From: Marco Elver <elver@google.com>
To: elver@google.com, paulmck@kernel.org
Cc: will@kernel.org, peterz@infradead.org, bp@alien8.de,
tglx@linutronix.de, mingo@kernel.org, dvyukov@google.com,
cai@lca.pw, kasan-dev@googlegroups.com,
linux-kernel@vger.kernel.org, Martin Liska <mliska@suse.cz>
Subject: [PATCH 1/3] kcsan: Re-add GCC as a supported compiler
Date: Thu, 18 Jun 2020 11:31:16 +0200 [thread overview]
Message-ID: <20200618093118.247375-2-elver@google.com> (raw)
In-Reply-To: <20200618093118.247375-1-elver@google.com>
GCC version 11 recently implemented all requirements to correctly
support KCSAN:
1. Correct no_sanitize-attribute inlining behaviour:
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=4089df8ef4a63126b0774c39b6638845244c20d2
2. --param=tsan-distinguish-volatile
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=ab2789ec507a94f1a75a6534bca51c7b39037ce0
3. --param=tsan-instrument-func-entry-exit
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=06712fc68dc9843d9af7c7ac10047f49d305ad76
Therefore, we can re-enable GCC for KCSAN, and document the new compiler
requirements.
Signed-off-by: Marco Elver <elver@google.com>
Cc: Martin Liska <mliska@suse.cz>
---
For anyone interested to try it out before GCC 11 is released, I'd
recommend building a stable GCC 10 with the patches applied:
git clone git://gcc.gnu.org/git/gcc.git && cd gcc
git checkout -b gcc-10-for-kcsan releases/gcc-10.1.0
git cherry-pick \
4089df8ef4a63126b0774c39b6638845244c20d2 \
ab2789ec507a94f1a75a6534bca51c7b39037ce0 \
06712fc68dc9843d9af7c7ac10047f49d305ad76
./configure --prefix <your-prefix> --enable-languages=c,c++
make -j$(nproc) && make install
---
Documentation/dev-tools/kcsan.rst | 3 ++-
lib/Kconfig.kcsan | 3 ++-
scripts/Makefile.kcsan | 2 +-
3 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/Documentation/dev-tools/kcsan.rst b/Documentation/dev-tools/kcsan.rst
index ce4bbd918648..8fa0dd6c8614 100644
--- a/Documentation/dev-tools/kcsan.rst
+++ b/Documentation/dev-tools/kcsan.rst
@@ -8,7 +8,8 @@ approach to detect races. KCSAN's primary purpose is to detect `data races`_.
Usage
-----
-KCSAN requires Clang version 11 or later.
+KCSAN is supported by both GCC and Clang. With GCC we require version 11 or
+later, and with Clang also require version 11 or later.
To enable KCSAN configure the kernel with::
diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index 3f3b5bca7a8f..3d282d51849b 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -4,7 +4,8 @@ config HAVE_ARCH_KCSAN
bool
config HAVE_KCSAN_COMPILER
- def_bool CC_IS_CLANG && $(cc-option,-fsanitize=thread -mllvm -tsan-distinguish-volatile=1)
+ def_bool (CC_IS_CLANG && $(cc-option,-fsanitize=thread -mllvm -tsan-distinguish-volatile=1)) || \
+ (CC_IS_GCC && $(cc-option,-fsanitize=thread --param tsan-distinguish-volatile=1))
help
For the list of compilers that support KCSAN, please see
<file:Documentation/dev-tools/kcsan.rst>.
diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
index bd4da1af5953..dd66206f4578 100644
--- a/scripts/Makefile.kcsan
+++ b/scripts/Makefile.kcsan
@@ -6,7 +6,7 @@ ifdef CONFIG_KCSAN
ifdef CONFIG_CC_IS_CLANG
cc-param = -mllvm -$(1)
else
-cc-param = --param -$(1)
+cc-param = --param $(1)
endif
# Keep most options here optional, to allow enabling more compilers if absence
--
2.27.0.290.gba653c62da-goog
next prev parent reply other threads:[~2020-06-18 9:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-18 9:31 [PATCH 0/3] kcsan: Re-add GCC support, and compiler flags improvements Marco Elver
2020-06-18 9:31 ` Marco Elver [this message]
2020-06-18 9:31 ` [PATCH 2/3] kcsan: Simplify compiler flags Marco Elver
2020-06-18 9:31 ` [PATCH 3/3] kcsan: Disable branch tracing in core runtime Marco Elver
2020-06-19 3:25 ` [PATCH 0/3] kcsan: Re-add GCC support, and compiler flags improvements Paul E. McKenney
2020-06-19 21:49 ` Paul E. McKenney
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