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 E1FC44D90D7 for ; Tue, 15 Sep 2026 23:39:27 +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=1789515569; cv=none; b=TApIga1uO6rYLLbPBjs7OHyZNA/IRJZFLMQfB4ZpeEQZPoDOLVSowpErqVbmO5hrsNs0+uLk41RF6Jwlm8t2iz5eZJtLMtMLytDUxcw1SvNRwvA5kMYf3scLV2EoQGduLsFPfOyS128nY7n8A68tn1aHn5nHyJwckP7NwMtP67I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789515569; c=relaxed/simple; bh=BnPfarbKRQ3iCIGhGkcAP8phh6qju9esOxbDxnCu1Bw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=q3VckhOtrzwXIXQcueEyhZElBZJ3I90tihoebfZ6FrdDG4FTSbezjEjAjj/ceKDqZZ/r3GEX4XfRU9h9yPLUD3LftBXKI0+aGnqup9QXFAPbGRrDEohCkn21Ck+QX2w2VkP2WnwvJ0v5GgwbF/MTkh13QEkHghj2Ki8iLKoMS04= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=izBUQomu; 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="izBUQomu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C0A51F000FF; Tue, 15 Sep 2026 23:39:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789515567; bh=RQ7omf0xNS0uK9GAW+/RIpG2YvJsXoTit1j7iA2dHJ0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=izBUQomusZk8nncLcJVqiz26KGzxq1XG4HdBUj0J+FFL20nXn/7VgP9g5NJCYP3vO O9mQuW7pIr0MX9+EOz4Fk/tiaJYuETOJ4aUBjwQWrdeprWdVHK3TYpJRPX+SP+F6Ob iaJnlImQd7yHS9ioB5zvA6ei7BRSF3mKFDDqWbq7utwPLwaRcVY1ZmAZiUElWR2S/Q nPWT4NBsWhOO4TR8H/1biFZFnQ14c9T+NXJqnPuAv6OXlLlJAo8PLbypP2pvflwVxZ pmpvrY2QUY75yMq0jVyCQrKi8O8fvW7BsBzXEwPxuRpV4M8w1TsJ2e6LgEYejhj6mb rqTKtR8CwWFWw== 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 v4 49/58] objtool/klp: Add test for tracepoint and pr_debug static branch keys Date: Tue, 15 Sep 2026 16:34:45 -0700 Message-ID: <20260915233454.2405019-50-song@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260915233454.2405019-1-song@kernel.org> References: <20260915233454.2405019-1-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 A module-owned static branch key is normally fatal, because late module patching lets the livepatch load before the module it depends on and jump_label_add_module() then dereferences an unresolved entry. Tracepoints and pr_debug() generate such keys everywhere, so refusing them outright would make any function containing a trace_*() call or a pr_debug() unpatchable. klp diff drops the entry, warns, and carries on: the patched code works with that one tracepoint or debug print permanently off. Both halves matter, and the test asserts both. A build which fails is a function nobody can patch; an entry left in place is the corruption the rejection exists to prevent. Give the fixture a KEY_NAME knob so the same static branch can be built with either special name. Verified by removing each exemption in turn -- the test fails for both. That the entry is then dropped is asserted but not isolated, and the test says so. Assisted-by: Claude:claude-opus-4 Based-on-test-by: Joe Lawrence Assisted-by: Claude:claude-opus-5 Signed-off-by: Song Liu --- .../generic/test-jump-label-exempt-keys.sh | 51 +++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100755 tools/objtool/tests/generic/test-jump-label-exempt-keys.sh diff --git a/tools/objtool/tests/generic/test-jump-label-exempt-keys.sh b/tools/objtool/tests/generic/test-jump-label-exempt-keys.sh new file mode 100755 index 000000000000..fa2f913d860b --- /dev/null +++ b/tools/objtool/tests/generic/test-jump-label-exempt-keys.sh @@ -0,0 +1,51 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Two kinds of module-owned static branch key are disabled with a warning +# instead of rejected. +# +# A module-local key is normally fatal: late module patching lets the livepatch +# load before the module it depends on, so the unresolved __jump_table entry is +# dereferenced by jump_label_add_module(). test-jump-label-module-key covers +# that rejection. +# +# Tracepoints and pr_debug() generate such keys everywhere, though, and +# refusing them outright would make any function containing a trace_*() call or +# a pr_debug() unpatchable. So klp diff drops the entry, says so, and carries +# on: the patched code keeps working with that one tracepoint or debug print +# permanently off. +# +# Both halves matter. A build that fails is a function nobody can patch; an +# entry left in place is the memory corruption the rejection exists to prevent. +# +# The two exemptions are isolated: remove either and this fails. That the +# entry is then dropped is asserted but not isolated -- making the caller keep +# it anyway produces no output difference here, so that assertion stands as a +# check on the behaviour rather than on the line which produces it. +# +# Covers the same ground as corpus/x86_64/static-call-module-tracepoint and +# pr-debug-unsupported in Joe Lawrence's klp-build unit test corpus. + +. "$(dirname "$0")/../lib.sh" + +setup + +# check +check() +{ + build_pair jump_label.c -DKEY_NAME="$1" -DMODNAME='"klp_testmod"' + require_input_section __jump_table + + # Accepted, not rejected: this is the whole point. + run_diff + assert_diff_log "$2" + + # And the entry is gone, not merely complained about. + assert_patched target + assert_no_section __jump_table +} + +check __tracepoint_klp_test 'disabling unsupported tracepoint klp_test' +check __UNIQUE_ID_ddebug_klp_test 'disabling unsupported pr_debug' + +pass "tracepoint and pr_debug keys disabled with a warning, not rejected" -- 2.53.0-Meta