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Subject: Re: [PATCH v6 01/19] kernel: Standardize vdso_datapage
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     linux-arch <linux-arch@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mips@vger.kernel.org,
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        <linux-kselftest@vger.kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Russell King <linux@armlinux.org.uk>,
        Ralf Baechle <ralf@linux-mips.org>,
        Paul Burton <paul.burton@mips.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Mark Salyzyn <salyzyn@android.com>,
        Peter Collingbourne <pcc@google.com>,
        Shuah Khan <shuah@kernel.org>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Huw Davies <huw@codeweavers.com>
References: <20190530141531.43462-1-vincenzo.frascino@arm.com>
 <20190530141531.43462-2-vincenzo.frascino@arm.com>
 <CAK8P3a3EnvkLND2RJdZtEY64PhK5g0sbbuytQro=f0cPur2g9g@mail.gmail.com>
From:   Vincenzo Frascino <vincenzo.frascino@arm.com>
Message-ID: <bb5253b2-623c-c927-27a2-1d3a2990d20f@arm.com>
Date:   Tue, 4 Jun 2019 13:05:40 +0100
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On 31/05/2019 09:16, Arnd Bergmann wrote:
> On Thu, May 30, 2019 at 4:15 PM Vincenzo Frascino
> <vincenzo.frascino@arm.com> wrote:
> 
>> + * vdso_data will be accessed by 64 bit and compat code at the same time
>> + * so we should be careful before modifying this structure.
>> + */
>> +struct vdso_data {
>> +       u32                     seq;
>> +
>> +       s32                     clock_mode;
>> +       u64                     cycle_last;
>> +       u64                     mask;
>> +       u32                     mult;
>> +       u32                     shift;
>> +
>> +       struct vdso_timestamp   basetime[VDSO_BASES];
>> +
>> +       s32                     tz_minuteswest;
>> +       s32                     tz_dsttime;
>> +       u32                     hrtimer_res;
>> +};
> 
> The structure contains four padding bytes at the end, which is
> something we try to avoid, at least if this ends up being used as
> an ABI. Maybe add "u32 __unused" at the end?
> 

Agreed, I will fix this in v7.

>      Arnd
> 

-- 
Regards,
Vincenzo