diff options
Diffstat (limited to 'src/random.cpp')
| -rw-r--r-- | src/random.cpp | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/src/random.cpp b/src/random.cpp index e1ccfa5f24..67efc7d945 100644 --- a/src/random.cpp +++ b/src/random.cpp @@ -65,6 +65,70 @@ static inline int64_t GetPerformanceCounter() #endif } + +#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__) +static std::atomic<bool> hwrand_initialized{false}; +static bool rdrand_supported = false; +static constexpr uint32_t CPUID_F1_ECX_RDRAND = 0x40000000; +static void RDRandInit() +{ + uint32_t eax, ecx, edx; +#if defined(__i386__) && ( defined(__PIC__) || defined(__PIE__)) + // Avoid clobbering ebx, as that is used for PIC on x86. + uint32_t tmp; + __asm__ ("mov %%ebx, %1; cpuid; mov %1, %%ebx": "=a"(eax), "=g"(tmp), "=c"(ecx), "=d"(edx) : "a"(1)); +#else + uint32_t ebx; + __asm__ ("cpuid": "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx) : "a"(1)); +#endif + //! When calling cpuid function #1, ecx register will have this set if RDRAND is available. + if (ecx & CPUID_F1_ECX_RDRAND) { + LogPrintf("Using RdRand as entropy source\n"); + rdrand_supported = true; + } + hwrand_initialized.store(true); +} +#else +static void RDRandInit() {} +#endif + +static bool GetHWRand(unsigned char* ent32) { +#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__) + assert(hwrand_initialized.load(std::memory_order_relaxed)); + if (rdrand_supported) { + uint8_t ok; + // Not all assemblers support the rdrand instruction, write it in hex. +#ifdef __i386__ + for (int iter = 0; iter < 4; ++iter) { + uint32_t r1, r2; + __asm__ volatile (".byte 0x0f, 0xc7, 0xf0;" // rdrand %eax + ".byte 0x0f, 0xc7, 0xf2;" // rdrand %edx + "setc %2" : + "=a"(r1), "=d"(r2), "=q"(ok) :: "cc"); + if (!ok) return false; + WriteLE32(ent32 + 8 * iter, r1); + WriteLE32(ent32 + 8 * iter + 4, r2); + } +#else + uint64_t r1, r2, r3, r4; + __asm__ volatile (".byte 0x48, 0x0f, 0xc7, 0xf0, " // rdrand %rax + "0x48, 0x0f, 0xc7, 0xf3, " // rdrand %rbx + "0x48, 0x0f, 0xc7, 0xf1, " // rdrand %rcx + "0x48, 0x0f, 0xc7, 0xf2; " // rdrand %rdx + "setc %4" : + "=a"(r1), "=b"(r2), "=c"(r3), "=d"(r4), "=q"(ok) :: "cc"); + if (!ok) return false; + WriteLE64(ent32, r1); + WriteLE64(ent32 + 8, r2); + WriteLE64(ent32 + 16, r3); + WriteLE64(ent32 + 24, r4); +#endif + return true; + } +#endif + return false; +} + void RandAddSeed() { // Seed with CPU performance counter @@ -255,6 +319,11 @@ void GetStrongRandBytes(unsigned char* out, int num) GetOSRand(buf); hasher.Write(buf, 32); + // Third source: HW RNG, if available. + if (GetHWRand(buf)) { + hasher.Write(buf, 32); + } + // Combine with and update state { std::unique_lock<std::mutex> lock(cs_rng_state); @@ -381,3 +450,8 @@ FastRandomContext::FastRandomContext(bool fDeterministic) : requires_seed(!fDete uint256 seed; rng.SetKey(seed.begin(), 32); } + +void RandomInit() +{ + RDRandInit(); +} |