From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0D19513AF2; Tue, 27 Jan 2026 14:54:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769525686; cv=none; b=nCvGuAlAcKh7GOD6213zNDwDnNVGlWUqgSe/DsoXS213nodz2FQ7jw+QsDTfvS2RSGdUO2pO7ZweQPMfmVee2C6Y2mJ0Jhqv4N9Cw9yzSDvO4IZD6OjmYCGPU6BnbqT3BswvR8APy2G88mMyi80J9zVsIjIkRa8cEys5rKXJaS8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769525686; c=relaxed/simple; bh=EjITxFfaHrNpRvj40ij3H0cLe0GrW6QZX2QjuknHNxY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QLmfo0+8FKeO91IZX3nsHE5oJAQWblPGfkuwHiA5PKZvnI40Fito1Gqzw98fgOBJw9zTrlisjawsO2XAQ45VA0byBMe5Kha7zDMWmP3iWgalF+8egoPScnRqhP3XQXLedFWhbce9yLfRvwPG7S8cx7Rsb2NRx2iLtQ+tWIy/EEw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D7E6F1595; Tue, 27 Jan 2026 06:54:37 -0800 (PST) Received: from [10.57.52.3] (unknown [10.57.52.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3A14F3F632; Tue, 27 Jan 2026 06:54:38 -0800 (PST) Message-ID: <666db2a4-6015-46ac-8eba-565beff8b0c1@arm.com> Date: Tue, 27 Jan 2026 15:54:35 +0100 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: [PATCH v10 04/16] arm64/ptrace: Refactor syscall_trace_enter/exit() To: Jinjie Ruan , Will Deacon Cc: catalin.marinas@arm.com, oleg@redhat.com, tglx@linutronix.de, peterz@infradead.org, luto@kernel.org, shuah@kernel.org, kees@kernel.org, wad@chromium.org, macro@orcam.me.uk, charlie@rivosinc.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, mark.rutland@arm.com, thuth@redhat.com, song@kernel.org, ryan.roberts@arm.com, ada.coupriediaz@arm.com, broonie@kernel.org, liqiang01@kylinos.cn, pengcan@kylinos.cn, kmal@cock.li, dvyukov@google.com, richard.weiyang@gmail.com, reddybalavignesh9979@gmail.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20251222114737.1334364-1-ruanjinjie@huawei.com> <20251222114737.1334364-5-ruanjinjie@huawei.com> <4f07254d-b158-a1ce-69a7-4fa4b0f339c1@huawei.com> <532b42e2-3417-4e0f-af59-8c79521c34a3@arm.com> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 27/01/2026 12:02, Jinjie Ruan wrote: > > On 2026/1/27 17:43, Kevin Brodsky wrote: >> On 27/01/2026 04:01, Jinjie Ruan wrote: >>>> I understand that you're gradually making the arch code more similar to >>>> the core code so that we can switch over to it, but I'm struggling to >>>> understand why syscall_trace_enter() takes the 'syscall' argument. >>>> >>>> Even the core code just seems to use it as a local variable, which it >>>> overrides before it ever uses it. What am I missing? >>> Hi, >>> >>> You're absolutely right. The 'syscall' parameter is indeed treated as a >>> local variable and gets overridden before any real use. Should we >>> refactor to remove the parameter entirely in generic entry? >> I noticed this as well, removing it from the generic function would make >> sense. AFAICT that removal could be propagated quite far in fact: >> syscall_enter_from_user_mode_work(), syscall_enter_from_user_mode(), >> even arch implementation (do_syscall_64() on x86). > Not really, it is the default return value of > syscall_enter_from_user_mode_work() as below, so we only need to remove > the parameter in syscall_trace_enter(). > > static __always_inline long syscall_enter_from_user_mode_work(struct > pt_regs *regs, long syscall) > { > unsigned long work = READ_ONCE(current_thread_info()->syscall_work); > > if (work & SYSCALL_WORK_ENTER) > syscall = syscall_trace_enter(regs, work); > > return syscall; > } You're right, hadn't realised the call to syscall_trace_enter() was conditional. - Kevin