Merge branch 'tools/bpftool: Some build fixes'

Jean-Philippe Brucker says:

====================

A few fixes for cross and out-of-tree build of bpftool and runqslower.
These changes allow to build for different target architectures, using
the same source tree.

Since [v2], I addressed Andrii's comments on patches 3 and 5, and added
patch 7 which fixes a build slowdown.

[v2] https://lore.kernel.org/bpf/20201109110929.1223538-1-jean-philippe@linaro.org/
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

8 files changed, 70 insertions, 66 deletions

diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index f60e6ad3a1df..804ade95929f 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -19,22 +19,39 @@ BPF_DIR = $(srctree)/tools/lib/bpf/
 ifneq ($(OUTPUT),)
   LIBBPF_OUTPUT = $(OUTPUT)/libbpf/
   LIBBPF_PATH = $(LIBBPF_OUTPUT)
+  BOOTSTRAP_OUTPUT = $(OUTPUT)/bootstrap/
 else
+  LIBBPF_OUTPUT =
   LIBBPF_PATH = $(BPF_DIR)
+  BOOTSTRAP_OUTPUT = $(CURDIR)/bootstrap/
 endif
 
 LIBBPF = $(LIBBPF_PATH)libbpf.a
+LIBBPF_BOOTSTRAP_OUTPUT = $(BOOTSTRAP_OUTPUT)libbpf/
+LIBBPF_BOOTSTRAP = $(LIBBPF_BOOTSTRAP_OUTPUT)libbpf.a
 
-BPFTOOL_VERSION ?= $(shell make -rR --no-print-directory -sC ../../.. kernelversion)
+ifeq ($(BPFTOOL_VERSION),)
+BPFTOOL_VERSION := $(shell make -rR --no-print-directory -sC ../../.. kernelversion)
+endif
+
+$(LIBBPF_OUTPUT) $(BOOTSTRAP_OUTPUT) $(LIBBPF_BOOTSTRAP_OUTPUT):
+	$(QUIET_MKDIR)mkdir -p $@
 
-$(LIBBPF): FORCE
-	$(if $(LIBBPF_OUTPUT),@mkdir -p $(LIBBPF_OUTPUT))
+$(LIBBPF): FORCE | $(LIBBPF_OUTPUT)
 	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) $(LIBBPF_OUTPUT)libbpf.a
 
-$(LIBBPF)-clean:
+$(LIBBPF_BOOTSTRAP): FORCE | $(LIBBPF_BOOTSTRAP_OUTPUT)
+	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) \
+		ARCH= CC=$(HOSTCC) LD=$(HOSTLD) $@
+
+$(LIBBPF)-clean: $(LIBBPF_OUTPUT)
 	$(call QUIET_CLEAN, libbpf)
 	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) clean >/dev/null
 
+$(LIBBPF_BOOTSTRAP)-clean: $(LIBBPF_BOOTSTRAP_OUTPUT)
+	$(call QUIET_CLEAN, libbpf-bootstrap)
+	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) clean >/dev/null
+
 prefix ?= /usr/local
 bash_compdir ?= /usr/share/bash-completion/completions
 
@@ -92,6 +109,7 @@ CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
 endif
 
 LIBS = $(LIBBPF) -lelf -lz
+LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf -lz
 ifeq ($(feature-libcap), 1)
 CFLAGS += -DUSE_LIBCAP
 LIBS += -lcap
@@ -118,9 +136,9 @@ CFLAGS += -DHAVE_LIBBFD_SUPPORT
 SRCS += $(BFD_SRCS)
 endif
 
-BPFTOOL_BOOTSTRAP := $(if $(OUTPUT),$(OUTPUT)bpftool-bootstrap,./bpftool-bootstrap)
+BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool
 
-BOOTSTRAP_OBJS = $(addprefix $(OUTPUT),main.o common.o json_writer.o gen.o btf.o)
+BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o)
 OBJS = $(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o
 
 VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)				\
@@ -167,12 +185,16 @@ $(OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c
 
 $(OUTPUT)feature.o: | zdep
 
-$(BPFTOOL_BOOTSTRAP): $(BOOTSTRAP_OBJS) $(LIBBPF)
-	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $(BOOTSTRAP_OBJS) $(LIBS)
+$(BPFTOOL_BOOTSTRAP): $(BOOTSTRAP_OBJS) $(LIBBPF_BOOTSTRAP)
+	$(QUIET_LINK)$(HOSTCC) $(CFLAGS) $(LDFLAGS) -o $@ $(BOOTSTRAP_OBJS) \
+		$(LIBS_BOOTSTRAP)
 
 $(OUTPUT)bpftool: $(OBJS) $(LIBBPF)
 	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $(OBJS) $(LIBS)
 
+$(BOOTSTRAP_OUTPUT)%.o: %.c | $(BOOTSTRAP_OUTPUT)
+	$(QUIET_CC)$(HOSTCC) $(CFLAGS) -c -MMD -o $@ $<
+
 $(OUTPUT)%.o: %.c
 	$(QUIET_CC)$(CC) $(CFLAGS) -c -MMD -o $@ $<
 
@@ -180,11 +202,11 @@ feature-detect-clean:
 	$(call QUIET_CLEAN, feature-detect)
 	$(Q)$(MAKE) -C $(srctree)/tools/build/feature/ clean >/dev/null
 
-clean: $(LIBBPF)-clean feature-detect-clean
+clean: $(LIBBPF)-clean $(LIBBPF_BOOTSTRAP)-clean feature-detect-clean
 	$(call QUIET_CLEAN, bpftool)
 	$(Q)$(RM) -- $(OUTPUT)bpftool $(OUTPUT)*.o $(OUTPUT)*.d
-	$(Q)$(RM) -- $(BPFTOOL_BOOTSTRAP) $(OUTPUT)*.skel.h $(OUTPUT)vmlinux.h
-	$(Q)$(RM) -r -- $(OUTPUT)libbpf/
+	$(Q)$(RM) -- $(OUTPUT)*.skel.h $(OUTPUT)vmlinux.h
+	$(Q)$(RM) -r -- $(LIBBPF_OUTPUT) $(BOOTSTRAP_OUTPUT)
 	$(call QUIET_CLEAN, core-gen)
 	$(Q)$(RM) -- $(OUTPUT)FEATURE-DUMP.bpftool
 	$(Q)$(RM) -r -- $(OUTPUT)feature/
diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
index 66cb92136de4..bf656432ad73 100644
--- a/tools/bpf/resolve_btfids/Makefile
+++ b/tools/bpf/resolve_btfids/Makefile
@@ -18,15 +18,6 @@ else
 endif
 
 # always use the host compiler
-ifneq ($(LLVM),)
-HOSTAR  ?= llvm-ar
-HOSTCC  ?= clang
-HOSTLD  ?= ld.lld
-else
-HOSTAR  ?= ar
-HOSTCC  ?= gcc
-HOSTLD  ?= ld
-endif
 AR       = $(HOSTAR)
 CC       = $(HOSTCC)
 LD       = $(HOSTLD)
diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile
index fb1337d69868..4d5ca54fcd4c 100644
--- a/tools/bpf/runqslower/Makefile
+++ b/tools/bpf/runqslower/Makefile
@@ -1,13 +1,18 @@
 # SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
-OUTPUT := .output
+include ../../scripts/Makefile.include
+
+OUTPUT ?= $(abspath .output)/
+
 CLANG ?= clang
 LLC ?= llc
 LLVM_STRIP ?= llvm-strip
-DEFAULT_BPFTOOL := $(OUTPUT)/sbin/bpftool
+BPFTOOL_OUTPUT := $(OUTPUT)bpftool/
+DEFAULT_BPFTOOL := $(BPFTOOL_OUTPUT)bpftool
 BPFTOOL ?= $(DEFAULT_BPFTOOL)
 LIBBPF_SRC := $(abspath ../../lib/bpf)
-BPFOBJ := $(OUTPUT)/libbpf.a
-BPF_INCLUDE := $(OUTPUT)
+BPFOBJ_OUTPUT := $(OUTPUT)libbpf/
+BPFOBJ := $(BPFOBJ_OUTPUT)libbpf.a
+BPF_INCLUDE := $(BPFOBJ_OUTPUT)
 INCLUDES := -I$(OUTPUT) -I$(BPF_INCLUDE) -I$(abspath ../../lib)        \
        -I$(abspath ../../include/uapi)
 CFLAGS := -g -Wall
@@ -18,13 +23,10 @@ VMLINUX_BTF_PATHS := /sys/kernel/btf/vmlinux /boot/vmlinux-$(KERNEL_REL)
 VMLINUX_BTF_PATH := $(or $(VMLINUX_BTF),$(firstword			       \
 					  $(wildcard $(VMLINUX_BTF_PATHS))))
 
-abs_out := $(abspath $(OUTPUT))
 ifeq ($(V),1)
 Q =
-msg =
 else
 Q = @
-msg = @printf '  %-8s %s%s\n' "$(1)" "$(notdir $(2))" "$(if $(3), $(3))";
 MAKEFLAGS += --no-print-directory
 submake_extras := feature_display=0
 endif
@@ -37,12 +39,15 @@ all: runqslower
 runqslower: $(OUTPUT)/runqslower
 
 clean:
-	$(call msg,CLEAN)
-	$(Q)rm -rf $(OUTPUT) runqslower
+	$(call QUIET_CLEAN, runqslower)
+	$(Q)$(RM) -r $(BPFOBJ_OUTPUT) $(BPFTOOL_OUTPUT)
+	$(Q)$(RM) $(OUTPUT)*.o $(OUTPUT)*.d
+	$(Q)$(RM) $(OUTPUT)*.skel.h $(OUTPUT)vmlinux.h
+	$(Q)$(RM) $(OUTPUT)runqslower
+	$(Q)$(RM) -r .output
 
 $(OUTPUT)/runqslower: $(OUTPUT)/runqslower.o $(BPFOBJ)
-	$(call msg,BINARY,$@)
-	$(Q)$(CC) $(CFLAGS) $^ -lelf -lz -o $@
+	$(QUIET_LINK)$(CC) $(CFLAGS) $^ -lelf -lz -o $@
 
 $(OUTPUT)/runqslower.o: runqslower.h $(OUTPUT)/runqslower.skel.h	      \
 			$(OUTPUT)/runqslower.bpf.o
@@ -50,36 +55,30 @@ $(OUTPUT)/runqslower.o: runqslower.h $(OUTPUT)/runqslower.skel.h	      \
 $(OUTPUT)/runqslower.bpf.o: $(OUTPUT)/vmlinux.h runqslower.h
 
 $(OUTPUT)/%.skel.h: $(OUTPUT)/%.bpf.o | $(BPFTOOL)
-	$(call msg,GEN-SKEL,$@)
-	$(Q)$(BPFTOOL) gen skeleton $< > $@
+	$(QUIET_GEN)$(BPFTOOL) gen skeleton $< > $@
 
 $(OUTPUT)/%.bpf.o: %.bpf.c $(BPFOBJ) | $(OUTPUT)
-	$(call msg,BPF,$@)
-	$(Q)$(CLANG) -g -O2 -target bpf $(INCLUDES)			      \
+	$(QUIET_GEN)$(CLANG) -g -O2 -target bpf $(INCLUDES)		      \
 		 -c $(filter %.c,$^) -o $@ &&				      \
 	$(LLVM_STRIP) -g $@
 
 $(OUTPUT)/%.o: %.c | $(OUTPUT)
-	$(call msg,CC,$@)
-	$(Q)$(CC) $(CFLAGS) $(INCLUDES) -c $(filter %.c,$^) -o $@
+	$(QUIET_CC)$(CC) $(CFLAGS) $(INCLUDES) -c $(filter %.c,$^) -o $@
 
-$(OUTPUT):
-	$(call msg,MKDIR,$@)
-	$(Q)mkdir -p $(OUTPUT)
+$(OUTPUT) $(BPFOBJ_OUTPUT) $(BPFTOOL_OUTPUT):
+	$(QUIET_MKDIR)mkdir -p $@
 
 $(OUTPUT)/vmlinux.h: $(VMLINUX_BTF_PATH) | $(OUTPUT) $(BPFTOOL)
-	$(call msg,GEN,$@)
 	$(Q)if [ ! -e "$(VMLINUX_BTF_PATH)" ] ; then \
 		echo "Couldn't find kernel BTF; set VMLINUX_BTF to"	       \
 			"specify its location." >&2;			       \
 		exit 1;\
 	fi
-	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@
+	$(QUIET_GEN)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@
 
-$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(OUTPUT)
-	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC)			       \
-		    OUTPUT=$(abspath $(dir $@))/ $(abspath $@)
+$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(BPFOBJ_OUTPUT)
+	$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) OUTPUT=$(BPFOBJ_OUTPUT) $@
 
-$(DEFAULT_BPFTOOL):
-	$(Q)$(MAKE) $(submake_extras) -C ../bpftool			      \
-		    prefix= OUTPUT=$(abs_out)/ DESTDIR=$(abs_out) install
+$(DEFAULT_BPFTOOL): | $(BPFTOOL_OUTPUT)
+	$(Q)$(MAKE) $(submake_extras) -C ../bpftool OUTPUT=$(BPFTOOL_OUTPUT)   \
+		    CC=$(HOSTCC) LD=$(HOSTLD)
diff --git a/tools/build/Makefile b/tools/build/Makefile
index 722f1700d96a..bae48e6fa995 100644
--- a/tools/build/Makefile
+++ b/tools/build/Makefile
@@ -15,10 +15,6 @@ endef
 $(call allow-override,CC,$(CROSS_COMPILE)gcc)
 $(call allow-override,LD,$(CROSS_COMPILE)ld)
 
-HOSTCC ?= gcc
-HOSTLD ?= ld
-HOSTAR ?= ar
-
 export HOSTCC HOSTLD HOSTAR
 
 ifeq ($(V),1)
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 4ea9a833dde7..5cdb19036d7f 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -3,15 +3,6 @@ include ../scripts/Makefile.include
 include ../scripts/Makefile.arch
 
 # always use the host compiler
-ifneq ($(LLVM),)
-HOSTAR	?= llvm-ar
-HOSTCC	?= clang
-HOSTLD	?= ld.lld
-else
-HOSTAR	?= ar
-HOSTCC	?= gcc
-HOSTLD	?= ld
-endif
 AR	 = $(HOSTAR)
 CC	 = $(HOSTCC)
 LD	 = $(HOSTLD)
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 7ce3f2e8b9c7..62f3deb1d3a8 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -175,10 +175,6 @@ endef
 
 LD += $(EXTRA_LDFLAGS)
 
-HOSTCC  ?= gcc
-HOSTLD  ?= ld
-HOSTAR  ?= ar
-
 PKG_CONFIG = $(CROSS_COMPILE)pkg-config
 LLVM_CONFIG ?= llvm-config
 
diff --git a/tools/power/acpi/Makefile.config b/tools/power/acpi/Makefile.config
index 54a2857c2510..331f6d30f472 100644
--- a/tools/power/acpi/Makefile.config
+++ b/tools/power/acpi/Makefile.config
@@ -54,7 +54,6 @@ INSTALL_SCRIPT = ${INSTALL_PROGRAM}
 CROSS = #/usr/i386-linux-uclibc/usr/bin/i386-uclibc-
 CROSS_COMPILE ?= $(CROSS)
 LD = $(CC)
-HOSTCC = gcc
 
 # check if compiler option is supported
 cc-supports = ${shell if $(CC) ${1} -S -o /dev/null -x c /dev/null > /dev/null 2>&1; then echo "$(1)"; fi;}
diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index a7974638561c..1358e89cdf7d 100644
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -59,6 +59,16 @@ $(call allow-override,LD,$(CROSS_COMPILE)ld)
 $(call allow-override,CXX,$(CROSS_COMPILE)g++)
 $(call allow-override,STRIP,$(CROSS_COMPILE)strip)
 
+ifneq ($(LLVM),)
+HOSTAR  ?= llvm-ar
+HOSTCC  ?= clang
+HOSTLD  ?= ld.lld
+else
+HOSTAR  ?= ar
+HOSTCC  ?= gcc
+HOSTLD  ?= ld
+endif
+
 ifeq ($(CC_NO_CLANG), 1)
 EXTRA_WARNINGS += -Wstrict-aliasing=3
 endif