From: Peter Zijlstra <peterz@infradead.org>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>
Subject: Re: [RFC][PATCH 0/4] x86/entry: disallow #DB more
Date: Mon, 25 May 2020 12:40:38 +0200 [thread overview]
Message-ID: <20200525104038.GC317569@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <cd2f91e4-aa90-eb98-7f8c-218e8521ac85@rasmusvillemoes.dk>
On Mon, May 25, 2020 at 12:02:48PM +0200, Rasmus Villemoes wrote:
> Naive question: did you check disassembly to see whether gcc threw your
> native_get_debugreg() away, given that the asm isn't volatile and the
> result is not used for anything? Testing here only shows a "mov
> %r9,%db7", but the read did seem to get thrown away.
Argh.. no I did not. Writing it all in asm gets me:
[ 1.627405] XXX: 3900 8304 22632
which is a lot worse...
next prev parent reply other threads:[~2020-05-25 10:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 20:47 [RFC][PATCH 0/4] x86/entry: disallow #DB more Peter Zijlstra
2020-05-22 20:47 ` [RFC][PATCH 1/4] x86/entry: Introduce local_db_{rave,restore}() Peter Zijlstra
2020-05-22 20:47 ` [RFC][PATCH 2/4] x86/entry, nmi: Disable #DB Peter Zijlstra
2020-05-22 20:47 ` [RFC][PATCH 3/4] x86/entry: Remove debug IST frobbing Peter Zijlstra
2020-05-25 11:33 ` kbuild test robot
2020-05-25 12:33 ` kbuild test robot
2020-05-22 20:47 ` [RFC][PATCH 4/4] x86/entry, mce: Disallow #DB during #MC Peter Zijlstra
2020-05-22 22:13 ` [RFC][PATCH 0/4] x86/entry: disallow #DB more Andy Lutomirski
2020-05-22 22:20 ` Sean Christopherson
2020-05-22 22:43 ` Andy Lutomirski
2020-05-23 12:59 ` Peter Zijlstra
2020-05-23 21:32 ` Peter Zijlstra
2020-05-25 10:02 ` Rasmus Villemoes
2020-05-25 10:40 ` Peter Zijlstra [this message]
2020-05-25 11:01 ` Peter Zijlstra
2020-05-25 17:19 ` Andy Lutomirski
2020-05-25 18:08 ` Peter Zijlstra
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