From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Michael Jeanson <mjeanson@efficios.com>,
Jens Axboe <axboe@kernel.dk>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
x86@kernel.org, Sean Christopherson <seanjc@google.com>,
Wei Liu <wei.liu@kernel.org>
Subject: Re: [patch V5 28/31] rseq: Switch to fast path processing on exit to user
Date: Thu, 23 Oct 2025 11:04:38 +0200 [thread overview]
Message-ID: <20251023090438.GX3245006@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20251022121943.156913457@linutronix.de>
On Wed, Oct 22, 2025 at 02:52:35PM +0200, Thomas Gleixner wrote:
> +static __always_inline unsigned long __exit_to_user_mode_loop(struct pt_regs *regs,
> + unsigned long ti_work)
> {
> /*
> * Before returning to user space ensure that all pending work
> @@ -62,6 +57,23 @@ void __weak arch_do_signal_or_restart(st
> return ti_work;
> }
>
> +/**
> + * exit_to_user_mode_loop - do any pending work before leaving to user space
> + * @regs: Pointer to pt_regs on entry stack
> + * @ti_work: TIF work flags as read by the caller
> + */
> +__always_inline unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
> + unsigned long ti_work)
> +{
> + for (;;) {
> + ti_work = __exit_to_user_mode_loop(regs, ti_work);
> +
> + if (likely(!rseq_exit_to_user_mode_restart(regs)))
> + return ti_work;
> + ti_work = read_thread_flags();
> + }
> +}
Loops in loops seems to be your favourite new theme :-)
next prev parent reply other threads:[~2025-10-23 9:04 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-22 12:52 [patch V5 00/31] rseq: Optimize exit to user space Thomas Gleixner
2025-10-22 12:52 ` [patch V5 01/31] rseq: Avoid pointless evaluation in __rseq_notify_resume() Thomas Gleixner
2025-10-22 12:52 ` [patch V5 02/31] rseq: Condense the inline stubs Thomas Gleixner
2025-10-22 12:52 ` [patch V5 03/31] rseq: Move algorithm comment to top Thomas Gleixner
2025-10-22 12:52 ` [patch V5 04/31] rseq: Remove the ksig argument from rseq_handle_notify_resume() Thomas Gleixner
2025-10-22 12:52 ` [patch V5 05/31] rseq: Simplify registration Thomas Gleixner
2025-10-22 12:52 ` [patch V5 06/31] rseq: Simplify the event notification Thomas Gleixner
2025-10-22 12:52 ` [patch V5 07/31] rseq, virt: Retrigger RSEQ after vcpu_run() Thomas Gleixner
2025-10-22 12:52 ` [patch V5 08/31] rseq: Avoid CPU/MM CID updates when no event pending Thomas Gleixner
2025-10-22 12:52 ` [patch V5 09/31] rseq: Introduce struct rseq_data Thomas Gleixner
2025-10-22 12:52 ` [patch V5 10/31] entry: Cleanup header Thomas Gleixner
2025-10-22 12:52 ` [patch V5 11/31] entry: Remove syscall_enter_from_user_mode_prepare() Thomas Gleixner
2025-10-22 12:52 ` [patch V5 12/31] entry: Inline irqentry_enter/exit_from/to_user_mode() Thomas Gleixner
2025-10-22 12:52 ` [patch V5 13/31] sched: Move MM CID related functions to sched.h Thomas Gleixner
2025-10-22 12:52 ` [patch V5 14/31] rseq: Cache CPU ID and MM CID values Thomas Gleixner
2025-10-22 12:52 ` [patch V5 15/31] rseq: Record interrupt from user space Thomas Gleixner
2025-10-22 12:52 ` [patch V5 16/31] rseq: Provide tracepoint wrappers for inline code Thomas Gleixner
2025-10-22 12:52 ` [patch V5 17/31] rseq: Expose lightweight statistics in debugfs Thomas Gleixner
2025-10-22 12:52 ` [patch V5 18/31] rseq: Provide static branch for runtime debugging Thomas Gleixner
2025-10-22 12:52 ` [patch V5 19/31] rseq: Provide and use rseq_update_user_cs() Thomas Gleixner
2025-10-22 12:52 ` [patch V5 20/31] rseq: Replace the original debug implementation Thomas Gleixner
2025-10-22 12:52 ` [patch V5 21/31] rseq: Make exit debugging static branch based Thomas Gleixner
2025-10-22 12:52 ` [patch V5 22/31] rseq: Use static branch for syscall exit debug when GENERIC_IRQ_ENTRY=y Thomas Gleixner
2025-10-22 12:52 ` [patch V5 23/31] rseq: Provide and use rseq_set_ids() Thomas Gleixner
2025-10-22 12:52 ` [patch V5 24/31] rseq: Separate the signal delivery path Thomas Gleixner
2025-10-22 12:52 ` [patch V5 25/31] rseq: Rework the TIF_NOTIFY handler Thomas Gleixner
2025-10-22 13:31 ` Sean Christopherson
2025-10-22 12:52 ` [patch V5 26/31] rseq: Optimize event setting Thomas Gleixner
2025-10-22 12:52 ` [patch V5 27/31] rseq: Implement fast path for exit to user Thomas Gleixner
2025-10-23 8:51 ` Peter Zijlstra
2025-10-22 12:52 ` [patch V5 28/31] rseq: Switch to fast path processing on " Thomas Gleixner
2025-10-23 9:04 ` Peter Zijlstra [this message]
2025-10-22 12:52 ` [patch V5 29/31] entry: Split up exit_to_user_mode_prepare() Thomas Gleixner
2025-10-22 12:52 ` [patch V5 30/31] rseq: Split up rseq_exit_to_user_mode() Thomas Gleixner
2025-10-22 12:52 ` [patch V5 31/31] rseq: Switch to TIF_RSEQ if supported Thomas Gleixner
2025-10-23 9:22 ` [patch V5 00/31] rseq: Optimize exit to user space Peter Zijlstra
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