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

Paul E. McKenney
2019-11-04T16:47:22Z

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>

> 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
>