From: Marc Zyngier <maz@kernel.org>
To: Oliver Upton <oupton@google.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Shier <pshier@google.com>,
Raghavendra Rao Ananta <rananta@google.com>,
Ricardo Koller <ricarkol@google.com>,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Linus Walleij <linus.walleij@linaro.org>,
kernel-team@android.com
Subject: Re: [PATCH 05/13] clocksource/arm_arch_timer: Fix MMIO base address vs callback ordering issue
Date: Tue, 10 Aug 2021 09:27:32 +0100 [thread overview]
Message-ID: <87fsvhbt6z.wl-maz@kernel.org> (raw)
In-Reply-To: <CAOQ_QsjATdRRFdiG5kR+Ni7X-_kMaF+V_XQx3uuxivk0t4xt_w@mail.gmail.com>
On Mon, 09 Aug 2021 17:52:00 +0100,
Oliver Upton <oupton@google.com> wrote:
>
> On Mon, Aug 9, 2021 at 8:27 AM Marc Zyngier <maz@kernel.org> wrote:
> >
> > The MMIO timer base address gets published after we have registered
> > the callbacks and the interrupt handler, which is... a bit dangerous.
> >
> > Fix this by moving the base address publication to the point where
> > we register the timer, and expose a pointer to the timer structure
> > itself rather than a naked value.
> >
> > Signed-off-by: Marc Zyngier <maz@kernel.org>
>
> Is this patch stable-worthy? I take it there haven't been any reports
> of issues, though this seems rather perilous.
It *could* deserve a Cc stable, although I suspect it doesn't easily
fall over with the current code:
- When programming a timer, the driver uses the base contained in
struct arch_timer, and derived from the clock_event_device.
- As long as you don't need to read the counter, you are good (the
whole point of using TVAL is that you avoid reading the counter).
It is only if someone called into the standalone counter accessor that
there would be a firework, and that's rather unlikely.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2021-08-10 8:29 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-09 15:26 [PATCH 00/13] clocksource/arm_arch_timer: Add basic ARMv8.6 support Marc Zyngier
2021-08-09 15:26 ` [PATCH 01/13] clocksource/arm_arch_timer: Drop CNT*_TVAL read accessors Marc Zyngier
2021-08-11 7:02 ` Oliver Upton
2021-08-24 16:20 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 02/13] clocksource/arm_arch_timer: Extend write side of timer register accessors to u64 Marc Zyngier
2021-08-09 16:12 ` Oliver Upton
2021-08-24 16:20 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 03/13] clocksource/arm_arch_timer: Move system register timer programming over to CVAL Marc Zyngier
2021-08-11 7:15 ` Oliver Upton
2021-08-24 16:21 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 04/13] clocksource/arm_arch_timer: Move drop _tval from erratum function names Marc Zyngier
2021-08-09 16:16 ` Oliver Upton
2021-08-24 16:29 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 05/13] clocksource/arm_arch_timer: Fix MMIO base address vs callback ordering issue Marc Zyngier
2021-08-09 16:52 ` Oliver Upton
2021-08-10 8:27 ` Marc Zyngier [this message]
2021-08-24 16:44 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 06/13] clocksource/arm_arch_timer: Move MMIO timer programming over to CVAL Marc Zyngier
2021-08-09 15:26 ` [PATCH 07/13] clocksource/arm_arch_timer: Advertise 56bit timer to the core code Marc Zyngier
2021-08-09 15:26 ` [PATCH 08/13] clocksource/arm_arch_timer: Work around broken CVAL implementations Marc Zyngier
2021-08-10 12:34 ` Mark Rutland
2021-08-10 13:15 ` Marc Zyngier
2021-08-09 15:26 ` [PATCH 09/13] clocksource/arm_arch_timer: Remove any trace of the TVAL programming interface Marc Zyngier
2021-08-09 15:26 ` [PATCH 10/13] clocksource/arm_arch_timer: Drop unnecessary ISB on CVAL programming Marc Zyngier
2021-08-09 15:26 ` [PATCH 11/13] clocksource/arm_arch_timer: Fix masking for high freq counters Marc Zyngier
2021-08-09 16:45 ` Oliver Upton
2021-08-10 8:40 ` Marc Zyngier
2021-08-10 9:09 ` Oliver Upton
2021-08-09 15:26 ` [PATCH 12/13] arm64: Add a capability for FEAT_EVC Marc Zyngier
2021-08-09 16:30 ` Oliver Upton
2021-08-09 16:34 ` Oliver Upton
2021-08-09 18:02 ` Marc Zyngier
2021-08-09 18:21 ` Oliver Upton
2021-08-09 18:23 ` Oliver Upton
2021-08-09 15:26 ` [PATCH 13/13] arm64: Add CNT{P, V}CTSS_EL0 alternatives to cnt{p, v}ct_el0 Marc Zyngier
2021-08-09 16:42 ` Oliver Upton
2021-08-09 18:11 ` Marc Zyngier
2021-08-09 18:17 ` Oliver Upton
2021-08-10 7:59 ` Marc Zyngier
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