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Use the APIC to determine the hardware processor id - x86_64
hard_smp_processor_id used to be just a macro that hard-coded hard_smp_processor_id to 0 in the non SMP case. When booting non SMP kernels on hardware where the boot ioapic id is not 0 this turns out to be a problem. This is happens frequently in the case of kdump and once in a great while in the case of real hardware. Use the APIC to determine the hardware processor id in both UP and SMP kernels to fix this issue. Notice that hard_smp_processor_id is only used by SMP code or by code that works with apics so we do not need to handle the case when apics are not present and hard_smp_processor_id should never be called there. Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Cc: "Luck, Tony" <tony.luck@intel.com> Acked-by: Andi Kleen <ak@suse.de> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1 changed files with 6 additions and 8 deletions
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@ -57,12 +57,6 @@ static inline int num_booting_cpus(void)
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#define raw_smp_processor_id() read_pda(cpunumber)
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static inline int hard_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_ID(*(unsigned int *)(APIC_BASE+APIC_ID));
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}
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extern int __cpu_disable(void);
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extern void __cpu_die(unsigned int cpu);
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extern void prefill_possible_map(void);
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@ -71,10 +65,14 @@ extern unsigned __cpuinitdata disabled_cpus;
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#define NO_PROC_ID 0xFF /* No processor magic marker */
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#else /* CONFIG_SMP */
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#define hard_smp_processor_id() 0
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#endif /* CONFIG_SMP */
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static inline int hard_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_ID(*(unsigned int *)(APIC_BASE+APIC_ID));
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}
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/*
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* Some lowlevel functions might want to know about
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* the real APIC ID <-> CPU # mapping.
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