[PATCH 08/15] kbuild/recordmcount: Add RECORDMCOUNT_WARN to warn about mcount

Steven Rostedt
2011-05-18T16:11:32Z

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From: Steven Rostedt <srostedt@redhat.com>

When mcount is called in a section that ftrace will not modify it into
a nop, we want to warn about this. But not warn about this always. Now
if the user builds the kernel with the option RECORDMCOUNT_WARN=1 then
the build will warn about mcount callers that are ignored and will just
waste execution time.

Acked-by: Michal Marek <mmarek@suse.cz>
Cc: linux-kbuild@vger.kernel.org
Link: http://lkml.kernel.org/r/20110421023738.714956282@goodmis.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
Makefile | 1 +
scripts/Makefile.build | 5 ++++-
2 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/Makefile b/Makefile
index 41ea6fb..e7d01ad 100644
--- a/Makefile
+++ b/Makefile
@@ -1268,6 +1268,7 @@ help:
@echo ' make C=1 [targets] Check all c source with $$CHECK (sparse by default)'
@echo ' make C=2 [targets] Force check of all c source with $$CHECK'
@echo ' make W=1 [targets] Enable extra gcc checks'
+ @echo ' make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'
@echo ''
@echo 'Execute "make" or "make all" to build all targets marked with [*] '
@echo 'For further info see the ./README file'
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 7d3f903..6165622 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -244,13 +244,16 @@ endif

ifdef CONFIG_FTRACE_MCOUNT_RECORD
ifdef BUILD_C_RECORDMCOUNT
+ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
+ RECORDMCOUNT_FLAGS = -w
+endif
# Due to recursion, we must skip empty.o.
# The empty.o file is created in the make process in order to determine
# the target endianness and word size. It is made before all other C
# files, including recordmcount.
sub_cmd_record_mcount = \
if [ $(@) != "scripts/mod/empty.o" ]; then \
- $(objtree)/scripts/recordmcount "$(@)"; \
+ $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
fi;
recordmcount_source := $(srctree)/scripts/recordmcount.c \
$(srctree)/scripts/recordmcount.h
--
1.7.4.4