From 18ad51dd342a7eb09dbcd059d0b451b616d4dafc Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Wed, 4 Jul 2012 20:37:11 +0000 Subject: powerpc: Add VDSO version of getcpu We have a request for a fast method of getting CPU and NUMA node IDs from userspace. This patch implements a getcpu VDSO function, similar to x86. Ben suggested we use SPRG3 which is userspace readable. SPRG3 can be modified by a KVM guest, so we save the SPRG3 value in the paca and restore it when transitioning from the guest to the host. I have a glibc patch that implements sched_getcpu on top of this. Testing on a POWER7: baseline: 538 cycles vdso: 30 cycles Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/vdso32/Makefile | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/powerpc/kernel/vdso32/Makefile') diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile index 9a7946c41738..53e6c9b979ec 100644 --- a/arch/powerpc/kernel/vdso32/Makefile +++ b/arch/powerpc/kernel/vdso32/Makefile @@ -1,7 +1,9 @@ # List of files in the vdso, has to be asm only for now -obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o +obj-vdso32-$(CONFIG_PPC64) = getcpu.o +obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o \ + $(obj-vdso32-y) # Build rules -- cgit v1.2.3