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From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>, Andy Lutomirski <luto@kernel.org>
Cc: 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 11:01:01 +0200	[thread overview]
Message-ID: <87imfwd5f6.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CALCETrVQxFq2b5ydSk-w4W-7+6OMro0jyHQqtFoM2Tvn_=aLSQ@mail.gmail.com>

Andy Lutomirski <luto@kernel.org> writes:
> On Thu, Jun 11, 2020 at 4:22 PM Andy Lutomirski <luto@kernel.org> wrote:
>
> Two bugs here.
>
> 1. We had an issue with WARN. Patch sent.

Grabbed it

> 2. idtentry.h has, for x86_32:
>
> # define DEFINE_IDTENTRY_IST  DEFINE_IDTENTRY
>
> This is nonsense.  It's getting late over here and I'd rather focus on
> the more interesting RCU issue, so that's all from me today.

Well, this might be nonsense, but it's exactly matching the current code
in mainline which, e.g. for #DB does:

SYM_CODE_START(debug)
	/*
	 * Entry from sysenter is now handled in common_exception
	 */
	ASM_CLAC
	pushl	$0
	pushl	$do_debug
	jmp	common_exception
SYM_CODE_END(debug)

There is no IST on 32bit, never was. We do software stack switching for
device interrupts, but that's a different story.

Thanks,

        tglx

  reply	other threads:[~2020-06-12  9:01 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 [this message]
2020-06-12  9:18           ` Andy Lutomirski
2020-06-12 10:34             ` Thomas Gleixner
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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