tor-browser

The Tor Browser
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ppc_cpudetect.c (1991B)

      1 /*
      2 * Copyright (c) 2018, Alliance for Open Media. All rights reserved.
      3 *
      4 * This source code is subject to the terms of the BSD 2 Clause License and
      5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
      6 * was not distributed with this source code in the LICENSE file, you can
      7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
      8 * Media Patent License 1.0 was not distributed with this source code in the
      9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
     10 */
     11 
     12 #include <fcntl.h>
     13 #include <unistd.h>
     14 #include <stdint.h>
     15 
     16 #include "config/aom_config.h"
     17 
     18 #include "aom_ports/ppc.h"
     19 
     20 #if CONFIG_RUNTIME_CPU_DETECT
     21 #include <asm/cputable.h>
     22 #include <linux/auxvec.h>
     23 
     24 static int cpu_env_flags(int *flags) {
     25  char *env;
     26  env = getenv("AOM_SIMD_CAPS");
     27  if (env && *env) {
     28    *flags = (int)strtol(env, NULL, 0);
     29    return 0;
     30  }
     31  *flags = 0;
     32  return -1;
     33 }
     34 
     35 static int cpu_env_mask(void) {
     36  char *env;
     37  env = getenv("AOM_SIMD_CAPS_MASK");
     38  return env && *env ? (int)strtol(env, NULL, 0) : ~0;
     39 }
     40 
     41 int ppc_simd_caps(void) {
     42  int flags;
     43  int mask;
     44  int fd;
     45  ssize_t count;
     46  unsigned int i;
     47  uint64_t buf[64];
     48 
     49  // If AOM_SIMD_CAPS_MASK is set then allow only those capabilities.
     50  if (!cpu_env_flags(&flags)) {
     51    return flags;
     52  }
     53 
     54  mask = cpu_env_mask();
     55 
     56  fd = open("/proc/self/auxv", O_RDONLY);
     57  if (fd < 0) {
     58    return 0;
     59  }
     60 
     61  while ((count = read(fd, buf, sizeof(buf))) > 0) {
     62    for (i = 0; i < (count / sizeof(*buf)); i += 2) {
     63      if (buf[i] == AT_HWCAP) {
     64 #if HAVE_VSX
     65        if (buf[i + 1] & PPC_FEATURE_HAS_VSX) {
     66          flags |= HAS_VSX;
     67        }
     68 #endif  // HAVE_VSX
     69        goto out_close;
     70      } else if (buf[i] == AT_NULL) {
     71        goto out_close;
     72      }
     73    }
     74  }
     75 out_close:
     76  close(fd);
     77  return flags & mask;
     78 }
     79 #else
     80 // If there is no RTCD the function pointers are not used and can not be
     81 // changed.
     82 int ppc_simd_caps(void) { return 0; }
     83 #endif  // CONFIG_RUNTIME_CPU_DETECT