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x86: change init_gdt to update the gdt via write_gdt, rather than a direct write. 

By writing directly, a memory access violation can occur whilst
hotplugging a CPU if the entry was previously marked read-only.

Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Cc: Jeremy Fitzhardinge <Jeremy.Fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Alex Nixon 2008-08-15 17:21:14 +01:00 committed by Ingo Molnar
parent 529d0e402e
commit fc0091b3c8
1 changed files with 10 additions and 7 deletions
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17
arch/x86/kernel/smpcommon.c
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@ -8,18 +8,21 @@
DEFINE_PER_CPU(unsigned long, this_cpu_off);
EXPORT_PER_CPU_SYMBOL(this_cpu_off);
/* Initialize the CPU's GDT. This is either the boot CPU doing itself
(still using the master per-cpu area), or a CPU doing it for a
secondary which will soon come up. */
/*
* Initialize the CPU's GDT. This is either the boot CPU doing itself
* (still using the master per-cpu area), or a CPU doing it for a
* secondary which will soon come up.
*/
__cpuinit void init_gdt(int cpu)
{
struct desc_struct *gdt = get_cpu_gdt_table(cpu);
struct desc_struct gdt;
pack_descriptor(&gdt[GDT_ENTRY_PERCPU],
__per_cpu_offset[cpu], 0xFFFFF,
pack_descriptor(&gdt, __per_cpu_offset[cpu], 0xFFFFF,
0x2 | DESCTYPE_S, 0x8);
gdt.s = 1;
gdt[GDT_ENTRY_PERCPU].s = 1;
write_gdt_entry(get_cpu_gdt_table(cpu),
GDT_ENTRY_PERCPU, &gdt, DESCTYPE_S);
per_cpu(this_cpu_off, cpu) = __per_cpu_offset[cpu];
per_cpu(cpu_number, cpu) = cpu;