| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 36/49] trace: Use -mcount-record for dynamic ftrace | Date | Mon, 22 Feb 2021 13:36:34 +0100 |
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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 @@ -222,6 +222,11 @@ 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 @@ -264,6 +269,7 @@ endif ifdef CONFIG_GCOV_KERNEL objtool_args += --no-unreachable endif +endif # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
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