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[PATCH] i386: Initialize the per-CPU data area

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When a CPU is brought up, a PDA and GDT are allocated for it.  The GDT's
__KERNEL_PDA entry is pointed to the allocated PDA memory, so that all
references using this segment descriptor will refer to the PDA.

This patch rearranges CPU initialization a bit, so that the GDT/PDA are set up
as early as possible in cpu_init().  Also for secondary CPUs, GDT+PDA are
preallocated and initialized so all the secondary CPU needs to do is set up
the ldt and load %gs.  This will be important once smp_processor_id() and
current use the PDA.

In all cases, the PDA is set up in head.S, before a CPU starts running C code,
so the PDA is always available.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Cc: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Matt Tolentino <matthew.e.tolentino@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
This commit is contained in:
Jeremy Fitzhardinge
2006-12-07 02:14:02 +01:00
committed by Andi Kleen
parent 9ca36101a8
commit 6211119580
4 changed files with 177 additions and 55 deletions
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28
arch/i386/kernel/smpboot.c
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@@ -52,6 +52,7 @@
#include <asm/desc.h>
#include <asm/arch_hooks.h>
#include <asm/nmi.h>
#include <asm/pda.h>
#include <mach_apic.h>
#include <mach_wakecpu.h>
@@ -536,11 +537,11 @@ set_cpu_sibling_map(int cpu)
static void __devinit start_secondary(void *unused)
{
/*
* Dont put anything before smp_callin(), SMP
* Don't put *anything* before secondary_cpu_init(), SMP
* booting is too fragile that we want to limit the
* things done here to the most necessary things.
*/
cpu_init();
secondary_cpu_init();
preempt_disable();
smp_callin();
while (!cpu_isset(smp_processor_id(), smp_commenced_mask))
@@ -599,13 +600,16 @@ void __devinit initialize_secondary(void)
"movl %0,%%esp\n\t"
"jmp *%1"
:
:"r" (current->thread.esp),"r" (current->thread.eip));
:"m" (current->thread.esp),"m" (current->thread.eip));
}
/* Static state in head.S used to set up a CPU */
extern struct {
void * esp;
unsigned short ss;
} stack_start;
extern struct i386_pda *start_pda;
extern struct Xgt_desc_struct cpu_gdt_descr;
#ifdef CONFIG_NUMA
@@ -936,9 +940,6 @@ static int __devinit do_boot_cpu(int apicid, int cpu)
unsigned long start_eip;
unsigned short nmi_high = 0, nmi_low = 0;
++cpucount;
alternatives_smp_switch(1);
/*
* We can't use kernel_thread since we must avoid to
* reschedule the child.
@@ -946,15 +947,30 @@ static int __devinit do_boot_cpu(int apicid, int cpu)
idle = alloc_idle_task(cpu);
if (IS_ERR(idle))
panic("failed fork for CPU %d", cpu);
/* Pre-allocate and initialize the CPU's GDT and PDA so it
doesn't have to do any memory allocation during the
delicate CPU-bringup phase. */
if (!init_gdt(cpu, idle)) {
printk(KERN_INFO "Couldn't allocate GDT/PDA for CPU %d\n", cpu);
return -1; /* ? */
}
idle->thread.eip = (unsigned long) start_secondary;
/* start_eip had better be page-aligned! */
start_eip = setup_trampoline();
++cpucount;
alternatives_smp_switch(1);
/* So we see what's up */
printk("Booting processor %d/%d eip %lx\n", cpu, apicid, start_eip);
/* Stack for startup_32 can be just as for start_secondary onwards */
stack_start.esp = (void *) idle->thread.esp;
start_pda = cpu_pda(cpu);
cpu_gdt_descr = per_cpu(cpu_gdt_descr, cpu);
irq_ctx_init(cpu);
x86_cpu_to_apicid[cpu] = apicid;