From: Joey Gouly <joey.gouly@arm.com>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Marco Elver <elver@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, mark.rutland@arm.com, nd@arm.com
Subject: Re: [PATCH v3] arm64: Enable KCSAN
Date: Thu, 2 Dec 2021 16:13:10 +0000 [thread overview]
Message-ID: <20211202161310.GA27207@e124191.cambridge.arm.com> (raw)
In-Reply-To: <20211202143331.15259-1-wangkefeng.wang@huawei.com>
Hi all,
On Thu, Dec 02, 2021 at 10:33:31PM +0800, Kefeng Wang wrote:
> This patch enables KCSAN for arm64, with updates to build rules
> to not use KCSAN for several incompatible compilation units.
>
> Resent GCC version(at least GCC10) made outline-atomics as the
> default option(unlike Clang), which will cause linker errors
> for kernel/kcsan/core.o. Disables the out-of-line atomics by
> no-outline-atomics to fix the linker errors.
>
> Meanwhile, as Mark said[1], there is a specific issue on arm64
> about ARM64_BTI with Clang 11 if KCSAN enabled, which is fixed
> by Clang 12, add CLANG_VERSION check. And also some latent issues
> are need to be fixed which isn't just a KCSAN problem, we make
> the KCSAN depends on EXPERT for now.
>
> Tested selftest and kcsan_test(built with GCC11 and Clang 13),
> and all passed.
>
> [1] https://lkml.org/lkml/2021/12/1/354
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Confirming that I get KCSAN errors such as:
[ 285.188576] ==================================================================
[ 285.189514] BUG: KCSAN: data-race in el0_svc_common.constprop.0+0x84/0x14c
[ 285.190599]
[ 285.191092] race at unknown origin, with read to 0xffff0000e3ce3700 of 8 bytes by task 19946 on cpu 5:
[ 285.192576] el0_svc_common.constprop.0+0x84/0x14c
[ 285.193601] do_el0_svc+0x30/0x40
[ 285.194457] el0_svc+0x3c/0x70
[ 285.194954] el0t_64_sync_handler+0x9c/0x120
[ 285.195618] el0t_64_sync+0x18c/0x190
[ 285.196371]
[ 285.196823] value changed: 0x0000000000000008 -> 0x000000000000000a
[ 285.197674]
[ 285.198172] Reported by Kernel Concurrency Sanitizer on:
[ 285.198941] CPU: 5 PID: 19946 Comm: stress-ng Not tainted 5.16.0-rc3+ #842 95517f70e70f029451088b9dec0b9074aa29ae52
[ 285.201191] ==================================================================
This particular case is fixed by Mark's thread flag series [1], which is in linux-next now.
Tested with gcc 11 and clang 14.0 (built from git) on qemu and FVP.
Tested-by: Joey Gouly <joey.gouly@arm.com>
Thanks,
Joey
[1] https://lore.kernel.org/lkml/20211129130653.2037928-1-mark.rutland@arm.com/
WARNING: multiple messages have this Message-ID (diff)
From: Joey Gouly <joey.gouly@arm.com>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Marco Elver <elver@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, mark.rutland@arm.com, nd@arm.com
Subject: Re: [PATCH v3] arm64: Enable KCSAN
Date: Thu, 2 Dec 2021 16:13:10 +0000 [thread overview]
Message-ID: <20211202161310.GA27207@e124191.cambridge.arm.com> (raw)
In-Reply-To: <20211202143331.15259-1-wangkefeng.wang@huawei.com>
Hi all,
On Thu, Dec 02, 2021 at 10:33:31PM +0800, Kefeng Wang wrote:
> This patch enables KCSAN for arm64, with updates to build rules
> to not use KCSAN for several incompatible compilation units.
>
> Resent GCC version(at least GCC10) made outline-atomics as the
> default option(unlike Clang), which will cause linker errors
> for kernel/kcsan/core.o. Disables the out-of-line atomics by
> no-outline-atomics to fix the linker errors.
>
> Meanwhile, as Mark said[1], there is a specific issue on arm64
> about ARM64_BTI with Clang 11 if KCSAN enabled, which is fixed
> by Clang 12, add CLANG_VERSION check. And also some latent issues
> are need to be fixed which isn't just a KCSAN problem, we make
> the KCSAN depends on EXPERT for now.
>
> Tested selftest and kcsan_test(built with GCC11 and Clang 13),
> and all passed.
>
> [1] https://lkml.org/lkml/2021/12/1/354
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Confirming that I get KCSAN errors such as:
[ 285.188576] ==================================================================
[ 285.189514] BUG: KCSAN: data-race in el0_svc_common.constprop.0+0x84/0x14c
[ 285.190599]
[ 285.191092] race at unknown origin, with read to 0xffff0000e3ce3700 of 8 bytes by task 19946 on cpu 5:
[ 285.192576] el0_svc_common.constprop.0+0x84/0x14c
[ 285.193601] do_el0_svc+0x30/0x40
[ 285.194457] el0_svc+0x3c/0x70
[ 285.194954] el0t_64_sync_handler+0x9c/0x120
[ 285.195618] el0t_64_sync+0x18c/0x190
[ 285.196371]
[ 285.196823] value changed: 0x0000000000000008 -> 0x000000000000000a
[ 285.197674]
[ 285.198172] Reported by Kernel Concurrency Sanitizer on:
[ 285.198941] CPU: 5 PID: 19946 Comm: stress-ng Not tainted 5.16.0-rc3+ #842 95517f70e70f029451088b9dec0b9074aa29ae52
[ 285.201191] ==================================================================
This particular case is fixed by Mark's thread flag series [1], which is in linux-next now.
Tested with gcc 11 and clang 14.0 (built from git) on qemu and FVP.
Tested-by: Joey Gouly <joey.gouly@arm.com>
Thanks,
Joey
[1] https://lore.kernel.org/lkml/20211129130653.2037928-1-mark.rutland@arm.com/
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next prev parent reply other threads:[~2021-12-02 16:13 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-02 14:33 [PATCH v3] arm64: Enable KCSAN Kefeng Wang
2021-12-02 14:33 ` Kefeng Wang
2021-12-02 14:36 ` Marco Elver
2021-12-02 14:36 ` Marco Elver
2021-12-02 14:44 ` Mark Rutland
2021-12-02 14:44 ` Mark Rutland
2021-12-03 2:29 ` Kefeng Wang
2021-12-03 2:29 ` Kefeng Wang
2021-12-03 10:41 ` Mark Rutland
2021-12-03 10:41 ` Mark Rutland
2021-12-10 6:58 ` Kefeng Wang
2021-12-10 6:58 ` Kefeng Wang
2021-12-02 16:13 ` Joey Gouly [this message]
2021-12-02 16:13 ` Joey Gouly
2021-12-02 16:56 ` Nathan Chancellor
2021-12-02 16:56 ` Nathan Chancellor
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