linux-kernel - Re: [PATCH v9 15/16] entry: Inline syscall_exit

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Message-ID: <e55e9aae-1d84-42a2-bf6a-edc73608733a@arm.com>
Date: Thu, 11 Dec 2025 10:52:11 +0100
From: Kevin Brodsky <kevin.brodsky@....com>
To: Thomas Gleixner <tglx@...utronix.de>, Jinjie Ruan
 <ruanjinjie@...wei.com>, catalin.marinas@....com, will@...nel.org,
 oleg@...hat.com, peterz@...radead.org, luto@...nel.org, shuah@...nel.org,
 kees@...nel.org, wad@...omium.org, deller@....de, macro@...am.me.uk,
 charlie@...osinc.com, ldv@...ace.io, mark.rutland@....com, song@...nel.org,
 ryan.roberts@....com, ada.coupriediaz@....com, anshuman.khandual@....com,
 broonie@...nel.org, pengcan@...inos.cn, dvyukov@...gle.com,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v9 15/16] entry: Inline syscall_exit_work()

On 11/12/2025 07:55, Thomas Gleixner wrote:
> I have a suspicion that it is TIF_NOTIFY_RESUME. If that's the case
> you're seing the RSEQ overhead, which should be completely gone with the
> rewrite that got just merged into Linus tree.

I don't think this is related. This patch inlines syscall_exit_work(),
which is called if some flag in SYSCALL_WORK_EXIT is set. This includes
syscall-specific stuff like tracing and singlestep. TIF_NOTIFY_RESUME is
part of EXIT_TO_USER_MODE_WORK, handled in exit_to_user_mode_prepare(),
and isn't specific to syscall handling.

- Kevin