Date:   Fri, 3 Dec 2021 14:38:17 +0100
From:   Marco Elver <elver@google.com>
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Kees Cook <keescook@chromium.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Arnd Bergmann <arnd@arndb.de>, Miguel Ojeda <ojeda@kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Tom Stellard <tstellar@redhat.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Jakub Kicinski <kuba@kernel.org>, cki-project@redhat.com,
        kernelci@groups.io, llvm@lists.linux.dev,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        glider@google.com
Subject: Re: [PATCH RFC 0/6] Bump minimum supported version of LLVM to 11.0.0
Message-ID: <YaodyZzu0MTCJcvO@elver.google.com>
References: <20211129165803.470795-1-nathan@kernel.org>
 <202112011140.DA93B3E@keescook>
 <CAK7LNASW2F3SxgR6ydMaW7-ZumsxDv2QQTDqVxqJA1JWN3r4FA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAK7LNASW2F3SxgR6ydMaW7-ZumsxDv2QQTDqVxqJA1JWN3r4FA@mail.gmail.com>
User-Agent: Mutt/2.0.5 (2021-01-21)
Precedence: bulk

On Thu, Dec 02, 2021 at 05:26PM +0900, Masahiro Yamada wrote:
> On Thu, Dec 2, 2021 at 4:41 AM Kees Cook <keescook@chromium.org> wrote:
> >
> > On Mon, Nov 29, 2021 at 09:57:57AM -0700, Nathan Chancellor wrote:
> > > This patch series raises the minimum supported version of LLVM to
> > > 11.0.0.
[...]
> Only positive feedback so far.
> 
> All applied to linux-kbuild.

Some of the "dynamic" checks for compiler support unfortunately aren't
as easily grepable -- as far as I can tell, we can also include the
below, which would save us 2 cc-option invocations for all clang builds.

And just in case:

Acked-by: Marco Elver <elver@google.com>

for the rest as well.

Thanks,
-- Marco

------ >8 ------

From: Marco Elver <elver@google.com>
Date: Fri, 3 Dec 2021 14:18:44 +0100
Subject: [PATCH] Revert "ubsan, kcsan: Don't combine sanitizer with kcov on
 clang"

This reverts commit ea91a1d45d19469001a4955583187b0d75915759.

The minimum Clang version is now 11.0, which fixed the UBSAN/KCSAN vs.
KCOV incompatibilities.

Link: https://bugs.llvm.org/show_bug.cgi?id=45831
Signed-off-by: Marco Elver <elver@google.com>
---
 lib/Kconfig.kcsan | 11 -----------
 lib/Kconfig.ubsan | 12 ------------
 2 files changed, 23 deletions(-)

diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index e0a93ffdef30..b81454b2a0d0 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -10,21 +10,10 @@ config HAVE_KCSAN_COMPILER
 	  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
-	depends on !$(cc-option,-Werror=unused-command-line-argument -fsanitize=thread -fsanitize-coverage=trace-pc)
-	help
-	  Some versions of clang support either KCSAN and KCOV but not the
-	  combination of the two.
-	  See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status
-	  in newer releases.
-
 menuconfig KCSAN
 	bool "KCSAN: dynamic data race detector"
 	depends on HAVE_ARCH_KCSAN && HAVE_KCSAN_COMPILER
 	depends on DEBUG_KERNEL && !KASAN
-	depends on !KCSAN_KCOV_BROKEN
 	select STACKTRACE
 	help
 	  The Kernel Concurrency Sanitizer (KCSAN) is a dynamic
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index e5372a13511d..31f38e7fe948 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -27,16 +27,6 @@ config UBSAN_TRAP
 	  the system. For some system builders this is an acceptable
 	  trade-off.
 
-config UBSAN_KCOV_BROKEN
-	def_bool KCOV && CC_HAS_SANCOV_TRACE_PC
-	depends on CC_IS_CLANG
-	depends on !$(cc-option,-Werror=unused-command-line-argument -fsanitize=bounds -fsanitize-coverage=trace-pc)
-	help
-	  Some versions of clang support either UBSAN or KCOV but not the
-	  combination of the two.
-	  See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status
-	  in newer releases.
-
 config CC_HAS_UBSAN_BOUNDS
 	def_bool $(cc-option,-fsanitize=bounds)
 
@@ -46,7 +36,6 @@ config CC_HAS_UBSAN_ARRAY_BOUNDS
 config UBSAN_BOUNDS
 	bool "Perform array index bounds checking"
 	default UBSAN
-	depends on !UBSAN_KCOV_BROKEN
 	depends on CC_HAS_UBSAN_ARRAY_BOUNDS || CC_HAS_UBSAN_BOUNDS
 	help
 	  This option enables detection of directly indexed out of bounds
@@ -72,7 +61,6 @@ config UBSAN_ARRAY_BOUNDS
 config UBSAN_LOCAL_BOUNDS
 	bool "Perform array local bounds checking"
 	depends on UBSAN_TRAP
-	depends on !UBSAN_KCOV_BROKEN
 	depends on $(cc-option,-fsanitize=local-bounds)
 	help
 	  This option enables -fsanitize=local-bounds which traps when an
-- 
2.34.0.384.gca35af8252-goog