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authorMarco Elver <elver@google.com>2020-05-21 17:20:42 +0300
committerThomas Gleixner <tglx@linutronix.de>2020-06-11 21:04:00 +0300
commit0e1aa5b62160500bb2ed3150367fba83c0a194e5 (patch)
treec892fcffdfdab1e1406cb4ee0aa43c031e335ae3 /lib/Kconfig.kcsan
parent17168f5c1bef4ec7c239e2dd5e3e60b862727dd4 (diff)
downloadlinux-0e1aa5b62160500bb2ed3150367fba83c0a194e5.tar.xz
kcsan: Restrict supported compilers
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. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lkml.kernel.org/r/CANpmjNMTsY_8241bS7=XAfqvZHFLrVEkv_uM4aDUWE_kh3Rvbw@mail.gmail.com Link: https://lkml.kernel.org/r/20200521142047.169334-7-elver@google.com
Diffstat (limited to 'lib/Kconfig.kcsan')
-rw-r--r--lib/Kconfig.kcsan9
1 files changed, 8 insertions, 1 deletions
diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index b5d88acbf99d..5ee88e5119c2 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