[PATCH bpf-next] tools: Factor Clang, LLC and LLVM utils definitions

[Sedat Dilek]

When dealing with BPF/BTF/pahole and DWARF v5 I wanted to build bpftool.

While looking into the source code I found duplicate assignments
in misc tools for the LLVM eco system, e.g. clang and llvm-objcopy.

Move the Clang, LLC and/or LLVM utils definitions to
tools/scripts/Makefile.include file and add missing
includes where needed.
Honestly, I was inspired by commit c8a950d0d3b9
("tools: Factor HOSTCC, HOSTLD, HOSTAR definitions").

I tested with bpftool and perf on Debian/testing AMD64 and
LLVM/Clang v11.1.0-rc1.

Build instructions:

[ make and make-options ]
MAKE="make V=1"
MAKE_OPTS="HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang LD=ld.lld LLVM=1 LLVM_IAS=1"
MAKE_OPTS="$MAKE_OPTS PAHOLE=/opt/pahole/bin/pahole"

[ clean-up ]
$MAKE $MAKE_OPTS -C tools/ clean

[ bpftool ]
$MAKE $MAKE_OPTS -C tools/bpf/bpftool/

[ perf ]
PYTHON=python3 $MAKE $MAKE_OPTS -C tools/perf/

I was careful with respecting the user's wish to override custom compiler,
linker, GNU/binutils and/or LLVM utils settings.

Some personal notes:
1. I have NOT tested with cross-toolchain for other archs (cross compiler/linker etc.).
2. This patch is on top of bpf-next.

CC: bpf@xxxxxxxxxxxxxxx
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> # tools/build and tools/perf
Signed-off-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
---
 tools/bpf/bpftool/Makefile                  | 2 --
 tools/bpf/runqslower/Makefile               | 3 ---
 tools/build/feature/Makefile                | 4 ++--
 tools/perf/Makefile.perf                    | 1 -
 tools/scripts/Makefile.include              | 7 +++++++
 tools/testing/selftests/bpf/Makefile        | 2 --
 tools/testing/selftests/tc-testing/Makefile | 3 +--
 7 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index 45ac2f9e0aa9..8ced1655fea6 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -75,8 +75,6 @@ endif
 
 INSTALL ?= install
 RM ?= rm -f
-CLANG ?= clang
-LLVM_STRIP ?= llvm-strip
 
 FEATURE_USER = .bpftool
 FEATURE_TESTS = libbfd disassembler-four-args reallocarray zlib libcap \
diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile
index 4d5ca54fcd4c..9d9fb6209be1 100644
--- a/tools/bpf/runqslower/Makefile
+++ b/tools/bpf/runqslower/Makefile
@@ -3,9 +3,6 @@ include ../../scripts/Makefile.include
 
 OUTPUT ?= $(abspath .output)/
 
-CLANG ?= clang
-LLC ?= llc
-LLVM_STRIP ?= llvm-strip
 BPFTOOL_OUTPUT := $(OUTPUT)bpftool/
 DEFAULT_BPFTOOL := $(BPFTOOL_OUTPUT)bpftool
 BPFTOOL ?= $(DEFAULT_BPFTOOL)
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 89ba522e377d..3e55edb3ea54 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -1,4 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
+include ../../scripts/Makefile.include
+
 FILES=                                          \
          test-all.bin                           \
          test-backtrace.bin                     \
@@ -76,8 +78,6 @@ FILES=                                          \
 FILES := $(addprefix $(OUTPUT),$(FILES))
 
 PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config
-LLVM_CONFIG ?= llvm-config
-CLANG ?= clang
 
 all: $(FILES)
 
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 62f3deb1d3a8..f4df7534026d 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -176,7 +176,6 @@ endef
 LD += $(EXTRA_LDFLAGS)
 
 PKG_CONFIG = $(CROSS_COMPILE)pkg-config
-LLVM_CONFIG ?= llvm-config
 
 RM      = rm -f
 LN      = ln -f
diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index 1358e89cdf7d..4255e71f72b7 100644
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -69,6 +69,13 @@ HOSTCC  ?= gcc
 HOSTLD  ?= ld
 endif
 
+# Some tools require Clang, LLC and/or LLVM utils
+CLANG		?= clang
+LLC		?= llc
+LLVM_CONFIG	?= llvm-config
+LLVM_OBJCOPY	?= llvm-objcopy
+LLVM_STRIP	?= llvm-strip
+
 ifeq ($(CC_NO_CLANG), 1)
 EXTRA_WARNINGS += -Wstrict-aliasing=3
 endif
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 63d6288e419c..f0674d406f40 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -19,8 +19,6 @@ ifneq ($(wildcard $(GENHDR)),)
   GENFLAGS := -DHAVE_GENHDR
 endif
 
-CLANG		?= clang
-LLVM_OBJCOPY	?= llvm-objcopy
 BPF_GCC		?= $(shell command -v bpf-gcc;)
 SAN_CFLAGS	?=
 CFLAGS += -g -rdynamic -Wall -O2 $(GENFLAGS) $(SAN_CFLAGS)		\
diff --git a/tools/testing/selftests/tc-testing/Makefile b/tools/testing/selftests/tc-testing/Makefile
index 91fee5c43274..4d639279f41e 100644
--- a/tools/testing/selftests/tc-testing/Makefile
+++ b/tools/testing/selftests/tc-testing/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+include ../../../scripts/Makefile.include
 
 top_srcdir = $(abspath ../../../..)
 APIDIR := $(top_scrdir)/include/uapi
@@ -7,8 +8,6 @@ TEST_GEN_FILES = action.o
 KSFT_KHDR_INSTALL := 1
 include ../lib.mk
 
-CLANG ?= clang
-LLC   ?= llc
 PROBE := $(shell $(LLC) -march=bpf -mcpu=probe -filetype=null /dev/null 2>&1)
 
 ifeq ($(PROBE),)
-- 
2.30.0