[tip:perf/core] kbuild/recordmcount: Add RECORDMCOUNT_WARN to warn about mcount callers

From: tip-bot for Steven Rostedt
Date: Thu Jun 16 2011 - 10:07:17 EST

Commit-ID: a3a8350ab2f588f3a7a08dc86658bf90773f9a52
Gitweb: http://git.kernel.org/tip/a3a8350ab2f588f3a7a08dc86658bf90773f9a52
Author: Steven Rostedt <srostedt@xxxxxxxxxx>
AuthorDate: Tue, 12 Apr 2011 18:59:10 -0400
Committer: Steven Rostedt <rostedt@xxxxxxxxxxx>
CommitDate: Tue, 17 May 2011 10:41:49 -0400

kbuild/recordmcount: Add RECORDMCOUNT_WARN to warn about mcount callers

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@xxxxxxx>
Cc: linux-kbuild@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20110421023738.714956282@xxxxxxxxxxx
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
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

+ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
# 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 $(RECORDMCOUNT_FLAGS) "$(@)"; \
recordmcount_source := $(srctree)/scripts/recordmcount.c \
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