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#ifndef __ARCH_DESC_H
#define __ARCH_DESC_H
#include <asm/ldt.h>
/*
* The layout of the GDT under Linux:
*
* 0 - null
* 1 - not used
* 2 - kernel code segment
* 3 - kernel data segment
* 4 - user code segment <-- new cacheline
* 5 - user data segment
* 6 - not used
* 7 - not used
* 8 - APM BIOS support <-- new cacheline
* 9 - APM BIOS support
* 10 - APM BIOS support
* 11 - APM BIOS support
*
* The TSS+LDT descriptors are spread out a bit so that every CPU
* has an exclusive cacheline for the per-CPU TSS and LDT:
*
* 12 - CPU#0 TSS <-- new cacheline
* 13 - CPU#0 LDT
* 14 - not used
* 15 - not used
* 16 - CPU#1 TSS <-- new cacheline
* 17 - CPU#1 LDT
* 18 - not used
* 19 - not used
* ... NR_CPUS per-CPU TSS+LDT's if on SMP
*
* Entry into gdt where to find first TSS.
*/
#define __FIRST_TSS_ENTRY 12
#define __FIRST_LDT_ENTRY (__FIRST_TSS_ENTRY+1)
#define __TSS(n) (((n)<<2) + __FIRST_TSS_ENTRY)
#define __LDT(n) (((n)<<2) + __FIRST_LDT_ENTRY)
#ifndef __ASSEMBLY__
struct desc_struct {
unsigned long a,b;
};
extern struct desc_struct gdt_table[];
extern struct desc_struct *idt, *gdt;
struct Xgt_desc_struct {
unsigned short size;
unsigned long address __attribute__((packed));
};
#define idt_descr (*(struct Xgt_desc_struct *)((char *)&idt - 2))
#define gdt_descr (*(struct Xgt_desc_struct *)((char *)&gdt - 2))
#define load_TR(n) __asm__ __volatile__("ltr %%ax"::"a" (__TSS(n)<<3))
#define __load_LDT(n) __asm__ __volatile__("lldt %%ax"::"a" (__LDT(n)<<3))
/*
* This is the ldt that every process will get unless we need
* something other than this.
*/
extern struct desc_struct default_ldt[];
extern void set_intr_gate(unsigned int irq, void * addr);
extern void set_ldt_desc(unsigned int n, void *addr, unsigned int size);
extern void set_tss_desc(unsigned int n, void *addr);
static inline void clear_LDT(void)
{
int cpu = smp_processor_id();
set_ldt_desc(cpu, &default_ldt[0], 5);
__load_LDT(cpu);
}
/*
* load one particular LDT into the current CPU
*/
static inline void load_LDT (struct mm_struct *mm)
{
int cpu = smp_processor_id();
void *segments = mm->context.segments;
int count = LDT_ENTRIES;
if (!segments) {
segments = &default_ldt[0];
count = 5;
}
set_ldt_desc(cpu, segments, count);
__load_LDT(cpu);
}
#endif /* !__ASSEMBLY__ */
#endif
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