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From: changbin.du@intel.com
To: yamada.masahiro@socionext.com, michal.lkml@markovi.net,
	tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org
Cc: x86@kernel.org, lgirdwood@gmail.com, broonie@kernel.org,
	arnd@arndb.de, linux-kbuild@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	Changbin Du <changbin.du@intel.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH 3/5] kernel hacking: new config NO_AUTO_INLINE to disable compiler atuo-inline optimizations
Date: Tue,  1 May 2018 21:00:12 +0800	[thread overview]
Message-ID: <1525179614-14571-4-git-send-email-changbin.du@intel.com> (raw)
In-Reply-To: <1525179614-14571-1-git-send-email-changbin.du@intel.com>

From: Changbin Du <changbin.du@intel.com>

This patch add a new kernel hacking option NO_AUTO_INLINE. Selecting
this option will make compiler not auto-inline kernel functions. By
enabling this option, all the kernel functions (including static ones)
will not be optimized out except those marked as inline or always_inline.
This is useful when you are using ftrace to understand the control flow
of kernel code or tracing some static functions.

Signed-off-by: Changbin Du <changbin.du@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
 Makefile          |  6 ++++++
 lib/Kconfig.debug | 13 +++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/Makefile b/Makefile
index 619a85a..eb694f6 100644
--- a/Makefile
+++ b/Makefile
@@ -775,6 +775,12 @@ 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
 ifndef CC_FLAGS_FTRACE
 CC_FLAGS_FTRACE := -pg
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c40c7b7..90f35ad 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -198,6 +198,19 @@ config GDB_SCRIPTS
 	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
 	  for further details.
 
+config NO_AUTO_INLINE
+	bool "Disable compiler atuo-inline optimizations"
+	default n
+	help
+	  This will make compiler not auto-inline kernel functions for
+	  optimization. By enabling this option, all the kernel functions
+	  (including static ones) will not be optimized out except those
+	  marked as inline or always_inline. This is useful when you are
+	  using ftrace to understand the control flow of kernel code or
+	  tracing some static functions.
+
+	  Use only if you want to debug the kernel.
+
 config ENABLE_WARN_DEPRECATED
 	bool "Enable __deprecated logic"
 	default y
-- 
2.7.4

  parent reply	other threads:[~2018-05-01 13:11 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-01 13:00 [PATCH 0/5] kernel hacking: GCC optimization for debug experience (-Og) changbin.du
2018-05-01 13:00 ` [PATCH 1/5] x86/mm: surround level4_kernel_pgt with #ifdef CONFIG_X86_5LEVEL...#endif changbin.du
2018-05-01 13:00 ` [PATCH 2/5] regulator: add dummy of_find_regulator_by_node changbin.du
2018-05-01 20:40   ` Mark Brown
2018-05-02  9:24     ` Du, Changbin
2018-05-05  1:44   ` Applied "regulator: add dummy function of_find_regulator_by_node" to the regulator tree Mark Brown
2018-05-01 13:00 ` changbin.du [this message]
2018-05-01 14:54   ` [PATCH 3/5] kernel hacking: new config NO_AUTO_INLINE to disable compiler atuo-inline optimizations Steven Rostedt
2018-05-02  9:27     ` Du, Changbin
2018-05-01 13:00 ` [PATCH 4/5] kernel hacking: new config DEBUG_EXPERIENCE to apply GCC -Og optimization changbin.du
2018-05-01 15:25   ` Randy Dunlap
2018-05-02  9:24     ` Du, Changbin
2018-05-02 20:30   ` Arnd Bergmann
2018-05-01 13:00 ` [PATCH 5/5] asm-generic: fix build error in fix_to_virt with CONFIG_DEBUG_EXPERIENCE changbin.du
2018-05-02  7:33 ` [PATCH 0/5] kernel hacking: GCC optimization for debug experience (-Og) Ingo Molnar
2018-05-02  9:07   ` Du, Changbin
2018-05-02 11:09     ` Ingo Molnar

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