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* kcsan: Add missing license and copyright headersMarco Elver2021-03-081-0/+5
| | | | | | | Adds missing license and/or copyright headers for KCSAN source files. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* kcsan: Fix encoding masks and regain address bitMarco Elver2020-11-071-8/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The watchpoint encoding masks for size and address were off-by-one bit each, with the size mask using 1 unnecessary bit and the address mask missing 1 bit. However, due to the way the size is shifted into the encoded watchpoint, we were effectively wasting and never using the extra bit. For example, on x86 with PAGE_SIZE==4K, we have 1 bit for the is-write bit, 14 bits for the size bits, and then 49 bits left for the address. Prior to this fix we would end up with this usage: [ write<1> | size<14> | wasted<1> | address<48> ] Fix it by subtracting 1 bit from the GENMASK() end and start ranges of size and address respectively. The added static_assert()s verify that the masks are as expected. With the fixed version, we get the expected usage: [ write<1> | size<14> | address<49> ] Functionally no change is expected, since that extra address bit is insignificant for enabled architectures. Acked-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* kcsan: Never set up watchpoints on NULL pointersMarco Elver2020-11-031-1/+5
| | | | | | | | | | | | Avoid setting up watchpoints on NULL pointers, as otherwise we would crash inside the KCSAN runtime (when checking for value changes) instead of the instrumented code. Because that may be confusing, skip any address less than PAGE_SIZE. Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* kernel/: fix repeated words in commentsRandy Dunlap2020-10-161-1/+1
| | | | | | | | | | | | | Fix multiple occurrences of duplicated words in kernel/. Fix one typo/spello on the same line as a duplicate word. Change one instance of "the the" to "that the". Otherwise just drop one of the repeated words. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: https://lkml.kernel.org/r/98202fa6-8919-ef63-9efe-c0fad5ca7af1@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kcsan: Prefer __always_inline for fast-pathMarco Elver2020-03-211-7/+7
| | | | | | | | | | | | | | | Prefer __always_inline for fast-path functions that are called outside of user_access_save, to avoid generating UACCESS warnings when optimizing for size (CC_OPTIMIZE_FOR_SIZE). It will also avoid future surprises with compiler versions that change the inlining heuristic even when optimizing for performance. Reported-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/58708908-84a0-0a81-a836-ad97e33dbb62@infradead.org
* kcsan: Improve various small stylistic detailsIngo Molnar2019-11-201-12/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tidy up a few bits: - Fix typos and grammar, improve wording. - Remove spurious newlines that are col80 warning artifacts where the resulting line-break is worse than the disease it's curing. - Use core kernel coding style to improve readability and reduce spurious code pattern variations. - Use better vertical alignment for structure definitions and initialization sequences. - Misc other small details. No change in functionality intended. Cc: linux-kernel@vger.kernel.org Cc: Marco Elver <elver@google.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
* kcsan: Add Kernel Concurrency Sanitizer infrastructureMarco Elver2019-11-161-0/+94
Kernel Concurrency Sanitizer (KCSAN) is a dynamic data-race detector for kernel space. KCSAN is a sampling watchpoint-based data-race detector. See the included Documentation/dev-tools/kcsan.rst for more details. This patch adds basic infrastructure, but does not yet enable KCSAN for any architecture. Signed-off-by: Marco Elver <elver@google.com> Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>