kbuild: unify vdso_install rules

Currently, there is no standard implementation for vdso_install,
leading to various issues:

 1. Code duplication

    Many architectures duplicate similar code just for copying files
    to the install destination.

    Some architectures (arm, sparc, x86) create build-id symlinks,
    introducing more code duplication.

 2. Unintended updates of in-tree build artifacts

    The vdso_install rule depends on the vdso files to install.
    It may update in-tree build artifacts. This can be problematic,
    as explained in commit 19514fc665ff ("arm, kbuild: make
    "make install" not depend on vmlinux").

 3. Broken code in some architectures

    Makefile code is often copied from one architecture to another
    without proper adaptation.

    'make vdso_install' for parisc does not work.

    'make vdso_install' for s390 installs vdso64, but not vdso32.

To address these problems, this commit introduces a generic vdso_install
rule.

Architectures that support vdso_install need to define vdso-install-y
in arch/*/Makefile. vdso-install-y lists the files to install.

For example, arch/x86/Makefile looks like this:

  vdso-install-$(CONFIG_X86_64)           += arch/x86/entry/vdso/vdso64.so.dbg
  vdso-install-$(CONFIG_X86_X32_ABI)      += arch/x86/entry/vdso/vdsox32.so.dbg
  vdso-install-$(CONFIG_X86_32)           += arch/x86/entry/vdso/vdso32.so.dbg
  vdso-install-$(CONFIG_IA32_EMULATION)   += arch/x86/entry/vdso/vdso32.so.dbg

These files will be installed to $(MODLIB)/vdso/ with the .dbg suffix,
if exists, stripped away.

vdso-install-y can optionally take the second field after the colon
separator. This is needed because some architectures install a vdso
file as a different base name.

The following is a snippet from arch/arm64/Makefile.

  vdso-install-$(CONFIG_COMPAT_VDSO)      += arch/arm64/kernel/vdso32/vdso.so.dbg:vdso32.so

This will rename vdso.so.dbg to vdso32.so during installation. If such
architectures change their implementation so that the base names match,
this workaround will go away.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sven Schnelle <svens@linux.ibm.com> # s390
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Guo Ren <guoren@kernel.org>
Acked-by: Helge Deller <deller@gmx.de>  # parisc
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

2 files changed, 1 insertions, 31 deletions

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 547e5856eaa0..5ba42f69f8ce 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -304,11 +304,7 @@ $(INSTALL_TARGETS): KBUILD_IMAGE = $(boot)/$(patsubst %install,%Image,$@)
 $(INSTALL_TARGETS):
 	$(call cmd,install)
 
-PHONY += vdso_install
-vdso_install:
-ifeq ($(CONFIG_VDSO),y)
-	$(Q)$(MAKE) $(build)=arch/arm/vdso $@
-endif
+vdso-install-$(CONFIG_VDSO) += arch/arm/vdso/vdso.so.dbg
 
 # My testing targets (bypasses dependencies)
 bp:;	$(Q)$(MAKE) $(build)=$(boot) $(boot)/bootpImage
@@ -331,7 +327,6 @@ define archhelp
   echo  '                  Install using (your) ~/bin/$(INSTALLKERNEL) or'
   echo  '                  (distribution) /sbin/$(INSTALLKERNEL) or'
   echo  '                  install to $$(INSTALL_PATH) and run lilo'
-  echo  '  vdso_install  - Install unstripped vdso.so to $$(INSTALL_MOD_PATH)/vdso'
   echo
   echo  '  multi_v7_lpae_defconfig     - multi_v7_defconfig with CONFIG_ARM_LPAE enabled'
 endef
diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile
index 515ca33b854c..d761bd2e2f40 100644
--- a/arch/arm/vdso/Makefile
+++ b/arch/arm/vdso/Makefile
@@ -63,28 +63,3 @@ quiet_cmd_vdsold_and_vdso_check = LD      $@
 
 quiet_cmd_vdsomunge = MUNGE   $@
       cmd_vdsomunge = $(objtree)/$(obj)/vdsomunge $< $@
-
-#
-# Install the unstripped copy of vdso.so.dbg.  If our toolchain
-# supports build-id, install .build-id links as well.
-#
-# Cribbed from arch/x86/vdso/Makefile.
-#
-quiet_cmd_vdso_install = INSTALL $<
-define cmd_vdso_install
-	cp $< "$(MODLIB)/vdso/vdso.so"; \
-	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 "../../vdso.so" "$(MODLIB)/vdso/.build-id/$$first/$$last.debug"; \
-	fi
-endef
-
-$(MODLIB)/vdso: FORCE
-	@mkdir -p $(MODLIB)/vdso
-
-PHONY += vdso_install
-vdso_install: $(obj)/vdso.so.dbg $(MODLIB)/vdso
-	$(call cmd,vdso_install)