Commit dd988528 authored May 09, 2007 by Fernando Luis Vazquez Cao Committed by Linus Torvalds May 09, 2007

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>

parent a36166c6

include/asm-x86_64/smp.h

+6 −8

Original line number	Diff line number	Diff line
		@@ -57,12 +57,6 @@ static inline int num_booting_cpus(void)

		#define raw_smp_processor_id() read_pda(cpunumber)

		static inline int hard_smp_processor_id(void)
		{
		/* we don't want to mark this access volatile - bad code generation */
		return GET_APIC_ID((unsigned int )(APIC_BASE+APIC_ID));
		}

		extern int __cpu_disable(void);
		extern void __cpu_die(unsigned int cpu);
		extern void prefill_possible_map(void);
		@@ -71,10 +65,14 @@ extern unsigned __cpuinitdata disabled_cpus;

		#define NO_PROC_ID 0xFF /* No processor magic marker */

		#else /* CONFIG_SMP */
		#define hard_smp_processor_id() 0
		#endif /* CONFIG_SMP */

		static inline int hard_smp_processor_id(void)
		{
		/* we don't want to mark this access volatile - bad code generation */
		return GET_APIC_ID((unsigned int )(APIC_BASE+APIC_ID));
		}

		/*
		* Some lowlevel functions might want to know about
		* the real APIC ID <-> CPU # mapping.