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, 4 insertions, 30 deletions

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 5bfe5caaa444..3ff53a2d4ff0 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -291,9 +291,10 @@ PHONY += install
 install:
 	$(call cmd,install)
 
-PHONY += vdso_install
-vdso_install:
-	$(Q)$(MAKE) $(build)=arch/x86/entry/vdso $@
+vdso-install-$(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
 
 archprepare: checkbin
 checkbin:
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 6a1821bd7d5e..c197efd82922 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -190,31 +190,4 @@ GCOV_PROFILE := n
 quiet_cmd_vdso_and_check = VDSO    $@
       cmd_vdso_and_check = $(cmd_vdso); $(cmd_vdso_check)
 
-#
-# 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_%=%)
-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 := $(vdso_img_sodbg:%.dbg=install_%)
-
-$(MODLIB)/vdso: FORCE
-	@mkdir -p $(MODLIB)/vdso
-
-$(vdso_img_insttargets): install_%: $(obj)/%.dbg $(MODLIB)/vdso
-	$(call cmd,vdso_install)
-
-PHONY += vdso_install $(vdso_img_insttargets)
-vdso_install: $(vdso_img_insttargets)
-
 clean-files := vdso32.so vdso32.so.dbg vdso64* vdso-image-*.c vdsox32.so*