From: Changbin Du <changbin.du@gmail.com>
To: yamada.masahiro@socionext.com, michal.lkml@markovi.net,
tglx@linutronix.de, mingo@redhat.com, linux@armlinux.org.uk,
akpm@linux-foundation.org, gregkh@linuxfoundation.org
Cc: rostedt@goodmis.org, x86@kernel.org,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-sparse@vger.kernel.org, robin.murphy@arm.com,
Changbin Du <changbin.du@gmail.com>
Subject: [PATCH v3 2/4] kernel hacking: new config NO_AUTO_INLINE to disable compiler auto-inline optimizations
Date: Sun, 28 Oct 2018 13:09:43 +0000 [thread overview]
Message-ID: <20181028130945.23581-3-changbin.du@gmail.com> (raw)
In-Reply-To: <20181028130945.23581-1-changbin.du@gmail.com>
This patch add a new kernel hacking option NO_AUTO_INLINE. Selecting
this option will prevent the compiler from optimizing the kernel by
auto-inlining functions not marked with the inline keyword.
With this option, only functions explicitly marked with "inline" will
be inlined. This will allow the function tracer to trace more functions
because it only traces functions that the compiler has not inlined.
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
Makefile | 6 ++++++
lib/Kconfig.debug | 17 +++++++++++++++++
2 files changed, 23 insertions(+)
diff --git a/Makefile b/Makefile
index 7d4ba5196010..04beb822ddfc 100644
--- a/Makefile
+++ b/Makefile
@@ -749,6 +749,12 @@ KBUILD_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly) \
$(call cc-option,-fno-var-tracking)
endif
+ifdef CONFIG_NO_AUTO_INLINE
+KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions) \
+ $(call cc-option, -fno-inline-small-functions) \
+ $(call cc-option, -fno-inline-functions-called-once)
+endif
+
ifdef CONFIG_FUNCTION_TRACER
ifdef CONFIG_FTRACE_MCOUNT_RECORD
# gcc 5 supports generating the mcount tables directly
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 04adfc3b185e..d50711b41dad 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -211,6 +211,23 @@ config GDB_SCRIPTS
instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
for further details.
+config NO_AUTO_INLINE
+ bool "Disable compiler auto-inline optimizations"
+ help
+ This will prevent the compiler from optimizing the kernel by
+ auto-inlining functions not marked with the inline keyword.
+ With this option, only functions explicitly marked with
+ "inline" will be inlined. This will allow the function tracer
+ to trace more functions because it only traces functions that
+ the compiler has not inlined.
+
+ Enabling this function can help debugging a kernel if using
+ the function tracer. But it can also change how the kernel
+ works, because inlining functions may change the timing,
+ which could make it difficult while debugging race conditions.
+
+ If unsure, select N.
+
config ENABLE_MUST_CHECK
bool "Enable __must_check logic"
default y
--
2.17.1
next prev parent reply other threads:[~2018-10-28 13:10 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-28 13:09 [PATCH v3 0/4] kernel hacking: GCC optimization for better debug experience (-Og) Changbin Du
2018-10-28 13:09 ` [PATCH v3 1/4] x86/mm: declare check_la57_support() as inline Changbin Du
2018-10-28 18:09 ` Steven Rostedt
2018-10-29 13:04 ` Masahiro Yamada
2018-11-02 11:27 ` Borislav Petkov
2018-11-09 16:27 ` Masahiro Yamada
2018-11-10 1:41 ` Changbin Du
2018-10-28 13:09 ` Changbin Du [this message]
2018-10-29 13:03 ` [PATCH v3 2/4] kernel hacking: new config NO_AUTO_INLINE to disable compiler auto-inline optimizations Masahiro Yamada
2018-10-28 13:09 ` [PATCH v3 3/4] ARM: mm: fix build error in fix_to_virt with CONFIG_CC_OPTIMIZE_FOR_DEBUGGING Changbin Du
2018-10-29 13:05 ` Masahiro Yamada
2018-10-28 13:09 ` [PATCH v3 4/4] kernel hacking: new config CC_OPTIMIZE_FOR_DEBUGGING to apply GCC -Og optimization Changbin Du
2018-10-29 13:16 ` Masahiro Yamada
2018-10-29 14:54 ` Changbin Du
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