tools/dwarves: add host package

dwarves is a set of tools that use the debugging information inserted in
ELF binaries by compilers such as GCC. Utilities in the dwarves suite
include pahole, which can be used to find alignment holes in structs and
classes, and also extracts other information such as CPU cacheline
alignment, helping pack those structures to achieve more cache hits.

These tools are also used to encode and read the BTF type information
format used with the bpf syscall, making this a Linux build dependency
when using kernel BTF information.

Signed-off-by: Tony Ambardar <itugrok@yahoo.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
[bump to 1.23, add elfutils dep, drop host lib usage, drop cmake release
target, use RM macro]
Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>

toolchain/Config.in

@@ -247,6 +247,14 @@ comment "Binary tools"
 
 source "toolchain/binutils/Config.in"
 
+config DWARVES
+	bool
+	prompt "Build pahole" if TOOLCHAINOPTS
+	depends on !HOST_OS_MACOS
+	default n
+	help
+	  Enable if you want to build pahole and the dwarves tools.
+
 comment "Compiler"
 	depends on TOOLCHAINOPTS
 

tools/Makefile

@@ -84,7 +84,9 @@ endif
 ifeq ($(HOST_OS),Darwin)
   tools-y += bash
 else
+  $(curdir)/dwarves/compile += $(curdir)/elfutils/compile
   $(curdir)/elfutils/compile := $(curdir)/zlib/compile
+  tools-$(CONFIG_DWARVES) += dwarves
   tools-y += elfutils
 endif
 

tools/dwarves/Makefile

@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=dwarves
+
+PKG_SOURCE_VERSION:=v1.23
+PKG_SOURCE_PROTO:=git
+PKG_SOURCE_URL:=https://git.kernel.org/pub/scm/devel/pahole/pahole.git
+PKG_MIRROR_HASH:=6ab1bb1dbdf6c73ffcf485d909229dc1da1a3d24efd213e92c56489b58d6a4bd
+PKG_LICENSE:=GPL-2.0-only
+PKG_LICENSE_FILES:=COPYING
+
+HOST_BUILD_PARALLEL:=1
+
+include $(INCLUDE_DIR)/host-build.mk
+include $(INCLUDE_DIR)/cmake.mk
+
+CMAKE_HOST_OPTIONS += \
+	-D__LIB=lib \
+	-DCMAKE_INSTALL_RPATH="$(STAGING_DIR_HOST)/lib" \
+	-DCMAKE_SKIP_RPATH=FALSE
+
+define Host/Clean
+	$(RM) $(STAGING_DIR_HOST)/bin/{codiff,ctracer,dtagnames,pahole,pdwtags}
+	$(RM) $(STAGING_DIR_HOST)/bin/{pfunct,pglobal,prefcnt,scncopy,syscse}
+	$(RM) $(STAGING_DIR_HOST)/bin/{ostra-cg,btfdiff,fullcircle}
+	$(RM) $(STAGING_DIR_HOST)/lib/libdwarves*.so*
+	$(RM) $(STAGING_DIR_HOST)/share/man/man1/pahole.1
+	rm -rf $(STAGING_DIR_HOST)/include/dwarves
+	rm -rf $(STAGING_DIR_HOST)/share/dwarves
+	$(call Host/Clean/Default)
+endef
+
+$(eval $(call HostBuild))