arm.cpp (4669B)
1 /* This Source Code Form is subject to the terms of the Mozilla Public 2 * License, v. 2.0. If a copy of the MPL was not distributed with this 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 4 5 /* compile-time and runtime tests for whether to use various ARM extensions */ 6 7 #include "arm.h" 8 #include "mozilla/Attributes.h" 9 10 #if defined(MOZILLA_ARM_HAVE_CPUID_DETECTION) 11 12 // arm.h has parallel #ifs which declare MOZILLA_ARM_HAVE_CPUID_DETECTION. 13 // We don't check it here so that we get compile errors if it's defined, but 14 // we don't compile one of these detection methods. The detection code here is 15 // based on the CPU detection in libtheora. 16 17 # if defined(__linux__) || defined(ANDROID) 18 # include <stdio.h> 19 # include <stdlib.h> 20 # include <string.h> 21 22 enum { 23 MOZILLA_HAS_EDSP_FLAG = 1, 24 MOZILLA_HAS_ARMV6_FLAG = 2, 25 MOZILLA_HAS_ARMV7_FLAG = 4, 26 MOZILLA_HAS_NEON_FLAG = 8, 27 MOZILLA_HAS_AES_FLAG = 16 28 }; 29 30 static unsigned get_arm_cpu_flags(void) { 31 unsigned flags; 32 FILE* fin; 33 bool armv6_processor = false; 34 flags = 0; 35 /*Reading /proc/self/auxv would be easier, but that doesn't work reliably on 36 Android. This also means that detection will fail in Scratchbox, which is 37 desirable, as NEON does not work in the qemu shipped with the Maemo 5 SDK. 38 I don't know if /proc/self/auxv would do any better in that case, anyway, 39 or if it would return random flags from the host CPU.*/ 40 fin = fopen("/proc/cpuinfo", "r"); 41 if (fin != nullptr) { 42 /*512 should be enough for anybody (it's even enough for all the flags that 43 x86 has accumulated... so far).*/ 44 char buf[512]; 45 while (fgets(buf, 511, fin) != nullptr) { 46 if (memcmp(buf, "Features", 8) == 0) { 47 char* p; 48 p = strstr(buf, " edsp"); 49 if (p != nullptr && (p[5] == ' ' || p[5] == '\n')) 50 flags |= MOZILLA_HAS_EDSP_FLAG; 51 p = strstr(buf, " neon"); 52 if (p != nullptr && (p[5] == ' ' || p[5] == '\n')) 53 flags |= MOZILLA_HAS_NEON_FLAG; 54 p = strstr(buf, " aes"); 55 if (p != nullptr && (p[4] == ' ' || p[4] == '\n')) { 56 flags |= MOZILLA_HAS_AES_FLAG; 57 } 58 } 59 if (memcmp(buf, "CPU architecture:", 17) == 0) { 60 int version; 61 version = atoi(buf + 17); 62 if (version >= 6) flags |= MOZILLA_HAS_ARMV6_FLAG; 63 if (version >= 7) flags |= MOZILLA_HAS_ARMV7_FLAG; 64 } 65 /* media/webrtc/trunk/src/system_wrappers/source/cpu_features_arm.c 66 * Unfortunately, it seems that certain ARMv6-based CPUs 67 * report an incorrect architecture number of 7! 68 * 69 * We try to correct this by looking at the 'elf_format' 70 * field reported by the 'Processor' field, which is of the 71 * form of "(v7l)" for an ARMv7-based CPU, and "(v6l)" for 72 * an ARMv6-one. 73 */ 74 if (memcmp(buf, "Processor\t:", 11) == 0) { 75 if (strstr(buf, "(v6l)") != 0) { 76 armv6_processor = true; 77 } 78 } 79 } 80 fclose(fin); 81 } 82 if (armv6_processor) { 83 // ARMv6 pretending to be ARMv7? clear flag 84 if (flags & MOZILLA_HAS_ARMV7_FLAG) { 85 flags &= ~MOZILLA_HAS_ARMV7_FLAG; 86 } 87 } 88 return flags; 89 } 90 91 // Cache a local copy so we only have to read /proc/cpuinfo once. 92 MOZ_RUNINIT static unsigned arm_cpu_flags = get_arm_cpu_flags(); 93 94 # if !defined(MOZILLA_PRESUME_EDSP) 95 static bool check_edsp(void) { 96 return (arm_cpu_flags & MOZILLA_HAS_EDSP_FLAG) != 0; 97 } 98 # endif 99 100 # if !defined(MOZILLA_PRESUME_ARMV6) 101 static bool check_armv6(void) { 102 return (arm_cpu_flags & MOZILLA_HAS_ARMV6_FLAG) != 0; 103 } 104 # endif 105 106 # if !defined(MOZILLA_PRESUME_ARMV7) 107 static bool check_armv7(void) { 108 return (arm_cpu_flags & MOZILLA_HAS_ARMV7_FLAG) != 0; 109 } 110 # endif 111 112 # if !defined(MOZILLA_PRESUME_NEON) 113 static bool check_neon(void) { 114 return (arm_cpu_flags & MOZILLA_HAS_NEON_FLAG) != 0; 115 } 116 # endif 117 118 # if !defined(MOZILLA_PRESUME_ARM_AES) 119 static bool check_aes(void) { 120 return (arm_cpu_flags & MOZILLA_HAS_AES_FLAG) != 0; 121 } 122 # endif 123 124 # endif // defined(__linux__) || defined(ANDROID) 125 126 namespace mozilla { 127 namespace arm_private { 128 # if !defined(MOZILLA_PRESUME_EDSP) 129 MOZ_RUNINIT bool edsp_enabled = check_edsp(); 130 # endif 131 # if !defined(MOZILLA_PRESUME_ARMV6) 132 MOZ_RUNINIT bool armv6_enabled = check_armv6(); 133 # endif 134 # if !defined(MOZILLA_PRESUME_ARMV7) 135 MOZ_RUNINIT bool armv7_enabled = check_armv7(); 136 # endif 137 # if !defined(MOZILLA_PRESUME_NEON) 138 MOZ_RUNINIT bool neon_enabled = check_neon(); 139 # endif 140 # if !defined(MOZILLA_PRESUME_ARM_AES) 141 MOZ_RUNINIT bool aes_enabled = check_aes(); 142 # endif 143 } // namespace arm_private 144 } // namespace mozilla 145 146 #endif // MOZILLA_ARM_HAVE_CPUID_DETECTION