mdw@git.distorted.org.uk Git - catacomb/blob - base/dispatch.c

   1 /* -*-c-*-
   2  *
   3  * CPU-specific dispatch
   4  *
   5  * (c) 2015 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Catacomb.
  11  *
  12  * Catacomb is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Library General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * Catacomb is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with Catacomb; if not, write to the Free
  24  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25  * MA 02111-1307, USA.
  26  */
  27
  28 /*----- Header files ------------------------------------------------------*/
  29
  30 #include "config.h"
  31
  32 #include <ctype.h>
  33 #include <stdarg.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37
  38 #include <mLib/macros.h>
  39
  40 #include "dispatch.h"
  41
  42 /*----- Intel x86/AMD64 feature probing -----------------------------------*/
  43
  44 #if CPUFAM_X86 || CPUFAM_AMD64
  45
  46 #  define EFLAGS_ID (1u << 21)
  47 #  define CPUID1D_SSE2 (1u << 26)
  48 #  define CPUID1D_FXSR (1u << 24)
  49 #  define CPUID1C_PCLMUL (1u << 1)
  50 #  define CPUID1C_SSSE3 (1u << 9)
  51 #  define CPUID1C_AESNI (1u << 25)
  52 #  define CPUID1C_AVX (1u << 28)
  53 #  define CPUID1C_RDRAND (1u << 30)
  54
  55 struct cpuid { unsigned a, b, c, d; };
  56
  57 /* --- @cpuid@ --- *
  58  *
  59  * Arguments:   @struct cpuid *cc@ = where to write the result
  60  *              @unsigned a, c@ = EAX and ECX registers to set
  61  *
  62  * Returns:     ---
  63  *
  64  * Use:         Minimal C wrapper around the x86 `CPUID' instruction.  Checks
  65  *              that the instruction is actually available before invoking
  66  *              it; fills the output structure with zero if it's not going to
  67  *              work.
  68  */
  69
  70 #ifdef __GNUC__
  71 #  if CPUFAM_X86
  72 static __inline__ unsigned getflags(void)
  73   { unsigned f; __asm__ ("pushf; popl %0" : "=g" (f)); return (f); }
  74 static __inline__ unsigned setflags(unsigned f)
  75 {
  76   unsigned ff;
  77   __asm__ ("pushf; pushl %1; popf; pushf; popl %0; popf"
  78            : "=r" (ff)
  79            : "r" (f));
  80   return (ff);
  81 }
  82 #  else
  83 static __inline__ unsigned long getflags(void)
  84   { unsigned long f; __asm__ ("pushf; popq %0" : "=g" (f)); return (f); }
  85 static __inline__ unsigned long long setflags(unsigned long f)
  86 {
  87   unsigned long ff;
  88   __asm__ ("pushf; pushq %1; popf; pushf; popq %0; popf"
  89            : "=r" (ff)
  90            : "r" (f));
  91   return (ff);
  92 }
  93 #  endif
  94 #endif
  95
  96 static void cpuid(struct cpuid *cc, unsigned a, unsigned c)
  97 {
  98 #ifdef __GNUC__
  99   unsigned f;
 100 #endif
 101
 102   cc->a = cc->b = cc->c = cc->d = 0;
 103
 104 #ifdef __GNUC__
 105   /* Stupid dance to detect whether the CPUID instruction is available. */
 106   f = getflags();
 107   if (!(setflags(f |  EFLAGS_ID) & EFLAGS_ID) ||
 108         setflags(f & ~EFLAGS_ID) & EFLAGS_ID) {
 109     dispatch_debug("CPUID instruction not available");
 110     return;
 111   }
 112   setflags(f);
 113
 114   /* Alas, EBX is magical in PIC code, so abuse ESI instead.  This isn't
 115    * pretty, but it works.
 116    */
 117 #  if CPUFAM_X86
 118   __asm__ ("pushl %%ebx; cpuid; movl %%ebx, %%esi; popl %%ebx"
 119            : "=a" (cc->a), "=S" (cc->b), "=c" (cc->c), "=d" (cc->d)
 120            : "a" (a) , "c" (c));
 121 #  elif CPUFAM_AMD64
 122   __asm__ ("pushq %%rbx; cpuid; movl %%ebx, %%esi; popq %%rbx"
 123            : "=a" (cc->a), "=S" (cc->b), "=c" (cc->c), "=d" (cc->d)
 124            : "a" (a) , "c" (c));
 125 #  else
 126 #    error "I'm confused."
 127 #  endif
 128   dispatch_debug("CPUID(%08x, %08x) -> %08x, %08x, %08x, %08x",
 129                  a, c, cc->a, cc->b, cc->c, cc->d);
 130 #else
 131   dispatch_debug("GNU inline assembler not available; can't CPUID");
 132 #endif
 133 }
 134
 135 static unsigned cpuid_maxleaf(void)
 136   { struct cpuid c; cpuid(&c, 0, 0); return (c.a); }
 137
 138 /* --- @cpuid_features_p@ --- *
 139  *
 140  * Arguments:   @unsigned dbits@ = bits to check in EDX
 141  *              @unsigned cbits@ = bits to check in ECX
 142  *
 143  * Returns:     Nonzero if all the requested bits are set in the CPUID result
 144  *              on leaf 1.
 145  */
 146
 147 static int cpuid_features_p(unsigned dbits, unsigned cbits)
 148 {
 149   struct cpuid c;
 150   if (cpuid_maxleaf() < 1) return (0);
 151   cpuid(&c, 1, 0);
 152   return ((c.d & dbits) == dbits && (c.c & cbits) == cbits);
 153 }
 154
 155 /* --- @xmm_registers_available_p@ --- *
 156  *
 157  * Arguments:   ---
 158  *
 159  * Returns:     Nonzero if the operating system has made the XMM registers
 160  *              available for use.
 161  */
 162
 163 static int xmm_registers_available_p(void)
 164 {
 165 #ifdef __GNUC__
 166   unsigned f;
 167   /* This hack is by Agner Fog.  Use FXSAVE/FXRSTOR to figure out whether the
 168    * XMM registers are actually alive.
 169    */
 170   if (!cpuid_features_p(CPUID1D_FXSR, 0)) return (0);
 171 #  if CPUFAM_X86
 172   __asm__ ("movl %%esp, %%edx; subl $512, %%esp; andl $~15, %%esp\n"
 173            "fxsave (%%esp)\n"
 174            "movl 160(%%esp), %%eax; xorl $0xaaaa5555, 160(%%esp)\n"
 175            "fxrstor (%%esp); fxsave (%%esp)\n"
 176            "movl 160(%%esp), %%ecx; movl %%eax, 160(%%esp)\n"
 177            "fxrstor (%%esp); movl %%edx, %%esp\n"
 178            "xorl %%ecx, %%eax"
 179            : "=a" (f)
 180            : /* no inputs */
 181            : "%ecx", "%edx");
 182 #  elif CPUFAM_AMD64
 183   __asm__ ("movq %%rsp, %%rdx; subq $512, %%rsp; andq $~15, %%rsp\n"
 184            "fxsave (%%rsp)\n"
 185            "movl 160(%%rsp), %%eax; xorl $0xaaaa5555, 160(%%rsp)\n"
 186            "fxrstor (%%rsp); fxsave (%%rsp)\n"
 187            "movl 160(%%rsp), %%ecx; movl %%eax, 160(%%rsp)\n"
 188            "fxrstor (%%rsp); movq %%rdx, %%rsp\n"
 189            "xorl %%ecx, %%eax"
 190            : "=a" (f)
 191            : /* no inputs */
 192            : "%ecx", "%rdx");
 193 #  else
 194 #    error "I'm confused."
 195 #  endif
 196   dispatch_debug("XMM registers %savailable", f ? "" : "not ");
 197   return (f);
 198 #else
 199   dispatch_debug("GNU inline assembler not available; can't check for XMM");
 200   return (0);
 201 #endif
 202 }
 203
 204 /* --- @rdrand_works_p@ --- *
 205  *
 206  *
 207  * Arguments:   ---
 208  *
 209  * Returns:     Nonzero if the `rdrand' instruction actually works.  Assumes
 210  *              that it's already been verified to be safe to issue.
 211  */
 212
 213 #ifdef __GNUC__
 214 static int rdrand(unsigned *x)
 215 {
 216   int i, rc;
 217   unsigned _t;
 218
 219   i = 16;
 220   __asm__ ("" : "=g" (_t));
 221   __asm__ ("0: rdrand %2; jc 1f; decl %1; jnz 0b\n"
 222            "mov $-1, %0; jmp 9f\n"
 223            "1: movl %2, (%3); xorl %0, %0\n"
 224            "9:"
 225            : "=r" (rc), "+r" (i), "+r" (_t)
 226            : "r" (x)
 227            : "cc");
 228   return (rc);
 229 }
 230 #endif
 231
 232 static int rdrand_works_p(void)
 233 {
 234   unsigned ref, x, i;
 235
 236   /* Check that it doesn't always give the same answer.  Try four times: this
 237    * will fail with probability %$2^{-128}$% with a truly random generator,
 238    * which seems fair enough.
 239    */
 240   if (rdrand(&ref)) goto fail;
 241   for (i = 0; i < 4; i++) {
 242     if (rdrand(&x)) goto fail;
 243     if (x != ref) goto not_stuck;
 244   }
 245   dispatch_debug("RDRAND always returns 0x%08x!", ref);
 246   return (0);
 247
 248 not_stuck:
 249   dispatch_debug("RDRAND instruction looks plausible");
 250   return (1);
 251
 252 fail:
 253   dispatch_debug("RDRAND instruction fails too often");
 254   return (0);
 255 }
 256
 257 #endif
 258
 259 /*----- General feature probing using auxiliary vectors -------------------*/
 260
 261 /* Try to find the system's definitions for auxiliary vector entries. */
 262 #ifdef HAVE_SYS_AUXV_H
 263 #  include <sys/auxv.h>
 264 #endif
 265 #ifdef HAVE_LINUX_AUXVEC_H
 266 #  include <linux/auxvec.h>
 267 #endif
 268 #ifdef HAVE_ASM_HWCAP_H
 269 #  include <asm/hwcap.h>
 270 #endif
 271
 272 /* The type of entries in the auxiliary vector.  I'm assuming that `unsigned
 273  * long' matches each platform's word length; if this is false then we'll
 274  * need some host-specific tweaking here.
 275  */
 276 union auxval { long i; unsigned long u; const void *p; };
 277 struct auxentry { unsigned long type; union auxval value; };
 278
 279 /* Register each CPU family's interest in the auxiliary vector.  Make sure
 280  * that the necessary entry types are defined.  This is primarily ordered by
 281  * entry type to minimize duplication.
 282  */
 283 #if defined(AT_HWCAP) && CPUFAM_ARMEL
 284 #  define WANT_ANY 1
 285 #  define WANT_AT_HWCAP(_) _(AT_HWCAP, u, hwcap)
 286 #endif
 287
 288 #if defined(AT_HWCAP) && CPUFAM_ARM64
 289 #  define WANT_ANY 1
 290 #  define WANT_AT_HWCAP(_) _(AT_HWCAP, u, hwcap)
 291 #endif
 292
 293 #if defined(AT_HWCAP2) && CPUFAM_ARMEL
 294 #  define WANT_ANY 1
 295 #  define WANT_AT_HWCAP2(_) _(AT_HWCAP2, u, hwcap2)
 296 #endif
 297
 298 /* If we couldn't find any interesting entries then we can switch all of this
 299  * machinery off.  Also do that if we have no means for atomic updates.
 300  */
 301 #if WANT_ANY && CPU_DISPATCH_P
 302
 303 /* The main output of this section is a bitmask of detected features.  The
 304  * least significant bit will be set if we've tried to probe.  Always access
 305  * this using `DISPATCH_LOAD' and `DISPATCH_STORE'.
 306  */
 307 static unsigned hwcaps = 0;
 308
 309 /* For each potentially interesting type which turned out not to exist or be
 310  * wanted, define a dummy macro for the sake of the next step.
 311  */
 312 #ifndef WANT_AT_HWCAP
 313 #  define WANT_AT_HWCAP(_)
 314 #endif
 315 #ifndef WANT_AT_HWCAP2
 316 #  define WANT_AT_HWCAP2(_)
 317 #endif
 318
 319 /* For each CPU family, define two lists.
 320  *
 321  *   * `WANTAUX' is a list of the `WANT_AT_MUMBLE' macros which the CPU
 322  *     family tried to register interest in above.  Each entry contains the
 323  *     interesting auxiliary vector entry type, the name of the union branch
 324  *     for its value, and the name of the slot in `struct auxprobe' in which
 325  *     to store the value.
 326  *
 327  *   * `CAPMAP' is a list describing the output features which the CPU family
 328  *     intends to satisfy from the auxiliary vector.  Each entry contains a
 329  *     feature name suffix, and the token name (for `check_env').
 330  */
 331 #if CPUFAM_ARMEL
 332 #  define WANTAUX(_)                                                    \
 333         WANT_AT_HWCAP(_)                                                \
 334         WANT_AT_HWCAP2(_)
 335 #  define CAPMAP(_)                                                     \
 336         _(ARM_VFP, "arm:vfp")                                           \
 337         _(ARM_NEON, "arm:neon")                                         \
 338         _(ARM_V4, "arm:v4")                                             \
 339         _(ARM_D32, "arm:d32")                                           \
 340         _(ARM_AES, "arm:aes")                                           \
 341         _(ARM_PMULL, "arm:pmull")
 342 #endif
 343 #if CPUFAM_ARM64
 344 #  define WANTAUX(_)                                                    \
 345         WANT_AT_HWCAP(_)
 346 #  define CAPMAP(_)                                                     \
 347         _(ARM_NEON, "arm:neon")                                         \
 348         _(ARM_AES, "arm:aes")                                           \
 349         _(ARM_PMULL, "arm:pmull")
 350 #endif
 351
 352 /* Build the bitmask for `hwcaps' from the `CAPMAP' list. */
 353 enum {
 354   HFI_PROBED = 0,
 355 #define HFI__ENUM(feat, tok) HFI_##feat,
 356   CAPMAP(HFI__ENUM)
 357 #undef HFI__ENUM
 358   HFI__END
 359 };
 360 enum {
 361   HF_PROBED = 1,
 362 #define HF__FLAG(feat, tok) HF_##feat = 1 << HFI_##feat,
 363   CAPMAP(HF__FLAG)
 364 #undef HF__FLAG
 365   HF__END
 366 };
 367
 368 /* Build a structure in which we can capture the interesting data from the
 369  * auxiliary vector.
 370  */
 371 #define AUXUTYPE_i long
 372 #define AUXUTYPE_u unsigned long
 373 #define AUXUTYPE_p const void *
 374 struct auxprobe {
 375 #define AUXPROBE__SLOT(type, ubranch, slot) AUXUTYPE_##ubranch slot;
 376   WANTAUX(AUXPROBE__SLOT)
 377 #undef AUXPROBE_SLOT
 378 };
 379
 380 /* --- @probe_hwcaps@ --- *
 381  *
 382  * Arguments:   ---
 383  *
 384  * Returns:     ---
 385  *
 386  * Use:         Attempt to find the auxiliary vector (which is well hidden)
 387  *              and discover interesting features from it.
 388  */
 389
 390 static void probe_hwcaps(void)
 391 {
 392   unsigned hw = HF_PROBED;
 393   struct auxprobe probed = { 0 };
 394
 395   /* Populate `probed' with the information we manage to retrieve from the
 396    * auxiliary vector.  Slots we couldn't find are left zero-valued.
 397    */
 398 #if defined(HAVE_GETAUXVAL)
 399   /* Shiny new libc lets us request individual entry types.  This is almost
 400    * too easy.
 401    */
 402 #  define CAP__GET(type, ubranch, slot)                                 \
 403         probed.slot = (AUXUTYPE_##ubranch)getauxval(type);
 404   WANTAUX(CAP__GET)
 405 #else
 406   /* Otherwise we're a bit stuck, really.  Modern Linux kernels make a copy
 407    * of the vector available in `/procc' so we could try that.
 408    *
 409    * The usual place is stuck on the end of the environment vector, but that
 410    * may well have moved, and we have no way of telling whether it has or
 411    * whether there was ever an auxiliary vector there at all; so don't do
 412    * that.
 413    */
 414   {
 415     FILE *fp = 0;
 416     unsigned char *p = 0, *q = 0;
 417     const struct auxentry *a;
 418     size_t sz, off, n;
 419
 420     /* Open the file and read it into a memory chunk. */
 421     if ((fp = fopen("/proc/self/auxv", "rb")) == 0) goto clean;
 422     sz = 4096; off = 0;
 423     if ((p = malloc(sz)) == 0) goto clean;
 424     for (;;) {
 425       n = fread(p + off, 1, sz - off, fp);
 426       off += n;
 427       if (off < sz) break;
 428       sz *= 2; if ((q = realloc(p, sz)) == 0) break;
 429       p = q;
 430     }
 431
 432     /* Work through the vector (or as much of it as we found) and extract the
 433      * types we're interested in.
 434      */
 435     for (a = (const struct auxentry *)p,
 436            n = sz/sizeof(struct auxentry);
 437          n--; a++) {
 438       switch (a->type) {
 439 #define CAP__SWITCH(type, ubranch, slot)                                \
 440         case type: probed.slot = a->value.ubranch; break;
 441         WANTAUX(CAP__SWITCH)
 442         case AT_NULL: goto clean;
 443       }
 444     }
 445
 446   clean:
 447     if (p) free(p);
 448     if (fp) fclose(fp);
 449   }
 450 #endif
 451
 452   /* Each CPU family now has to pick through what was found and stashed in
 453    * `probed', and set the appropriate flag bits in `hw'.
 454    */
 455 #if CPUFAM_ARMEL
 456   if (probed.hwcap & HWCAP_VFPv3) hw |= HF_ARM_VFP;
 457   if (probed.hwcap & HWCAP_NEON) hw |= HF_ARM_NEON;
 458   if (probed.hwcap & HWCAP_VFPD32) hw |= HF_ARM_D32;
 459   if (probed.hwcap & HWCAP_VFPv4) hw |= HF_ARM_V4;
 460 #  ifdef HWCAP2_AES
 461   if (probed.hwcap2 & HWCAP2_AES) hw |= HF_ARM_AES;
 462 #  endif
 463 #  ifdef HWCAP2_PMULL
 464   if (probed.hwcap2 & HWCAP2_PMULL) hw |= HF_ARM_PMULL;
 465 #  endif
 466 #endif
 467 #if CPUFAM_ARM64
 468   if (probed.hwcap & HWCAP_ASIMD) hw |= HF_ARM_NEON;
 469   if (probed.hwcap & HWCAP_AES) hw |= HF_ARM_AES;
 470   if (probed.hwcap & HWCAP_PMULL) hw |= HF_ARM_PMULL;
 471 #endif
 472
 473   /* Store the bitmask of features we probed for everyone to see. */
 474   DISPATCH_STORE(hwcaps, hw);
 475
 476   /* Finally, make a report about the things we found.  (Doing this earlier
 477    * will pointlessly widen the window in which multiple threads will do the
 478    * above auxiliary-vector probing.)
 479    */
 480 #define CAP__DEBUG(feat, tok)                                           \
 481   dispatch_debug("check auxv for feature `%s': %s", tok,                \
 482                  hw & HF_##feat ? "available" : "absent");
 483   CAPMAP(CAP__DEBUG)
 484 #undef CAP__DEBUG
 485 }
 486
 487 /* --- @get_hwcaps@ --- *
 488  *
 489  * Arguments:   ---
 490  *
 491  * Returns:     A mask of hardware capabilities and other features, as probed
 492  *              from the auxiliary vector.
 493  */
 494
 495 static unsigned get_hwcaps(void)
 496 {
 497   unsigned hw;
 498
 499   DISPATCH_LOAD(hwcaps, hw);
 500   if (!(hwcaps & HF_PROBED)) { probe_hwcaps(); DISPATCH_LOAD(hwcaps, hw); }
 501   return (hw);
 502 }
 503
 504 #endif
 505
 506 /*----- External interface ------------------------------------------------*/
 507
 508 /* --- @dispatch_debug@ --- *
 509  *
 510  * Arguments:   @const char *fmt@ = a format string
 511  *              @...@ = additional arguments
 512  *
 513  * Returns:     ---
 514  *
 515  * Use:         Writes a formatted message to standard output if dispatch
 516  *              debugging is enabled.
 517  */
 518
 519 void dispatch_debug(const char *fmt, ...)
 520 {
 521   va_list ap;
 522   const char *e = getenv("CATACOMB_CPUDISPATCH_DEBUG");
 523
 524   if (e && *e != 'n' && *e != '0') {
 525     va_start(ap, fmt);
 526     fputs("Catacomb CPUDISPATCH: ", stderr);
 527     vfprintf(stderr, fmt, ap);
 528     fputc('\n', stderr);
 529     va_end(ap);
 530   }
 531 }
 532
 533 /* --- @check_env@ --- *
 534  *
 535  * Arguments:   @const char *ftok@ = feature token
 536  *
 537  * Returns:     Zero if the feature is forced off; positive if it's forced
 538  *              on; negative if the user hasn't decided.
 539  *
 540  * Use:         Checks the environment variable `CATACOMB_CPUFEAT' for the
 541  *              feature token @ftok@.  The variable, if it exists, should be
 542  *              a space-separated sequence of `+tok' and `-tok' items.  These
 543  *              tokens may end in `*', which matches any suffix.
 544  */
 545
 546 static int IGNORABLE check_env(const char *ftok)
 547 {
 548   const char *p, *q, *pp;
 549   int d;
 550
 551   p = getenv("CATACOMB_CPUFEAT");
 552   if (!p) return (-1);
 553
 554   for (;;) {
 555     while (isspace((unsigned char)*p)) p++;
 556     if (!*p) return (-1);
 557     switch (*p) {
 558       case '+': d = +1; p++; break;
 559       case '-': d =  0; p++; break;
 560       default:  d = -1;      break;
 561     }
 562     for (q = p; *q && !isspace((unsigned char)*q); q++);
 563     if (d >= 0) {
 564       for (pp = ftok; p < q && *pp && *p == *pp; p++, pp++);
 565       if ((p == q && !*pp) || (*p == '*' && p + 1 == q)) return (d);
 566     }
 567     p = q;
 568   }
 569   return (-1);
 570 }
 571
 572 /* --- @cpu_feature_p@ --- *
 573  *
 574  * Arguments:   @unsigned feat@ = a @CPUFEAT_...@ code
 575  *
 576  * Returns:     Nonzero if the feature is available.
 577  */
 578
 579 #include <stdio.h>
 580
 581 static int IGNORABLE
 582   feat_debug(const char *ftok, const char *check, int verdict)
 583 {
 584   if (verdict >= 0) {
 585     dispatch_debug("feature `%s': %s -> %s", ftok, check,
 586                    verdict ? "available" : "absent");
 587   }
 588   return (verdict);
 589 }
 590
 591 int cpu_feature_p(int feat)
 592 {
 593   int IGNORABLE f;
 594   IGNORE(f);
 595 #define CASE_CPUFEAT(feat, ftok, cond) case CPUFEAT_##feat:             \
 596   if ((f = feat_debug(ftok, "environment override",                     \
 597                       check_env(ftok))) >= 0)                           \
 598     return (f);                                                         \
 599   else                                                                  \
 600     return (feat_debug(ftok, "runtime probe", cond));
 601
 602   switch (feat) {
 603 #if CPUFAM_X86 || CPUFAM_AMD64
 604     CASE_CPUFEAT(X86_SSE2, "x86:sse2",
 605                  cpuid_features_p(CPUID1D_SSE2, 0) &&
 606                  xmm_registers_available_p());
 607     CASE_CPUFEAT(X86_AESNI, "x86:aesni",
 608                  cpuid_features_p(CPUID1D_SSE2, CPUID1C_AESNI) &&
 609                  xmm_registers_available_p());
 610     CASE_CPUFEAT(X86_RDRAND, "x86:rdrand",
 611                  cpuid_features_p(0, CPUID1C_RDRAND) && rdrand_works_p());
 612     CASE_CPUFEAT(X86_AVX, "x86:avx",
 613                  cpuid_features_p(0, CPUID1C_AVX) &&
 614                  xmm_registers_available_p());
 615     CASE_CPUFEAT(X86_SSSE3, "x86:ssse3",
 616                  cpuid_features_p(0, CPUID1C_SSSE3) &&
 617                  xmm_registers_available_p());
 618     CASE_CPUFEAT(X86_PCLMUL, "x86:pclmul",
 619                  cpuid_features_p(0, CPUID1C_PCLMUL) &&
 620                  xmm_registers_available_p());
 621 #endif
 622 #ifdef CAPMAP
 623 #  define FEATP__CASE(feat, tok)                                        \
 624         CASE_CPUFEAT(feat, tok, get_hwcaps() & HF_##feat)
 625     CAPMAP(FEATP__CASE)
 626 #undef FEATP__CASE
 627 #endif
 628     default:
 629       dispatch_debug("denying unknown feature %d", feat);
 630       return (0);
 631   }
 632 #undef CASE_CPUFEAT
 633 }
 634
 635 /*----- That's all, folks -------------------------------------------------*/