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https://github.com/torvalds/linux
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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>
80 lines
1.5 KiB
C
80 lines
1.5 KiB
C
#ifndef __PPC64_VDSO_H__
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#define __PPC64_VDSO_H__
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#ifdef __KERNEL__
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/* Default link addresses for the vDSOs */
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#define VDSO32_LBASE 0x100000
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#define VDSO64_LBASE 0x100000
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/* Default map addresses for 32bit vDSO */
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#define VDSO32_MBASE VDSO32_LBASE
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#define VDSO_VERSION_STRING LINUX_2.6.15
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/* Define if 64 bits VDSO has procedure descriptors */
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#undef VDS64_HAS_DESCRIPTORS
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#ifndef __ASSEMBLY__
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/* Offsets relative to thread->vdso_base */
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extern unsigned long vdso64_rt_sigtramp;
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extern unsigned long vdso32_sigtramp;
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extern unsigned long vdso32_rt_sigtramp;
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int __cpuinit vdso_getcpu_init(void);
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#else /* __ASSEMBLY__ */
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#ifdef __VDSO64__
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#ifdef VDS64_HAS_DESCRIPTORS
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#define V_FUNCTION_BEGIN(name) \
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.globl name; \
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.section ".opd","a"; \
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.align 3; \
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name: \
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.quad .name,.TOC.@tocbase,0; \
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.previous; \
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.globl .name; \
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.type .name,@function; \
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.name: \
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#define V_FUNCTION_END(name) \
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.size .name,.-.name;
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#define V_LOCAL_FUNC(name) (.name)
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#else /* VDS64_HAS_DESCRIPTORS */
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#define V_FUNCTION_BEGIN(name) \
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.globl name; \
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name: \
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#define V_FUNCTION_END(name) \
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.size name,.-name;
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#define V_LOCAL_FUNC(name) (name)
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#endif /* VDS64_HAS_DESCRIPTORS */
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#endif /* __VDSO64__ */
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#ifdef __VDSO32__
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#define V_FUNCTION_BEGIN(name) \
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.globl name; \
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.type name,@function; \
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name: \
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#define V_FUNCTION_END(name) \
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.size name,.-name;
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#define V_LOCAL_FUNC(name) (name)
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#endif /* __VDSO32__ */
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#endif /* __ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* __PPC64_VDSO_H__ */
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