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 5A6073A63FB; Wed, 8 Jul 2026 00:55:45 +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=1783472146; cv=none; b=qRY8hcBBZHXaI4YuPWtNrw8m0FyrUQ649hXV/tWusNdQIBmzuTI/tf0RjMYwIzSbIP+65hOIRhE2dE2w81yRr6IXej6nyQShEZ/dE+uQ72Zvk1c6RkKA+wtpYCvrToy37+1b9OyVRXyCssqkOuyenKUayy8hY0G5a44Qlla92b4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783472146; c=relaxed/simple; bh=y5hhRHC7vKyufrVYCl4P8U8W+OF7RqDoVp1egTbeEy8=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=UyPNrRJP/SsJgjk6qsGU26nLDZLp1ToW36rI7zH0tIJh8Z4Ttm97SD2O4BQ3LKXPKwlVePm3dbltERFvnsviTE86JhfozPldXoDoOVrsaVxP8M/rCzDarAapoIGoZXbafXjKI3XsF9BQI5H+gz8jYT/ackLgulc9/fB9dCKhfTk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oZ/nGzZe; 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="oZ/nGzZe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 124341F000E9; Wed, 8 Jul 2026 00:55:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783472145; bh=XRAnSmciVx2Uv4vUT+zMl7S2GSv+W3820dA+59HEuQ8=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=oZ/nGzZeYoH2tT49qy0JP7bPImKjYNCoqtGmbMWIGBgeDFbE8SO6DCo58NrcxAN9C vATmCqgUsIO930R4BTHH5pyVrRwvJE3cr7M+WPLO/9u+C3n/bh8NYmZOVUcUQh8Let VUFVvI2f4FLqj609hnDneqUzOMRM2WxJ2VujUxQIuIfL/SNghUH0mp3Aa/Z/F1frBk UVx8xtryZ64qzN+191OYfvfG19bkyM8FiPZfL8W2Hquykb22LHoa5K2nWO7lpPjfDc WxwIrJWtZ3Ow3AZcvyfZSILzOGb0Frvq8B09eK2qhR8k84fXcIiORHFICg53bIfXIP VLojfCpZDBDXg== Date: Wed, 8 Jul 2026 09:55:40 +0900 From: Masami Hiramatsu (Google) To: Pu Hu Cc: "ada.coupriediaz@arm.com" , "catalin.marinas@arm.com" , "davem@davemloft.net" , Hongyan Xia , Jiazi Li , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-trace-kernel@vger.kernel.org" , "naveen@kernel.org" , "will@kernel.org" , "yang@os.amperecomputing.com" Subject: Re: [RFC 0/3] arm64: kprobes: Fix single-step fault and reentry handling Message-Id: <20260708095540.31c97fcbe9a56f3fd7f0b284@kernel.org> In-Reply-To: <20260706083636.159883-1-hupu@transsion.com> References: <20260704234730.46d51c47d75e7d208e7bec9f@kernel.org> <20260706083636.159883-1-hupu@transsion.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Hi, Pu, Thanks for updating the series. But even if it just update the signed-off-by, please update the version. Also, can you check the Sashiko's comments? https://sashiko.dev/#/patchset/20260706083636.159883-1-hupu%40transsion.com Thank you, On Mon, 6 Jul 2026 08:36:46 +0000 Pu Hu wrote: > From: Pu Hu > > This series fixes two arm64 kprobes issues observed when running > simpleperf with preemptirq tracepoints and dwarf callchains while a > kprobe is active on a frequently executed kernel function. > > The crash happens in the kprobe debug exception path. While a kprobe is > preparing or executing its XOL single-step instruction, perf/trace code > can run in the same window. That code may either take a fault of its own > or hit another kprobe. > > Patch 1 makes kprobe_fault_handler() handle a fault in > KPROBE_HIT_SS/KPROBE_REENTER only when the faulting PC points at the > current kprobe's XOL instruction. Otherwise the fault is left to the > normal fault handling path. > > Patch 2 allows a kprobe hit in KPROBE_HIT_SS to be handled as a > recoverable one-level reentry. Only a hit while already in > KPROBE_REENTER remains unrecoverable. > > Patch 3 adds a kprobes selftest which registers a kprobe on a frequently > executed filemap fault path and drives repeated file-backed page faults > from userspace. This provides a smaller reproducer for validating the > fault handling fix. > > This follows the same logic as the existing x86 fixes: > 6381c24cd6d5 ("kprobes/x86: Fix page-fault handling logic") > 6a5022a56ac3 ("kprobes/x86: Allow to handle reentered kprobe on single-stepping") > > Reproducer: > > simpleperf record -p -f 10000 \ > -e preemptirq:preempt_disable \ > -e preemptirq:preempt_enable \ > --duration 9 --call-graph dwarf \ > -o /data/local/tmp/perf.data > > The new selftest can be built from tools/testing/selftests/kprobe/ and > used to exercise the page fault handling path with the test kprobe > module loaded. > > Before this series, the crash reproduced frequently. With both patches > applied, it was no longer reproduced in our testing. > > > Pu Hu (3): > arm64: kprobes: Do not handle non-XOL faults as kprobe faults > arm64: kprobes: Allow reentering kprobes while single-stepping > selftests/kprobes: Add kprobe stress test for page fault handling > > arch/arm64/kernel/probes/kprobes.c | 22 +++- > tools/testing/selftests/kprobe/.gitignore | 2 + > tools/testing/selftests/kprobe/Makefile | 75 +++++++++++++ > tools/testing/selftests/kprobe/fault_stress.c | 105 ++++++++++++++++++ > .../selftests/kprobe/kprobe_folio_stress.c | 70 ++++++++++++ > 5 files changed, 273 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/kprobe/.gitignore > create mode 100644 tools/testing/selftests/kprobe/Makefile > create mode 100644 tools/testing/selftests/kprobe/fault_stress.c > create mode 100644 tools/testing/selftests/kprobe/kprobe_folio_stress.c > > -- > 2.43.0 > -- Masami Hiramatsu (Google)