1 /*
2  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #include <stdlib.h>
12 #include <string.h>
13 #include <features.h>
14 #ifndef __GLIBC_PREREQ
15 #define __GLIBC_PREREQ(a, b) 0
16 #endif
17 #if __GLIBC_PREREQ(2, 16)
18 #include <sys/auxv.h>
19 #else
20 #include <fcntl.h>
21 #include <unistd.h>
22 #include <errno.h>
23 #include <link.h>
24 #endif
25 #include "rtc_base/system/arch.h"
26 #include "system_wrappers/include/cpu_features_wrapper.h"
27 
28 #if defined(WEBRTC_ARCH_ARM_FAMILY)
29 #include <asm/hwcap.h>
30 
WebRtc_GetCPUFeaturesARM(void)31 uint64_t WebRtc_GetCPUFeaturesARM(void) {
32   uint64_t result = 0;
33   int architecture = 0;
34   unsigned long hwcap = 0;
35   const char* platform = NULL;
36 #if __GLIBC_PREREQ(2, 16)
37   hwcap = getauxval(AT_HWCAP);
38   platform = (const char*)getauxval(AT_PLATFORM);
39 #else
40   ElfW(auxv_t) auxv;
41   int fd = open("/proc/self/auxv", O_RDONLY);
42   if (fd >= 0) {
43     while (hwcap == 0 || platform == NULL) {
44       if (read(fd, &auxv, sizeof(auxv)) < (ssize_t)sizeof(auxv)) {
45         if (errno == EINTR)
46           continue;
47         break;
48       }
49       switch (auxv.a_type) {
50         case AT_HWCAP:
51           hwcap = auxv.a_un.a_val;
52           break;
53         case AT_PLATFORM:
54           platform = (const char*)auxv.a_un.a_val;
55           break;
56       }
57     }
58     close(fd);
59   }
60 #endif  // __GLIBC_PREREQ(2,16)
61 #if defined(__aarch64__)
62   architecture = 8;
63   if ((hwcap & HWCAP_FP) != 0)
64     result |= kCPUFeatureVFPv3;
65   if ((hwcap & HWCAP_ASIMD) != 0)
66     result |= kCPUFeatureNEON;
67 #else
68   if (platform != NULL) {
69     /* expect a string in the form "v6l" or "v7l", etc.
70      */
71     if (platform[0] == 'v' && '0' <= platform[1] && platform[1] <= '9' &&
72         (platform[2] == 'l' || platform[2] == 'b')) {
73       architecture = platform[1] - '0';
74     }
75   }
76   if ((hwcap & HWCAP_VFPv3) != 0)
77     result |= kCPUFeatureVFPv3;
78   if ((hwcap & HWCAP_NEON) != 0)
79     result |= kCPUFeatureNEON;
80 #endif
81   if (architecture >= 7)
82     result |= kCPUFeatureARMv7;
83   if (architecture >= 6)
84     result |= kCPUFeatureLDREXSTREX;
85   return result;
86 }
87 #endif  // WEBRTC_ARCH_ARM_FAMILY
88