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 B91684AB3C0 for ; Wed, 16 Sep 2026 18:46:20 +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=1789584398; cv=none; b=Sc6M5C9a3nS3kAMJjaW84XI4SHL0rt3l+vNg+qAhem/gjhwdu3w4bkrkqPm9Kj8E+8FC4Jl0oE1pNobPuPuBd9CkURvabc7V6E5Ue2AEo8MdYuonn7LeJE/uvNRMbxMytCsSF02veS8K4Gqe0kYetPNzYjp56P1fr4w96jqLl0E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789584398; c=relaxed/simple; bh=OV3PG5RHEQDDlfYICSq8BEj5/hfrpKxcNJpcc4Pl8iM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=k6t9UEezu8AoDJX1ETPMvXPx+XNyegQCXv/k1n2BdfWiuVJe80h2/QnSuyu3Iqc7wUVfziAfXYQk8nxAZ6kyQLE7ZXPPaXJpg8KfNXy39Sv/G/KTZKLx7ehDW+pcUhzX1rhdSOrMnGUzakbDU/cynaYJtWR7Uuk1HgHYDccy0Ec= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CZfr0cZl; 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="CZfr0cZl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51DA41F000FF; Wed, 16 Sep 2026 18:46:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789584377; bh=+mQmUlzGh2hgexbyzeasUkjBtvD1pESiZPPcrmg700o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CZfr0cZlNZAceyyyJQ13+U8GYMuvogME43cCDB+opZhzrlgLmWU+y4KvofoRZNwYD LpUKZCVGtqvh6D4WZVmmfZ15yU5IbGYb+B7J+UR5nNhhrP1uAPV9rDZChcZj+RpN4Z 335M2lmxxU0JRBZAiOeQQXx+ia0Frf39yXv1R7RvGhtVQTsTRYkhzJ2nHARn5Adyq3 LX6ac7GXW6zjWgzn+7nzcRFUgSHxOk65YNn/ynho1ysYZAUf++aZv+BgvXUldz9wDQ 9IDgiUsLHD6tjRe+oOVFYwvOgrqEFWYPfuzs67pPqRgVmMs/4c7q0Qvm2ouxwH3xon Mb7Ht0EbBRNpw== 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 , Dylan Hatch Subject: [PATCH v5 29/58] objtool/klp: Add test for vmlinux relocs in a patched module Date: Wed, 16 Sep 2026 11:43:22 -0700 Message-ID: <20260916184351.2720310-30-song@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260916184351.2720310-1-song@kernel.org> References: <20260916184351.2720310-1-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 The kernel refuses a module-targeted klp relocation which names a vmlinux symbol. An EXPORT_SYMBOL_FOR_MODULES() symbol needs a klp relocation, so patching a module function that references one only loads if klp diff files that relocation under vmlinux rather than under the patched module. This fails at load, not at build: klp-build produces a module and static checks of it find nothing wrong. Hence the assertion on which object the relocation is filed against. Reported by Dylan Hatch, whose mod-ns-lp branch carries the kernel-side half of this case. Signed-off-by: Dylan Hatch Assisted-by: Claude:claude-opus-5 Signed-off-by: Song Liu --- .../generic/test-module-vmlinux-reloc.sh | 40 +++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100755 tools/objtool/tests/generic/test-module-vmlinux-reloc.sh diff --git a/tools/objtool/tests/generic/test-module-vmlinux-reloc.sh b/tools/objtool/tests/generic/test-module-vmlinux-reloc.sh new file mode 100755 index 000000000000..635a75f6b8ba --- /dev/null +++ b/tools/objtool/tests/generic/test-module-vmlinux-reloc.sh @@ -0,0 +1,40 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Patching a module, where the patched code references a vmlinux symbol which +# needs a klp relocation. +# +# The kernel does not allow a module-targeted klp relocation to reference a +# vmlinux symbol, and a symbol exported with EXPORT_SYMBOL_FOR_MODULES gets a +# klp relocation. Put together, filing that relocation under the patched +# module produces a patch the kernel refuses to apply to its target. +# +# So it goes under vmlinux instead, and is applied when the patch module loads +# rather than when the patched module does. That is the opposite of the rule +# for a reference to a module's symbol, which test-module-object covers; this +# is the other branch of the same decision. + +. "$(dirname "$0")/../lib.sh" + +setup +# The object being patched is a module ... +build_module_pair cross_module.c klp_testmod + +# ... and the symbol it references belongs to vmlinux, exported in a way that +# still requires a klp relocation. +export_syms +add_exports_ns vmlinux module:kvm other_mod_func +run_diff + +# Filed against vmlinux, applied when the patch loads. +assert_section __klp_relocs.vmlinux +assert_klp_sym other_mod_func vmlinux + +# Not against the patched module: that is the relocation the kernel rejects. +assert_no_section __klp_relocs.klp_testmod + +run_post_link +assert_klp_rela vmlinux .text.target +assert_no_section ".klp.rela.klp_testmod..text.target" + +pass "klp relocation to a vmlinux symbol filed under vmlinux, not the patched module" -- 2.53.0-Meta