Vf7M20yaYKt4zU+hyMC q1etTLo04Vksw== From: Song Liu To: live-patching@vger.kernel.org Cc: jpoimboe@kernel.org, peterz@infradead.org, jikos@kernel.org, mbenes@suse.cz, pmladek@suse.com, joe.lawrence@redhat.com, puranjay@kernel.org, kernel-team@meta.com, Song Liu Subject: [PATCH v2 22/58] objtool/klp: Add test for symids in discarded sections Date: Sun, 13 Sep 2026 23:24:38 -0700 Message-ID: <20260914062514.926997-23-song@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260914062514.926997-1-song@kernel.org> References: <20260914062514.926997-1-song@kernel.org> Precedence: bulk X-Mailing-List: live-patching@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Puranjay Mohan .klp.symid records duplicate-named locals so klp diff can work out their sympos. Symbols in sections the vmlinux link throws away have to be left out, or the table references symbols which no longer exist and the link fails: `__exitcall_foo' referenced in section `.klp.symid' of vmlinux.o: defined in discarded section `.exitcall.exit' of vmlinux.o Two translation units are compiled from one fixture and partially linked so the result has duplicate locals, which symid_needed() requires. One duplicate is in a live section and one in .exitcall.exit. Checking the live duplicate as well keeps the test honest: it would otherwise pass just as happily if symid generation stopped working entirely. Signed-off-by: Puranjay Mohan Assisted-by: Claude:claude-opus-5 Signed-off-by: Song Liu --- .../tests/generic/fixtures/symid_discarded.c | 25 +++++++++++ .../tests/generic/test-symid-discarded.sh | 44 +++++++++++++++++++ 2 files changed, 69 insertions(+) create mode 100644 tools/objtool/tests/generic/fixtures/symid_discarded.c create mode 100755 tools/objtool/tests/generic/test-symid-discarded.sh diff --git a/tools/objtool/tests/generic/fixtures/symid_discarded.c b/tools/objtool/tests/generic/fixtures/symid_discarded.c new file mode 100644 index 000000000000..573cc2d4474b --- /dev/null +++ b/tools/objtool/tests/generic/fixtures/symid_discarded.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Compiled twice and partially linked so the result has duplicate locals, + * which is what symid_needed() requires. dup_normal is in a live section, + * dup_discarded in one the vmlinux link throws away. DISCARDED_SEC selects + * which discarded section, since there is more than one and each was its own + * bug. + */ + +#ifndef DISCARDED_SEC +#define DISCARDED_SEC ".exitcall.exit" +#endif + +static const char __modinfo[] + __attribute__((section(".modinfo"), used, aligned(1))) = "\0name=vmlinux"; + +static int dup_normal = 1; + +static void *dup_discarded + __attribute__((section(DISCARDED_SEC), used)) = &dup_normal; + +int FUNC_NAME(void) +{ + return dup_normal + (dup_discarded != (void *)0); +} diff --git a/tools/objtool/tests/generic/test-symid-discarded.sh b/tools/objtool/tests/generic/test-symid-discarded.sh new file mode 100755 index 000000000000..388a24984ec0 --- /dev/null +++ b/tools/objtool/tests/generic/test-symid-discarded.sh @@ -0,0 +1,44 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# .klp.symid must not reference symbols in sections the vmlinux link discards. +# Each such section has been its own bug, found only when someone built a +# config where a duplicate happened to land there, so cover the whole list +# rather than whichever one was reported last. + +. "$(dirname "$0")/../lib.sh" + +setup + +# Allocated sections which vmlinux.lds.h discards unconditionally. A symid +# referencing one of these fails the vmlinux link outright: +# +# `__exitcall_hid_exit' referenced in section `.klp.symid' of vmlinux.o: +# defined in discarded section `.exitcall.exit' of vmlinux.o +for sec in .exitcall.exit .no_trim_symbol; do + build_one symid_discarded.c a.o \ + -DFUNC_NAME=use_a -DDISCARDED_SEC="\"$sec\"" + build_one symid_discarded.c b.o \ + -DFUNC_NAME=use_b -DDISCARDED_SEC="\"$sec\"" + + # --klp-symids only runs on a file named vmlinux.o + rm -f "$workdir/vmlinux.o" + partial_link "$workdir/vmlinux.o" "$workdir/a.o" "$workdir/b.o" || + probe_skip "partial link unavailable" + + "$OBJTOOL" --klp-symids --link "$workdir/vmlinux.o" || + fail "objtool --klp-symids failed" + + symids="$(in_relocs vmlinux.o | + awk '/rela.klp.symid/,/^$/')" + + # Without this the test would also pass if symid generation stopped + # entirely. + echo "$symids" | grep -q 'dup_normal' || + fail "$sec: no symid for the duplicate in a live section" + + echo "$symids" | grep -q 'dup_discarded' && + fail "symid emitted for a symbol in discarded section $sec" +done + +pass "no symids for symbols in discarded sections" -- 2.53.0-Meta