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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
Show Stats 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)
{

28
arch/i386/kernel/smpboot.c
View File

@ -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;

14
arch/i386/mach-voyager/voyager_smp.c
View File

@ -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());
}

3
include/asm-i386/processor.h
View File

@ -727,4 +727,7 @@ extern unsigned long boot_option_idle_override;
extern void enable_sep_cpu(void);
extern int sysenter_setup(void);
extern int init_gdt(int cpu, struct task_struct *idle);
extern void secondary_cpu_init(void);
#endif /* __ASM_I386_PROCESSOR_H */