[PATCH] perf tools: Enable warnings through HOSTCFLAGS

From: John Garry
Date: Fri Oct 29 2021 - 12:35:49 EST


The tools build system uses KBUILD_HOSTCFLAGS symbol for obvious purposes.

However this is not set for anything under tools/

As such, host tools apps built have no compiler warnings enabled.

Declare HOSTCFLAGS for perf tools build, and also use that symbol in
declaration of host_c_flags. HOSTCFLAGS comes from EXTRA_WARNINGS, which
is independent of target platform/arch warning flags.

Suggested-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
--
Using HOSTCFLAGS, as opposed to KBUILD_HOSTCFLAGS, is going opposite
direction to commit 96f14fe738b6 ("kbuild: Rename HOSTCFLAGS to
KBUILD_HOSTCFLAGS"), so would like further opinion from Laura and
Masahiro.

diff --git a/tools/build/Build.include b/tools/build/Build.include
index 2cf3b1bde86e..c2a95ab47379 100644
--- a/tools/build/Build.include
+++ b/tools/build/Build.include
@@ -99,7 +99,7 @@ cxx_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(CXXFLAGS) -D"BUILD_STR(s)=\#s" $(CXX
###
## HOSTCC C flags

-host_c_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(KBUILD_HOSTCFLAGS) -D"BUILD_STR(s)=\#s" $(HOSTCFLAGS_$(basetarget).o) $(HOSTCFLAGS_$(obj))
+host_c_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(HOSTCFLAGS) -D"BUILD_STR(s)=\#s" $(HOSTCFLAGS_$(basetarget).o) $(HOSTCFLAGS_$(obj))

# output directory for tests below
TMPOUT = .tmp_$$$$
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 4a9baed28f2e..9b95ba09657f 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -17,6 +17,7 @@ detected = $(shell echo "$(1)=y" >> $(OUTPUT).config-detected)
detected_var = $(shell echo "$(1)=$($(1))" >> $(OUTPUT).config-detected)

CFLAGS := $(EXTRA_CFLAGS) $(filter-out -Wnested-externs,$(EXTRA_WARNINGS))
+HOSTCFLAGS := $(filter-out -Wnested-externs,$(EXTRA_WARNINGS))

include $(srctree)/tools/scripts/Makefile.arch

@@ -211,6 +212,7 @@ endif
ifneq ($(WERROR),0)
CORE_CFLAGS += -Werror
CXXFLAGS += -Werror
+ HOSTCFLAGS += -Werror
endif

ifndef DEBUG
@@ -292,6 +294,9 @@ CXXFLAGS += -ggdb3
CXXFLAGS += -funwind-tables
CXXFLAGS += -Wno-strict-aliasing

+HOSTCFLAGS += -Wall
+HOSTCFLAGS += -Wextra
+
# Enforce a non-executable stack, as we may regress (again) in the future by
# adding assembler files missing the .GNU-stack linker note.
LDFLAGS += -Wl,-z,noexecstack
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index a3966f290297..8ca656aa8b06 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -226,7 +226,7 @@ else
endif

export srctree OUTPUT RM CC CXX LD AR CFLAGS CXXFLAGS V BISON FLEX AWK
-export HOSTCC HOSTLD HOSTAR
+export HOSTCC HOSTLD HOSTAR HOSTCFLAGS

include $(srctree)/tools/build/Makefile.include

--
2.17.1