[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>

1 files changed, 13 insertions, 1 deletions

diff --git a/arch/i386/mach-voyager/voyager_smp.c b/arch/i386/mach-voyager/voyager_smp.c
index f3fea2a..55428e6 100644
--- a/arch/i386/mach-voyager/voyager_smp.c
+++ b/arch/i386/mach-voyager/voyager_smp.c
@@ -28,6 +28,7 @@
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 #include <asm/arch_hooks.h>
+#include <asm/pda.h>
 
 /* TLB state -- visible externally, indexed physically */
 DEFINE_PER_CPU(struct tlb_state, cpu_tlbstate) ____cacheline_aligned = { &init_mm, 0 };
@@ -422,6 +423,7 @@ find_smp_config(void)
 	     VOYAGER_SUS_IN_CONTROL_PORT);
 
 	current_thread_info()->cpu = boot_cpu_id;
+	write_pda(cpu_number, boot_cpu_id);
 }
 
 /*
@@ -458,7 +460,7 @@ start_secondary(void *unused)
 	/* external functions not defined in the headers */
 	extern void calibrate_delay(void);
 
-	cpu_init();
+	secondary_cpu_init();
 
 	/* OK, we're in the routine */
 	ack_CPI(VIC_CPU_BOOT_CPI);
@@ -578,6 +580,15 @@ do_boot_cpu(__u8 cpu)
 	/* init_tasks (in sched.c) is indexed logically */
 	stack_start.esp = (void *) idle->thread.esp;
 
+	/* 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);
+		cpucount--;
+		return;
+	}
+
 	irq_ctx_init(cpu);
 
 	/* Note: Don't modify initial ss override */
@@ -1963,4 +1974,5 @@ void __init
 smp_setup_processor_id(void)
 {
 	current_thread_info()->cpu = hard_smp_processor_id();
+	write_pda(cpu_number, hard_smp_processor_id());
 }