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>
Subject: Re: [PATCH -tip v3 1/2] kcov: Make runtime functions noinstr-compatible
Date: Mon, 15 Jun 2020 17:03:27 +0200 [thread overview]
Message-ID: <20200615150327.GW2531@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200615145336.GA220132@google.com>
On Mon, Jun 15, 2020 at 04:53:36PM +0200, Marco Elver wrote:
> On Mon, 15 Jun 2020, Peter Zijlstra wrote:
>
> > On Mon, Jun 15, 2020 at 09:53:06AM +0200, Marco Elver wrote:
> > >
> > > Disabling KCOV for smp_processor_id now moves the crash elsewhere. In
> > > the case of KASAN into its 'memcpy' wrapper, called after
> > > __this_cpu_read in fixup_bad_iret. This is making me suspicious,
> > > because it shouldn't be called from the noinstr functions.
> >
> > With your .config, objtool complains about exactly that though:
> >
> > vmlinux.o: warning: objtool: fixup_bad_iret()+0x8e: call to memcpy() leaves .noinstr.text section
> >
> > The utterly gruesome thing below 'cures' that.
>
> Is __memcpy() generally available? I think that bypasses KASAN and
> whatever else.
Yes, I think so. x86_64 needs lib/memcpy_64.S in .noinstr.text then. For
i386 it's an __always_inline inline-asm thing.
next prev parent reply other threads:[~2020-06-15 15:04 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 [this message]
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
2020-06-17 18:06 ` Marco Elver
2020-06-15 14:54 ` Peter Zijlstra
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