include/asm-i386/system.h

   1 #ifndef __ASM_SYSTEM_H
   2 #define __ASM_SYSTEM_H
   3
   4 #include <linux/config.h>
   5 #include <linux/kernel.h>
   6 #include <asm/segment.h>
   7 #include <asm/cpufeature.h>
   8 #include <linux/bitops.h> /* for LOCK_PREFIX */
   9
  10 #ifdef __KERNEL__
  11
  12 struct task_struct;     /* one of the stranger aspects of C forward declarations.. */
  13 extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struct task_struct *next));
  14
  15 #define switch_to(prev,next,last) do {                                  \
  16         unsigned long esi,edi;                                          \
  17         asm volatile("pushl %%ebp\n\t"                                  \
  18                      "movl %%esp,%0\n\t"        /* save ESP */          \
  19                      "movl %5,%%esp\n\t"        /* restore ESP */       \
  20                      "movl $1f,%1\n\t"          /* save EIP */          \
  21                      "pushl %6\n\t"             /* restore EIP */       \
  22                      "jmp __switch_to\n"                                \
  23                      "1:\t"                                             \
  24                      "popl %%ebp\n\t"                                   \
  25                      :"=m" (prev->thread.esp),"=m" (prev->thread.eip),  \
  26                       "=a" (last),"=S" (esi),"=D" (edi)                 \
  27                      :"m" (next->thread.esp),"m" (next->thread.eip),    \
  28                       "2" (prev), "d" (next));                          \
  29 } while (0)
  30
  31 #define _set_base(addr,base) do { unsigned long __pr; \
  32 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
  33         "rorl $16,%%edx\n\t" \
  34         "movb %%dl,%2\n\t" \
  35         "movb %%dh,%3" \
  36         :"=&d" (__pr) \
  37         :"m" (*((addr)+2)), \
  38          "m" (*((addr)+4)), \
  39          "m" (*((addr)+7)), \
  40          "0" (base) \
  41         ); } while(0)
  42
  43 #define _set_limit(addr,limit) do { unsigned long __lr; \
  44 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
  45         "rorl $16,%%edx\n\t" \
  46         "movb %2,%%dh\n\t" \
  47         "andb $0xf0,%%dh\n\t" \
  48         "orb %%dh,%%dl\n\t" \
  49         "movb %%dl,%2" \
  50         :"=&d" (__lr) \
  51         :"m" (*(addr)), \
  52          "m" (*((addr)+6)), \
  53          "0" (limit) \
  54         ); } while(0)
  55
  56 #define set_base(ldt,base) _set_base( ((char *)&(ldt)) , (base) )
  57 #define set_limit(ldt,limit) _set_limit( ((char *)&(ldt)) , ((limit)-1) )
  58
  59 /*
  60  * Load a segment. Fall back on loading the zero
  61  * segment if something goes wrong..
  62  */
  63 #define loadsegment(seg,value)                  \
  64         asm volatile("\n"                       \
  65                 "1:\t"                          \
  66                 "mov %0,%%" #seg "\n"           \
  67                 "2:\n"                          \
  68                 ".section .fixup,\"ax\"\n"      \
  69                 "3:\t"                          \
  70                 "pushl $0\n\t"                  \
  71                 "popl %%" #seg "\n\t"           \
  72                 "jmp 2b\n"                      \
  73                 ".previous\n"                   \
  74                 ".section __ex_table,\"a\"\n\t" \
  75                 ".align 4\n\t"                  \
  76                 ".long 1b,3b\n"                 \
  77                 ".previous"                     \
  78                 : :"rm" (value))
  79
  80 /*
  81  * Save a segment register away
  82  */
  83 #define savesegment(seg, value) \
  84         asm volatile("mov %%" #seg ",%0":"=rm" (value))
  85
  86 /*
  87  * Clear and set 'TS' bit respectively
  88  */
  89 #define clts() __asm__ __volatile__ ("clts")
  90 #define read_cr0() ({ \
  91         unsigned int __dummy; \
  92         __asm__ __volatile__( \
  93                 "movl %%cr0,%0\n\t" \
  94                 :"=r" (__dummy)); \
  95         __dummy; \
  96 })
  97 #define write_cr0(x) \
  98         __asm__ __volatile__("movl %0,%%cr0": :"r" (x));
  99
 100 #define read_cr2() ({ \
 101         unsigned int __dummy; \
 102         __asm__ __volatile__( \
 103                 "movl %%cr2,%0\n\t" \
 104                 :"=r" (__dummy)); \
 105         __dummy; \
 106 })
 107 #define write_cr2(x) \
 108         __asm__ __volatile__("movl %0,%%cr2": :"r" (x));
 109
 110 #define read_cr3() ({ \
 111         unsigned int __dummy; \
 112         __asm__ ( \
 113                 "movl %%cr3,%0\n\t" \
 114                 :"=r" (__dummy)); \
 115         __dummy; \
 116 })
 117 #define write_cr3(x) \
 118         __asm__ __volatile__("movl %0,%%cr3": :"r" (x));
 119
 120 #define read_cr4() ({ \
 121         unsigned int __dummy; \
 122         __asm__( \
 123                 "movl %%cr4,%0\n\t" \
 124                 :"=r" (__dummy)); \
 125         __dummy; \
 126 })
 127
 128 #define read_cr4_safe() ({                            \
 129         unsigned int __dummy;                         \
 130         /* This could fault if %cr4 does not exist */ \
 131         __asm__("1: movl %%cr4, %0              \n"   \
 132                 "2:                             \n"   \
 133                 ".section __ex_table,\"a\"      \n"   \
 134                 ".long 1b,2b                    \n"   \
 135                 ".previous                      \n"   \
 136                 : "=r" (__dummy): "0" (0));           \
 137         __dummy;                                      \
 138 })
 139
 140 #define write_cr4(x) \
 141         __asm__ __volatile__("movl %0,%%cr4": :"r" (x));
 142 #define stts() write_cr0(8 | read_cr0())
 143
 144 #endif  /* __KERNEL__ */
 145
 146 #define wbinvd() \
 147         __asm__ __volatile__ ("wbinvd": : :"memory");
 148
 149 static inline unsigned long get_limit(unsigned long segment)
 150 {
 151         unsigned long __limit;
 152         __asm__("lsll %1,%0"
 153                 :"=r" (__limit):"r" (segment));
 154         return __limit+1;
 155 }
 156
 157 #define nop() __asm__ __volatile__ ("nop")
 158
 159 #define xchg(ptr,v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v),(ptr),sizeof(*(ptr))))
 160
 161 #define tas(ptr) (xchg((ptr),1))
 162
 163 struct __xchg_dummy { unsigned long a[100]; };
 164 #define __xg(x) ((struct __xchg_dummy *)(x))
 165
 166
 167 #ifdef CONFIG_X86_CMPXCHG64
 168
 169 /*
 170  * The semantics of XCHGCMP8B are a bit strange, this is why
 171  * there is a loop and the loading of %%eax and %%edx has to
 172  * be inside. This inlines well in most cases, the cached
 173  * cost is around ~38 cycles. (in the future we might want
 174  * to do an SIMD/3DNOW!/MMX/FPU 64-bit store here, but that
 175  * might have an implicit FPU-save as a cost, so it's not
 176  * clear which path to go.)
 177  *
 178  * cmpxchg8b must be used with the lock prefix here to allow
 179  * the instruction to be executed atomically, see page 3-102
 180  * of the instruction set reference 24319102.pdf. We need
 181  * the reader side to see the coherent 64bit value.
 182  */
 183 static inline void __set_64bit (unsigned long long * ptr,
 184                 unsigned int low, unsigned int high)
 185 {
 186         __asm__ __volatile__ (
 187                 "\n1:\t"
 188                 "movl (%0), %%eax\n\t"
 189                 "movl 4(%0), %%edx\n\t"
 190                 "lock cmpxchg8b (%0)\n\t"
 191                 "jnz 1b"
 192                 : /* no outputs */
 193                 :       "D"(ptr),
 194                         "b"(low),
 195                         "c"(high)
 196                 :       "ax","dx","memory");
 197 }
 198
 199 static inline void __set_64bit_constant (unsigned long long *ptr,
 200                                                  unsigned long long value)
 201 {
 202         __set_64bit(ptr,(unsigned int)(value), (unsigned int)((value)>>32ULL));
 203 }
 204 #define ll_low(x)       *(((unsigned int*)&(x))+0)
 205 #define ll_high(x)      *(((unsigned int*)&(x))+1)
 206
 207 static inline void __set_64bit_var (unsigned long long *ptr,
 208                          unsigned long long value)
 209 {
 210         __set_64bit(ptr,ll_low(value), ll_high(value));
 211 }
 212
 213 #define set_64bit(ptr,value) \
 214 (__builtin_constant_p(value) ? \
 215  __set_64bit_constant(ptr, value) : \
 216  __set_64bit_var(ptr, value) )
 217
 218 #define _set_64bit(ptr,value) \
 219 (__builtin_constant_p(value) ? \
 220  __set_64bit(ptr, (unsigned int)(value), (unsigned int)((value)>>32ULL) ) : \
 221  __set_64bit(ptr, ll_low(value), ll_high(value)) )
 222
 223 #endif
 224
 225 /*
 226  * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
 227  * Note 2: xchg has side effect, so that attribute volatile is necessary,
 228  *        but generally the primitive is invalid, *ptr is output argument. --ANK
 229  */
 230 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
 231 {
 232         switch (size) {
 233                 case 1:
 234                         __asm__ __volatile__("xchgb %b0,%1"
 235                                 :"=q" (x)
 236                                 :"m" (*__xg(ptr)), "0" (x)
 237                                 :"memory");
 238                         break;
 239                 case 2:
 240                         __asm__ __volatile__("xchgw %w0,%1"
 241                                 :"=r" (x)
 242                                 :"m" (*__xg(ptr)), "0" (x)
 243                                 :"memory");
 244                         break;
 245                 case 4:
 246                         __asm__ __volatile__("xchgl %0,%1"
 247                                 :"=r" (x)
 248                                 :"m" (*__xg(ptr)), "0" (x)
 249                                 :"memory");
 250                         break;
 251         }
 252         return x;
 253 }
 254
 255 /*
 256  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 257  * store NEW in MEM.  Return the initial value in MEM.  Success is
 258  * indicated by comparing RETURN with OLD.
 259  */
 260
 261 #ifdef CONFIG_X86_CMPXCHG
 262 #define __HAVE_ARCH_CMPXCHG 1
 263 #define cmpxchg(ptr,o,n)\
 264         ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
 265                                         (unsigned long)(n),sizeof(*(ptr))))
 266 #endif
 267
 268 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 269                                       unsigned long new, int size)
 270 {
 271         unsigned long prev;
 272         switch (size) {
 273         case 1:
 274                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgb %b1,%2"
 275                                      : "=a"(prev)
 276                                      : "q"(new), "m"(*__xg(ptr)), "0"(old)
 277                                      : "memory");
 278                 return prev;
 279         case 2:
 280                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
 281                                      : "=a"(prev)
 282                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
 283                                      : "memory");
 284                 return prev;
 285         case 4:
 286                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2"
 287                                      : "=a"(prev)
 288                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
 289                                      : "memory");
 290                 return prev;
 291         }
 292         return old;
 293 }
 294
 295 #ifndef CONFIG_X86_CMPXCHG
 296 /*
 297  * Building a kernel capable running on 80386. It may be necessary to
 298  * simulate the cmpxchg on the 80386 CPU. For that purpose we define
 299  * a function for each of the sizes we support.
 300  */
 301
 302 extern unsigned long cmpxchg_386_u8(volatile void *, u8, u8);
 303 extern unsigned long cmpxchg_386_u16(volatile void *, u16, u16);
 304 extern unsigned long cmpxchg_386_u32(volatile void *, u32, u32);
 305
 306 static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
 307                                       unsigned long new, int size)
 308 {
 309         switch (size) {
 310         case 1:
 311                 return cmpxchg_386_u8(ptr, old, new);
 312         case 2:
 313                 return cmpxchg_386_u16(ptr, old, new);
 314         case 4:
 315                 return cmpxchg_386_u32(ptr, old, new);
 316         }
 317         return old;
 318 }
 319
 320 #define cmpxchg(ptr,o,n)                                                \
 321 ({                                                                      \
 322         __typeof__(*(ptr)) __ret;                                       \
 323         if (likely(boot_cpu_data.x86 > 3))                              \
 324                 __ret = __cmpxchg((ptr), (unsigned long)(o),            \
 325                                         (unsigned long)(n), sizeof(*(ptr))); \
 326         else                                                            \
 327                 __ret = cmpxchg_386((ptr), (unsigned long)(o),          \
 328                                         (unsigned long)(n), sizeof(*(ptr))); \
 329         __ret;                                                          \
 330 })
 331 #endif
 332
 333 #ifdef CONFIG_X86_CMPXCHG64
 334
 335 static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long long old,
 336                                       unsigned long long new)
 337 {
 338         unsigned long long prev;
 339         __asm__ __volatile__(LOCK_PREFIX "cmpxchg8b %3"
 340                              : "=A"(prev)
 341                              : "b"((unsigned long)new),
 342                                "c"((unsigned long)(new >> 32)),
 343                                "m"(*__xg(ptr)),
 344                                "0"(old)
 345                              : "memory");
 346         return prev;
 347 }
 348
 349 #define cmpxchg64(ptr,o,n)\
 350         ((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
 351                                         (unsigned long long)(n)))
 352
 353 #endif
 354
 355 #ifdef __KERNEL__
 356 struct alt_instr {
 357         __u8 *instr;            /* original instruction */
 358         __u8 *replacement;
 359         __u8  cpuid;            /* cpuid bit set for replacement */
 360         __u8  instrlen;         /* length of original instruction */
 361         __u8  replacementlen;   /* length of new instruction, <= instrlen */
 362         __u8  pad;
 363 };
 364 #endif
 365
 366 /*
 367  * Alternative instructions for different CPU types or capabilities.
 368  *
 369  * This allows to use optimized instructions even on generic binary
 370  * kernels.
 371  *
 372  * length of oldinstr must be longer or equal the length of newinstr
 373  * It can be padded with nops as needed.
 374  *
 375  * For non barrier like inlines please define new variants
 376  * without volatile and memory clobber.
 377  */
 378 #define alternative(oldinstr, newinstr, feature)        \
 379         asm volatile ("661:\n\t" oldinstr "\n662:\n"                 \
 380                       ".section .altinstructions,\"a\"\n"            \
 381                       "  .align 4\n"                                   \
 382                       "  .long 661b\n"            /* label */          \
 383                       "  .long 663f\n"            /* new instruction */         \
 384                       "  .byte %c0\n"             /* feature bit */    \
 385                       "  .byte 662b-661b\n"       /* sourcelen */      \
 386                       "  .byte 664f-663f\n"       /* replacementlen */ \
 387                       ".previous\n"                                             \
 388                       ".section .altinstr_replacement,\"ax\"\n"                 \
 389                       "663:\n\t" newinstr "\n664:\n"   /* replacement */    \
 390                       ".previous" :: "i" (feature) : "memory")
 391
 392 /*
 393  * Alternative inline assembly with input.
 394  *
 395  * Pecularities:
 396  * No memory clobber here.
 397  * Argument numbers start with 1.
 398  * Best is to use constraints that are fixed size (like (%1) ... "r")
 399  * If you use variable sized constraints like "m" or "g" in the
 400  * replacement maake sure to pad to the worst case length.
 401  */
 402 #define alternative_input(oldinstr, newinstr, feature, input...)                \
 403         asm volatile ("661:\n\t" oldinstr "\n662:\n"                            \
 404                       ".section .altinstructions,\"a\"\n"                       \
 405                       "  .align 4\n"                                            \
 406                       "  .long 661b\n"            /* label */                   \
 407                       "  .long 663f\n"            /* new instruction */         \
 408                       "  .byte %c0\n"             /* feature bit */             \
 409                       "  .byte 662b-661b\n"       /* sourcelen */               \
 410                       "  .byte 664f-663f\n"       /* replacementlen */          \
 411                       ".previous\n"                                             \
 412                       ".section .altinstr_replacement,\"ax\"\n"                 \
 413                       "663:\n\t" newinstr "\n664:\n"   /* replacement */        \
 414                       ".previous" :: "i" (feature), ##input)
 415
 416 /*
 417  * Force strict CPU ordering.
 418  * And yes, this is required on UP too when we're talking
 419  * to devices.
 420  *
 421  * For now, "wmb()" doesn't actually do anything, as all
 422  * Intel CPU's follow what Intel calls a *Processor Order*,
 423  * in which all writes are seen in the program order even
 424  * outside the CPU.
 425  *
 426  * I expect future Intel CPU's to have a weaker ordering,
 427  * but I'd also expect them to finally get their act together
 428  * and add some real memory barriers if so.
 429  *
 430  * Some non intel clones support out of order store. wmb() ceases to be a
 431  * nop for these.
 432  */
 433
 434
 435 /*
 436  * Actually only lfence would be needed for mb() because all stores done
 437  * by the kernel should be already ordered. But keep a full barrier for now.
 438  */
 439
 440 #define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
 441 #define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
 442
 443 /**
 444  * read_barrier_depends - Flush all pending reads that subsequents reads
 445  * depend on.
 446  *
 447  * No data-dependent reads from memory-like regions are ever reordered
 448  * over this barrier.  All reads preceding this primitive are guaranteed
 449  * to access memory (but not necessarily other CPUs' caches) before any
 450  * reads following this primitive that depend on the data return by
 451  * any of the preceding reads.  This primitive is much lighter weight than
 452  * rmb() on most CPUs, and is never heavier weight than is
 453  * rmb().
 454  *
 455  * These ordering constraints are respected by both the local CPU
 456  * and the compiler.
 457  *
 458  * Ordering is not guaranteed by anything other than these primitives,
 459  * not even by data dependencies.  See the documentation for
 460  * memory_barrier() for examples and URLs to more information.
 461  *
 462  * For example, the following code would force ordering (the initial
 463  * value of "a" is zero, "b" is one, and "p" is "&a"):
 464  *
 465  * <programlisting>
 466  *      CPU 0                           CPU 1
 467  *
 468  *      b = 2;
 469  *      memory_barrier();
 470  *      p = &b;                         q = p;
 471  *                                      read_barrier_depends();
 472  *                                      d = *q;
 473  * </programlisting>
 474  *
 475  * because the read of "*q" depends on the read of "p" and these
 476  * two reads are separated by a read_barrier_depends().  However,
 477  * the following code, with the same initial values for "a" and "b":
 478  *
 479  * <programlisting>
 480  *      CPU 0                           CPU 1
 481  *
 482  *      a = 2;
 483  *      memory_barrier();
 484  *      b = 3;                          y = b;
 485  *                                      read_barrier_depends();
 486  *                                      x = a;
 487  * </programlisting>
 488  *
 489  * does not enforce ordering, since there is no data dependency between
 490  * the read of "a" and the read of "b".  Therefore, on some CPUs, such
 491  * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()
 492  * in cases like thiswhere there are no data dependencies.
 493  **/
 494
 495 #define read_barrier_depends()  do { } while(0)
 496
 497 #ifdef CONFIG_X86_OOSTORE
 498 /* Actually there are no OOO store capable CPUs for now that do SSE,
 499    but make it already an possibility. */
 500 #define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
 501 #else
 502 #define wmb()   __asm__ __volatile__ ("": : :"memory")
 503 #endif
 504
 505 #ifdef CONFIG_SMP
 506 #define smp_mb()        mb()
 507 #define smp_rmb()       rmb()
 508 #define smp_wmb()       wmb()
 509 #define smp_read_barrier_depends()      read_barrier_depends()
 510 #define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
 511 #else
 512 #define smp_mb()        barrier()
 513 #define smp_rmb()       barrier()
 514 #define smp_wmb()       barrier()
 515 #define smp_read_barrier_depends()      do { } while(0)
 516 #define set_mb(var, value) do { var = value; barrier(); } while (0)
 517 #endif
 518
 519 #define set_wmb(var, value) do { var = value; wmb(); } while (0)
 520
 521 /* interrupt control.. */
 522 #define local_save_flags(x)     do { typecheck(unsigned long,x); __asm__ __volatile__("pushfl ; popl %0":"=g" (x): /* no input */); } while (0)
 523 #define local_irq_restore(x)    do { typecheck(unsigned long,x); __asm__ __volatile__("pushl %0 ; popfl": /* no output */ :"g" (x):"memory", "cc"); } while (0)
 524 #define local_irq_disable()     __asm__ __volatile__("cli": : :"memory")
 525 #define local_irq_enable()      __asm__ __volatile__("sti": : :"memory")
 526 /* used in the idle loop; sti takes one instruction cycle to complete */
 527 #define safe_halt()             __asm__ __volatile__("sti; hlt": : :"memory")
 528 /* used when interrupts are already enabled or to shutdown the processor */
 529 #define halt()                  __asm__ __volatile__("hlt": : :"memory")
 530
 531 #define irqs_disabled()                 \
 532 ({                                      \
 533         unsigned long flags;            \
 534         local_save_flags(flags);        \
 535         !(flags & (1<<9));              \
 536 })
 537
 538 /* For spinlocks etc */
 539 #define local_irq_save(x)       __asm__ __volatile__("pushfl ; popl %0 ; cli":"=g" (x): /* no input */ :"memory")
 540
 541 /*
 542  * disable hlt during certain critical i/o operations
 543  */
 544 #define HAVE_DISABLE_HLT
 545 void disable_hlt(void);
 546 void enable_hlt(void);
 547
 548 extern int es7000_plat;
 549 void cpu_idle_wait(void);
 550
 551 /*
 552  * On SMP systems, when the scheduler does migration-cost autodetection,
 553  * it needs a way to flush as much of the CPU's caches as possible:
 554  */
 555 static inline void sched_cacheflush(void)
 556 {
 557         wbinvd();
 558 }
 559
 560 extern unsigned long arch_align_stack(unsigned long sp);
 561
 562 #endif