From:   "Zeh, Werner" <werner.zeh@siemens.com>
To:     Alexandre Belloni <alexandre.belloni@bootlin.com>
CC:     "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "bp@alien8.de" <bp@alien8.de>, "x86@kernel.org" <x86@kernel.org>,
        "a.zummo@towertech.it" <a.zummo@towertech.it>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 1/1] x86/kernel/rtc: add sanity check for RTC date and
 time
Thread-Topic: [PATCH 1/1] x86/kernel/rtc: add sanity check for RTC date and
 time
Thread-Index: AQHXYQ31AXoAwWTUBE6ivSpoWZHRXqsi3/mAgAbU2gCAAnnIUIADp2wAgPsOCCA=
Date:   Thu, 9 Dec 2021 08:05:10 +0000
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Hi Alexandre.

Is there anything more I can do for that patch in order to get some process=
 on it?
Or why is this patch stuck for a long time?

Thanks
Werner

> -----Original Message-----
> From: Alexandre Belloni <alexandre.belloni@bootlin.com>
> Sent: Friday, July 2, 2021 4:11 PM
> To: Zeh, Werner (DI MC MTS SP HW 1) <werner.zeh@siemens.com>
> Cc: tglx@linutronix.de; mingo@redhat.com; bp@alien8.de; x86@kernel.org;
> a.zummo@towertech.it; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH 1/1] x86/kernel/rtc: add sanity check for RTC date an=
d
> time
>
> On 30/06/2021 06:25:44+0000, Zeh, Werner wrote:
> > Hi Alexandre
> >
> > > Hello,
> > >
> > > On 24/06/2021 10:15:07+0200, Werner Zeh wrote:
> > > > The timekeeper is synchronized with the CMOS RTC when it is
> initialized.
> > > > If the RTC buffering is bad (not buffered at all, empty battery)
> > > > the RTC registers can contain random data. In order to avoid date
> > > > and time being completely rubbish check the sanity of the
> > > > registers before calling mktime64. If the values are not valid,
> > > > set tv_sec to 0 so that at least the starting time is valid.
> > > >
> > > > Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
> > > > ---
> > > > [resent due to wrong lkml address] [added RTC maintainers to the
> > > > recipients] This change introduces the same validity check that is
> > > > already done in drivers/rtc/interface.c.
> > > > If it is not done here, the timekeeper can be set up wrongly in
> > > > the first run and won't be corrected once the RTC driver is
> > > > started because the validity check in the RTC driver drops the
> > > > time and date due to invalid entries.
> > > >
> > > >  arch/x86/kernel/rtc.c | 12 +++++++++++-
> > > >  1 file changed, 11 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c index
> > > > 586f718b8e95..f4af7b18c6c0 100644
> > > > --- a/arch/x86/kernel/rtc.c
> > > > +++ b/arch/x86/kernel/rtc.c
> > > > @@ -9,6 +9,7 @@
> > > >  #include <linux/export.h>
> > > >  #include <linux/pnp.h>
> > > >  #include <linux/of.h>
> > > > +#include <linux/rtc.h>
> > > >
> > > >  #include <asm/vsyscall.h>
> > > >  #include <asm/x86_init.h>
> > > > @@ -64,6 +65,7 @@ void mach_get_cmos_time(struct timespec64
> *now)
> > > {
> > > >         unsigned int status, year, mon, day, hour, min, sec, centur=
y =3D 0;
> > > >         unsigned long flags;
> > > > +       struct rtc_time tm =3D {0};
> > > >
> > > >         /*
> > > >          * If pm_trace abused the RTC as storage, set the timespec =
to 0,
> > > > @@
> > > > -118,7 +120,15 @@ void mach_get_cmos_time(struct timespec64
> *now)
> > > >         } else
> > > >                 year +=3D CMOS_YEARS_OFFS;
> > > >
> > > > -       now->tv_sec =3D mktime64(year, mon, day, hour, min, sec);
> > > > +       tm.tm_sec =3D sec;
> > > > +       tm.tm_min =3D min;
> > > > +       tm.tm_hour =3D hour;
> > > > +       tm.tm_mday =3D day;
> > > > +       tm.tm_mon =3D mon;
> > > > +       tm.tm_year =3D year;
> > > > +       now->tv_sec =3D 0;
> > > > +       if (rtc_valid_tm(&tm) =3D=3D 0)
> > >
> > > Doesn't that make the x86 architecture depend on CONFIG_RTC_LIB?
> > >
> > CONFIG_RTC_LIB is already default enabled for x86, see arch/x86/Kconfig=
.
> > Do you have any other dependencies in mind I have overseen?
> >
>
> Nope, everything is fine, it would be better if we could get rid of
> mach_get_cmos_time but I don't have any clue as to why this is necessary.
>
>
> --
> Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel
> engineering
> https://bootlin.com/