linux/include/asm-x86/desc.h
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   1#ifndef _ASM_DESC_H_
   2#define _ASM_DESC_H_
   3
   4#ifndef __ASSEMBLY__
   5#include <asm/desc_defs.h>
   6#include <asm/ldt.h>
   7#include <asm/mmu.h>
   8#include <linux/smp.h>
   9
  10static inline void fill_ldt(struct desc_struct *desc,
  11                            const struct user_desc *info)
  12{
  13        desc->limit0 = info->limit & 0x0ffff;
  14        desc->base0 = info->base_addr & 0x0000ffff;
  15
  16        desc->base1 = (info->base_addr & 0x00ff0000) >> 16;
  17        desc->type = (info->read_exec_only ^ 1) << 1;
  18        desc->type |= info->contents << 2;
  19        desc->s = 1;
  20        desc->dpl = 0x3;
  21        desc->p = info->seg_not_present ^ 1;
  22        desc->limit = (info->limit & 0xf0000) >> 16;
  23        desc->avl = info->useable;
  24        desc->d = info->seg_32bit;
  25        desc->g = info->limit_in_pages;
  26        desc->base2 = (info->base_addr & 0xff000000) >> 24;
  27}
  28
  29extern struct desc_ptr idt_descr;
  30extern gate_desc idt_table[];
  31
  32#ifdef CONFIG_X86_64
  33extern struct desc_struct cpu_gdt_table[GDT_ENTRIES];
  34extern struct desc_ptr cpu_gdt_descr[];
  35/* the cpu gdt accessor */
  36#define get_cpu_gdt_table(x) ((struct desc_struct *)cpu_gdt_descr[x].address)
  37
  38static inline void pack_gate(gate_desc *gate, unsigned type, unsigned long func,
  39                             unsigned dpl, unsigned ist, unsigned seg)
  40{
  41        gate->offset_low = PTR_LOW(func);
  42        gate->segment = __KERNEL_CS;
  43        gate->ist = ist;
  44        gate->p = 1;
  45        gate->dpl = dpl;
  46        gate->zero0 = 0;
  47        gate->zero1 = 0;
  48        gate->type = type;
  49        gate->offset_middle = PTR_MIDDLE(func);
  50        gate->offset_high = PTR_HIGH(func);
  51}
  52
  53#else
  54struct gdt_page {
  55        struct desc_struct gdt[GDT_ENTRIES];
  56} __attribute__((aligned(PAGE_SIZE)));
  57DECLARE_PER_CPU(struct gdt_page, gdt_page);
  58
  59static inline struct desc_struct *get_cpu_gdt_table(unsigned int cpu)
  60{
  61        return per_cpu(gdt_page, cpu).gdt;
  62}
  63
  64static inline void pack_gate(gate_desc *gate, unsigned char type,
  65       unsigned long base, unsigned dpl, unsigned flags, unsigned short seg)
  66
  67{
  68        gate->a = (seg << 16) | (base & 0xffff);
  69        gate->b = (base & 0xffff0000) |
  70                  (((0x80 | type | (dpl << 5)) & 0xff) << 8);
  71}
  72
  73#endif
  74
  75static inline int desc_empty(const void *ptr)
  76{
  77        const u32 *desc = ptr;
  78        return !(desc[0] | desc[1]);
  79}
  80
  81#ifdef CONFIG_PARAVIRT
  82#include <asm/paravirt.h>
  83#else
  84#define load_TR_desc() native_load_tr_desc()
  85#define load_gdt(dtr) native_load_gdt(dtr)
  86#define load_idt(dtr) native_load_idt(dtr)
  87#define load_tr(tr) __asm__ __volatile("ltr %0"::"m" (tr))
  88#define load_ldt(ldt) __asm__ __volatile("lldt %0"::"m" (ldt))
  89
  90#define store_gdt(dtr) native_store_gdt(dtr)
  91#define store_idt(dtr) native_store_idt(dtr)
  92#define store_tr(tr) (tr = native_store_tr())
  93#define store_ldt(ldt) __asm__ ("sldt %0":"=m" (ldt))
  94
  95#define load_TLS(t, cpu) native_load_tls(t, cpu)
  96#define set_ldt native_set_ldt
  97
  98#define write_ldt_entry(dt, entry, desc) \
  99                                native_write_ldt_entry(dt, entry, desc)
 100#define write_gdt_entry(dt, entry, desc, type) \
 101                                native_write_gdt_entry(dt, entry, desc, type)
 102#define write_idt_entry(dt, entry, g) native_write_idt_entry(dt, entry, g)
 103#endif
 104
 105static inline void native_write_idt_entry(gate_desc *idt, int entry,
 106                                          const gate_desc *gate)
 107{
 108        memcpy(&idt[entry], gate, sizeof(*gate));
 109}
 110
 111static inline void native_write_ldt_entry(struct desc_struct *ldt, int entry,
 112                                          const void *desc)
 113{
 114        memcpy(&ldt[entry], desc, 8);
 115}
 116
 117static inline void native_write_gdt_entry(struct desc_struct *gdt, int entry,
 118                                          const void *desc, int type)
 119{
 120        unsigned int size;
 121        switch (type) {
 122        case DESC_TSS:
 123                size = sizeof(tss_desc);
 124                break;
 125        case DESC_LDT:
 126                size = sizeof(ldt_desc);
 127                break;
 128        default:
 129                size = sizeof(struct desc_struct);
 130                break;
 131        }
 132        memcpy(&gdt[entry], desc, size);
 133}
 134
 135static inline void pack_descriptor(struct desc_struct *desc, unsigned long base,
 136                                   unsigned long limit, unsigned char type,
 137                                   unsigned char flags)
 138{
 139        desc->a = ((base & 0xffff) << 16) | (limit & 0xffff);
 140        desc->b = (base & 0xff000000) | ((base & 0xff0000) >> 16) |
 141                  (limit & 0x000f0000) | ((type & 0xff) << 8) |
 142                  ((flags & 0xf) << 20);
 143        desc->p = 1;
 144}
 145
 146
 147static inline void set_tssldt_descriptor(void *d, unsigned long addr,
 148                                         unsigned type, unsigned size)
 149{
 150#ifdef CONFIG_X86_64
 151        struct ldttss_desc64 *desc = d;
 152        memset(desc, 0, sizeof(*desc));
 153        desc->limit0 = size & 0xFFFF;
 154        desc->base0 = PTR_LOW(addr);
 155        desc->base1 = PTR_MIDDLE(addr) & 0xFF;
 156        desc->type = type;
 157        desc->p = 1;
 158        desc->limit1 = (size >> 16) & 0xF;
 159        desc->base2 = (PTR_MIDDLE(addr) >> 8) & 0xFF;
 160        desc->base3 = PTR_HIGH(addr);
 161#else
 162
 163        pack_descriptor((struct desc_struct *)d, addr, size, 0x80 | type, 0);
 164#endif
 165}
 166
 167static inline void __set_tss_desc(unsigned cpu, unsigned int entry, void *addr)
 168{
 169        struct desc_struct *d = get_cpu_gdt_table(cpu);
 170        tss_desc tss;
 171
 172        /*
 173         * sizeof(unsigned long) coming from an extra "long" at the end
 174         * of the iobitmap. See tss_struct definition in processor.h
 175         *
 176         * -1? seg base+limit should be pointing to the address of the
 177         * last valid byte
 178         */
 179        set_tssldt_descriptor(&tss, (unsigned long)addr, DESC_TSS,
 180                IO_BITMAP_OFFSET + IO_BITMAP_BYTES + sizeof(unsigned long) - 1);
 181        write_gdt_entry(d, entry, &tss, DESC_TSS);
 182}
 183
 184#define set_tss_desc(cpu, addr) __set_tss_desc(cpu, GDT_ENTRY_TSS, addr)
 185
 186static inline void native_set_ldt(const void *addr, unsigned int entries)
 187{
 188        if (likely(entries == 0))
 189                __asm__ __volatile__("lldt %w0"::"q" (0));
 190        else {
 191                unsigned cpu = smp_processor_id();
 192                ldt_desc ldt;
 193
 194                set_tssldt_descriptor(&ldt, (unsigned long)addr,
 195                                      DESC_LDT, entries * sizeof(ldt) - 1);
 196                write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_LDT,
 197                                &ldt, DESC_LDT);
 198                __asm__ __volatile__("lldt %w0"::"q" (GDT_ENTRY_LDT*8));
 199        }
 200}
 201
 202static inline void native_load_tr_desc(void)
 203{
 204        asm volatile("ltr %w0"::"q" (GDT_ENTRY_TSS*8));
 205}
 206
 207static inline void native_load_gdt(const struct desc_ptr *dtr)
 208{
 209        asm volatile("lgdt %0"::"m" (*dtr));
 210}
 211
 212static inline void native_load_idt(const struct desc_ptr *dtr)
 213{
 214        asm volatile("lidt %0"::"m" (*dtr));
 215}
 216
 217static inline void native_store_gdt(struct desc_ptr *dtr)
 218{
 219        asm volatile("sgdt %0":"=m" (*dtr));
 220}
 221
 222static inline void native_store_idt(struct desc_ptr *dtr)
 223{
 224        asm volatile("sidt %0":"=m" (*dtr));
 225}
 226
 227static inline unsigned long native_store_tr(void)
 228{
 229        unsigned long tr;
 230        asm volatile("str %0":"=r" (tr));
 231        return tr;
 232}
 233
 234static inline void native_load_tls(struct thread_struct *t, unsigned int cpu)
 235{
 236        unsigned int i;
 237        struct desc_struct *gdt = get_cpu_gdt_table(cpu);
 238
 239        for (i = 0; i < GDT_ENTRY_TLS_ENTRIES; i++)
 240                gdt[GDT_ENTRY_TLS_MIN + i] = t->tls_array[i];
 241}
 242
 243#define _LDT_empty(info) (\
 244        (info)->base_addr       == 0    && \
 245        (info)->limit           == 0    && \
 246        (info)->contents        == 0    && \
 247        (info)->read_exec_only  == 1    && \
 248        (info)->seg_32bit       == 0    && \
 249        (info)->limit_in_pages  == 0    && \
 250        (info)->seg_not_present == 1    && \
 251        (info)->useable         == 0)
 252
 253#ifdef CONFIG_X86_64
 254#define LDT_empty(info) (_LDT_empty(info) && ((info)->lm == 0))
 255#else
 256#define LDT_empty(info) (_LDT_empty(info))
 257#endif
 258
 259static inline void clear_LDT(void)
 260{
 261        set_ldt(NULL, 0);
 262}
 263
 264/*
 265 * load one particular LDT into the current CPU
 266 */
 267static inline void load_LDT_nolock(mm_context_t *pc)
 268{
 269        set_ldt(pc->ldt, pc->size);
 270}
 271
 272static inline void load_LDT(mm_context_t *pc)
 273{
 274        preempt_disable();
 275        load_LDT_nolock(pc);
 276        preempt_enable();
 277}
 278
 279static inline unsigned long get_desc_base(const struct desc_struct *desc)
 280{
 281        return desc->base0 | ((desc->base1) << 16) | ((desc->base2) << 24);
 282}
 283
 284static inline unsigned long get_desc_limit(const struct desc_struct *desc)
 285{
 286        return desc->limit0 | (desc->limit << 16);
 287}
 288
 289static inline void _set_gate(int gate, unsigned type, void *addr,
 290                              unsigned dpl, unsigned ist, unsigned seg)
 291{
 292        gate_desc s;
 293        pack_gate(&s, type, (unsigned long)addr, dpl, ist, seg);
 294        /*
 295         * does not need to be atomic because it is only done once at
 296         * setup time
 297         */
 298        write_idt_entry(idt_table, gate, &s);
 299}
 300
 301/*
 302 * This needs to use 'idt_table' rather than 'idt', and
 303 * thus use the _nonmapped_ version of the IDT, as the
 304 * Pentium F0 0F bugfix can have resulted in the mapped
 305 * IDT being write-protected.
 306 */
 307static inline void set_intr_gate(unsigned int n, void *addr)
 308{
 309        BUG_ON((unsigned)n > 0xFF);
 310        _set_gate(n, GATE_INTERRUPT, addr, 0, 0, __KERNEL_CS);
 311}
 312
 313/*
 314 * This routine sets up an interrupt gate at directory privilege level 3.
 315 */
 316static inline void set_system_intr_gate(unsigned int n, void *addr)
 317{
 318        BUG_ON((unsigned)n > 0xFF);
 319        _set_gate(n, GATE_INTERRUPT, addr, 0x3, 0, __KERNEL_CS);
 320}
 321
 322static inline void set_trap_gate(unsigned int n, void *addr)
 323{
 324        BUG_ON((unsigned)n > 0xFF);
 325        _set_gate(n, GATE_TRAP, addr, 0, 0, __KERNEL_CS);
 326}
 327
 328static inline void set_system_gate(unsigned int n, void *addr)
 329{
 330        BUG_ON((unsigned)n > 0xFF);
 331#ifdef CONFIG_X86_32
 332        _set_gate(n, GATE_TRAP, addr, 0x3, 0, __KERNEL_CS);
 333#else
 334        _set_gate(n, GATE_INTERRUPT, addr, 0x3, 0, __KERNEL_CS);
 335#endif
 336}
 337
 338static inline void set_task_gate(unsigned int n, unsigned int gdt_entry)
 339{
 340        BUG_ON((unsigned)n > 0xFF);
 341        _set_gate(n, GATE_TASK, (void *)0, 0, 0, (gdt_entry<<3));
 342}
 343
 344static inline void set_intr_gate_ist(int n, void *addr, unsigned ist)
 345{
 346        BUG_ON((unsigned)n > 0xFF);
 347        _set_gate(n, GATE_INTERRUPT, addr, 0, ist, __KERNEL_CS);
 348}
 349
 350static inline void set_system_gate_ist(int n, void *addr, unsigned ist)
 351{
 352        BUG_ON((unsigned)n > 0xFF);
 353        _set_gate(n, GATE_INTERRUPT, addr, 0x3, ist, __KERNEL_CS);
 354}
 355
 356#else
 357/*
 358 * GET_DESC_BASE reads the descriptor base of the specified segment.
 359 *
 360 * Args:
 361 *    idx - descriptor index
 362 *    gdt - GDT pointer
 363 *    base - 32bit register to which the base will be written
 364 *    lo_w - lo word of the "base" register
 365 *    lo_b - lo byte of the "base" register
 366 *    hi_b - hi byte of the low word of the "base" register
 367 *
 368 * Example:
 369 *    GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah)
 370 *    Will read the base address of GDT_ENTRY_ESPFIX_SS and put it into %eax.
 371 */
 372#define GET_DESC_BASE(idx, gdt, base, lo_w, lo_b, hi_b) \
 373        movb idx*8+4(gdt), lo_b; \
 374        movb idx*8+7(gdt), hi_b; \
 375        shll $16, base; \
 376        movw idx*8+2(gdt), lo_w;
 377
 378
 379#endif /* __ASSEMBLY__ */
 380
 381#endif
 382
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