linux-kernel - Re: [patch 1/5] tracehook: Provide TIF_NOTIFY

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190801144814.GC31398@hirez.programming.kicks-ass.net>
Date:   Thu, 1 Aug 2019 16:48:14 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Ingo Molnar <mingo@...nel.org>,
        Sebastian Siewior <bigeasy@...utronix.de>,
        Anna-Maria Gleixner <anna-maria@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Julia Cartwright <julia@...com>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, kvm@...r.kernel.org,
        Radim Krcmar <rkrcmar@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        John Stultz <john.stultz@...aro.org>,
        Andy Lutomirski <luto@...nel.org>,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>
Subject: Re: [patch 1/5] tracehook: Provide TIF_NOTIFY_RESUME handling for KVM

On Thu, Aug 01, 2019 at 04:32:51PM +0200, Thomas Gleixner wrote:
> +#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
> +/**
> + * tracehook_handle_notify_resume - Notify resume handling for virt
> + *
> + * Called with interrupts and preemption enabled from VMENTER/EXIT.
> + */
> +void tracehook_handle_notify_resume(void)
> +{
> +	local_irq_disable();
> +	while (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) {
> +		local_irq_enable();
> +		tracehook_notify_resume(NULL);
> +		local_irq_disable();
> +	}
> +	local_irq_enable();

I'm confused by the IRQ state swizzling here, what is it doing?

> +}
> +EXPORT_SYMBOL_GPL(tracehook_handle_notify_resume);
> +#endif
> 
>