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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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0816b0f036
Add "read-mostly" qualifier to the following variables in smp.h: - cpu_sibling_map - cpu_core_map - cpu_llc_shared_map - cpu_llc_id - cpu_number - x86_cpu_to_apicid - x86_bios_cpu_apicid - x86_cpu_to_logical_apicid As long as all the variables above are only written during the initialization, this change is meant to prevent the false sharing. More specifically, on vSMP Foundation platform x86_cpu_to_apicid shared the same internode_cache_line with frequently written lapic_events. From the analysis of the first 33 per_cpu variables out of 219 (memories they describe, to be more specific) the 8 have read_mostly nature (tlb_vector_offset, cpu_loops_per_jiffy, xen_debug_irq, etc.) and 25 are frequently written (irq_stack_union, gdt_page, exception_stacks, idt_desc, etc.). Assuming that the spread of the rest of the per_cpu variables is similar, identifying the read mostly memories will make more sense in terms of long-term code maintenance comparing to identifying frequently written memories. Signed-off-by: Vlad Zolotarov <vlad@scalemp.com> Acked-by: Shai Fultheim <shai@scalemp.com> Cc: Shai Fultheim (Shai@ScaleMP.com) <Shai@scalemp.com> Cc: ido@wizery.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1719258.EYKzE4Zbq5@vlad Signed-off-by: Ingo Molnar <mingo@kernel.org>
239 lines
5.6 KiB
C
239 lines
5.6 KiB
C
#ifndef _ASM_X86_SMP_H
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#define _ASM_X86_SMP_H
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#ifndef __ASSEMBLY__
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#include <linux/cpumask.h>
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#include <linux/init.h>
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#include <asm/percpu.h>
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/*
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* We need the APIC definitions automatically as part of 'smp.h'
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*/
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#ifdef CONFIG_X86_LOCAL_APIC
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# include <asm/mpspec.h>
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# include <asm/apic.h>
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# ifdef CONFIG_X86_IO_APIC
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# include <asm/io_apic.h>
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# endif
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#endif
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#include <asm/thread_info.h>
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#include <asm/cpumask.h>
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#include <asm/cpufeature.h>
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extern int smp_num_siblings;
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extern unsigned int num_processors;
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static inline bool cpu_has_ht_siblings(void)
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{
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bool has_siblings = false;
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#ifdef CONFIG_SMP
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has_siblings = cpu_has_ht && smp_num_siblings > 1;
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#endif
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return has_siblings;
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}
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DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_map);
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DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_core_map);
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/* cpus sharing the last level cache: */
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DECLARE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
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DECLARE_PER_CPU_READ_MOSTLY(u16, cpu_llc_id);
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DECLARE_PER_CPU_READ_MOSTLY(int, cpu_number);
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static inline struct cpumask *cpu_sibling_mask(int cpu)
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{
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return per_cpu(cpu_sibling_map, cpu);
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}
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static inline struct cpumask *cpu_core_mask(int cpu)
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{
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return per_cpu(cpu_core_map, cpu);
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}
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static inline struct cpumask *cpu_llc_shared_mask(int cpu)
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{
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return per_cpu(cpu_llc_shared_map, cpu);
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}
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DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid);
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DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_bios_cpu_apicid);
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#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_32)
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DECLARE_EARLY_PER_CPU_READ_MOSTLY(int, x86_cpu_to_logical_apicid);
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#endif
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/* Static state in head.S used to set up a CPU */
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extern unsigned long stack_start; /* Initial stack pointer address */
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struct task_struct;
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struct smp_ops {
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void (*smp_prepare_boot_cpu)(void);
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void (*smp_prepare_cpus)(unsigned max_cpus);
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void (*smp_cpus_done)(unsigned max_cpus);
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void (*stop_other_cpus)(int wait);
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void (*smp_send_reschedule)(int cpu);
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int (*cpu_up)(unsigned cpu, struct task_struct *tidle);
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int (*cpu_disable)(void);
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void (*cpu_die)(unsigned int cpu);
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void (*play_dead)(void);
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void (*send_call_func_ipi)(const struct cpumask *mask);
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void (*send_call_func_single_ipi)(int cpu);
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};
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/* Globals due to paravirt */
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extern void set_cpu_sibling_map(int cpu);
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#ifdef CONFIG_SMP
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#ifndef CONFIG_PARAVIRT
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#define startup_ipi_hook(phys_apicid, start_eip, start_esp) do { } while (0)
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#endif
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extern struct smp_ops smp_ops;
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static inline void smp_send_stop(void)
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{
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smp_ops.stop_other_cpus(0);
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}
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static inline void stop_other_cpus(void)
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{
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smp_ops.stop_other_cpus(1);
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}
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static inline void smp_prepare_boot_cpu(void)
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{
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smp_ops.smp_prepare_boot_cpu();
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}
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static inline void smp_prepare_cpus(unsigned int max_cpus)
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{
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smp_ops.smp_prepare_cpus(max_cpus);
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}
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static inline void smp_cpus_done(unsigned int max_cpus)
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{
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smp_ops.smp_cpus_done(max_cpus);
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}
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static inline int __cpu_up(unsigned int cpu, struct task_struct *tidle)
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{
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return smp_ops.cpu_up(cpu, tidle);
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}
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static inline int __cpu_disable(void)
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{
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return smp_ops.cpu_disable();
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}
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static inline void __cpu_die(unsigned int cpu)
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{
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smp_ops.cpu_die(cpu);
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}
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static inline void play_dead(void)
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{
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smp_ops.play_dead();
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}
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static inline void smp_send_reschedule(int cpu)
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{
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smp_ops.smp_send_reschedule(cpu);
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}
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static inline void arch_send_call_function_single_ipi(int cpu)
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{
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smp_ops.send_call_func_single_ipi(cpu);
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}
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static inline void arch_send_call_function_ipi_mask(const struct cpumask *mask)
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{
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smp_ops.send_call_func_ipi(mask);
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}
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void cpu_disable_common(void);
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void native_smp_prepare_boot_cpu(void);
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void native_smp_prepare_cpus(unsigned int max_cpus);
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void native_smp_cpus_done(unsigned int max_cpus);
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int native_cpu_up(unsigned int cpunum, struct task_struct *tidle);
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int native_cpu_disable(void);
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void native_cpu_die(unsigned int cpu);
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void native_play_dead(void);
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void play_dead_common(void);
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void wbinvd_on_cpu(int cpu);
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int wbinvd_on_all_cpus(void);
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void native_send_call_func_ipi(const struct cpumask *mask);
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void native_send_call_func_single_ipi(int cpu);
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void x86_idle_thread_init(unsigned int cpu, struct task_struct *idle);
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void smp_store_cpu_info(int id);
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#define cpu_physical_id(cpu) per_cpu(x86_cpu_to_apicid, cpu)
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/* We don't mark CPUs online until __cpu_up(), so we need another measure */
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static inline int num_booting_cpus(void)
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{
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return cpumask_weight(cpu_callout_mask);
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}
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#else /* !CONFIG_SMP */
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#define wbinvd_on_cpu(cpu) wbinvd()
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static inline int wbinvd_on_all_cpus(void)
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{
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wbinvd();
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return 0;
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}
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#endif /* CONFIG_SMP */
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extern unsigned disabled_cpus __cpuinitdata;
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#ifdef CONFIG_X86_32_SMP
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/*
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* This function is needed by all SMP systems. It must _always_ be valid
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* from the initial startup. We map APIC_BASE very early in page_setup(),
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* so this is correct in the x86 case.
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*/
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#define raw_smp_processor_id() (this_cpu_read(cpu_number))
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extern int safe_smp_processor_id(void);
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#elif defined(CONFIG_X86_64_SMP)
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#define raw_smp_processor_id() (this_cpu_read(cpu_number))
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#define stack_smp_processor_id() \
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({ \
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struct thread_info *ti; \
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__asm__("andq %%rsp,%0; ":"=r" (ti) : "0" (CURRENT_MASK)); \
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ti->cpu; \
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})
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#define safe_smp_processor_id() smp_processor_id()
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#endif
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#ifdef CONFIG_X86_LOCAL_APIC
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#ifndef CONFIG_X86_64
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static inline int logical_smp_processor_id(void)
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{
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/* we don't want to mark this access volatile - bad code generation */
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return GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
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}
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#endif
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extern int hard_smp_processor_id(void);
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#else /* CONFIG_X86_LOCAL_APIC */
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# ifndef CONFIG_SMP
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# define hard_smp_processor_id() 0
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# endif
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#endif /* CONFIG_X86_LOCAL_APIC */
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#ifdef CONFIG_DEBUG_NMI_SELFTEST
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extern void nmi_selftest(void);
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#else
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#define nmi_selftest() do { } while (0)
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#endif
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#endif /* __ASSEMBLY__ */
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#endif /* _ASM_X86_SMP_H */
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