linux-kernel - Re: [PATCH v10 04/16] arm64/ptrace: Refactor syscall_trace

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Message-ID: <532b42e2-3417-4e0f-af59-8c79521c34a3@arm.com>
Date: Tue, 27 Jan 2026 10:43:36 +0100
From: Kevin Brodsky <kevin.brodsky@....com>
To: Jinjie Ruan <ruanjinjie@...wei.com>, Will Deacon <will@...nel.org>
Cc: catalin.marinas@....com, oleg@...hat.com, tglx@...utronix.de,
 peterz@...radead.org, luto@...nel.org, shuah@...nel.org, kees@...nel.org,
 wad@...omium.org, macro@...am.me.uk, charlie@...osinc.com,
 akpm@...ux-foundation.org, ldv@...ace.io, anshuman.khandual@....com,
 mark.rutland@....com, thuth@...hat.com, song@...nel.org,
 ryan.roberts@....com, ada.coupriediaz@....com, broonie@...nel.org,
 liqiang01@...inos.cn, pengcan@...inos.cn, kmal@...k.li, dvyukov@...gle.com,
 richard.weiyang@...il.com, reddybalavignesh9979@...il.com,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v10 04/16] arm64/ptrace: Refactor
 syscall_trace_enter/exit()

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).

- Kevin