From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Naresh Kamboju <naresh.kamboju@linaro.org>,
open list <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
cj.chengjian@huawei.com,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Borislav Petkov <bp@alien8.de>, Minchan Kim <minchan@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Michel Lespinasse <walken@google.com>,
lkft-triage@lists.linaro.org,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: Perf: WARNING: arch/x86/entry/common.c:624 idtentry_exit_cond_rcu+0x92/0xc0
Date: Fri, 12 Jun 2020 12:34:18 +0200 [thread overview]
Message-ID: <87d064d13p.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <8DD3180E-0E69-4FD6-92C3-311AAB3F688F@amacapital.net>
Andy Lutomirski <luto@amacapital.net> writes:
>> On Jun 12, 2020, at 2:01 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
>> There is no IST on 32bit, never was. We do software stack switching for
>> device interrupts, but that's a different story.
>>
>
> DEFINE_IDTENTRY does the idtentry_enter_cond_rcu() dance, which isn’t
> intended to be safe from NMI context. It should probably map to
> DEFINE_IDTENTRY_RAW() instead. The specific issue is that NMI ends up
> there, and at least DEFINE_IDTENTRY_NMI should be raw.
Yes, you are right. That's clearly broken.
> I haven’t tried this at all, nor have I dug through all the users of
> these macros to check what they expect. Perhaps we should not have
> the _IST one defined at all on 32 bit and rename it to
> DEFINE_IDTENTRY_IST_RAW on 64 bit to make it more clear what’s going
> on when reading the C code.
Let me go over it with a fine comb.
> Or maybe I’m too sleepy and I’m nuts. But I don’t think I am.
/me politely refrains from commenting
next prev parent reply other threads:[~2020-06-12 10:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 18:56 Perf: WARNING: arch/x86/entry/common.c:624 idtentry_exit_cond_rcu+0x92/0xc0 Naresh Kamboju
2020-06-11 19:10 ` Andy Lutomirski
2020-06-11 19:25 ` Peter Zijlstra
2020-06-11 23:22 ` Andy Lutomirski
2020-06-12 3:30 ` Andy Lutomirski
2020-06-12 9:01 ` Thomas Gleixner
2020-06-12 9:18 ` Andy Lutomirski
2020-06-12 10:34 ` Thomas Gleixner [this message]
2020-07-02 14:27 ` Naresh Kamboju
2020-07-02 15:02 ` Peter Zijlstra
2020-07-02 17:15 ` Naresh Kamboju
2020-07-02 18:21 ` Andy Lutomirski
2020-06-12 19:50 ` [tip: x86/entry] x86/entry: Make NMI use IDTENTRY_RAW tip-bot2 for Thomas Gleixner
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