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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
Download Patch File Download Diff File Expand all files Collapse all files

187
arch/i386/kernel/cpu/common.c
View File

@@ -18,12 +18,16 @@
#include <asm/apic.h>
#include <mach_apic.h>
#endif
#include <asm/pda.h>
#include "cpu.h"
DEFINE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr);
EXPORT_PER_CPU_SYMBOL(cpu_gdt_descr);
struct i386_pda *_cpu_pda[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(_cpu_pda);
static int cachesize_override __cpuinitdata = -1;
static int disable_x86_fxsr __cpuinitdata;
static int disable_x86_serial_nr __cpuinitdata = 1;
@@ -588,24 +592,113 @@ void __init early_cpu_init(void)
disable_pse = 1;
#endif
}
/*
* cpu_init() initializes state that is per-CPU. Some data is already
* initialized (naturally) in the bootstrap process, such as the GDT
* and IDT. We reload them nevertheless, this function acts as a
* 'CPU state barrier', nothing should get across.
*/
void __cpuinit cpu_init(void)
__cpuinit int alloc_gdt(int cpu)
{
int cpu = smp_processor_id();
struct tss_struct * t = &per_cpu(init_tss, cpu);
struct thread_struct *thread = &current->thread;
struct desc_struct *gdt;
struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
struct desc_struct *gdt;
struct i386_pda *pda;
gdt = (struct desc_struct *)cpu_gdt_descr->address;
pda = cpu_pda(cpu);
/*
* This is a horrible hack to allocate the GDT. The problem
* is that cpu_init() is called really early for the boot CPU
* (and hence needs bootmem) but much later for the secondary
* CPUs, when bootmem will have gone away
*/
if (NODE_DATA(0)->bdata->node_bootmem_map) {
BUG_ON(gdt != NULL || pda != NULL);
gdt = alloc_bootmem_pages(PAGE_SIZE);
pda = alloc_bootmem(sizeof(*pda));
/* alloc_bootmem(_pages) panics on failure, so no check */
memset(gdt, 0, PAGE_SIZE);
memset(pda, 0, sizeof(*pda));
} else {
/* GDT and PDA might already have been allocated if
this is a CPU hotplug re-insertion. */
if (gdt == NULL)
gdt = (struct desc_struct *)get_zeroed_page(GFP_KERNEL);
if (pda == NULL)
pda = kmalloc_node(sizeof(*pda), GFP_KERNEL, cpu_to_node(cpu));
if (unlikely(!gdt || !pda)) {
free_pages((unsigned long)gdt, 0);
kfree(pda);
return 0;
}
}
cpu_gdt_descr->address = (unsigned long)gdt;
cpu_pda(cpu) = pda;
return 1;
}
/* Initial PDA used by boot CPU */
struct i386_pda boot_pda = {
._pda = &boot_pda,
};
/* Initialize the CPU's GDT and PDA. The boot CPU does this for
itself, but secondaries find this done for them. */
__cpuinit int init_gdt(int cpu, struct task_struct *idle)
{
struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
struct desc_struct *gdt;
struct i386_pda *pda;
/* For non-boot CPUs, the GDT and PDA should already have been
allocated. */
if (!alloc_gdt(cpu)) {
printk(KERN_CRIT "CPU%d failed to allocate GDT or PDA\n", cpu);
return 0;
}
gdt = (struct desc_struct *)cpu_gdt_descr->address;
pda = cpu_pda(cpu);
BUG_ON(gdt == NULL || pda == NULL);
/*
* Initialize the per-CPU GDT with the boot GDT,
* and set up the GDT descriptor:
*/
memcpy(gdt, cpu_gdt_table, GDT_SIZE);
cpu_gdt_descr->size = GDT_SIZE - 1;
pack_descriptor((u32 *)&gdt[GDT_ENTRY_PDA].a,
(u32 *)&gdt[GDT_ENTRY_PDA].b,
(unsigned long)pda, sizeof(*pda) - 1,
0x80 | DESCTYPE_S | 0x2, 0); /* present read-write data segment */
memset(pda, 0, sizeof(*pda));
pda->_pda = pda;
return 1;
}
/* Common CPU init for both boot and secondary CPUs */
static void __cpuinit _cpu_init(int cpu, struct task_struct *curr)
{
struct tss_struct * t = &per_cpu(init_tss, cpu);
struct thread_struct *thread = &curr->thread;
struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
/* Reinit these anyway, even if they've already been done (on
the boot CPU, this will transition from the boot gdt+pda to
the real ones). */
load_gdt(cpu_gdt_descr);
if (cpu_test_and_set(cpu, cpu_initialized)) {
printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
for (;;) local_irq_enable();
}
printk(KERN_INFO "Initializing CPU#%d\n", cpu);
if (cpu_has_vme || cpu_has_tsc || cpu_has_de)
@@ -617,49 +710,16 @@ void __cpuinit cpu_init(void)
set_in_cr4(X86_CR4_TSD);
}
/* The CPU hotplug case */
if (cpu_gdt_descr->address) {
gdt = (struct desc_struct *)cpu_gdt_descr->address;
memset(gdt, 0, PAGE_SIZE);
goto old_gdt;
}
/*
* This is a horrible hack to allocate the GDT. The problem
* is that cpu_init() is called really early for the boot CPU
* (and hence needs bootmem) but much later for the secondary
* CPUs, when bootmem will have gone away
*/
if (NODE_DATA(0)->bdata->node_bootmem_map) {
gdt = (struct desc_struct *)alloc_bootmem_pages(PAGE_SIZE);
/* alloc_bootmem_pages panics on failure, so no check */
memset(gdt, 0, PAGE_SIZE);
} else {
gdt = (struct desc_struct *)get_zeroed_page(GFP_KERNEL);
if (unlikely(!gdt)) {
printk(KERN_CRIT "CPU%d failed to allocate GDT\n", cpu);
for (;;)
local_irq_enable();
}
}
old_gdt:
/*
* Initialize the per-CPU GDT with the boot GDT,
* and set up the GDT descriptor:
*/
memcpy(gdt, cpu_gdt_table, GDT_SIZE);
cpu_gdt_descr->size = GDT_SIZE - 1;
cpu_gdt_descr->address = (unsigned long)gdt;
load_gdt(cpu_gdt_descr);
load_idt(&idt_descr);
/*
* Set up and load the per-CPU TSS and LDT
*/
atomic_inc(&init_mm.mm_count);
current->active_mm = &init_mm;
BUG_ON(current->mm);
enter_lazy_tlb(&init_mm, current);
curr->active_mm = &init_mm;
if (curr->mm)
BUG();
enter_lazy_tlb(&init_mm, curr);
load_esp0(t, thread);
set_tss_desc(cpu,t);
@@ -690,6 +750,37 @@ old_gdt:
mxcsr_feature_mask_init();
}
/* Entrypoint to initialize secondary CPU */
void __cpuinit secondary_cpu_init(void)
{
int cpu = smp_processor_id();
struct task_struct *curr = current;
_cpu_init(cpu, curr);
}
/*
* cpu_init() initializes state that is per-CPU. Some data is already
* initialized (naturally) in the bootstrap process, such as the GDT
* and IDT. We reload them nevertheless, this function acts as a
* 'CPU state barrier', nothing should get across.
*/
void __cpuinit cpu_init(void)
{
int cpu = smp_processor_id();
struct task_struct *curr = current;
/* Set up the real GDT and PDA, so we can transition from the
boot versions. */
if (!init_gdt(cpu, curr)) {
/* failed to allocate something; not much we can do... */
for (;;)
local_irq_enable();
}
_cpu_init(cpu, curr);
}
#ifdef CONFIG_HOTPLUG_CPU
void __cpuinit cpu_uninit(void)
{