source: trunk/packages/xen-3.1/xen-3.1/linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/desc.h @ 34

/* Written 2000 by Andi Kleen */ 
#ifndef __ARCH_DESC_H
#define __ARCH_DESC_H

#include <linux/threads.h>
#include <asm/ldt.h>

#ifndef __ASSEMBLY__

#include <linux/string.h>
#include <linux/smp.h>

#include <asm/segment.h>
#include <asm/mmu.h>

// 8 byte segment descriptor
struct desc_struct { 
        u16 limit0;
        u16 base0;
        unsigned base1 : 8, type : 4, s : 1, dpl : 2, p : 1;
        unsigned limit : 4, avl : 1, l : 1, d : 1, g : 1, base2 : 8;
} __attribute__((packed)); 

struct n_desc_struct { 
        unsigned int a,b;
};      

enum { 
        GATE_INTERRUPT = 0xE, 
        GATE_TRAP = 0xF,        
        GATE_CALL = 0xC,
};      

// 16byte gate
struct gate_struct {          
        u16 offset_low;
        u16 segment; 
        unsigned ist : 3, zero0 : 5, type : 5, dpl : 2, p : 1;
        u16 offset_middle;
        u32 offset_high;
        u32 zero1; 
} __attribute__((packed));

#define PTR_LOW(x) ((unsigned long)(x) & 0xFFFF) 
#define PTR_MIDDLE(x) (((unsigned long)(x) >> 16) & 0xFFFF)
#define PTR_HIGH(x) ((unsigned long)(x) >> 32)

enum { 
        DESC_TSS = 0x9,
        DESC_LDT = 0x2,
}; 

// LDT or TSS descriptor in the GDT. 16 bytes.
struct ldttss_desc { 
        u16 limit0;
        u16 base0;
        unsigned base1 : 8, type : 5, dpl : 2, p : 1;
        unsigned limit1 : 4, zero0 : 3, g : 1, base2 : 8;
        u32 base3;
        u32 zero1; 
} __attribute__((packed)); 

struct desc_ptr {
        unsigned short size;
        unsigned long address;
} __attribute__((packed)) ;

extern struct desc_ptr idt_descr, cpu_gdt_descr[NR_CPUS];

extern struct desc_struct cpu_gdt_table[GDT_ENTRIES];

#define load_TR_desc() asm volatile("ltr %w0"::"r" (GDT_ENTRY_TSS*8))
#define load_LDT_desc() asm volatile("lldt %w0"::"r" (GDT_ENTRY_LDT*8))

static inline void clear_LDT(void)
{
        int cpu = get_cpu();

        /*
         * NB. We load the default_ldt for lcall7/27 handling on demand, as
         * it slows down context switching. Noone uses it anyway.
         */
        cpu = cpu;              /* XXX avoid compiler warning */
        xen_set_ldt(0UL, 0);
        put_cpu();
}

/*
 * This is the ldt that every process will get unless we need
 * something other than this.
 */
extern struct desc_struct default_ldt[];
#ifndef CONFIG_X86_NO_IDT
extern struct gate_struct idt_table[]; 
#endif
extern struct desc_ptr cpu_gdt_descr[];

/* the cpu gdt accessor */
#define cpu_gdt(_cpu) ((struct desc_struct *)cpu_gdt_descr[_cpu].address)

static inline void _set_gate(void *adr, unsigned type, unsigned long func, unsigned dpl, unsigned ist)  
{
        struct gate_struct s;   
        s.offset_low = PTR_LOW(func); 
        s.segment = __KERNEL_CS;
        s.ist = ist; 
        s.p = 1;
        s.dpl = dpl; 
        s.zero0 = 0;
        s.zero1 = 0; 
        s.type = type; 
        s.offset_middle = PTR_MIDDLE(func); 
        s.offset_high = PTR_HIGH(func); 
        /* does not need to be atomic because it is only done once at setup time */ 
        memcpy(adr, &s, 16); 
} 

#ifndef CONFIG_X86_NO_IDT
static inline void set_intr_gate(int nr, void *func) 
{ 
        BUG_ON((unsigned)nr > 0xFF);
        _set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 0, 0); 
} 

static inline void set_intr_gate_ist(int nr, void *func, unsigned ist) 
{ 
        BUG_ON((unsigned)nr > 0xFF);
        _set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 0, ist); 
} 

static inline void set_system_gate(int nr, void *func) 
{ 
        BUG_ON((unsigned)nr > 0xFF);
        _set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 3, 0); 
} 

static inline void set_system_gate_ist(int nr, void *func, unsigned ist)
{
        _set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 3, ist);
}
#endif

static inline void set_tssldt_descriptor(void *ptr, unsigned long tss, unsigned type, 
                                         unsigned size) 
{ 
        struct ldttss_desc d;
        memset(&d,0,sizeof(d)); 
        d.limit0 = size & 0xFFFF;
        d.base0 = PTR_LOW(tss); 
        d.base1 = PTR_MIDDLE(tss) & 0xFF; 
        d.type = type;
        d.p = 1; 
        d.limit1 = (size >> 16) & 0xF;
        d.base2 = (PTR_MIDDLE(tss) >> 8) & 0xFF; 
        d.base3 = PTR_HIGH(tss); 
        memcpy(ptr, &d, 16); 
}

#ifndef CONFIG_X86_NO_TSS
static inline void set_tss_desc(unsigned cpu, void *addr)
{ 
        /*
         * sizeof(unsigned long) coming from an extra "long" at the end
         * of the iobitmap. See tss_struct definition in processor.h
         *
         * -1? seg base+limit should be pointing to the address of the
         * last valid byte
         */
        set_tssldt_descriptor(&cpu_gdt(cpu)[GDT_ENTRY_TSS], 
                (unsigned long)addr, DESC_TSS,
                IO_BITMAP_OFFSET + IO_BITMAP_BYTES + sizeof(unsigned long) - 1);
} 
#endif

static inline void set_ldt_desc(unsigned cpu, void *addr, int size)
{ 
        set_tssldt_descriptor(&cpu_gdt(cpu)[GDT_ENTRY_LDT], (unsigned long)addr,
                              DESC_LDT, size * 8 - 1);
}

static inline void set_seg_base(unsigned cpu, int entry, void *base)
{ 
        struct desc_struct *d = &cpu_gdt(cpu)[entry];
        u32 addr = (u32)(u64)base;
        BUG_ON((u64)base >> 32); 
        d->base0 = addr & 0xffff;
        d->base1 = (addr >> 16) & 0xff;
        d->base2 = (addr >> 24) & 0xff;
} 

#define LDT_entry_a(info) \
        ((((info)->base_addr & 0x0000ffff) << 16) | ((info)->limit & 0x0ffff))
/* Don't allow setting of the lm bit. It is useless anyways because 
   64bit system calls require __USER_CS. */ 
#define LDT_entry_b(info) \
        (((info)->base_addr & 0xff000000) | \
        (((info)->base_addr & 0x00ff0000) >> 16) | \
        ((info)->limit & 0xf0000) | \
        (((info)->read_exec_only ^ 1) << 9) | \
        ((info)->contents << 10) | \
        (((info)->seg_not_present ^ 1) << 15) | \
        ((info)->seg_32bit << 22) | \
        ((info)->limit_in_pages << 23) | \
        ((info)->useable << 20) | \
        /* ((info)->lm << 21) | */ \
        0x7000)

#define LDT_empty(info) (\
        (info)->base_addr       == 0    && \
        (info)->limit           == 0    && \
        (info)->contents        == 0    && \
        (info)->read_exec_only  == 1    && \
        (info)->seg_32bit       == 0    && \
        (info)->limit_in_pages  == 0    && \
        (info)->seg_not_present == 1    && \
        (info)->useable         == 0    && \
        (info)->lm              == 0)

#if TLS_SIZE != 24
# error update this code.
#endif

static inline void load_TLS(struct thread_struct *t, unsigned int cpu)
{
#if 0
        u64 *gdt = (u64 *)(cpu_gdt(cpu) + GDT_ENTRY_TLS_MIN);
        gdt[0] = t->tls_array[0];
        gdt[1] = t->tls_array[1];
        gdt[2] = t->tls_array[2];
#endif
#define C(i) \
        HYPERVISOR_update_descriptor(virt_to_machine(&cpu_gdt(cpu)[GDT_ENTRY_TLS_MIN + i]), t->tls_array[i])

        C(0); C(1); C(2);
#undef C
} 

/*
 * load one particular LDT into the current CPU
 */
static inline void load_LDT_nolock (mm_context_t *pc, int cpu)
{
        void *segments = pc->ldt;
        int count = pc->size;

        if (likely(!count))
                segments = NULL;

        xen_set_ldt((unsigned long)segments, count);
}

static inline void load_LDT(mm_context_t *pc)
{
        int cpu = get_cpu();
        load_LDT_nolock(pc, cpu);
        put_cpu();
}

extern struct desc_ptr idt_descr;

#endif /* !__ASSEMBLY__ */

#endif