On Wed, Oct 16, 2019 at 12:06:51PM +0200, Marco Elver wrote: > On Wed, 16 Oct 2019 at 11:42, Boqun Feng <[email protected]> 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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