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@xxxxxxxxx> Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> --- 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
