From 34e3ab1447db13daad066bb9fcf76cb88a827da6 Mon Sep 17 00:00:00 2001 From: Quentin Monnet Date: Sat, 9 Oct 2021 22:03:39 +0100 Subject: bpftool: Fix install for libbpf's internal header(s) We recently updated bpftool's Makefile to make it install the headers from libbpf, instead of pulling them directly from libbpf's directory. There is also an additional header, internal to libbpf, that needs be installed. The way that bpftool's Makefile installs that particular header is currently correct, but would break if we were to modify $(LIBBPF_INTERNAL_HDRS) to make it point to more than one header. Use a static pattern rule instead, so that the Makefile can withstand the addition of other headers to install. The objective is simply to make the Makefile more robust. It should _not_ be read as an invitation to import more internal headers from libbpf into bpftool. Fixes: f012ade10b34 ("bpftool: Install libbpf headers instead of including the dir") Reported-by: Andrii Nakryiko Signed-off-by: Quentin Monnet Signed-off-by: Andrii Nakryiko Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20211009210341.6291-2-quentin@isovalent.com --- tools/bpf/bpftool/Makefile | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 9c2d13c513f0..646fd40b3253 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -14,7 +14,7 @@ else Q = @ endif -BPF_DIR = $(srctree)/tools/lib/bpf/ +BPF_DIR = $(srctree)/tools/lib/bpf ifneq ($(OUTPUT),) _OUTPUT := $(OUTPUT) @@ -25,6 +25,7 @@ BOOTSTRAP_OUTPUT := $(_OUTPUT)/bootstrap/ LIBBPF_OUTPUT := $(_OUTPUT)/libbpf/ LIBBPF_DESTDIR := $(LIBBPF_OUTPUT) LIBBPF_INCLUDE := $(LIBBPF_DESTDIR)/include +LIBBPF_HDRS_DIR := $(LIBBPF_INCLUDE)/bpf LIBBPF = $(LIBBPF_OUTPUT)libbpf.a LIBBPF_BOOTSTRAP_OUTPUT = $(BOOTSTRAP_OUTPUT)libbpf/ @@ -32,7 +33,7 @@ LIBBPF_BOOTSTRAP = $(LIBBPF_BOOTSTRAP_OUTPUT)libbpf.a # We need to copy nlattr.h which is not otherwise exported by libbpf, but still # required by bpftool. -LIBBPF_INTERNAL_HDRS := nlattr.h +LIBBPF_INTERNAL_HDRS := $(addprefix $(LIBBPF_HDRS_DIR)/,nlattr.h) ifeq ($(BPFTOOL_VERSION),) BPFTOOL_VERSION := $(shell make -rR --no-print-directory -sC ../../.. kernelversion) @@ -45,10 +46,9 @@ $(LIBBPF): FORCE | $(LIBBPF_OUTPUT) $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) \ DESTDIR=$(LIBBPF_DESTDIR) prefix= $(LIBBPF) install_headers -$(LIBBPF_INCLUDE)/bpf/$(LIBBPF_INTERNAL_HDRS): \ - $(addprefix $(BPF_DIR),$(LIBBPF_INTERNAL_HDRS)) $(LIBBPF) - $(call QUIET_INSTALL, bpf/$(notdir $@)) - $(Q)install -m 644 -t $(LIBBPF_INCLUDE)/bpf/ $(BPF_DIR)$(notdir $@) +$(LIBBPF_INTERNAL_HDRS): $(LIBBPF_HDRS_DIR)/%.h: $(BPF_DIR)/%.h $(LIBBPF) + $(call QUIET_INSTALL, $@) + $(Q)install -m 644 -t $(LIBBPF_HDRS_DIR) $< $(LIBBPF_BOOTSTRAP): FORCE | $(LIBBPF_BOOTSTRAP_OUTPUT) $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) \ @@ -150,7 +150,7 @@ BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o g $(BOOTSTRAP_OBJS): $(LIBBPF_BOOTSTRAP) OBJS = $(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o -$(OBJS): $(LIBBPF) $(LIBBPF_INCLUDE)/bpf/$(LIBBPF_INTERNAL_HDRS) +$(OBJS): $(LIBBPF) $(LIBBPF_INTERNAL_HDRS) VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux) \ $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux) \ -- cgit v1.2.3 From ced846c65e8ffdaac7138936cdbbc9337a939fb9 Mon Sep 17 00:00:00 2001 From: Quentin Monnet Date: Sat, 9 Oct 2021 22:03:40 +0100 Subject: bpftool: Do not FORCE-build libbpf In bpftool's Makefile, libbpf has a FORCE dependency, to make sure we rebuild it in case its source files changed. Let's instead make the rebuild depend on the source files directly, through a call to the "$(wildcard ...)" function. This avoids descending into libbpf's directory if there is nothing to update. Do the same for the bootstrap libbpf version. This results in a slightly faster operation and less verbose output when running make a second time in bpftool's directory. Before: Auto-detecting system features: ... libbfd: [ on ] ... disassembler-four-args: [ on ] ... zlib: [ on ] ... libcap: [ on ] ... clang-bpf-co-re: [ on ] make[1]: Entering directory '/root/dev/linux/tools/lib/bpf' make[1]: Entering directory '/root/dev/linux/tools/lib/bpf' make[1]: Nothing to be done for 'install_headers'. make[1]: Leaving directory '/root/dev/linux/tools/lib/bpf' make[1]: Leaving directory '/root/dev/linux/tools/lib/bpf' After: Auto-detecting system features: ... libbfd: [ on ] ... disassembler-four-args: [ on ] ... zlib: [ on ] ... libcap: [ on ] ... clang-bpf-co-re: [ on ] Other ways to clean up the output could be to pass the "-s" option, or to redirect the output to >/dev/null, when calling make recursively to descend into libbpf's directory. However, this would suppress some useful output if something goes wrong during the build. A better alternative would be to pass "--no-print-directory" to the recursive make, but that would still leave us with some noise for "install_headers". Skipping the descent into libbpf's directory if no source file has changed works best, and seems the most logical option overall. Reported-by: Andrii Nakryiko Signed-off-by: Quentin Monnet Signed-off-by: Andrii Nakryiko Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20211009210341.6291-3-quentin@isovalent.com --- tools/bpf/bpftool/Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 646fd40b3253..331019f6d5b1 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -42,7 +42,7 @@ endif $(LIBBPF_OUTPUT) $(BOOTSTRAP_OUTPUT) $(LIBBPF_BOOTSTRAP_OUTPUT): $(QUIET_MKDIR)mkdir -p $@ -$(LIBBPF): FORCE | $(LIBBPF_OUTPUT) +$(LIBBPF): $(wildcard $(BPF_DIR)/*.[ch] $(BPF_DIR)/Makefile) | $(LIBBPF_OUTPUT) $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) \ DESTDIR=$(LIBBPF_DESTDIR) prefix= $(LIBBPF) install_headers @@ -50,7 +50,7 @@ $(LIBBPF_INTERNAL_HDRS): $(LIBBPF_HDRS_DIR)/%.h: $(BPF_DIR)/%.h $(LIBBPF) $(call QUIET_INSTALL, $@) $(Q)install -m 644 -t $(LIBBPF_HDRS_DIR) $< -$(LIBBPF_BOOTSTRAP): FORCE | $(LIBBPF_BOOTSTRAP_OUTPUT) +$(LIBBPF_BOOTSTRAP): $(wildcard $(BPF_DIR)/*.[ch] $(BPF_DIR)/Makefile) | $(LIBBPF_BOOTSTRAP_OUTPUT) $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) \ ARCH= CC=$(HOSTCC) LD=$(HOSTLD) $@ -- cgit v1.2.3 From 062e1fc008ded14a637ed9c8631fa31f57534dfc Mon Sep 17 00:00:00 2001 From: Quentin Monnet Date: Sat, 9 Oct 2021 22:03:41 +0100 Subject: bpftool: Turn check on zlib from a phony target into a conditional error One of bpftool's object files depends on zlib. To make sure we do not attempt to build that object when the library is not available, commit d66fa3c70e59 ("tools: bpftool: add feature check for zlib") introduced a feature check to detect whether zlib is present. This check comes as a rule for which the target ("zdep") is a nonexistent file (phony target), which means that the Makefile always attempts to rebuild it. It is mostly harmless. However, one side effect is that, on running again once bpftool is already built, make considers that "something" (the recipe for zdep) was executed, and does not print the usual message "make: Nothing to be done for 'all'", which is a user-friendly indicator that the build went fine. Before, with some level of debugging information: $ make --debug=m [...] Reading makefiles... Auto-detecting system features: ... libbfd: [ on ] ... disassembler-four-args: [ on ] ... zlib: [ on ] ... libcap: [ on ] ... clang-bpf-co-re: [ on ] Updating makefiles.... Updating goal targets.... File 'all' does not exist. File 'zdep' does not exist. Must remake target 'zdep'. File 'all' does not exist. Must remake target 'all'. Successfully remade target file 'all'. After the patch: $ make --debug=m [...] Auto-detecting system features: ... libbfd: [ on ] ... disassembler-four-args: [ on ] ... zlib: [ on ] ... libcap: [ on ] ... clang-bpf-co-re: [ on ] Updating makefiles.... Updating goal targets.... File 'all' does not exist. Must remake target 'all'. Successfully remade target file 'all'. make: Nothing to be done for 'all'. (Note the last line, which is not part of make's debug information.) Signed-off-by: Quentin Monnet Signed-off-by: Andrii Nakryiko Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20211009210341.6291-4-quentin@isovalent.com --- tools/bpf/bpftool/Makefile | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 331019f6d5b1..abcef1f72d65 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -198,7 +198,10 @@ $(BOOTSTRAP_OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c $(OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c $(QUIET_CC)$(CC) $(CFLAGS) -c -MMD -o $@ $< -$(OUTPUT)feature.o: | zdep +$(OUTPUT)feature.o: +ifneq ($(feature-zlib), 1) + $(error "No zlib found") +endif $(BPFTOOL_BOOTSTRAP): $(BOOTSTRAP_OBJS) $(LIBBPF_BOOTSTRAP) $(QUIET_LINK)$(HOSTCC) $(CFLAGS) $(LDFLAGS) -o $@ $(BOOTSTRAP_OBJS) \ @@ -254,10 +257,7 @@ doc-uninstall: FORCE: -zdep: - @if [ "$(feature-zlib)" != "1" ]; then echo "No zlib found"; exit 1 ; fi - .SECONDARY: -.PHONY: all FORCE clean install-bin install uninstall zdep +.PHONY: all FORCE clean install-bin install uninstall .PHONY: doc doc-clean doc-install doc-uninstall .DEFAULT_GOAL := all -- cgit v1.2.3