From 0311956fa44265db45641df94544df72bfc7782f Mon Sep 17 00:00:00 2001
From: Brad Smith <brad@comstyle.com>
Date: Sat, 29 Oct 2022 19:27:16 -0400
Subject: [PATCH] Add OpenBSD/arm64 support for detection of CRC32 and PMULL

---
 util/crc32c_arm64.cc | 40 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 36 insertions(+), 4 deletions(-)

diff --git a/util/crc32c_arm64.cc b/util/crc32c_arm64.cc
index a799fb6058c..4885f4fe101 100644
--- a/util/crc32c_arm64.cc
+++ b/util/crc32c_arm64.cc
@@ -22,6 +22,12 @@
 #if defined(__APPLE__)
 #include <sys/sysctl.h>
 #endif
+#if defined(__OpenBSD__)
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <machine/cpu.h>
+#include <machine/armreg.h>
+#endif
 
 #ifdef HAVE_ARM64_CRYPTO
 /* unfolding to compute 8 * 3 = 24 bytes parallelly */
@@ -46,7 +52,7 @@
 extern bool pmull_runtime_flag;
 
 uint32_t crc32c_runtime_check(void) {
-#if !defined(__APPLE__)
+#if defined(ROCKSDB_AUXV_GETAUXVAL_PRESENT) || defined(__FreeBSD__)
   uint64_t auxv = 0;
 #if defined(ROCKSDB_AUXV_GETAUXVAL_PRESENT)
   auxv = getauxval(AT_HWCAP);
@@ -54,16 +60,29 @@ uint32_t crc32c_runtime_check(void) {
   elf_aux_info(AT_HWCAP, &auxv, sizeof(auxv));
 #endif
   return (auxv & HWCAP_CRC32) != 0;
-#else
+#elif defined(__APPLE__)
   int r;
   size_t l = sizeof(r);
   if (sysctlbyname("hw.optional.armv8_crc32", &r, &l, NULL, 0) == -1) return 0;
   return r == 1;
+#elif defined(__OpenBSD__)
+  int r = 0;
+  const int isar0_mib[] = { CTL_MACHDEP, CPU_ID_AA64ISAR0 };
+  uint64_t isar0;
+  size_t len = sizeof(isar0);
+
+  if (sysctl(isar0_mib, 2, &isar0, &len, NULL, 0) != -1) {
+      if (ID_AA64ISAR0_CRC32(isar0) >= ID_AA64ISAR0_CRC32_BASE)
+        r = 1;
+  }
+  return r;
+#else
+  return 0;
 #endif
 }
 
 bool crc32c_pmull_runtime_check(void) {
-#if !defined(__APPLE__)
+#if defined(ROCKSDB_AUXV_GETAUXVAL_PRESENT) || defined(__FreeBSD__)
   uint64_t auxv = 0;
 #if defined(ROCKSDB_AUXV_GETAUXVAL_PRESENT)
   auxv = getauxval(AT_HWCAP);
@@ -71,8 +90,21 @@ bool crc32c_pmull_runtime_check(void) {
   elf_aux_info(AT_HWCAP, &auxv, sizeof(auxv));
 #endif
   return (auxv & HWCAP_PMULL) != 0;
-#else
+#elif defined(__APPLE__)
   return true;
+#elif defined(__OpenBSD__)
+  bool r = false;
+  const int isar0_mib[] = { CTL_MACHDEP, CPU_ID_AA64ISAR0 };
+  uint64_t isar0;
+  size_t len = sizeof(isar0);
+
+  if (sysctl(isar0_mib, 2, &isar0, &len, NULL, 0) != -1) {
+      if (ID_AA64ISAR0_AES(isar0) >= ID_AA64ISAR0_AES_PMULL)
+        r = true;
+  }
+  return r;
+#else
+  return false;
 #endif
 }