Cherry picked commit 'Preserve floating point state when calling rand…

…omx_calculate_hash' from tevador/RandomX@6a764e9
Veil-Project · Jan 26, 2021 · c6a8be7 · c6a8be7
1 parent 6cb9858
commit c6a8be7
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Showing 3 changed files with 18 additions and 2 deletions.
diff --git a/src/crypto/randomx/randomx.cpp b/src/crypto/randomx/randomx.cpp
@@ -39,7 +39,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <limits>
 #include "utiltime.h"
 #include "logging.h"
-
+#include <cfenv>
 extern "C" {
 
 	randomx_flags randomx_get_flags() {
@@ -493,6 +493,8 @@ extern "C" {
 		assert(machine != nullptr);
 		assert(inputSize == 0 || input != nullptr);
 		assert(output != nullptr);
+        fenv_t fpstate;
+        fegetenv(&fpstate);
 		alignas(16) uint64_t tempHash[8];
 		int blakeResult = blake2b(tempHash, sizeof(tempHash), input, inputSize, nullptr, 0);
 		assert(blakeResult == 0);
@@ -505,6 +507,7 @@ extern "C" {
 		}
 		machine->run(&tempHash);
 		machine->getFinalResult(output, RANDOMX_HASH_SIZE);
+        fesetenv(&fpstate);
 	}
 
     void randomx_calculate_hash_first(randomx_vm* machine, const void* input, size_t inputSize) {

diff --git a/src/crypto/randomx/randomx.h b/src/crypto/randomx/randomx.h
@@ -245,6 +245,8 @@ RANDOMX_EXPORT void randomx_calculate_hash(randomx_vm *machine, const void *inpu
  *                              and begin the calculation of the next hash.
  * randomx_calculate_hash_last  will output the hash value of the previous input.
  *
+ * WARNING: These functions may alter the floating point rounding mode of the calling thread.
+ *
  * @param machine is a pointer to a randomx_vm structure. Must not be NULL.
  * @param tempHash an array of 8 64-bit values used to store intermediate data between calls to randomx_calculate_hash_first and randomx_calculate_hash_next.
  * @param input is a pointer to memory to be hashed. Must not be NULL.

diff --git a/src/test/randomx_tests.cpp b/src/test/randomx_tests.cpp
@@ -18,8 +18,8 @@
 #include "crypto/randomx/intrin_portable.h"
 #include "crypto/randomx/jit_compiler.hpp"
 #include "crypto/randomx/aes_hash.hpp"
-
 #include "crypto/randomx/utility.hpp"
+#include <cfenv>
 
 #include <array>
 
@@ -1164,6 +1164,10 @@ BOOST_AUTO_TEST_CASE(randomx_run_tests)
         assert(cacheMemory[33554431] == 0x1f47f056d05cd99b);
     });
 
+    if (cache != nullptr)
+    randomx_release_cache(cache);
+    cache = randomx_alloc_cache(RANDOMX_FLAG_DEFAULT);
+
     runTest("Hash batch test", RANDOMX_HAVE_COMPILER && stringsEqual(RANDOMX_ARGON_SALT, "RandomX\x03"), []() {
         char hash1[RANDOMX_HASH_SIZE];
         char hash2[RANDOMX_HASH_SIZE];
@@ -1183,6 +1187,13 @@ BOOST_AUTO_TEST_CASE(randomx_run_tests)
         assert(equalsHex(hash3, "c36d4ed4191e617309867ed66a443be4075014e2b061bcdaf9ce7b721d2b77a8"));
     });
 
+    runTest("Preserve rounding mode", RANDOMX_FREQ_CFROUND > 0, []() {
+        fesetround(FE_TONEAREST);
+        char hash[RANDOMX_HASH_SIZE];
+        calcStringHash("test key 000", "Lorem ipsum dolor sit amet", &hash);
+        assert(fegetround() == FE_TONEAREST);
+    });
+
     randomx_destroy_vm(vm);
     vm = nullptr;