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From: Nick Desaulniers <ndesaulniers@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Bill Wendling <wcw@google.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Peter Oberparleiter <oberpar@linux.ibm.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
	Ard Biesheuvel <ardb@kernel.org>, Will Deacon <will@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	x86@kernel.org, Borislav Petkov <bp@alien8.de>,
	Martin Liska <mliska@suse.cz>, Marco Elver <elver@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Fangrui Song <maskray@google.com>,
	linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org,
	Dmitry Vyukov <dvyukov@google.com>,
	johannes.berg@intel.com, linux-toolchains@vger.kernel.org,
	Nick Desaulniers <ndesaulniers@google.com>
Subject: [PATCH 2/2] Kconfig: CC_HAS_NO_PROFILE_FN_ATTR, depend on for GCOV and PGO
Date: Fri, 18 Jun 2021 16:30:23 -0700	[thread overview]
Message-ID: <20210618233023.1360185-3-ndesaulniers@google.com> (raw)
In-Reply-To: <20210618233023.1360185-1-ndesaulniers@google.com>

We don't want compiler instrumentation to touch noinstr functions, which
are annotated with the no_profile function attribute. Add a Kconfig test
for this and make PGO and GCOV depend on it.

Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Link: https://lore.kernel.org/lkml/YMTn9yjuemKFLbws@hirez.programming.kicks-ass.net/
Link: https://lore.kernel.org/lkml/YMcssV%2Fn5IBGv4f0@hirez.programming.kicks-ass.net/
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
 init/Kconfig        | 3 +++
 kernel/gcov/Kconfig | 1 +
 kernel/pgo/Kconfig  | 3 ++-
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/init/Kconfig b/init/Kconfig
index 1ea12c64e4c9..540f862b40c6 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -83,6 +83,9 @@ config TOOLS_SUPPORT_RELR
 config CC_HAS_ASM_INLINE
 	def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
 
+config CC_HAS_NO_PROFILE_FN_ATTR
+	def_bool $(success,echo '__attribute__((no_profile)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
+
 config CONSTRUCTORS
 	bool
 
diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
index 58f87a3092f3..19facd4289cd 100644
--- a/kernel/gcov/Kconfig
+++ b/kernel/gcov/Kconfig
@@ -5,6 +5,7 @@ config GCOV_KERNEL
 	bool "Enable gcov-based kernel profiling"
 	depends on DEBUG_FS
 	depends on !CC_IS_CLANG || CLANG_VERSION >= 110000
+	depends on !X86 || (X86 && CC_HAS_NO_PROFILE_FN_ATTR)
 	select CONSTRUCTORS
 	default n
 	help
diff --git a/kernel/pgo/Kconfig b/kernel/pgo/Kconfig
index d2053df1111c..26f75ac4c6c1 100644
--- a/kernel/pgo/Kconfig
+++ b/kernel/pgo/Kconfig
@@ -8,7 +8,8 @@ config PGO_CLANG
 	bool "Enable clang's PGO-based kernel profiling"
 	depends on DEBUG_FS
 	depends on ARCH_SUPPORTS_PGO_CLANG
-	depends on CC_IS_CLANG && CLANG_VERSION >= 120000
+	depends on CC_IS_CLANG
+	depends on CC_HAS_NO_PROFILE_FN_ATTR
 	help
 	  This option enables clang's PGO (Profile Guided Optimization) based
 	  code profiling to better optimize the kernel.
-- 
2.32.0.288.g62a8d224e6-goog


  parent reply	other threads:[~2021-06-18 23:30 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-18 23:30 [PATCH 0/2] no_profile fn attr and Kconfig for GCOV+PGO Nick Desaulniers
2021-06-18 23:30 ` [PATCH 1/2] compiler_attributes.h: define __no_profile, add to noinstr Nick Desaulniers
2021-06-19 11:26   ` Miguel Ojeda
2021-06-19 11:32     ` Miguel Ojeda
2021-06-21 18:10       ` Nick Desaulniers
2021-06-21 18:24         ` Fangrui Song
2021-06-21 19:09           ` Miguel Ojeda
2021-06-18 23:30 ` Nick Desaulniers [this message]
2021-06-19  6:23   ` [PATCH 2/2] Kconfig: CC_HAS_NO_PROFILE_FN_ATTR, depend on for GCOV and PGO Marco Elver
2021-06-21 18:22     ` Nick Desaulniers
2021-06-21 18:50       ` Bill Wendling
2021-06-21 20:43         ` Nick Desaulniers
2021-06-21 21:15           ` Nathan Chancellor
2021-06-22  9:25           ` Catalin Marinas
2021-06-22  9:29             ` Mark Rutland
2021-06-22  9:32               ` Catalin Marinas
2021-06-18 23:52 ` [PATCH 0/2] no_profile fn attr and Kconfig for GCOV+PGO Fangrui Song
2021-06-19  2:45 ` Kees Cook
2021-06-20  8:08   ` Bill Wendling
2021-06-20 14:53   ` Miguel Ojeda

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