linux-kernel - Re: [PATCH 2/2] clocksource/drivers/fttmr010: Be stricter on IRQs

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: <24366a2b-787d-960f-a7cb-99f3330ffb75@roeck-us.net>
Date:   Fri, 27 Aug 2021 15:31:59 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Andrew Jeffery <andrew@...id.au>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Cédric Le Goater <clg@...d.org>,
        Joel Stanley <joel@....id.au>
Subject: Re: [PATCH 2/2] clocksource/drivers/fttmr010: Be stricter on IRQs

On 8/27/21 3:01 PM, Linus Walleij wrote:
> On Sat, Aug 21, 2021 at 6:20 AM Guenter Roeck <linux@...ck-us.net> wrote:
>> On Sun, Jul 25, 2021 at 12:44:24AM +0200, Linus Walleij wrote:
> 
>>> Make sure we check that the right interrupt occurred before
>>> calling the event handler for timer 1. Report spurious IRQs
>>> as IRQ_NONE.
>>>
>>> Cc: Cédric Le Goater <clg@...d.org>
>>> Cc: Joel Stanley <joel@....id.au>
>>> Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
>>
>> This patch results in boot stalls with several qemu aspeed emulations
>> (quanta-q71l-bmc, palmetto-bmc, witherspoon-bmc, ast2500-evb,
>> romulus-bmc, g220a-bmc). Reverting this patch together with
>> "clocksource/drivers/fttmr010: Clear also overflow bit on AST2600"
>> fixes the problem. Bisect log is attached.
> 
> Has it been tested on real hardware?
> 
> We are reading register 0x34 TIMER_INTR_STATE for this.
> So this should reflect the state of raw interrupts from the timers.
> 
> I looked in qemu/hw/timer/aspeed_timer.c
> and the aspeed_timer_read() looks dubious.
> It rather looks like this falls down to returning whatever
> was written to this register and not reflect which IRQ
> was fired at all.
> 

Interesting question. There is aspeed_timer_read(), which doesn't return
anything useful for register 0x34, and there is aspeed_{2400,2500,2600}_timer_read,
which does. No idea what is actually executed.

Guenter

> Andrew: have you tested this when developing the
> QEMU driver?
> 
> Yours,
> Linus Walleij
>