1 files changed, 75 insertions, 3 deletions

diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index 6a665dd09848..a02e1ca2a1bc 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -1,7 +1,15 @@
 #
-# x86-64 vDSO.
+# Building vDSO images for x86.
 #
 
+VDSO64-$(CONFIG_X86_64)         := y
+VDSO32-$(CONFIG_X86_32)         := y
+VDSO32-$(CONFIG_COMPAT)         := y
+
+vdso-install-$(VDSO64-y)        += vdso.so
+vdso-install-$(VDSO32-y)        += $(vdso32-y:=.so)
+
+
 # files to link into the vdso
 vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vvar.o
 
@@ -57,10 +65,74 @@ quiet_cmd_vdsosym = VDSOSYM $@
 $(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE
         $(call if_changed,vdsosym)
 
+#
+# Build multiple 32-bit vDSO images to choose from at boot time.
+#
+vdso32.so-$(CONFIG_X86_32)      += int80
+vdso32.so-$(VDSO32-y)           += sysenter
+
+CPPFLAGS_vdso32.lds = $(CPPFLAGS_vdso.lds)
+VDSO_LDFLAGS_vdso32.lds = -m elf_i386 -Wl,-soname=linux-gate.so.1
+
+# This makes sure the $(obj) subdirectory exists even though vdso32/
+# is not a kbuild sub-make subdirectory.
+override obj-dirs = $(dir $(obj)) $(obj)/vdso32/
+
+targets += vdso32/vdso32.lds
+targets += $(vdso32.so-y:%=vdso32-%.so.dbg) $(vdso32.so-y:%=vdso32-%.so)
+targets += vdso32/note.o $(vdso32.so-y:%=vdso32/%.o)
+
+extra-y += $(vdso32.so-y:%=vdso32-%.so)
+
+KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS))
+$(vdso32.so-y:%=$(obj)/vdso32-%.so.dbg): KBUILD_AFLAGS = $(KBUILD_AFLAGS_32)
+$(vdso32.so-y:%=$(obj)/vdso32-%.so.dbg): asflags-$(CONFIG_X86_64) += -m32
+
+$(vdso32.so-y:%=$(obj)/vdso32-%.so.dbg): $(obj)/vdso32-%.so.dbg: FORCE \
+                                         $(obj)/vdso32/vdso32.lds \
+                                         $(obj)/vdso32/note.o \
+                                         $(obj)/vdso32/%.o
+        $(call if_changed,vdso)
+
+# Make vdso32-*-syms.lds from each image, and then make sure they match.
+# The only difference should be that some do not define VDSO32_SYSENTER_RETURN.
+
+targets += vdso32-syms.lds $(vdso32.so-y:%=vdso32-%-syms.lds)
+
+quiet_cmd_vdso32sym = VDSOSYM $@
+define cmd_vdso32sym
+        if LC_ALL=C sort -u $(filter-out FORCE,$^) > $(@D)/.tmp_$(@F) && \
+           $(foreach H,$(filter-out FORCE,$^),\
+                     if grep -q VDSO32_SYSENTER_RETURN $H; \
+                     then diff -u $(@D)/.tmp_$(@F) $H; \
+                     else sed /VDSO32_SYSENTER_RETURN/d $(@D)/.tmp_$(@F) | \
+                          diff -u - $H; fi &&) : ;\
+        then mv -f $(@D)/.tmp_$(@F) $@; \
+        else rm -f $(@D)/.tmp_$(@F); exit 1; \
+        fi
+endef
+
+$(obj)/vdso32-syms.lds: $(vdso32.so-y:%=$(obj)/vdso32-%-syms.lds) FORCE
+        $(call if_changed,vdso32sym)
+
+#
+# The DSO images are built using a special linker script.
+#
+quiet_cmd_vdso = VDSO    $@
+      cmd_vdso = $(CC) -nostdlib -o $@ \
+                       $(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \
+                       -Wl,-T,$(filter %.lds,$^) $(filter %.o,$^)
+
+VDSO_LDFLAGS = -fPIC -shared $(call ld-option, -Wl$(comma)--hash-style=sysv)
+
+#
+# Install the unstripped copy of vdso*.so listed in $(vdso-install-y).
+#
 quiet_cmd_vdso_install = INSTALL $@
       cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
-vdso.so:
+$(vdso-install-y): %.so: $(obj)/%.so.dbg FORCE
         @mkdir -p $(MODLIB)/vdso
         $(call cmd,vdso_install)
 
-vdso_install: vdso.so
+PHONY += vdso_install $(vdso-install-y)
+vdso_install: $(vdso-install-y)