5b09b2876e
As a stopgap until Mike Travis's x86-64 gs-based percpu patches are ready, provide workaround functions for x86_read/write_percpu for Xen's use. Specifically, this means that we can't really make use of vcpu placement, because we can't use a single gs-based memory access to get to vcpu fields. So disable all that for now. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
218 lines
5.7 KiB
C
218 lines
5.7 KiB
C
#ifndef _ASM_X86_PERCPU_H_
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#define _ASM_X86_PERCPU_H_
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#ifdef CONFIG_X86_64
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#include <linux/compiler.h>
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/* Same as asm-generic/percpu.h, except that we store the per cpu offset
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in the PDA. Longer term the PDA and every per cpu variable
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should be just put into a single section and referenced directly
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from %gs */
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#ifdef CONFIG_SMP
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#include <asm/pda.h>
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#define __per_cpu_offset(cpu) (cpu_pda(cpu)->data_offset)
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#define __my_cpu_offset read_pda(data_offset)
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#define per_cpu_offset(x) (__per_cpu_offset(x))
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#endif
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#include <asm-generic/percpu.h>
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DECLARE_PER_CPU(struct x8664_pda, pda);
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/*
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* These are supposed to be implemented as a single instruction which
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* operates on the per-cpu data base segment. x86-64 doesn't have
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* that yet, so this is a fairly inefficient workaround for the
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* meantime. The single instruction is atomic with respect to
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* preemption and interrupts, so we need to explicitly disable
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* interrupts here to achieve the same effect. However, because it
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* can be used from within interrupt-disable/enable, we can't actually
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* disable interrupts; disabling preemption is enough.
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*/
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#define x86_read_percpu(var) \
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({ \
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typeof(per_cpu_var(var)) __tmp; \
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preempt_disable(); \
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__tmp = __get_cpu_var(var); \
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preempt_enable(); \
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__tmp; \
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})
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#define x86_write_percpu(var, val) \
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do { \
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preempt_disable(); \
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__get_cpu_var(var) = (val); \
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preempt_enable(); \
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} while(0)
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#else /* CONFIG_X86_64 */
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#ifdef __ASSEMBLY__
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/*
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* PER_CPU finds an address of a per-cpu variable.
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*
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* Args:
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* var - variable name
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* reg - 32bit register
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*
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* The resulting address is stored in the "reg" argument.
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*
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* Example:
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* PER_CPU(cpu_gdt_descr, %ebx)
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*/
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#ifdef CONFIG_SMP
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#define PER_CPU(var, reg) \
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movl %fs:per_cpu__##this_cpu_off, reg; \
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lea per_cpu__##var(reg), reg
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#define PER_CPU_VAR(var) %fs:per_cpu__##var
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#else /* ! SMP */
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#define PER_CPU(var, reg) \
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movl $per_cpu__##var, reg
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#define PER_CPU_VAR(var) per_cpu__##var
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#endif /* SMP */
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#else /* ...!ASSEMBLY */
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/*
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* PER_CPU finds an address of a per-cpu variable.
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*
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* Args:
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* var - variable name
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* cpu - 32bit register containing the current CPU number
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*
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* The resulting address is stored in the "cpu" argument.
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*
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* Example:
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* PER_CPU(cpu_gdt_descr, %ebx)
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*/
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#ifdef CONFIG_SMP
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#define __my_cpu_offset x86_read_percpu(this_cpu_off)
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/* fs segment starts at (positive) offset == __per_cpu_offset[cpu] */
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#define __percpu_seg "%%fs:"
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#else /* !SMP */
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#define __percpu_seg ""
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#endif /* SMP */
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#include <asm-generic/percpu.h>
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/* We can use this directly for local CPU (faster). */
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DECLARE_PER_CPU(unsigned long, this_cpu_off);
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/* For arch-specific code, we can use direct single-insn ops (they
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* don't give an lvalue though). */
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extern void __bad_percpu_size(void);
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#define percpu_to_op(op, var, val) \
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do { \
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typedef typeof(var) T__; \
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if (0) { \
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T__ tmp__; \
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tmp__ = (val); \
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} \
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switch (sizeof(var)) { \
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case 1: \
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asm(op "b %1,"__percpu_seg"%0" \
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: "+m" (var) \
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: "ri" ((T__)val)); \
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break; \
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case 2: \
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asm(op "w %1,"__percpu_seg"%0" \
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: "+m" (var) \
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: "ri" ((T__)val)); \
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break; \
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case 4: \
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asm(op "l %1,"__percpu_seg"%0" \
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: "+m" (var) \
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: "ri" ((T__)val)); \
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break; \
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default: __bad_percpu_size(); \
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} \
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} while (0)
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#define percpu_from_op(op, var) \
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({ \
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typeof(var) ret__; \
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switch (sizeof(var)) { \
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case 1: \
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asm(op "b "__percpu_seg"%1,%0" \
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: "=r" (ret__) \
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: "m" (var)); \
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break; \
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case 2: \
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asm(op "w "__percpu_seg"%1,%0" \
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: "=r" (ret__) \
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: "m" (var)); \
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break; \
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case 4: \
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asm(op "l "__percpu_seg"%1,%0" \
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: "=r" (ret__) \
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: "m" (var)); \
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break; \
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default: __bad_percpu_size(); \
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} \
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ret__; \
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})
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#define x86_read_percpu(var) percpu_from_op("mov", per_cpu__##var)
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#define x86_write_percpu(var, val) percpu_to_op("mov", per_cpu__##var, val)
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#define x86_add_percpu(var, val) percpu_to_op("add", per_cpu__##var, val)
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#define x86_sub_percpu(var, val) percpu_to_op("sub", per_cpu__##var, val)
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#define x86_or_percpu(var, val) percpu_to_op("or", per_cpu__##var, val)
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#endif /* !__ASSEMBLY__ */
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#endif /* !CONFIG_X86_64 */
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#ifdef CONFIG_SMP
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/*
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* Define the "EARLY_PER_CPU" macros. These are used for some per_cpu
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* variables that are initialized and accessed before there are per_cpu
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* areas allocated.
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*/
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#define DEFINE_EARLY_PER_CPU(_type, _name, _initvalue) \
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DEFINE_PER_CPU(_type, _name) = _initvalue; \
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__typeof__(_type) _name##_early_map[NR_CPUS] __initdata = \
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{ [0 ... NR_CPUS-1] = _initvalue }; \
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__typeof__(_type) *_name##_early_ptr = _name##_early_map
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#define EXPORT_EARLY_PER_CPU_SYMBOL(_name) \
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EXPORT_PER_CPU_SYMBOL(_name)
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#define DECLARE_EARLY_PER_CPU(_type, _name) \
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DECLARE_PER_CPU(_type, _name); \
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extern __typeof__(_type) *_name##_early_ptr; \
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extern __typeof__(_type) _name##_early_map[]
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#define early_per_cpu_ptr(_name) (_name##_early_ptr)
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#define early_per_cpu_map(_name, _idx) (_name##_early_map[_idx])
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#define early_per_cpu(_name, _cpu) \
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(early_per_cpu_ptr(_name) ? \
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early_per_cpu_ptr(_name)[_cpu] : \
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per_cpu(_name, _cpu))
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#else /* !CONFIG_SMP */
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#define DEFINE_EARLY_PER_CPU(_type, _name, _initvalue) \
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DEFINE_PER_CPU(_type, _name) = _initvalue
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#define EXPORT_EARLY_PER_CPU_SYMBOL(_name) \
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EXPORT_PER_CPU_SYMBOL(_name)
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#define DECLARE_EARLY_PER_CPU(_type, _name) \
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DECLARE_PER_CPU(_type, _name)
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#define early_per_cpu(_name, _cpu) per_cpu(_name, _cpu)
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#define early_per_cpu_ptr(_name) NULL
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/* no early_per_cpu_map() */
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#endif /* !CONFIG_SMP */
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#endif /* _ASM_X86_PERCPU_H_ */
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