Commit 96f60dfa authored Nov 27, 2017 by Andi Kleen Committed by Steven Rostedt (VMware) May 28, 2018

trace: Use -mcount-record for dynamic ftrace

gcc 5 supports a new -mcount-record option to generate ftrace
tables directly. This avoids the need to run record_mcount
manually.

Use this option when available.

So far doesn't use -mcount-nop, which also exists now.

This is needed to make ftrace work with LTO because the
normal record-mcount script doesn't run over the link
time output.

It should also improve build times slightly in the general
case.
Link: http://lkml.kernel.org/r/20171127213423.27218-12-andi@firstfloor.org



Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent 2824f503

scripts/Makefile.build

+6 −0

Original line number	Diff line number	Diff line
		@@ -207,6 +207,11 @@ cmd_modversions_c = \
		endif

		ifdef CONFIG_FTRACE_MCOUNT_RECORD
		# gcc 5 supports generating the mcount tables directly
		ifneq ($(call cc-option,-mrecord-mcount,y),y)
		KBUILD_CFLAGS += -mrecord-mcount
		else
		# else do it all manually
		ifdef BUILD_C_RECORDMCOUNT
		ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
		RECORDMCOUNT_FLAGS = -w
		@@ -259,6 +264,7 @@ ifneq ($(RETPOLINE_CFLAGS),)
		objtool_args += --retpoline
		endif
		endif
		endif


		ifdef CONFIG_MODVERSIONS