From: Andi Kleen ak@linux.intel.com
commit 96f60dfa5819a065bfdd2f2ba0df7d9cbce7f4dd upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- scripts/Makefile.build | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -224,6 +224,11 @@ 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 @@ -274,6 +279,7 @@ endif ifdef CONFIG_RETPOLINE objtool_args += --retpoline endif +endif
ifdef CONFIG_MODVERSIONS