linux-kernel - Re: [PATCH v22 07/11] acpi/arm64: Add GTDT table parse driver

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: <20170329102118.GB10807@red-moon>
Date:   Wed, 29 Mar 2017 11:21:18 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Fu Wei <fu.wei@...aro.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <marc.zyngier@....com>,
        Mark Rutland <mark.rutland@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Hanjun Guo <hanjun.guo@...aro.org>,
        linux-arm-kernel@...ts.infradead.org,
        Linaro ACPI Mailman List <linaro-acpi@...ts.linaro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        rruigrok@...eaurora.org, "Abdulhamid, Harb" <harba@...eaurora.org>,
        Christopher Covington <cov@...eaurora.org>,
        Timur Tabi <timur@...eaurora.org>,
        G Gregory <graeme.gregory@...aro.org>,
        Al Stone <al.stone@...aro.org>, Jon Masters <jcm@...hat.com>,
        Wei Huang <wei@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
        Leo Duran <leo.duran@....com>,
        Wim Van Sebroeck <wim@...ana.be>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-watchdog@...r.kernel.org, Tomasz Nowicki <tn@...ihalf.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Julien Grall <julien.grall@....com>
Subject: Re: [PATCH v22 07/11] acpi/arm64: Add GTDT table parse driver

On Wed, Mar 29, 2017 at 05:48:17PM +0800, Fu Wei wrote:

[...]

>  * @platform_timer_count: It points to a integer variable which is used
>  *                           for storing the number of platform timers.
>  *                           This pointer could be NULL, if the caller
>  *                           doesn't need this info.
> 
> >
> >> + *
> >> + * Return: 0 if success, -EINVAL if error.
> >> + */
> >> +int __init acpi_gtdt_init(struct acpi_table_header *table,
> >> +                       int *platform_timer_count)
> >> +{
> >> +     int ret = 0;
> >> +     int timer_count = 0;
> >> +     void *platform_timer = NULL;
> >> +     struct acpi_table_gtdt *gtdt;
> >> +
> >> +     gtdt = container_of(table, struct acpi_table_gtdt, header);
> >> +     acpi_gtdt_desc.gtdt = gtdt;
> >> +     acpi_gtdt_desc.gtdt_end = (void *)table + table->length;
> >> +
> >> +     if (table->revision < 2)
> >> +             pr_warn("Revision:%d doesn't support Platform Timers.\n",
> >> +                     table->revision);
> >
> > Ok, two points here. First, I am not sure why you should warn if the
> > table revision is < 2, is that a FW bug ? I do not think it is, you
> > can just return 0.
> 
> I used pr_debug here before v20, then I got Hanjun's suggestion:
> -------
> GTDT table revision is updated to 2 in ACPI 5.1, we will
> not support ACPI version under 5.1 and disable ACPI in FADT
> parse before this code is called, so if we get revision
> <2 here, I think we need to print warning (we need to keep
> the firmware stick to the spec on ARM64).
> -------
> https://lkml.org/lkml/2017/1/19/82
> 
> So I started to use pr_warn.

Thanks for the explanation, so it is a FW bug and the warning
is granted :) just leave it there.

Still, please check my comment on acpi_gtdt_init() being called
multiple times on patch 11.

Thanks,
Lorenzo