include/asm-i386/system.h

   1 #ifndef __ASM_SYSTEM_H
   2 #define __ASM_SYSTEM_H
   3
   4 #include <linux/kernel.h>
   5 #include <asm/segment.h>
   6 #include <asm/cpufeature.h>
   7 #include <linux/bitops.h> /* for LOCK_PREFIX */
   8
   9 #ifdef __KERNEL__
  10
  11 struct task_struct;     /* one of the stranger aspects of C forward declarations.. */
  12 extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struct task_struct *next));
  13
  14 #define switch_to(prev,next,last) do {                                  \
  15         unsigned long esi,edi;                                          \
  16         asm volatile("pushl %%ebp\n\t"                                  \
  17                      "movl %%esp,%0\n\t"        /* save ESP */          \
  18                      "movl %5,%%esp\n\t"        /* restore ESP */       \
  19                      "movl $1f,%1\n\t"          /* save EIP */          \
  20                      "pushl %6\n\t"             /* restore EIP */       \
  21                      "jmp __switch_to\n"                                \
  22                      "1:\t"                                             \
  23                      "popl %%ebp\n\t"                                   \
  24                      :"=m" (prev->thread.esp),"=m" (prev->thread.eip),  \
  25                       "=a" (last),"=S" (esi),"=D" (edi)                 \
  26                      :"m" (next->thread.esp),"m" (next->thread.eip),    \
  27                       "2" (prev), "d" (next));                          \
  28 } while (0)
  29
  30 #define _set_base(addr,base) do { unsigned long __pr; \
  31 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
  32         "rorl $16,%%edx\n\t" \
  33         "movb %%dl,%2\n\t" \
  34         "movb %%dh,%3" \
  35         :"=&d" (__pr) \
  36         :"m" (*((addr)+2)), \
  37          "m" (*((addr)+4)), \
  38          "m" (*((addr)+7)), \
  39          "0" (base) \
  40         ); } while(0)
  41
  42 #define _set_limit(addr,limit) do { unsigned long __lr; \
  43 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
  44         "rorl $16,%%edx\n\t" \
  45         "movb %2,%%dh\n\t" \
  46         "andb $0xf0,%%dh\n\t" \
  47         "orb %%dh,%%dl\n\t" \
  48         "movb %%dl,%2" \
  49         :"=&d" (__lr) \
  50         :"m" (*(addr)), \
  51          "m" (*((addr)+6)), \
  52          "0" (limit) \
  53         ); } while(0)
  54
  55 #define set_base(ldt,base) _set_base( ((char *)&(ldt)) , (base) )
  56 #define set_limit(ldt,limit) _set_limit( ((char *)&(ldt)) , ((limit)-1) )
  57
  58 /*
  59  * Load a segment. Fall back on loading the zero
  60  * segment if something goes wrong..
  61  */
  62 #define loadsegment(seg,value)                  \
  63         asm volatile("\n"                       \
  64                 "1:\t"                          \
  65                 "mov %0,%%" #seg "\n"           \
  66                 "2:\n"                          \
  67                 ".section .fixup,\"ax\"\n"      \
  68                 "3:\t"                          \
  69                 "pushl $0\n\t"                  \
  70                 "popl %%" #seg "\n\t"           \
  71                 "jmp 2b\n"                      \
  72                 ".previous\n"                   \
  73                 ".section __ex_table,\"a\"\n\t" \
  74                 ".align 4\n\t"                  \
  75                 ".long 1b,3b\n"                 \
  76                 ".previous"                     \
  77                 : :"rm" (value))
  78
  79 /*
  80  * Save a segment register away
  81  */
  82 #define savesegment(seg, value) \
  83         asm volatile("mov %%" #seg ",%0":"=rm" (value))
  84
  85 /*
  86  * Clear and set 'TS' bit respectively
  87  */
  88 #define clts() __asm__ __volatile__ ("clts")
  89 #define read_cr0() ({ \
  90         unsigned int __dummy; \
  91         __asm__ __volatile__( \
  92                 "movl %%cr0,%0\n\t" \
  93                 :"=r" (__dummy)); \
  94         __dummy; \
  95 })
  96 #define write_cr0(x) \
  97         __asm__ __volatile__("movl %0,%%cr0": :"r" (x));
  98
  99 #define read_cr2() ({ \
 100         unsigned int __dummy; \
 101         __asm__ __volatile__( \
 102                 "movl %%cr2,%0\n\t" \
 103                 :"=r" (__dummy)); \
 104         __dummy; \
 105 })
 106 #define write_cr2(x) \
 107         __asm__ __volatile__("movl %0,%%cr2": :"r" (x));
 108
 109 #define read_cr3() ({ \
 110         unsigned int __dummy; \
 111         __asm__ ( \
 112                 "movl %%cr3,%0\n\t" \
 113                 :"=r" (__dummy)); \
 114         __dummy; \
 115 })
 116 #define write_cr3(x) \
 117         __asm__ __volatile__("movl %0,%%cr3": :"r" (x));
 118
 119 #define read_cr4() ({ \
 120         unsigned int __dummy; \
 121         __asm__( \
 122                 "movl %%cr4,%0\n\t" \
 123                 :"=r" (__dummy)); \
 124         __dummy; \
 125 })
 126
 127 #define read_cr4_safe() ({                            \
 128         unsigned int __dummy;                         \
 129         /* This could fault if %cr4 does not exist */ \
 130         __asm__("1: movl %%cr4, %0              \n"   \
 131                 "2:                             \n"   \
 132                 ".section __ex_table,\"a\"      \n"   \
 133                 ".long 1b,2b                    \n"   \
 134                 ".previous                      \n"   \
 135                 : "=r" (__dummy): "0" (0));           \
 136         __dummy;                                      \
 137 })
 138
 139 #define write_cr4(x) \
 140         __asm__ __volatile__("movl %0,%%cr4": :"r" (x));
 141 #define stts() write_cr0(8 | read_cr0())
 142
 143 #endif  /* __KERNEL__ */
 144
 145 #define wbinvd() \
 146         __asm__ __volatile__ ("wbinvd": : :"memory");
 147
 148 static inline unsigned long get_limit(unsigned long segment)
 149 {
 150         unsigned long __limit;
 151         __asm__("lsll %1,%0"
 152                 :"=r" (__limit):"r" (segment));
 153         return __limit+1;
 154 }
 155
 156 #define nop() __asm__ __volatile__ ("nop")
 157
 158 #define xchg(ptr,v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v),(ptr),sizeof(*(ptr))))
 159
 160 #define tas(ptr) (xchg((ptr),1))
 161
 162 struct __xchg_dummy { unsigned long a[100]; };
 163 #define __xg(x) ((struct __xchg_dummy *)(x))
 164
 165
 166 #ifdef CONFIG_X86_CMPXCHG64
 167
 168 /*
 169  * The semantics of XCHGCMP8B are a bit strange, this is why
 170  * there is a loop and the loading of %%eax and %%edx has to
 171  * be inside. This inlines well in most cases, the cached
 172  * cost is around ~38 cycles. (in the future we might want
 173  * to do an SIMD/3DNOW!/MMX/FPU 64-bit store here, but that
 174  * might have an implicit FPU-save as a cost, so it's not
 175  * clear which path to go.)
 176  *
 177  * cmpxchg8b must be used with the lock prefix here to allow
 178  * the instruction to be executed atomically, see page 3-102
 179  * of the instruction set reference 24319102.pdf. We need
 180  * the reader side to see the coherent 64bit value.
 181  */
 182 static inline void __set_64bit (unsigned long long * ptr,
 183                 unsigned int low, unsigned int high)
 184 {
 185         __asm__ __volatile__ (
 186                 "\n1:\t"
 187                 "movl (%0), %%eax\n\t"
 188                 "movl 4(%0), %%edx\n\t"
 189                 "lock cmpxchg8b (%0)\n\t"
 190                 "jnz 1b"
 191                 : /* no outputs */
 192                 :       "D"(ptr),
 193                         "b"(low),
 194                         "c"(high)
 195                 :       "ax","dx","memory");
 196 }
 197
 198 static inline void __set_64bit_constant (unsigned long long *ptr,
 199                                                  unsigned long long value)
 200 {
 201         __set_64bit(ptr,(unsigned int)(value), (unsigned int)((value)>>32ULL));
 202 }
 203 #define ll_low(x)       *(((unsigned int*)&(x))+0)
 204 #define ll_high(x)      *(((unsigned int*)&(x))+1)
 205
 206 static inline void __set_64bit_var (unsigned long long *ptr,
 207                          unsigned long long value)
 208 {
 209         __set_64bit(ptr,ll_low(value), ll_high(value));
 210 }
 211
 212 #define set_64bit(ptr,value) \
 213 (__builtin_constant_p(value) ? \
 214  __set_64bit_constant(ptr, value) : \
 215  __set_64bit_var(ptr, value) )
 216
 217 #define _set_64bit(ptr,value) \
 218 (__builtin_constant_p(value) ? \
 219  __set_64bit(ptr, (unsigned int)(value), (unsigned int)((value)>>32ULL) ) : \
 220  __set_64bit(ptr, ll_low(value), ll_high(value)) )
 221
 222 #endif
 223
 224 /*
 225  * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
 226  * Note 2: xchg has side effect, so that attribute volatile is necessary,
 227  *        but generally the primitive is invalid, *ptr is output argument. --ANK
 228  */
 229 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
 230 {
 231         switch (size) {
 232                 case 1:
 233                         __asm__ __volatile__("xchgb %b0,%1"
 234                                 :"=q" (x)
 235                                 :"m" (*__xg(ptr)), "0" (x)
 236                                 :"memory");
 237                         break;
 238                 case 2:
 239                         __asm__ __volatile__("xchgw %w0,%1"
 240                                 :"=r" (x)
 241                                 :"m" (*__xg(ptr)), "0" (x)
 242                                 :"memory");
 243                         break;
 244                 case 4:
 245                         __asm__ __volatile__("xchgl %0,%1"
 246                                 :"=r" (x)
 247                                 :"m" (*__xg(ptr)), "0" (x)
 248                                 :"memory");
 249                         break;
 250         }
 251         return x;
 252 }
 253
 254 /*
 255  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 256  * store NEW in MEM.  Return the initial value in MEM.  Success is
 257  * indicated by comparing RETURN with OLD.
 258  */
 259
 260 #ifdef CONFIG_X86_CMPXCHG
 261 #define __HAVE_ARCH_CMPXCHG 1
 262 #define cmpxchg(ptr,o,n)\
 263         ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
 264                                         (unsigned long)(n),sizeof(*(ptr))))
 265 #endif
 266
 267 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 268                                       unsigned long new, int size)
 269 {
 270         unsigned long prev;
 271         switch (size) {
 272         case 1:
 273                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgb %b1,%2"
 274                                      : "=a"(prev)
 275                                      : "q"(new), "m"(*__xg(ptr)), "0"(old)
 276                                      : "memory");
 277                 return prev;
 278         case 2:
 279                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
 280                                      : "=a"(prev)
 281                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
 282                                      : "memory");
 283                 return prev;
 284         case 4:
 285                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2"
 286                                      : "=a"(prev)
 287                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
 288                                      : "memory");
 289                 return prev;
 290         }
 291         return old;
 292 }
 293
 294 #ifndef CONFIG_X86_CMPXCHG
 295 /*
 296  * Building a kernel capable running on 80386. It may be necessary to
 297  * simulate the cmpxchg on the 80386 CPU. For that purpose we define
 298  * a function for each of the sizes we support.
 299  */
 300
 301 extern unsigned long cmpxchg_386_u8(volatile void *, u8, u8);
 302 extern unsigned long cmpxchg_386_u16(volatile void *, u16, u16);
 303 extern unsigned long cmpxchg_386_u32(volatile void *, u32, u32);
 304
 305 static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
 306                                       unsigned long new, int size)
 307 {
 308         switch (size) {
 309         case 1:
 310                 return cmpxchg_386_u8(ptr, old, new);
 311         case 2:
 312                 return cmpxchg_386_u16(ptr, old, new);
 313         case 4:
 314                 return cmpxchg_386_u32(ptr, old, new);
 315         }
 316         return old;
 317 }
 318
 319 #define cmpxchg(ptr,o,n)                                                \
 320 ({                                                                      \
 321         __typeof__(*(ptr)) __ret;                                       \
 322         if (likely(boot_cpu_data.x86 > 3))                              \
 323                 __ret = __cmpxchg((ptr), (unsigned long)(o),            \
 324                                         (unsigned long)(n), sizeof(*(ptr))); \
 325         else                                                            \
 326                 __ret = cmpxchg_386((ptr), (unsigned long)(o),          \
 327                                         (unsigned long)(n), sizeof(*(ptr))); \
 328         __ret;                                                          \
 329 })
 330 #endif
 331
 332 #ifdef CONFIG_X86_CMPXCHG64
 333
 334 static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long long old,
 335                                       unsigned long long new)
 336 {
 337         unsigned long long prev;
 338         __asm__ __volatile__(LOCK_PREFIX "cmpxchg8b %3"
 339                              : "=A"(prev)
 340                              : "b"((unsigned long)new),
 341                                "c"((unsigned long)(new >> 32)),
 342                                "m"(*__xg(ptr)),
 343                                "0"(old)
 344                              : "memory");
 345         return prev;
 346 }
 347
 348 #define cmpxchg64(ptr,o,n)\
 349         ((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
 350                                         (unsigned long long)(n)))
 351
 352 #endif
 353
 354 /*
 355  * Force strict CPU ordering.
 356  * And yes, this is required on UP too when we're talking
 357  * to devices.
 358  *
 359  * For now, "wmb()" doesn't actually do anything, as all
 360  * Intel CPU's follow what Intel calls a *Processor Order*,
 361  * in which all writes are seen in the program order even
 362  * outside the CPU.
 363  *
 364  * I expect future Intel CPU's to have a weaker ordering,
 365  * but I'd also expect them to finally get their act together
 366  * and add some real memory barriers if so.
 367  *
 368  * Some non intel clones support out of order store. wmb() ceases to be a
 369  * nop for these.
 370  */
 371
 372
 373 /*
 374  * Actually only lfence would be needed for mb() because all stores done
 375  * by the kernel should be already ordered. But keep a full barrier for now.
 376  */
 377
 378 #define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
 379 #define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
 380
 381 /**
 382  * read_barrier_depends - Flush all pending reads that subsequents reads
 383  * depend on.
 384  *
 385  * No data-dependent reads from memory-like regions are ever reordered
 386  * over this barrier.  All reads preceding this primitive are guaranteed
 387  * to access memory (but not necessarily other CPUs' caches) before any
 388  * reads following this primitive that depend on the data return by
 389  * any of the preceding reads.  This primitive is much lighter weight than
 390  * rmb() on most CPUs, and is never heavier weight than is
 391  * rmb().
 392  *
 393  * These ordering constraints are respected by both the local CPU
 394  * and the compiler.
 395  *
 396  * Ordering is not guaranteed by anything other than these primitives,
 397  * not even by data dependencies.  See the documentation for
 398  * memory_barrier() for examples and URLs to more information.
 399  *
 400  * For example, the following code would force ordering (the initial
 401  * value of "a" is zero, "b" is one, and "p" is "&a"):
 402  *
 403  * <programlisting>
 404  *      CPU 0                           CPU 1
 405  *
 406  *      b = 2;
 407  *      memory_barrier();
 408  *      p = &b;                         q = p;
 409  *                                      read_barrier_depends();
 410  *                                      d = *q;
 411  * </programlisting>
 412  *
 413  * because the read of "*q" depends on the read of "p" and these
 414  * two reads are separated by a read_barrier_depends().  However,
 415  * the following code, with the same initial values for "a" and "b":
 416  *
 417  * <programlisting>
 418  *      CPU 0                           CPU 1
 419  *
 420  *      a = 2;
 421  *      memory_barrier();
 422  *      b = 3;                          y = b;
 423  *                                      read_barrier_depends();
 424  *                                      x = a;
 425  * </programlisting>
 426  *
 427  * does not enforce ordering, since there is no data dependency between
 428  * the read of "a" and the read of "b".  Therefore, on some CPUs, such
 429  * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()
 430  * in cases like this where there are no data dependencies.
 431  **/
 432
 433 #define read_barrier_depends()  do { } while(0)
 434
 435 #ifdef CONFIG_X86_OOSTORE
 436 /* Actually there are no OOO store capable CPUs for now that do SSE,
 437    but make it already an possibility. */
 438 #define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
 439 #else
 440 #define wmb()   __asm__ __volatile__ ("": : :"memory")
 441 #endif
 442
 443 #ifdef CONFIG_SMP
 444 #define smp_mb()        mb()
 445 #define smp_rmb()       rmb()
 446 #define smp_wmb()       wmb()
 447 #define smp_read_barrier_depends()      read_barrier_depends()
 448 #define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
 449 #else
 450 #define smp_mb()        barrier()
 451 #define smp_rmb()       barrier()
 452 #define smp_wmb()       barrier()
 453 #define smp_read_barrier_depends()      do { } while(0)
 454 #define set_mb(var, value) do { var = value; barrier(); } while (0)
 455 #endif
 456
 457 #define set_wmb(var, value) do { var = value; wmb(); } while (0)
 458
 459 /* interrupt control.. */
 460 #define local_save_flags(x)     do { typecheck(unsigned long,x); __asm__ __volatile__("pushfl ; popl %0":"=g" (x): /* no input */); } while (0)
 461 #define local_irq_restore(x)    do { typecheck(unsigned long,x); __asm__ __volatile__("pushl %0 ; popfl": /* no output */ :"g" (x):"memory", "cc"); } while (0)
 462 #define local_irq_disable()     __asm__ __volatile__("cli": : :"memory")
 463 #define local_irq_enable()      __asm__ __volatile__("sti": : :"memory")
 464 /* used in the idle loop; sti takes one instruction cycle to complete */
 465 #define safe_halt()             __asm__ __volatile__("sti; hlt": : :"memory")
 466 /* used when interrupts are already enabled or to shutdown the processor */
 467 #define halt()                  __asm__ __volatile__("hlt": : :"memory")
 468
 469 #define irqs_disabled()                 \
 470 ({                                      \
 471         unsigned long flags;            \
 472         local_save_flags(flags);        \
 473         !(flags & (1<<9));              \
 474 })
 475
 476 /* For spinlocks etc */
 477 #define local_irq_save(x)       __asm__ __volatile__("pushfl ; popl %0 ; cli":"=g" (x): /* no input */ :"memory")
 478
 479 /*
 480  * disable hlt during certain critical i/o operations
 481  */
 482 #define HAVE_DISABLE_HLT
 483 void disable_hlt(void);
 484 void enable_hlt(void);
 485
 486 extern int es7000_plat;
 487 void cpu_idle_wait(void);
 488
 489 /*
 490  * On SMP systems, when the scheduler does migration-cost autodetection,
 491  * it needs a way to flush as much of the CPU's caches as possible:
 492  */
 493 static inline void sched_cacheflush(void)
 494 {
 495         wbinvd();
 496 }
 497
 498 extern unsigned long arch_align_stack(unsigned long sp);
 499 extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
 500
 501 void default_idle(void);
 502
 503 #endif