| Message ID | 20181028130945.23581-3-changbin.du@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kernel hacking: GCC optimization for better debug experience (-Og) | expand |
On Sun, Oct 28, 2018 at 10:13 PM Changbin Du <changbin.du@gmail.com> wrote: > > This patch add a new kernel hacking option NO_AUTO_INLINE. Selecting I fixed "This patch add ..." to "This patch adds ..." then applied to linux-kbuild. > 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 >
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