From: Marco Elver <elver@google.com>
To: elver@google.com
Cc: paulmck@kernel.org, dvyukov@google.com, glider@google.com,
andreyknvl@google.com, kasan-dev@googlegroups.com,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
mingo@kernel.org, peterz@infradead.org, will@kernel.org,
clang-built-linux@googlegroups.com, bp@alien8.de
Subject: [PATCH -tip v2 06/11] kcsan: Restrict supported compilers
Date: Thu, 21 May 2020 13:08:49 +0200 [thread overview]
Message-ID: <20200521110854.114437-7-elver@google.com> (raw)
In-Reply-To: <20200521110854.114437-1-elver@google.com>
The first version of Clang that supports -tsan-distinguish-volatile will
be able to support KCSAN. The first Clang release to do so, will be
Clang 11. This is due to satisfying all the following requirements:
1. Never emit calls to __tsan_func_{entry,exit}.
2. __no_kcsan functions should not call anything, not even
kcsan_{enable,disable}_current(), when using __{READ,WRITE}_ONCE => Requires
leaving them plain!
3. Support atomic_{read,set}*() with KCSAN, which rely on
arch_atomic_{read,set}*() using __{READ,WRITE}_ONCE() => Because of
#2, rely on Clang 11's -tsan-distinguish-volatile support. We will
double-instrument atomic_{read,set}*(), but that's reasonable given
it's still lower cost than the data_race() variant due to avoiding 2
extra calls (kcsan_{en,dis}able_current() calls).
4. __always_inline functions inlined into __no_kcsan functions are never
instrumented.
5. __always_inline functions inlined into instrumented functions are
instrumented.
6. __no_kcsan_or_inline functions may be inlined into __no_kcsan functions =>
Implies leaving 'noinline' off of __no_kcsan_or_inline.
7. Because of #6, __no_kcsan and __no_kcsan_or_inline functions should never be
spuriously inlined into instrumented functions, causing the accesses of the
__no_kcsan function to be instrumented.
Older versions of Clang do not satisfy #3. The latest GCC currently doesn't
support at least #1, #3, and #7.
Link: https://lkml.kernel.org/r/CANpmjNMTsY_8241bS7=XAfqvZHFLrVEkv_uM4aDUWE_kh3Rvbw@mail.gmail.com
Signed-off-by: Marco Elver <elver@google.com>
---
lib/Kconfig.kcsan | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index a7276035ca0d..3f3b5bca7a8f 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -3,6 +3,12 @@
config HAVE_ARCH_KCSAN
bool
+config HAVE_KCSAN_COMPILER
+ def_bool CC_IS_CLANG && $(cc-option,-fsanitize=thread -mllvm -tsan-distinguish-volatile=1)
+ help
+ For the list of compilers that support KCSAN, please see
+ <file:Documentation/dev-tools/kcsan.rst>.
+
config KCSAN_KCOV_BROKEN
def_bool KCOV && CC_HAS_SANCOV_TRACE_PC
depends on CC_IS_CLANG
@@ -15,7 +21,8 @@ config KCSAN_KCOV_BROKEN
menuconfig KCSAN
bool "KCSAN: dynamic data race detector"
- depends on HAVE_ARCH_KCSAN && DEBUG_KERNEL && !KASAN
+ depends on HAVE_ARCH_KCSAN && HAVE_KCSAN_COMPILER
+ depends on DEBUG_KERNEL && !KASAN
depends on !KCSAN_KCOV_BROKEN
select STACKTRACE
help
--
2.26.2.761.g0e0b3e54be-goog
next prev parent reply other threads:[~2020-05-21 11:10 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 11:08 [PATCH -tip v2 00/11] Fix KCSAN for new ONCE (require Clang 11) Marco Elver
2020-05-21 11:08 ` [PATCH -tip v2 01/11] ubsan, kcsan: don't combine sanitizer with kcov on clang Marco Elver
2020-05-21 11:08 ` [PATCH -tip v2 02/11] kcsan: Avoid inserting __tsan_func_entry/exit if possible Marco Elver
2020-05-21 11:08 ` [PATCH -tip v2 03/11] kcsan: Support distinguishing volatile accesses Marco Elver
2020-05-21 13:18 ` Will Deacon
2020-05-21 13:26 ` Marco Elver
2020-05-21 11:08 ` [PATCH -tip v2 04/11] kcsan: Pass option tsan-instrument-read-before-write to Clang Marco Elver
2020-05-21 11:08 ` [PATCH -tip v2 05/11] kcsan: Remove 'noinline' from __no_kcsan_or_inline Marco Elver
2020-05-21 11:08 ` Marco Elver [this message]
2020-05-21 11:08 ` [PATCH -tip v2 07/11] kcsan: Update Documentation to change supported compilers Marco Elver
2020-05-21 13:33 ` Will Deacon
2020-05-21 13:35 ` Marco Elver
2020-05-21 11:08 ` [PATCH -tip v2 08/11] READ_ONCE, WRITE_ONCE: Remove data_race() and unnecessary checks Marco Elver
2020-05-21 11:08 ` [PATCH -tip v2 09/11] data_race: Avoid nested statement expression Marco Elver
2020-05-21 13:31 ` Will Deacon
2020-05-21 13:39 ` Marco Elver
2020-05-21 11:08 ` [PATCH -tip v2 10/11] compiler.h: Move function attributes to compiler_types.h Marco Elver
2020-05-21 11:08 ` [PATCH -tip v2 11/11] compiler_types.h, kasan: Use __SANITIZE_ADDRESS__ instead of CONFIG_KASAN to decide inlining Marco Elver
2020-05-21 13:36 ` [PATCH -tip v2 00/11] Fix KCSAN for new ONCE (require Clang 11) Will Deacon
2020-05-21 13:42 ` Marco Elver
2020-05-21 13:42 ` Will Deacon
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