From: Peter Zijlstra <peterz@infradead.org>
To: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
Andrey Konovalov <andreyknvl@google.com>,
Mark Rutland <mark.rutland@arm.com>,
Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Alexander Potapenko <glider@google.com>,
kasan-dev <kasan-dev@googlegroups.com>,
LKML <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
ndesaulniers@google.com, Andy Lutomirski <luto@amacapital.net>
Subject: Re: [PATCH -tip v3 1/2] kcov: Make runtime functions noinstr-compatible
Date: Wed, 17 Jun 2020 18:36:35 +0200 [thread overview]
Message-ID: <20200617163635.GC576905@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200617155517.GB576905@hirez.programming.kicks-ass.net>
On Wed, Jun 17, 2020 at 05:55:17PM +0200, Peter Zijlstra wrote:
> On Wed, Jun 17, 2020 at 05:19:59PM +0200, Marco Elver wrote:
>
> > > Does GCC (8, as per the new KASAN thing) have that
> > > __builtin_memcpy_inline() ?
> >
> > No, sadly it doesn't. Only Clang 11. :-/
> >
> > But using a call to __memcpy() somehow breaks with Clang+KCSAN. Yet,
> > it's not the memcpy that BUGs, but once again check_preemption_disabled
> > (which is noinstr!). Just adding calls anywhere here seems to results in
> > unpredictable behaviour. Are we running out of stack space?
>
> Very likely, bad_iret is running on that entry_stack you found, and as
> you found, it is puny.
>
> Andy wanted to make it a full page a while ago, so I suppose the
> question is do we do that now?
Andy suggested doing the full page; untested patches here:
git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git x86/entry
next prev parent reply other threads:[~2020-06-17 16:37 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-05 8:28 Marco Elver
2020-06-05 8:28 ` [PATCH -tip v3 2/2] kcov: Unconditionally add -fno-stack-protector to compiler options Marco Elver
2020-06-05 16:50 ` Nick Desaulniers
2020-06-05 10:57 ` [PATCH -tip v3 1/2] kcov: Make runtime functions noinstr-compatible Dmitry Vyukov
2020-06-05 12:03 ` Peter Zijlstra
2020-06-05 13:25 ` Andrey Konovalov
2020-06-07 9:37 ` Dmitry Vyukov
2020-06-08 7:48 ` Marco Elver
2020-06-08 7:57 ` Dmitry Vyukov
2020-06-08 11:01 ` Peter Zijlstra
2020-06-11 21:55 ` Peter Zijlstra
2020-06-11 21:58 ` Peter Zijlstra
2020-06-12 11:34 ` Peter Zijlstra
2020-06-12 4:04 ` Dmitry Vyukov
2020-06-12 11:49 ` Marco Elver
2020-06-13 17:24 ` Dmitry Vyukov
2020-06-15 7:53 ` Marco Elver
2020-06-15 14:29 ` Peter Zijlstra
2020-06-15 14:35 ` Peter Zijlstra
2020-06-15 14:53 ` Marco Elver
2020-06-15 15:03 ` Peter Zijlstra
2020-06-15 15:20 ` Peter Zijlstra
2020-06-17 14:32 ` Marco Elver
2020-06-17 14:49 ` Peter Zijlstra
2020-06-17 15:19 ` Peter Zijlstra
2020-06-17 15:19 ` Marco Elver
2020-06-17 15:55 ` Peter Zijlstra
2020-06-17 16:36 ` Peter Zijlstra [this message]
2020-06-17 18:06 ` Marco Elver
2020-06-15 14:54 ` Peter Zijlstra
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