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Date: Thu, 17 Oct 2019 08:25:51 +0800
From: Boqun Feng <boqun.feng@...il.com>
To: Marco Elver <elver@...gle.com>
Cc: LKMM Maintainers -- Akira Yokosawa <akiyks@...il.com>,
Alan Stern <stern@...land.harvard.edu>,
Alexander Potapenko <glider@...gle.com>,
Andrea Parri <parri.andrea@...il.com>,
Andrey Konovalov <andreyknvl@...gle.com>,
Andy Lutomirski <luto@...nel.org>, ard.biesheuvel@...aro.org,
Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
Daniel Axtens <dja@...ens.net>,
Daniel Lustig <dlustig@...dia.com>,
dave.hansen@...ux.intel.com, dhowells@...hat.com,
Dmitry Vyukov <dvyukov@...gle.com>,
"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
Jade Alglave <j.alglave@....ac.uk>,
Joel Fernandes <joel@...lfernandes.org>,
Jonathan Corbet <corbet@....net>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Luc Maranget <luc.maranget@...ia.fr>,
Mark Rutland <mark.rutland@....com>,
Nicholas Piggin <npiggin@...il.com>,
"Paul E. McKenney" <paulmck@...ux.ibm.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Will Deacon <will@...nel.org>,
kasan-dev <kasan-dev@...glegroups.com>,
linux-arch <linux-arch@...r.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
linux-efi@...r.kernel.org, linux-kbuild@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>,
Linux Memory Management List <linux-mm@...ck.org>,
the arch/x86 maintainers <x86@...nel.org>
Subject: Re: [PATCH 1/8] kcsan: Add Kernel Concurrency Sanitizer
infrastructure
On Wed, Oct 16, 2019 at 12:06:51PM +0200, Marco Elver wrote:
> On Wed, 16 Oct 2019 at 11:42, Boqun Feng <boqun.feng@...il.com> wrote:
> >
> > Hi Marco,
> >
> > On Wed, Oct 16, 2019 at 10:39:52AM +0200, Marco Elver wrote:
> > [...]
> > > --- /dev/null
> > > +++ b/kernel/kcsan/kcsan.c
> > > @@ -0,0 +1,81 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +
> > > +/*
> > > + * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. For more info please
> > > + * see Documentation/dev-tools/kcsan.rst.
> > > + */
> > > +
> > > +#include <linux/export.h>
> > > +
> > > +#include "kcsan.h"
> > > +
> > > +/*
> > > + * Concurrency Sanitizer uses the same instrumentation as Thread Sanitizer.
> >
> > Is there any documentation on the instrumentation? Like a complete list
> > for all instrumentation functions plus a description of where the
> > compiler will use those functions. Yes, the names of the below functions
> > are straightforward, but an accurate doc on the instrumentation will
> > cerntainly help people review KCSAN.
>
> As far as I'm aware neither GCC nor Clang have documentation on the
> emitted instrumentation that we could reference (other than look into
> the compiler passes).
>
Yeah, I don't find them either, which makes me surprised, because I
think the thread sanitizer has been there for a while...
> However it is as straightforward as it seems: the compiler emits
> instrumentation calls for all loads and stores that the compiler
> generates; inline asm is not instrumented. I will add a comment to
> that effect for v2.
>
Or you can push the compiler people to document it, and we can simply
reference it in kernel ;-)
Regards,
Boqun
> Thanks,
> -- Marco
>
> > Regards,
> > Boqun
> >
> > > + */
> > > +
> > > +#define DEFINE_TSAN_READ_WRITE(size) \
> > > + void __tsan_read##size(void *ptr) \
> > > + { \
> > > + __kcsan_check_access(ptr, size, false); \
> > > + } \
> > > + EXPORT_SYMBOL(__tsan_read##size); \
> > > + void __tsan_write##size(void *ptr) \
> > > + { \
> > > + __kcsan_check_access(ptr, size, true); \
> > > + } \
> > > + EXPORT_SYMBOL(__tsan_write##size)
> > > +
> > > +DEFINE_TSAN_READ_WRITE(1);
> > > +DEFINE_TSAN_READ_WRITE(2);
> > > +DEFINE_TSAN_READ_WRITE(4);
> > > +DEFINE_TSAN_READ_WRITE(8);
> > > +DEFINE_TSAN_READ_WRITE(16);
> > > +
> > > +/*
> > > + * Not all supported compiler versions distinguish aligned/unaligned accesses,
> > > + * but e.g. recent versions of Clang do.
> > > + */
> > > +#define DEFINE_TSAN_UNALIGNED_READ_WRITE(size) \
> > > + void __tsan_unaligned_read##size(void *ptr) \
> > > + { \
> > > + __kcsan_check_access(ptr, size, false); \
> > > + } \
> > > + EXPORT_SYMBOL(__tsan_unaligned_read##size); \
> > > + void __tsan_unaligned_write##size(void *ptr) \
> > > + { \
> > > + __kcsan_check_access(ptr, size, true); \
> > > + } \
> > > + EXPORT_SYMBOL(__tsan_unaligned_write##size)
> > > +
> > > +DEFINE_TSAN_UNALIGNED_READ_WRITE(2);
> > > +DEFINE_TSAN_UNALIGNED_READ_WRITE(4);
> > > +DEFINE_TSAN_UNALIGNED_READ_WRITE(8);
> > > +DEFINE_TSAN_UNALIGNED_READ_WRITE(16);
> > > +
> > > +void __tsan_read_range(void *ptr, size_t size)
> > > +{
> > > + __kcsan_check_access(ptr, size, false);
> > > +}
> > > +EXPORT_SYMBOL(__tsan_read_range);
> > > +
> > > +void __tsan_write_range(void *ptr, size_t size)
> > > +{
> > > + __kcsan_check_access(ptr, size, true);
> > > +}
> > > +EXPORT_SYMBOL(__tsan_write_range);
> > > +
> > > +/*
> > > + * The below are not required KCSAN, but can still be emitted by the compiler.
> > > + */
> > > +void __tsan_func_entry(void *call_pc)
> > > +{
> > > +}
> > > +EXPORT_SYMBOL(__tsan_func_entry);
> > > +void __tsan_func_exit(void)
> > > +{
> > > +}
> > > +EXPORT_SYMBOL(__tsan_func_exit);
> > > +void __tsan_init(void)
> > > +{
> > > +}
> > > +EXPORT_SYMBOL(__tsan_init);
> > [...]
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