[PATCH v4 bpf-next 02/14] bpf: Compile resolve_btfids tool at kernel compilation start

From: Jiri Olsa <jolsa@kernel.org>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
	Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
	Martin KaFai Lau <kafai@fb.com>, David Miller <davem@redhat.com>,
	John Fastabend <john.fastabend@gmail.com>,
	Wenbo Zhang <ethercflow@gmail.com>,
	KP Singh <kpsingh@chromium.org>, Andrii Nakryiko <andriin@fb.com>,
	Brendan Gregg <bgregg@netflix.com>,
	Florent Revest <revest@chromium.org>,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH v4 bpf-next 02/14] bpf: Compile resolve_btfids tool at kernel compilation start
Date: Fri, 26 Jun 2020 00:12:52 +0200	[thread overview]
Message-ID: <20200625221304.2817194-3-jolsa@kernel.org> (raw)
In-Reply-To: <20200625221304.2817194-1-jolsa@kernel.org>

The resolve_btfids tool will be used during the vmlinux linking,
so it's necessary it's ready for it.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 Makefile           | 22 ++++++++++++++++++----
 tools/Makefile     |  3 +++
 tools/bpf/Makefile |  5 ++++-
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index ae5d8220f431..8db4fd8097e0 100644
--- a/Makefile
+++ b/Makefile
@@ -1053,9 +1053,10 @@ export mod_sign_cmd
 
 HOST_LIBELF_LIBS = $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
 
+has_libelf = $(call try-run,\
+               echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
+
 ifdef CONFIG_STACK_VALIDATION
-  has_libelf := $(call try-run,\
-		echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
   ifeq ($(has_libelf),1)
     objtool_target := tools/objtool FORCE
   else
@@ -1064,6 +1065,14 @@ ifdef CONFIG_STACK_VALIDATION
   endif
 endif
 
+ifdef CONFIG_DEBUG_INFO_BTF
+  ifeq ($(has_libelf),1)
+    resolve_btfids_target := tools/bpf/resolve_btfids FORCE
+  else
+    ERROR_RESOLVE_BTFIDS := 1
+  endif
+endif
+
 PHONY += prepare0
 
 export MODORDER := $(extmod-prefix)modules.order
@@ -1175,7 +1184,7 @@ prepare0: archprepare
 	$(Q)$(MAKE) $(build)=.
 
 # All the preparing..
-prepare: prepare0 prepare-objtool
+prepare: prepare0 prepare-objtool prepare-resolve_btfids
 
 # Support for using generic headers in asm-generic
 asm-generic := -f $(srctree)/scripts/Makefile.asm-generic obj
@@ -1188,7 +1197,7 @@ uapi-asm-generic:
 	$(Q)$(MAKE) $(asm-generic)=arch/$(SRCARCH)/include/generated/uapi/asm \
 	generic=include/uapi/asm-generic
 
-PHONY += prepare-objtool
+PHONY += prepare-objtool prepare-resolve_btfids
 prepare-objtool: $(objtool_target)
 ifeq ($(SKIP_STACK_VALIDATION),1)
 ifdef CONFIG_UNWINDER_ORC
@@ -1199,6 +1208,11 @@ else
 endif
 endif
 
+prepare-resolve_btfids: $(resolve_btfids_target)
+ifeq ($(ERROR_RESOLVE_BTFIDS),1)
+	@echo "error: Cannot resolve BTF IDs for CONFIG_DEBUG_INFO_BTF, please install libelf-dev, libelf-devel or elfutils-libelf-devel" >&2
+	@false
+endif
 # Generate some files
 # ---------------------------------------------------------------------------
 
diff --git a/tools/Makefile b/tools/Makefile
index bd778812e915..85af6ebbce91 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -67,6 +67,9 @@ cpupower: FORCE
 cgroup firewire hv guest bootconfig spi usb virtio vm bpf iio gpio objtool leds wmi pci firmware debugging: FORCE
 	$(call descend,$@)
 
+bpf/%: FORCE
+	$(call descend,$@)
+
 liblockdep: FORCE
 	$(call descend,lib/lockdep)
 
diff --git a/tools/bpf/Makefile b/tools/bpf/Makefile
index 6df1850f8353..89ae235b790e 100644
--- a/tools/bpf/Makefile
+++ b/tools/bpf/Makefile
@@ -123,5 +123,8 @@ runqslower_install:
 runqslower_clean:
 	$(call descend,runqslower,clean)
 
+resolve_btfids:
+	$(call descend,resolve_btfids)
+
 .PHONY: all install clean bpftool bpftool_install bpftool_clean \
-	runqslower runqslower_install runqslower_clean
+	runqslower runqslower_install runqslower_clean resolve_btfids
-- 
2.25.4

