ARM: 8332/1: add CONFIG_VDSO Kconfig and Makefile bits

Allow users to enable the vdso in Kconfig; include the vdso in the
build if CONFIG_VDSO is enabled.  Add 'vdso_install' target.

Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 23 insertions, 0 deletions

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 7f99cd652203..6c13a84b6cd2 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -263,6 +263,7 @@ core-$(CONFIG_FPE_FASTFPE)	+= $(FASTFPE_OBJ)
 core-$(CONFIG_VFP)              += arch/arm/vfp/
 core-$(CONFIG_XEN)              += arch/arm/xen/
 core-$(CONFIG_KVM_ARM_HOST)     += arch/arm/kvm/
+core-$(CONFIG_VDSO)             += arch/arm/vdso/
 
 # If we have a machine-specific directory, then include it in the build.
 core-y                          += arch/arm/kernel/ arch/arm/mm/ arch/arm/common/
@@ -320,6 +321,12 @@ dtbs: prepare scripts
 dtbs_install:
         $(Q)$(MAKE) $(dtbinst)=$(boot)/dts
 
+PHONY += vdso_install
+vdso_install:
+ifeq ($(CONFIG_VDSO),y)
+        $(Q)$(MAKE) $(build)=arch/arm/vdso $@
+endif
+
 # We use MRPROPER_FILES and CLEAN_FILES now
 archclean:
         $(Q)$(MAKE) $(clean)=$(boot)
@@ -344,4 +351,5 @@ 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'
 endef
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 902397dd1000..3e316ca54e40 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -75,6 +75,7 @@ obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event.o perf_event_cpu.o
 CFLAGS_pj4-cp0.o                := -marm
 AFLAGS_iwmmxt.o                 := -Wa,-mcpu=iwmmxt
 obj-$(CONFIG_ARM_CPU_TOPOLOGY)  += topology.o
+obj-$(CONFIG_VDSO)              += vdso.o
 
 ifneq ($(CONFIG_ARCH_EBSA110),y)
   obj-y         += io.o
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 9b4f29e595a4..8a5f1e644104 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -825,6 +825,20 @@ config KUSER_HELPERS
           Say N here only if you are absolutely certain that you do not
           need these helpers; otherwise, the safe option is to say Y.
 
+config VDSO
+        bool "Enable VDSO for acceleration of some system calls"
+        depends on AEABI && MMU
+        default y if ARM_ARCH_TIMER
+        select GENERIC_TIME_VSYSCALL
+        help
+          Place in the process address space an ELF shared object
+          providing fast implementations of gettimeofday and
+          clock_gettime.  Systems that implement the ARM architected
+          timer will receive maximum benefit.
+
+          You must have glibc 2.22 or later for programs to seamlessly
+          take advantage of this.
+
 config DMA_CACHE_RWFO
         bool "Enable read/write for ownership DMA cache maintenance"
         depends on CPU_V6K && SMP