--- /dev/null
+// Copyright 2017 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "cpu_features_macros.h"
+#include "internal/filesystem.h"
+#include "internal/hwcaps.h"
+#include "internal/string_view.h"
+
+#if defined(NDEBUG)
+#define D(...)
+#else
+#include <stdio.h>
+#define D(...) \
+ do { \
+ printf(__VA_ARGS__); \
+ fflush(stdout); \
+ } while (0)
+#endif
+
+#if defined(CPU_FEATURES_ARCH_MIPS) || defined(CPU_FEATURES_ARCH_ANY_ARM)
+#define HWCAPS_ANDROID_MIPS_OR_ARM
+#endif
+
+#if defined(CPU_FEATURES_OS_LINUX_OR_ANDROID) && \
+ !defined(HWCAPS_ANDROID_MIPS_OR_ARM)
+#define HWCAPS_REGULAR_LINUX
+#endif
+
+#if defined(HWCAPS_ANDROID_MIPS_OR_ARM) || defined(HWCAPS_REGULAR_LINUX)
+#define HWCAPS_SUPPORTED
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+// Implementation of GetElfHwcapFromGetauxval
+////////////////////////////////////////////////////////////////////////////////
+
+// On Linux we simply use getauxval.
+#if defined(HWCAPS_REGULAR_LINUX)
+#include <dlfcn.h>
+#include <sys/auxv.h>
+static unsigned long GetElfHwcapFromGetauxval(uint32_t hwcap_type) {
+ return getauxval(hwcap_type);
+}
+#endif // defined(HWCAPS_REGULAR_LINUX)
+
+// On Android we probe the system's C library for a 'getauxval' function and
+// call it if it exits, or return 0 for failure. This function is available
+// since API level 20.
+//
+// This code does *NOT* check for '__ANDROID_API__ >= 20' to support the edge
+// case where some NDK developers use headers for a platform that is newer than
+// the one really targetted by their application. This is typically done to use
+// newer native APIs only when running on more recent Android versions, and
+// requires careful symbol management.
+//
+// Note that getauxval() can't really be re-implemented here, because its
+// implementation does not parse /proc/self/auxv. Instead it depends on values
+// that are passed by the kernel at process-init time to the C runtime
+// initialization layer.
+#if defined(HWCAPS_ANDROID_MIPS_OR_ARM)
+#include <dlfcn.h>
+#define AT_HWCAP 16
+#define AT_HWCAP2 26
+#define AT_PLATFORM 15
+#define AT_BASE_PLATFORM 24
+
+typedef unsigned long getauxval_func_t(unsigned long);
+
+static uint32_t GetElfHwcapFromGetauxval(uint32_t hwcap_type) {
+ uint32_t ret = 0;
+ void* libc_handle = NULL;
+ getauxval_func_t* func = NULL;
+
+ dlerror(); // Cleaning error state before calling dlopen.
+ libc_handle = dlopen("libc.so", RTLD_NOW);
+ if (!libc_handle) {
+ D("Could not dlopen() C library: %s\n", dlerror());
+ return 0;
+ }
+ func = (getauxval_func_t*)dlsym(libc_handle, "getauxval");
+ if (!func) {
+ D("Could not find getauxval() in C library\n");
+ } else {
+ // Note: getauxval() returns 0 on failure. Doesn't touch errno.
+ ret = (uint32_t)(*func)(hwcap_type);
+ }
+ dlclose(libc_handle);
+ return ret;
+}
+#endif // defined(HWCAPS_ANDROID_MIPS_OR_ARM)
+
+#if defined(HWCAPS_SUPPORTED)
+////////////////////////////////////////////////////////////////////////////////
+// Implementation of GetHardwareCapabilities for Android and Linux
+////////////////////////////////////////////////////////////////////////////////
+
+// Fallback when getauxval is not available, retrieves hwcaps from
+// "/proc/self/auxv".
+static uint32_t GetElfHwcapFromProcSelfAuxv(uint32_t hwcap_type) {
+ struct {
+ uint32_t tag;
+ uint32_t value;
+ } entry;
+ uint32_t result = 0;
+ const char filepath[] = "/proc/self/auxv";
+ const int fd = CpuFeatures_OpenFile(filepath);
+ if (fd < 0) {
+ D("Could not open %s\n", filepath);
+ return 0;
+ }
+ for (;;) {
+ const int ret = CpuFeatures_ReadFile(fd, (char*)&entry, sizeof entry);
+ if (ret < 0) {
+ D("Error while reading %s\n", filepath);
+ break;
+ }
+ // Detect end of list.
+ if (ret == 0 || (entry.tag == 0 && entry.value == 0)) {
+ break;
+ }
+ if (entry.tag == hwcap_type) {
+ result = entry.value;
+ break;
+ }
+ }
+ CpuFeatures_CloseFile(fd);
+ return result;
+}
+
+// Retrieves hardware capabilities by first trying to call getauxval, if not
+// available falls back to reading "/proc/self/auxv".
+static unsigned long GetHardwareCapabilitiesFor(uint32_t type) {
+ unsigned long hwcaps = GetElfHwcapFromGetauxval(type);
+ if (!hwcaps) {
+ D("Parsing /proc/self/auxv to extract ELF hwcaps!\n");
+ hwcaps = GetElfHwcapFromProcSelfAuxv(type);
+ }
+ return hwcaps;
+}
+
+HardwareCapabilities CpuFeatures_GetHardwareCapabilities(void) {
+ HardwareCapabilities capabilities;
+ capabilities.hwcaps = GetHardwareCapabilitiesFor(AT_HWCAP);
+ capabilities.hwcaps2 = GetHardwareCapabilitiesFor(AT_HWCAP2);
+ return capabilities;
+}
+
+PlatformType kEmptyPlatformType;
+
+PlatformType CpuFeatures_GetPlatformType(void) {
+ PlatformType type = kEmptyPlatformType;
+ char *platform = (char *)GetHardwareCapabilitiesFor(AT_PLATFORM);
+ char *base_platform = (char *)GetHardwareCapabilitiesFor(AT_BASE_PLATFORM);
+
+ if (platform != NULL)
+ CpuFeatures_StringView_CopyString(str(platform), type.platform,
+ sizeof(type.platform));
+ if (base_platform != NULL)
+ CpuFeatures_StringView_CopyString(str(base_platform), type.base_platform,
+ sizeof(type.base_platform));
+ return type;
+}
+#else // (defined(HWCAPS_SUPPORTED)
+
+////////////////////////////////////////////////////////////////////////////////
+// Implementation of GetHardwareCapabilities for unsupported platforms.
+////////////////////////////////////////////////////////////////////////////////
+
+const HardwareCapabilities kEmptyHardwareCapabilities;
+HardwareCapabilities CpuFeatures_GetHardwareCapabilities(void) {
+ return kEmptyHardwareCapabilities;
+}
+#endif
Code Review / iec.git / blobdiff