diff options
Diffstat (limited to 'third_party/abseil_cpp/absl/random/internal/randen_detect.cc')
| -rw-r--r-- | third_party/abseil_cpp/absl/random/internal/randen_detect.cc | 221 |
1 files changed, 0 insertions, 221 deletions
diff --git a/third_party/abseil_cpp/absl/random/internal/randen_detect.cc b/third_party/abseil_cpp/absl/random/internal/randen_detect.cc deleted file mode 100644 index d63230c255..0000000000 --- a/third_party/abseil_cpp/absl/random/internal/randen_detect.cc +++ /dev/null @@ -1,221 +0,0 @@ -// Copyright 2017 The Abseil Authors. -// -// 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 -// -// https://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. - -// HERMETIC NOTE: The randen_hwaes target must not introduce duplicate -// symbols from arbitrary system and other headers, since it may be built -// with different flags from other targets, using different levels of -// optimization, potentially introducing ODR violations. - -#include "absl/random/internal/randen_detect.h" - -#include <cstdint> -#include <cstring> - -#include "absl/random/internal/platform.h" - -#if defined(ABSL_ARCH_X86_64) -#define ABSL_INTERNAL_USE_X86_CPUID -#elif defined(ABSL_ARCH_PPC) || defined(ABSL_ARCH_ARM) || \ - defined(ABSL_ARCH_AARCH64) -#if defined(__ANDROID__) -#define ABSL_INTERNAL_USE_ANDROID_GETAUXVAL -#define ABSL_INTERNAL_USE_GETAUXVAL -#elif defined(__linux__) -#define ABSL_INTERNAL_USE_LINUX_GETAUXVAL -#define ABSL_INTERNAL_USE_GETAUXVAL -#endif -#endif - -#if defined(ABSL_INTERNAL_USE_X86_CPUID) -#if defined(_WIN32) || defined(_WIN64) -#include <intrin.h> // NOLINT(build/include_order) -#pragma intrinsic(__cpuid) -#else -// MSVC-equivalent __cpuid intrinsic function. -static void __cpuid(int cpu_info[4], int info_type) { - __asm__ volatile("cpuid \n\t" - : "=a"(cpu_info[0]), "=b"(cpu_info[1]), "=c"(cpu_info[2]), - "=d"(cpu_info[3]) - : "a"(info_type), "c"(0)); -} -#endif -#endif // ABSL_INTERNAL_USE_X86_CPUID - -// On linux, just use the c-library getauxval call. -#if defined(ABSL_INTERNAL_USE_LINUX_GETAUXVAL) - -extern "C" unsigned long getauxval(unsigned long type); // NOLINT(runtime/int) - -static uint32_t GetAuxval(uint32_t hwcap_type) { - return static_cast<uint32_t>(getauxval(hwcap_type)); -} - -#endif - -// On android, probe the system's C library for getauxval(). -// This is the same technique used by the android NDK cpu features library -// as well as the google open-source cpu_features library. -// -// TODO(absl-team): Consider implementing a fallback of directly reading -// /proc/self/auxval. -#if defined(ABSL_INTERNAL_USE_ANDROID_GETAUXVAL) -#include <dlfcn.h> - -static uint32_t GetAuxval(uint32_t hwcap_type) { - // NOLINTNEXTLINE(runtime/int) - typedef unsigned long (*getauxval_func_t)(unsigned long); - - dlerror(); // Cleaning error state before calling dlopen. - void* libc_handle = dlopen("libc.so", RTLD_NOW); - if (!libc_handle) { - return 0; - } - uint32_t result = 0; - void* sym = dlsym(libc_handle, "getauxval"); - if (sym) { - getauxval_func_t func; - memcpy(&func, &sym, sizeof(func)); - result = static_cast<uint32_t>((*func)(hwcap_type)); - } - dlclose(libc_handle); - return result; -} - -#endif - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace random_internal { - -// The default return at the end of the function might be unreachable depending -// on the configuration. Ignore that warning. -#if defined(__clang__) -#pragma clang diagnostic push -#pragma clang diagnostic ignored "-Wunreachable-code-return" -#endif - -// CPUSupportsRandenHwAes returns whether the CPU is a microarchitecture -// which supports the crpyto/aes instructions or extensions necessary to use the -// accelerated RandenHwAes implementation. -// -// 1. For x86 it is sufficient to use the CPUID instruction to detect whether -// the cpu supports AES instructions. Done. -// -// Fon non-x86 it is much more complicated. -// -// 2. When ABSL_INTERNAL_USE_GETAUXVAL is defined, use getauxval() (either -// the direct c-library version, or the android probing version which loads -// libc), and read the hardware capability bits. -// This is based on the technique used by boringssl uses to detect -// cpu capabilities, and should allow us to enable crypto in the android -// builds where it is supported. -// -// 3. Use the default for the compiler architecture. -// - -bool CPUSupportsRandenHwAes() { -#if defined(ABSL_INTERNAL_USE_X86_CPUID) - // 1. For x86: Use CPUID to detect the required AES instruction set. - int regs[4]; - __cpuid(reinterpret_cast<int*>(regs), 1); - return regs[2] & (1 << 25); // AES - -#elif defined(ABSL_INTERNAL_USE_GETAUXVAL) - // 2. Use getauxval() to read the hardware bits and determine - // cpu capabilities. - -#define AT_HWCAP 16 -#define AT_HWCAP2 26 -#if defined(ABSL_ARCH_PPC) - // For Power / PPC: Expect that the cpu supports VCRYPTO - // See https://members.openpowerfoundation.org/document/dl/576 - // VCRYPTO should be present in POWER8 >= 2.07. - // Uses Linux kernel constants from arch/powerpc/include/uapi/asm/cputable.h - static const uint32_t kVCRYPTO = 0x02000000; - const uint32_t hwcap = GetAuxval(AT_HWCAP2); - return (hwcap & kVCRYPTO) != 0; - -#elif defined(ABSL_ARCH_ARM) - // For ARM: Require crypto+neon - // http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0500f/CIHBIBBA.html - // Uses Linux kernel constants from arch/arm64/include/asm/hwcap.h - static const uint32_t kNEON = 1 << 12; - uint32_t hwcap = GetAuxval(AT_HWCAP); - if ((hwcap & kNEON) == 0) { - return false; - } - - // And use it again to detect AES. - static const uint32_t kAES = 1 << 0; - const uint32_t hwcap2 = GetAuxval(AT_HWCAP2); - return (hwcap2 & kAES) != 0; - -#elif defined(ABSL_ARCH_AARCH64) - // For AARCH64: Require crypto+neon - // http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0500f/CIHBIBBA.html - static const uint32_t kNEON = 1 << 1; - static const uint32_t kAES = 1 << 3; - const uint32_t hwcap = GetAuxval(AT_HWCAP); - return ((hwcap & kNEON) != 0) && ((hwcap & kAES) != 0); -#endif - -#else // ABSL_INTERNAL_USE_GETAUXVAL - // 3. By default, assume that the compiler default. - return ABSL_HAVE_ACCELERATED_AES ? true : false; - -#endif - // NOTE: There are some other techniques that may be worth trying: - // - // * Use an environment variable: ABSL_RANDOM_USE_HWAES - // - // * Rely on compiler-generated target-based dispatch. - // Using x86/gcc it might look something like this: - // - // int __attribute__((target("aes"))) HasAes() { return 1; } - // int __attribute__((target("default"))) HasAes() { return 0; } - // - // This does not work on all architecture/compiler combinations. - // - // * On Linux consider reading /proc/cpuinfo and/or /proc/self/auxv. - // These files have lines which are easy to parse; for ARM/AARCH64 it is quite - // easy to find the Features: line and extract aes / neon. Likewise for - // PPC. - // - // * Fork a process and test for SIGILL: - // - // * Many architectures have instructions to read the ISA. Unfortunately - // most of those require that the code is running in ring 0 / - // protected-mode. - // - // There are several examples. e.g. Valgrind detects PPC ISA 2.07: - // https://github.com/lu-zero/valgrind/blob/master/none/tests/ppc64/test_isa_2_07_part1.c - // - // MRS <Xt>, ID_AA64ISAR0_EL1 ; Read ID_AA64ISAR0_EL1 into Xt - // - // uint64_t val; - // __asm __volatile("mrs %0, id_aa64isar0_el1" :"=&r" (val)); - // - // * Use a CPUID-style heuristic database. - // - // * On Apple (__APPLE__), AES is available on Arm v8. - // https://stackoverflow.com/questions/45637888/how-to-determine-armv8-features-at-runtime-on-ios -} - -#if defined(__clang__) -#pragma clang diagnostic pop -#endif - -} // namespace random_internal -ABSL_NAMESPACE_END -} // namespace absl |