x86/vdso: Create .build-id links for unstripped vdso files (dda1e95c) · Commits · 戴 / test

With this change, doing 'make vdso_install' and telling gdb: set debug-file-directory /lib/modules/KVER/vdso will enable vdso debugging with symbols. This is useful for testing, but kernel RPM builds will probably want to manually delete these symlinks or otherwise do something sensible when they strip the vdso/*.so files. If ld does not support --build-id, then the symlinks will not be created. Note that kernel packagers that use vdso_install may need to adjust their packaging scripts to accomdate this change. For example, Fedora's scripts create build-id symlinks themselves in a different location, so the spec should probably be updated to remove the symlinks created by make vdso_install. Signed-off-by:

Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/a424b189ce3ced85fe1e82d032a20e765e0fe0d3.1403291930.git.luto@amacapital.net Signed-off-by:

H. Peter Anvin <hpa@linux.intel.com>

arch/x86/vdso/Makefile

+13 −3

Original line number	Diff line number	Diff line
		@@ -169,14 +169,24 @@ quiet_cmd_vdso = VDSO $@
		sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@'

		VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) \
		-Wl,-Bsymbolic $(LTO_CFLAGS)
		$(call cc-ldoption, -Wl$(comma)--build-id) -Wl,-Bsymbolic $(LTO_CFLAGS)
		GCOV_PROFILE := n

		#
		# Install the unstripped copies of vdso*.so.
		# Install the unstripped copies of vdso*.so. If our toolchain supports
		# build-id, install .build-id links as well.
		#
		quiet_cmd_vdso_install = INSTALL $(@:install_%=%)
		cmd_vdso_install = cp $< $(MODLIB)/vdso/$(@:install_%=%)
		define cmd_vdso_install
		cp $< "$(MODLIB)/vdso/$(@:install_%=%)"; \
		if readelf -n $< \|grep -q 'Build ID'; then \
		buildid=`readelf -n $< \|grep 'Build ID' \|sed -e 's/^.Build ID: $.$$$/\1/'`; \
		first=`echo $$buildid \| cut -b-2`; \
		last=`echo $$buildid \| cut -b3-`; \
		mkdir -p "$(MODLIB)/vdso/.build-id/$$first"; \
		ln -sf "../../$(@:install_%=%)" "$(MODLIB)/vdso/.build-id/$$first/$$last.debug"; \
		fi
		endef

		vdso_img_insttargets := $(vdso_img_sodbg:%.dbg=install_%)

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