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Wed, 18 Jun 2025 14:36:07 -0700 (PDT) Received: from [192.168.1.14] ([38.175.170.29]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-3de019d1ba0sm32296805ab.31.2025.06.18.14.36.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Jun 2025 14:36:07 -0700 (PDT) Message-ID: Date: Wed, 18 Jun 2025 15:36:06 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND PATCH] selftests/pidfd: align stack to fix SP alignment exception To: Shuai Xue , brauner@kernel.org, shuah@kernel.org, will@kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: baolin.wang@linux.alibaba.com, tianruidong@linux.alibaba.com, catalin.marinas@arm.com, mark.rutland@arm.com, Shuah Khan References: <20250616050648.58716-1-xueshuai@linux.alibaba.com> Content-Language: en-US From: Shuah Khan In-Reply-To: <20250616050648.58716-1-xueshuai@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/15/25 23:06, Shuai Xue wrote: > The pidfd_test fails on the ARM64 platform with the following error: > > Bail out! pidfd_poll check for premature notification on child thread exec test: Failed > > When exception-trace is enabled, the kernel logs the details: > > #echo 1 > /proc/sys/debug/exception-trace > #dmesg | tail -n 20 > [48628.713023] pidfd_test[1082142]: unhandled exception: SP Alignment, ESR 0x000000009a000000, SP/PC alignment exception in pidfd_test[400000+4000] > [48628.713049] CPU: 21 PID: 1082142 Comm: pidfd_test Kdump: loaded Tainted: G W E 6.6.71-3_rc1.al8.aarch64 #1 > [48628.713051] Hardware name: AlibabaCloud AliServer-Xuanwu2.0AM-1UC1P-5B/AS1111MG1, BIOS 1.2.M1.AL.P.157.00 07/29/2023 > [48628.713053] pstate: 60001800 (nZCv daif -PAN -UAO -TCO -DIT +SSBS BTYPE=-c) > [48628.713055] pc : 0000000000402100 > [48628.713056] lr : 0000ffff98288f9c > [48628.713056] sp : 0000ffffde49daa8 > [48628.713057] x29: 0000000000000000 x28: 0000000000000000 x27: 0000000000000000 > [48628.713060] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 > [48628.713062] x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000400e80 > [48628.713065] x20: 0000000000000000 x19: 0000000000402650 x18: 0000000000000000 > [48628.713067] x17: 00000000004200d8 x16: 0000ffff98288f40 x15: 0000ffffde49b92c > [48628.713070] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 > [48628.713072] x11: 0000000000001011 x10: 0000000000402100 x9 : 0000000000000010 > [48628.713074] x8 : 00000000000000dc x7 : 3861616239346564 x6 : 000000000000000a > [48628.713077] x5 : 0000ffffde49daa8 x4 : 000000000000000a x3 : 0000ffffde49daa8 > [48628.713079] x2 : 0000ffffde49dadc x1 : 0000ffffde49daa8 x0 : 0000000000000000 > > According to ARM ARM D1.3.10.2 SP alignment checking: > >> When the SP is used as the base address of a calculation, regardless of >> any offset applied by the instruction, if bits [3:0] of the SP are not >> 0b0000, there is a misaligned SP. > > To fix it, align the stack with 16 bytes. > > Signed-off-by: Shuai Xue > --- Assuming this is going through Christian's tree. Acked-by: Shuah Khan Let me know if you would like me to pick it up. thanks, -- Shuah