From nobody Fri Sep 25 00:41:21 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 D23F74E3257; Fri, 18 Sep 2026 10:15:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789726539; cv=none; b=GgJoALlWHsPGcDVZJGSbntQfI+Ik4V9Negjqe8JJ5mP4dhoSGaO0v1E2cOGuWY8T1IhlmTZvCJYU0iB84aPasYvflm5T23x16PztQeqgyLxe1BBa6oMtK20YtJZlCT6Sp/6ujr3AB2ocLKae79wfR1rLhRpoaiPRbCw60iFpszs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789726539; c=relaxed/simple; bh=1c7fMDS2Xem6bQaVT1AW6mFaQzB7CA5K4TaqUSYq6VU=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=YsG68shyac07jtBI2Ej3u9N7Xa4jTcwlsW7xax5eh/dE2G7jppT+xqZTJOi9cbVRbG4SzcmbnsaD+7zbJjyNTRh9Al3btQfQRipbdPQ7jqdEULO9rj7F+kg8rt6KeP5qt1t6DZHGgzU1yx7v49Q8M7JqQSJHReg/0yNDkfG9BZI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=GDYM64N2; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=+1c8B4r3; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="GDYM64N2"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="+1c8B4r3" Date: Fri, 18 Sep 2026 10:15:30 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1789726532; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5ycngHVESqsVXRgzq+n0kSaxWLkGxU514JzgjikaEH8=; b=GDYM64N2Th0S70rML+uOTQDxY65/NH3FI69IS/RORp1fxdnX6LfPBMzrmmzcHY5/tbXy5A W1Y53wh37Lmtyl8zZR1bJxgfSLzBlbVfLw8JB2LewTKJYP8xj6gHmMscuLOacWcbs423F/ otm7u8zjwP/QRRPU1+JzE3wPG1qQ76GiX0RkjYmmX/EPjoYcjYk+zyTXrtrKg9yt4cDgDU k6XImcKnPIych1seoIvCBQjDkxURx+XkVeThFyS8v1k88iwXbRDRJJs6XmnB/EVatHpCga EEFJwqqiwj9d2Vg39Ms5F6QqWykkOGv9TxQovdQCRS/xhzVUoP5asP6Q2AZBHA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1789726532; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5ycngHVESqsVXRgzq+n0kSaxWLkGxU514JzgjikaEH8=; b=+1c8B4r3ax4aJiDa6r97FEGRj1CTKXCvr0s9YKn2ooKb00jSqLt/jJRO1tdd/eR1InPUYA xEgxjfhzOnBNigBw== From: "tip-bot2 for Song Liu" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: objtool/core] objtool/klp: Add test for new references to exported symbols Cc: Song Liu , Josh Poimboeuf , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20260916184351.2720310-34-song@kernel.org> References: <20260916184351.2720310-34-song@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <178972653024.1720534.11943739963550459013.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the objtool/core branch of tip: Commit-ID: b45f394ee3afd2ff0a54894f95a01f96ecc8e30a Gitweb: https://git.kernel.org/tip/b45f394ee3afd2ff0a54894f95a01f96e= cc8e30a Author: Song Liu AuthorDate: Wed, 16 Sep 2026 11:43:26 -07:00 Committer: Josh Poimboeuf CommitterDate: Wed, 16 Sep 2026 17:13:29 -07:00 objtool/klp: Add test for new references to exported symbols A patch may introduce a reference the original object did not have. That is fine when the export belongs to vmlinux, and not fine when it belongs to a module: the livepatch would gain a module dependency nobody declared, and late module patching lets the patch load first. This tests the behavior of commit 72d76d0c18eb ("objtool/klp: Allow new references to module exports"). Assisted-by: Claude:claude-opus-4 Based-on-test-by: Joe Lawrence Assisted-by: Claude:claude-opus-5 Signed-off-by: Song Liu Link: https://patch.msgid.link/20260916184351.2720310-34-song@kernel.org Signed-off-by: Josh Poimboeuf --- tools/objtool/tests/generic/fixtures/new_export_ref.c | 35 ++++++++- tools/objtool/tests/generic/test-new-export-ref.sh | 46 ++++++++++- 2 files changed, 81 insertions(+) create mode 100644 tools/objtool/tests/generic/fixtures/new_export_ref.c create mode 100755 tools/objtool/tests/generic/test-new-export-ref.sh diff --git a/tools/objtool/tests/generic/fixtures/new_export_ref.c b/tools/= objtool/tests/generic/fixtures/new_export_ref.c new file mode 100644 index 0000000..73210aa --- /dev/null +++ b/tools/objtool/tests/generic/fixtures/new_export_ref.c @@ -0,0 +1,35 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A reference which only exists in the patched build. The symbol has no = twin + * in the original object, so what klp diff may do with it depends entirel= y on + * whether Module.symvers says it is exported, and by what. + */ + +static const char __modinfo[] + __attribute__((section(".modinfo"), used, aligned(1))) =3D "\0name=3Dvmli= nux"; + +extern int newly_referenced(int x); + +/* + * A reference both builds have. When Module.symvers says a module exports + * this one, the original already depends on that module, which is what ma= kes + * a new reference to it safe -- the loader will not let the patched module + * load without it. EXISTING_DEP leaves it out, for the case where there = is + * no such dependency to inherit. + */ +extern int existing_dep(int x); + +int target(int x) +{ +#ifdef EXISTING_DEP + int base =3D existing_dep(x); +#else + int base =3D x; +#endif + +#ifdef PATCHED + return newly_referenced(base); +#else + return base + 1; +#endif +} diff --git a/tools/objtool/tests/generic/test-new-export-ref.sh b/tools/obj= tool/tests/generic/test-new-export-ref.sh new file mode 100755 index 0000000..f0be2cf --- /dev/null +++ b/tools/objtool/tests/generic/test-new-export-ref.sh @@ -0,0 +1,46 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# A reference the patch adds has no counterpart in the original object. k= lp +# diff used to reject any such reference needing a klp relocation, which r= uled +# out patches that call something they did not call before -- a common eno= ugh +# thing for a fix to do. +# +# Module.symvers is what makes it safe: it says the symbol exists and who = owns +# it. But that is only sufficient for a vmlinux export. A new reference = to a +# module's export is a dependency the patch module does not declare, and t= he +# relocation would resolve only if that module happened to be loaded, so it +# stays an error. + +. "$(dirname "$0")/../lib.sh" + +setup +build_pair new_export_ref.c + +# Exported by vmlinux, in a module: namespace so it needs a klp relocation +# rather than an ordinary one. Allowed. +export_syms +add_exports_ns vmlinux module:kvm newly_referenced +run_diff +assert_klp_sym newly_referenced vmlinux + +# Exported by a module the patched object does not depend on. Rejected, a= nd +# for that reason rather than some other. +export_syms +add_exports other_mod newly_referenced +run_diff 255 +assert_diff_log 'undeclared module dependency' + +# ... unless the original already referenced something that module exports. +# The loader will not let the patched object load without other_mod, so the +# klp relocation has something to resolve against, and klp diff allows it. +# This is the other half of the rule, and it fails in the opposite directi= on: +# refusing here would reject a patch which is safe to apply. +rm -f "$workdir/out.o" +build_pair new_export_ref.c -DEXISTING_DEP +export_syms +add_exports other_mod newly_referenced existing_dep +run_diff +assert_klp_sym newly_referenced other_mod + +pass "new reference allowed for vmlinux and for a module already depended = on"