Merge #10377: Use rdrand as entropy source on supported platforms
cb24c85
Use rdrand as entropy source on supported platforms (Pieter Wuille)
Tree-SHA512: c42eaa01a14e6bc097c70b6bf8540d61854c2f76cb32be69c2a3c411a126f7b4bf4a4486e4493c4cc367cc689319abde0d4adb799d29a54fd3e81767ce0766fc
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b63be2c685
4 changed files with 73 additions and 0 deletions
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@ -1170,6 +1170,7 @@ bool AppInitSanityChecks()
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// ********************************************************* Step 4: sanity checks
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// Initialize elliptic curve code
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RandomInit();
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ECC_Start();
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globalVerifyHandle.reset(new ECCVerifyHandle());
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@ -65,6 +65,64 @@ static inline int64_t GetPerformanceCounter()
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#endif
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}
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#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__)
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static std::atomic<bool> hwrand_initialized{false};
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static bool rdrand_supported = false;
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static constexpr uint32_t CPUID_F1_ECX_RDRAND = 0x40000000;
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static void RDRandInit()
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{
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//! When calling cpuid function #1, ecx register will have this set if RDRAND is available.
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// Avoid clobbering ebx, as that is used for PIC on x86.
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uint32_t eax, tmp, ecx, edx;
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__asm__ ("mov %%ebx, %1; cpuid; mov %1, %%ebx": "=a"(eax), "=g"(tmp), "=c"(ecx), "=d"(edx) : "a"(1));
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if (ecx & CPUID_F1_ECX_RDRAND) {
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LogPrintf("Using RdRand as entropy source\n");
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rdrand_supported = true;
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}
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hwrand_initialized.store(true);
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}
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#else
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static void RDRandInit() {}
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#endif
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static bool GetHWRand(unsigned char* ent32) {
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#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__)
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assert(hwrand_initialized.load(std::memory_order_relaxed));
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if (rdrand_supported) {
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uint8_t ok;
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// Not all assemblers support the rdrand instruction, write it in hex.
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#ifdef __i386__
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for (int iter = 0; iter < 4; ++iter) {
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uint32_t r1, r2;
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__asm__ volatile (".byte 0x0f, 0xc7, 0xf0;" // rdrand %eax
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".byte 0x0f, 0xc7, 0xf2;" // rdrand %edx
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"setc %2" :
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"=a"(r1), "=d"(r2), "=q"(ok) :: "cc");
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if (!ok) return false;
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WriteLE32(ent32 + 8 * iter, r1);
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WriteLE32(ent32 + 8 * iter + 4, r2);
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}
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#else
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uint64_t r1, r2, r3, r4;
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__asm__ volatile (".byte 0x48, 0x0f, 0xc7, 0xf0, " // rdrand %rax
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"0x48, 0x0f, 0xc7, 0xf3, " // rdrand %rbx
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"0x48, 0x0f, 0xc7, 0xf1, " // rdrand %rcx
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"0x48, 0x0f, 0xc7, 0xf2; " // rdrand %rdx
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"setc %4" :
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"=a"(r1), "=b"(r2), "=c"(r3), "=d"(r4), "=q"(ok) :: "cc");
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if (!ok) return false;
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WriteLE64(ent32, r1);
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WriteLE64(ent32 + 8, r2);
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WriteLE64(ent32 + 16, r3);
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WriteLE64(ent32 + 24, r4);
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#endif
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return true;
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}
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#endif
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return false;
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}
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void RandAddSeed()
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{
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// Seed with CPU performance counter
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@ -255,6 +313,11 @@ void GetStrongRandBytes(unsigned char* out, int num)
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GetOSRand(buf);
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hasher.Write(buf, 32);
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// Third source: HW RNG, if available.
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if (GetHWRand(buf)) {
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hasher.Write(buf, 32);
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}
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// Combine with and update state
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{
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std::unique_lock<std::mutex> lock(cs_rng_state);
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@ -381,3 +444,8 @@ FastRandomContext::FastRandomContext(bool fDeterministic) : requires_seed(!fDete
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uint256 seed;
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rng.SetKey(seed.begin(), 32);
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}
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void RandomInit()
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{
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RDRandInit();
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}
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@ -140,4 +140,7 @@ void GetOSRand(unsigned char *ent32);
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*/
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bool Random_SanityCheck();
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/** Initialize the RNG. */
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void RandomInit();
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#endif // BITCOIN_RANDOM_H
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@ -33,6 +33,7 @@ extern void noui_connect();
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BasicTestingSetup::BasicTestingSetup(const std::string& chainName)
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{
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RandomInit();
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ECC_Start();
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SetupEnvironment();
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SetupNetworking();
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