Re: [PATCH v3 0/9] Add Kernel Concurrency Sanitizer (KCSAN)

Paul E. McKenney
2019-11-05T14:20:39Z

On Tue, Nov 05, 2019 at 12:10:56PM +0100, Marco Elver wrote:
> On Mon, 4 Nov 2019 at 20:47, Paul E. McKenney <paulmck@kernel.org> wrote:
> >
> > On Mon, Nov 04, 2019 at 07:41:30PM +0100, Marco Elver wrote:
> > > On Mon, 4 Nov 2019 at 17:47, Paul E. McKenney <paulmck@kernel.org> wrote:
> > > >
> > > > On Mon, Nov 04, 2019 at 03:27:36PM +0100, Marco Elver wrote:
> > > > > This is the patch-series for the Kernel Concurrency Sanitizer (KCSAN).
> > > > > KCSAN is a sampling watchpoint-based data-race detector. More details
> > > > > are included in Documentation/dev-tools/kcsan.rst. This patch-series
> > > > > only enables KCSAN for x86, but we expect adding support for other
> > > > > architectures is relatively straightforward (we are aware of
> > > > > experimental ARM64 and POWER support).
> > > > >
> > > > > To gather early feedback, we announced KCSAN back in September, and
> > > > > have integrated the feedback where possible:
> > > > > http://lkml.kernel.org/r/CANpmjNPJ_bHjfLZCAPV23AXFfiPiyXXqqu72n6TgWzb2Gnu1eA@mail.gmail.com
> > > > >
> > > > > We want to point out and acknowledge the work surrounding the LKMM,
> > > > > including several articles that motivate why data-races are dangerous
> > > > > [1, 2], justifying a data-race detector such as KCSAN.
> > > > > [1] https://lwn.net/Articles/793253/
> > > > > [2] https://lwn.net/Articles/799218/
> > > > >
> > > > > The current list of known upstream fixes for data-races found by KCSAN
> > > > > can be found here:
> > > > > https://github.com/google/ktsan/wiki/KCSAN#upstream-fixes-of-data-races-found-by-kcsan
> > > >
> > > > Making this more accessible to more people seems like a good thing.
> > > > So, for the series:
> > > >
> > > > Acked-by: Paul E. McKenney <paulmck@kernel.org>
> > >
> > > Much appreciated. Thanks, Paul!
> > >
> > > Any suggestions which tree this could eventually land in?
> >
> > I would guess that Dmitry might have some suggestions.
>
> I checked and we're both unclear what the most obvious tree to land in
> is (the other sanitizers are mm related, which KCSAN is not).
>
> One suggestion that comes to my mind is for KCSAN to go through the
> same tree (rcu?) as the LKMM due to their inherent relationship. Would
> that make most sense?

It works for me, though you guys have to continue to be the main
developers. ;-)

I will go through the patches more carefully, and please look into the
kbuild test robot complaint.

Thanx, Paul

> Thanks,
> -- Marco
>
> > >
> > > > > Changelog
> > > > > ---------
> > > > > v3:
> > > > > * Major changes:
> > > > > - Add microbenchmark.
> > > > > - Add instruction watchpoint skip randomization.
> > > > > - Refactor API and core runtime fast-path and slow-path. Compared to
> > > > > the previous version, with a default config and benchmarked using the
> > > > > added microbenchmark, this version is 3.8x faster.
> > > > > - Make __tsan_unaligned __alias of generic accesses.
> > > > > - Rename kcsan_{begin,end}_atomic ->
> > > > > kcsan_{nestable,flat}_atomic_{begin,end}
> > > > > - For filter list in debugfs.c use kmalloc+krealloc instead of
> > > > > kvmalloc.
> > > > > - Split Documentation into separate patch.
> > > > >
> > > > > v2: http://lkml.kernel.org/r/20191017141305.146193-1-elver@google.com
> > > > > * Major changes:
> > > > > - Replace kcsan_check_access(.., {true, false}) with
> > > > > kcsan_check_{read,write}.
> > > > > - Change atomic-instrumented.h to use __atomic_check_{read,write}.
> > > > > - Use common struct kcsan_ctx in task_struct and for per-CPU interrupt
> > > > > contexts.
> > > > >
> > > > > v1: http://lkml.kernel.org/r/20191016083959.186860-1-elver@google.com
> > > > >
> > > > > Marco Elver (9):
> > > > > kcsan: Add Kernel Concurrency Sanitizer infrastructure
> > > > > kcsan: Add Documentation entry in dev-tools
> > > > > objtool, kcsan: Add KCSAN runtime functions to whitelist
> > > > > build, kcsan: Add KCSAN build exceptions
> > > > > seqlock, kcsan: Add annotations for KCSAN
> > > > > seqlock: Require WRITE_ONCE surrounding raw_seqcount_barrier
> > > > > asm-generic, kcsan: Add KCSAN instrumentation for bitops
> > > > > locking/atomics, kcsan: Add KCSAN instrumentation
> > > > > x86, kcsan: Enable KCSAN for x86
> > > > >
> > > > > Documentation/dev-tools/index.rst | 1 +
> > > > > Documentation/dev-tools/kcsan.rst | 217 +++++++++
> > > > > MAINTAINERS | 11 +
> > > > > Makefile | 3 +-
> > > > > arch/x86/Kconfig | 1 +
> > > > > arch/x86/boot/Makefile | 2 +
> > > > > arch/x86/boot/compressed/Makefile | 2 +
> > > > > arch/x86/entry/vdso/Makefile | 3 +
> > > > > arch/x86/include/asm/bitops.h | 6 +-
> > > > > arch/x86/kernel/Makefile | 7 +
> > > > > arch/x86/kernel/cpu/Makefile | 3 +
> > > > > arch/x86/lib/Makefile | 4 +
> > > > > arch/x86/mm/Makefile | 3 +
> > > > > arch/x86/purgatory/Makefile | 2 +
> > > > > arch/x86/realmode/Makefile | 3 +
> > > > > arch/x86/realmode/rm/Makefile | 3 +
> > > > > drivers/firmware/efi/libstub/Makefile | 2 +
> > > > > include/asm-generic/atomic-instrumented.h | 393 +++++++--------
> > > > > include/asm-generic/bitops-instrumented.h | 18 +
> > > > > include/linux/compiler-clang.h | 9 +
> > > > > include/linux/compiler-gcc.h | 7 +
> > > > > include/linux/compiler.h | 35 +-
> > > > > include/linux/kcsan-checks.h | 97 ++++
> > > > > include/linux/kcsan.h | 115 +++++
> > > > > include/linux/sched.h | 4 +
> > > > > include/linux/seqlock.h | 51 +-
> > > > > init/init_task.c | 8 +
> > > > > init/main.c | 2 +
> > > > > kernel/Makefile | 6 +
> > > > > kernel/kcsan/Makefile | 11 +
> > > > > kernel/kcsan/atomic.h | 27 ++
> > > > > kernel/kcsan/core.c | 560 ++++++++++++++++++++++
> > > > > kernel/kcsan/debugfs.c | 275 +++++++++++
> > > > > kernel/kcsan/encoding.h | 94 ++++
> > > > > kernel/kcsan/kcsan.h | 131 +++++
> > > > > kernel/kcsan/report.c | 306 ++++++++++++
> > > > > kernel/kcsan/test.c | 121 +++++
> > > > > kernel/sched/Makefile | 6 +
> > > > > lib/Kconfig.debug | 2 +
> > > > > lib/Kconfig.kcsan | 119 +++++
> > > > > lib/Makefile | 3 +
> > > > > mm/Makefile | 8 +
> > > > > scripts/Makefile.kcsan | 6 +
> > > > > scripts/Makefile.lib | 10 +
> > > > > scripts/atomic/gen-atomic-instrumented.sh | 17 +-
> > > > > tools/objtool/check.c | 18 +
> > > > > 46 files changed, 2526 insertions(+), 206 deletions(-)
> > > > > create mode 100644 Documentation/dev-tools/kcsan.rst
> > > > > create mode 100644 include/linux/kcsan-checks.h
> > > > > create mode 100644 include/linux/kcsan.h
> > > > > create mode 100644 kernel/kcsan/Makefile
> > > > > create mode 100644 kernel/kcsan/atomic.h
> > > > > create mode 100644 kernel/kcsan/core.c
> > > > > create mode 100644 kernel/kcsan/debugfs.c
> > > > > create mode 100644 kernel/kcsan/encoding.h
> > > > > create mode 100644 kernel/kcsan/kcsan.h
> > > > > create mode 100644 kernel/kcsan/report.c
> > > > > create mode 100644 kernel/kcsan/test.c
> > > > > create mode 100644 lib/Kconfig.kcsan
> > > > > create mode 100644 scripts/Makefile.kcsan
> > > > >
> > > > > --
> > > > > 2.24.0.rc1.363.gb1bccd3e3d-goog
> > > > >
> > > >
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