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18ad51dd34
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 <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
51 lines
1.4 KiB
Makefile
51 lines
1.4 KiB
Makefile
# List of files in the vdso, has to be asm only for now
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obj-vdso64 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o getcpu.o
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# Build rules
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targets := $(obj-vdso64) vdso64.so vdso64.so.dbg
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obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
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GCOV_PROFILE := n
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ccflags-y := -shared -fno-common -fno-builtin
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ccflags-y += -nostdlib -Wl,-soname=linux-vdso64.so.1 \
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$(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
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asflags-y := -D__VDSO64__ -s
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obj-y += vdso64_wrapper.o
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extra-y += vdso64.lds
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CPPFLAGS_vdso64.lds += -P -C -U$(ARCH)
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# Force dependency (incbin is bad)
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$(obj)/vdso64_wrapper.o : $(obj)/vdso64.so
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# link rule for the .so file, .lds has to be first
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$(obj)/vdso64.so.dbg: $(src)/vdso64.lds $(obj-vdso64)
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$(call if_changed,vdso64ld)
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# strip rule for the .so file
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$(obj)/%.so: OBJCOPYFLAGS := -S
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$(obj)/%.so: $(obj)/%.so.dbg FORCE
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$(call if_changed,objcopy)
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# assembly rules for the .S files
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$(obj-vdso64): %.o: %.S
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$(call if_changed_dep,vdso64as)
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# actual build commands
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quiet_cmd_vdso64ld = VDSO64L $@
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cmd_vdso64ld = $(CC) $(c_flags) -Wl,-T $^ -o $@
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quiet_cmd_vdso64as = VDSO64A $@
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cmd_vdso64as = $(CC) $(a_flags) -c -o $@ $<
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# install commands for the unstripped file
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quiet_cmd_vdso_install = INSTALL $@
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cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
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vdso64.so: $(obj)/vdso64.so.dbg
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@mkdir -p $(MODLIB)/vdso
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$(call cmd,vdso_install)
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vdso_install: vdso64.so
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