Check for sys/auxv.h (#6359)

Summary:
Check for sys/auxv.h and getauxval before using them as they are not
always available (for example on uclibc)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6359

Differential Revision: D20239797

fbshipit-source-id: 175a098094d81545628c2372e7c388e70a32fd48

CMakeLists.txt

@@ -481,6 +481,11 @@ if(HAVE_SCHED_GETCPU)
   add_definitions(-DROCKSDB_SCHED_GETCPU_PRESENT)
 endif()
 
+check_cxx_symbol_exists(getauxval auvx.h HAVE_AUXV_GETAUXVAL)
+if(HAVE_AUXV_GETAUXVAL)
+  add_definitions(-DROCKSDB_AUXV_GETAUXVAL_PRESENT)
+endif()
+
 include_directories(${PROJECT_SOURCE_DIR})
 include_directories(${PROJECT_SOURCE_DIR}/include)
 include_directories(SYSTEM ${PROJECT_SOURCE_DIR}/third-party/gtest-1.8.1/fused-src)

build_tools/build_detect_platform

@@ -508,6 +508,20 @@ EOF
         fi
     fi
 
+    if ! test $ROCKSDB_DISABLE_AUXV_GETAUXVAL; then
+        # Test whether getauxval is supported
+        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+          #include <sys/auxv.h>
+          int main() {
+            uint64_t auxv = getauxval(AT_HWCAP);
+            (void)auxv;
+          }
+EOF
+        if [ "$?" = 0 ]; then
+            COMMON_FLAGS="$COMMON_FLAGS -DROCKSDB_AUXV_GETAUXVAL_PRESENT"
+        fi
+    fi
+
     if ! test $ROCKSDB_DISABLE_ALIGNED_NEW; then
         # Test whether c++17 aligned-new is supported
         $CXX $PLATFORM_CXXFLAGS -faligned-new -x c++ - -o /dev/null 2>/dev/null <<EOF

util/crc32c.cc

@@ -25,7 +25,9 @@
 #include "util/crc32c_ppc_constants.h"
 
 #if __linux__
+#ifdef ROCKSDB_AUXV_GETAUXVAL_PRESENT
 #include <sys/auxv.h>
+#endif
 
 #ifndef PPC_FEATURE2_VEC_CRYPTO
 #define PPC_FEATURE2_VEC_CRYPTO 0x02000000
@@ -451,7 +453,7 @@ uint32_t ExtendPPCImpl(uint32_t crc, const char *buf, size_t size) {
 static int arch_ppc_probe(void) {
   arch_ppc_crc32 = 0;
 
-#if defined(__powerpc64__)
+#if defined(__powerpc64__) && defined(ROCKSDB_AUXV_GETAUXVAL_PRESENT)
   if (getauxval(AT_HWCAP2) & PPC_FEATURE2_VEC_CRYPTO) arch_ppc_crc32 = 1;
 #endif /* __powerpc64__ */
 

util/crc32c_arm64.cc

@@ -8,7 +8,9 @@
 #if defined(__linux__) && defined(HAVE_ARM64_CRC)
 
 #include <asm/hwcap.h>
+#ifdef ROCKSDB_AUXV_GETAUXVAL_PRESENT
 #include <sys/auxv.h>
+#endif
 #ifndef HWCAP_CRC32
 #define HWCAP_CRC32 (1 << 7)
 #endif
@@ -34,8 +36,12 @@
 #endif
 
 uint32_t crc32c_runtime_check(void) {
+#ifdef ROCKSDB_AUXV_GETAUXVAL_PRESENT
   uint64_t auxv = getauxval(AT_HWCAP);
   return (auxv & HWCAP_CRC32) != 0;
+#else
+  return 0;
+#endif
 }
 
 uint32_t crc32c_arm64(uint32_t crc, unsigned char const *data,