From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Andy Lutomirski <luto@kernel.org>,
Huacai Chen <chenhc@lemote.com>, Maxime Bizon <mbizon@freebox.fr>
Cc: Thomas Gleixner <tglx@linutronix.de>,
chenhuacai@gmail.com, LKML <linux-kernel@vger.kernel.org>,
stable <stable@vger.kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Paul Burton <paul.burton@mips.com>,
linux-mips@vger.kernel.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] lib/vdso: Use __arch_use_vsyscall() to indicate fallback
Date: Fri, 18 Oct 2019 09:32:09 +0100 [thread overview]
Message-ID: <6581a6e8-45c9-a80c-d2a4-33466f5712fd@arm.com> (raw)
In-Reply-To: <CALCETrWXRgkQOJGRqa_sOLAG2zhjsEX6b86T2VTsNYN9ECRrtA@mail.gmail.com>
Hi Andy and Hucan,
On 10/18/19 4:15 AM, Andy Lutomirski wrote:
> On Thu, Oct 17, 2019 at 7:57 PM Huacai Chen <chenhc@lemote.com> wrote:
>>
>> In do_hres(), we currently use whether the return value of __arch_get_
>> hw_counter() is negtive to indicate fallback, but this is not a good
>> idea. Because:
>>
>> 1, ARM64 returns ULL_MAX but MIPS returns 0 when clock_mode is invalid;
>> 2, For a 64bit counter, a "negtive" value of counter is actually valid.
>
> s/negtive/negative
>
> What's the actual bug? Is it that MIPS is returning 0 but the check
> is < 0? Sounds like MIPS should get fixed.
>
I submitted a patch for this yesterday to the MIPS maintainers [1]. The MIPS32
r1 implementation had a bug when VDSO_CLOCK_NONE was set.
The issue has been reported by Maxime Bizon who tested the fix as well.
[1] https://patchwork.kernel.org/patch/11193391/
--
Regards,
Vincenzo
next prev parent reply other threads:[~2019-10-18 8:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 3:00 Huacai Chen
2019-10-18 3:15 ` Andy Lutomirski
2019-10-18 8:32 ` Vincenzo Frascino [this message]
2019-10-19 2:06 ` Huacai Chen
2019-10-19 10:01 ` Thomas Gleixner
2019-10-20 22:12 ` Andy Lutomirski
2019-10-21 9:32 ` Thomas Gleixner
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