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 <features.h>
12 #include <stdlib.h>
13 #include <string.h>
14
15 #ifdef __GLIBC_PREREQ
16 #define WEBRTC_GLIBC_PREREQ(a, b) __GLIBC_PREREQ(a, b)
17 #else
18 #define WEBRTC_GLIBC_PREREQ(a, b) 0
19 #endif
20
21 #if WEBRTC_GLIBC_PREREQ(2, 16)
22 #include <sys/auxv.h>
23 #else
24 #include <errno.h>
25 #include <fcntl.h>
26 #include <link.h>
27 #include <unistd.h>
28 #endif
29
30 #include "rtc_base/system/arch.h"
31 #include "system_wrappers/include/cpu_features_wrapper.h"
32
33 #if defined(WEBRTC_ARCH_ARM_FAMILY)
34 #include <asm/hwcap.h>
35
36 namespace webrtc {
37
GetCPUFeaturesARM(void)38 uint64_t GetCPUFeaturesARM(void) {
39 uint64_t result = 0;
40 int architecture = 0;
41 uint64_t hwcap = 0;
42 const char* platform = NULL;
43 #if WEBRTC_GLIBC_PREREQ(2, 16)
44 hwcap = getauxval(AT_HWCAP);
45 platform = (const char*)getauxval(AT_PLATFORM);
46 #else
47 ElfW(auxv_t) auxv;
48 int fd = open("/proc/self/auxv", O_RDONLY);
49 if (fd >= 0) {
50 while (hwcap == 0 || platform == NULL) {
51 if (read(fd, &auxv, sizeof(auxv)) < (ssize_t)sizeof(auxv)) {
52 if (errno == EINTR)
53 continue;
54 break;
55 }
56 switch (auxv.a_type) {
57 case AT_HWCAP:
58 hwcap = auxv.a_un.a_val;
59 break;
60 case AT_PLATFORM:
61 platform = (const char*)auxv.a_un.a_val;
62 break;
63 }
64 }
65 close(fd);
66 }
67 #endif // WEBRTC_GLIBC_PREREQ(2, 16)
68 #if defined(__aarch64__)
69 (void)platform;
70 architecture = 8;
71 if ((hwcap & HWCAP_FP) != 0)
72 result |= kCPUFeatureVFPv3;
73 if ((hwcap & HWCAP_ASIMD) != 0)
74 result |= kCPUFeatureNEON;
75 #else
76 if (platform != NULL) {
77 /* expect a string in the form "v6l" or "v7l", etc.
78 */
79 if (platform[0] == 'v' && '0' <= platform[1] && platform[1] <= '9' &&
80 (platform[2] == 'l' || platform[2] == 'b')) {
81 architecture = platform[1] - '0';
82 }
83 }
84 if ((hwcap & HWCAP_VFPv3) != 0)
85 result |= kCPUFeatureVFPv3;
86 if ((hwcap & HWCAP_NEON) != 0)
87 result |= kCPUFeatureNEON;
88 #endif
89 if (architecture >= 7)
90 result |= kCPUFeatureARMv7;
91 if (architecture >= 6)
92 result |= kCPUFeatureLDREXSTREX;
93 return result;
94 }
95
96 } // namespace webrtc
97 #endif // WEBRTC_ARCH_ARM_FAMILY
98