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[PATCH] x86: fix broken SMP boot sequence

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Recent GDT changes broke the SMP boot sequence if the booting CPU is
numbered anything other than zero.  There's also a subtle source of error
in that the boot time CPU now uses cpu_gdt_table (which is actually the GDT
for booting CPUs in head.S).  This patch fixes both problems by making GDT
descriptors themselves allocated from a per_cpu area and switching to them
in cpu_init(), which now means that cpu_gdt_table is exclusively used for
booting CPUs again.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Matt Tolentino <metolent@snoqualmie.dp.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
James Bottomley 2006-02-24 13:04:14 -08:00 committed by Linus Torvalds
parent 1e275d406b
commit 2b932f6cf0
6 changed files with 39 additions and 21 deletions
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32
arch/i386/kernel/cpu/common.c
View File

@ -4,6 +4,7 @@
#include <linux/smp.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/bootmem.h>
#include <asm/semaphore.h>
#include <asm/processor.h>
#include <asm/i387.h>
@ -18,6 +19,9 @@
#include "cpu.h"
DEFINE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr);
EXPORT_PER_CPU_SYMBOL(cpu_gdt_descr);
DEFINE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]);
EXPORT_PER_CPU_SYMBOL(cpu_16bit_stack);
@ -571,8 +575,9 @@ void __devinit cpu_init(void)
int cpu = smp_processor_id();
struct tss_struct * t = &per_cpu(init_tss, cpu);
struct thread_struct *thread = &current->thread;
struct desc_struct *gdt = get_cpu_gdt_table(cpu);
struct desc_struct *gdt;
__u32 stk16_off = (__u32)&per_cpu(cpu_16bit_stack, cpu);
struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
if (cpu_test_and_set(cpu, cpu_initialized)) {
printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
@ -589,6 +594,25 @@ void __devinit cpu_init(void)
set_in_cr4(X86_CR4_TSD);
}
/*
* 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();
}
}
/*
* Initialize the per-CPU GDT with the boot GDT,
* and set up the GDT descriptor:
@ -601,10 +625,10 @@ void __devinit cpu_init(void)
((((__u64)stk16_off) << 32) & 0xff00000000000000ULL) |
(CPU_16BIT_STACK_SIZE - 1);
cpu_gdt_descr[cpu].size = GDT_SIZE - 1;
cpu_gdt_descr[cpu].address = (unsigned long)gdt;
cpu_gdt_descr->size = GDT_SIZE - 1;
cpu_gdt_descr->address = (unsigned long)gdt;
load_gdt(&cpu_gdt_descr[cpu]);
load_gdt(cpu_gdt_descr);
load_idt(&idt_descr);
/*

12
arch/i386/kernel/efi.c
View File

@ -103,17 +103,19 @@ static void efi_call_phys_prelog(void)
*/
local_flush_tlb();
cpu_gdt_descr[0].address = __pa(cpu_gdt_descr[0].address);
load_gdt((struct Xgt_desc_struct *) __pa(&cpu_gdt_descr[0]));
per_cpu(cpu_gdt_descr, 0).address =
__pa(per_cpu(cpu_gdt_descr, 0).address);
load_gdt((struct Xgt_desc_struct *)__pa(&per_cpu(cpu_gdt_descr, 0)));
}
static void efi_call_phys_epilog(void)
{
unsigned long cr4;
cpu_gdt_descr[0].address =
(unsigned long) __va(cpu_gdt_descr[0].address);
load_gdt(&cpu_gdt_descr[0]);
per_cpu(cpu_gdt_descr, 0).address =
(unsigned long)__va(per_cpu(cpu_gdt_descr, 0).address);
load_gdt((struct Xgt_desc_struct *)__va(&per_cpu(cpu_gdt_descr, 0)));
cr4 = read_cr4();
if (cr4 & X86_CR4_PSE) {

2
arch/i386/kernel/head.S
View File

@ -534,5 +534,3 @@ ENTRY(cpu_gdt_table)
.quad 0x0000000000000000 /* 0xf0 - unused */
.quad 0x0000000000000000 /* 0xf8 - GDT entry 31: double-fault TSS */
/* Be sure this is zeroed to avoid false validations in Xen */
.fill PAGE_SIZE_asm / 8 - GDT_ENTRIES,8,0

2
arch/i386/kernel/i386_ksyms.c
View File

@ -3,8 +3,6 @@
#include <asm/checksum.h>
#include <asm/desc.h>
EXPORT_SYMBOL_GPL(cpu_gdt_descr);
EXPORT_SYMBOL(__down_failed);
EXPORT_SYMBOL(__down_failed_interruptible);
EXPORT_SYMBOL(__down_failed_trylock);

6
arch/i386/kernel/smpboot.c
View File

@ -898,12 +898,6 @@ static int __devinit do_boot_cpu(int apicid, int cpu)
unsigned long start_eip;
unsigned short nmi_high = 0, nmi_low = 0;
if (!cpu_gdt_descr[cpu].address &&
!(cpu_gdt_descr[cpu].address = get_zeroed_page(GFP_KERNEL))) {
printk("Failed to allocate GDT for CPU %d\n", cpu);
return 1;
}
++cpucount;
/*

6
include/asm-i386/desc.h
View File

@ -24,11 +24,13 @@ struct Xgt_desc_struct {
unsigned short pad;
} __attribute__ ((packed));
extern struct Xgt_desc_struct idt_descr, cpu_gdt_descr[NR_CPUS];
extern struct Xgt_desc_struct idt_descr;
DECLARE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr);
static inline struct desc_struct *get_cpu_gdt_table(unsigned int cpu)
{
return ((struct desc_struct *)cpu_gdt_descr[cpu].address);
return (struct desc_struct *)per_cpu(cpu_gdt_descr, cpu).address;
}
#define load_TR_desc() __asm__ __volatile__("ltr %w0"::"q" (GDT_ENTRY_TSS*8))