[PATCH] i386: Initialize the per-CPU data area
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>
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 4bb8b77..0956366 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -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 @@
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 @@
"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 @@
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 @@
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;