8310656: RISC-V: __builtin___clear_cache can fail silently.

Reviewed-by: luhenry, stuefe, fyang

src/hotspot/cpu/riscv/icache_riscv.cpp

@@ -1,6 +1,7 @@
 /*
- * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2020, 2022, Huawei Technologies Co., Ltd. All rights reserved.
+ * Copyright (c) 2023, Rivos Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,6 +26,8 @@
 
 #include "precompiled.hpp"
 #include "asm/macroAssembler.hpp"
+#include "riscv_flush_icache.hpp"
+#include "runtime/java.hpp"
 #include "runtime/icache.hpp"
 
 #define __ _masm->
@@ -33,16 +36,22 @@ static int icache_flush(address addr, int lines, int magic) {
   // To make a store to instruction memory visible to all RISC-V harts,
   // the writing hart has to execute a data FENCE before requesting that
   // all remote RISC-V harts execute a FENCE.I.
-  //
-  // No sush assurance is defined at the interface level of the builtin
-  // method, and so we should make sure it works.
+
+  // We need to make sure stores happens before the I/D cache synchronization.
   __asm__ volatile("fence rw, rw" : : : "memory");
 
-  __builtin___clear_cache(addr, addr + (lines << ICache::log2_line_size));
+  RiscvFlushIcache::flush((uintptr_t)addr, ((uintptr_t)lines) << ICache::log2_line_size);
+
   return magic;
 }
 
 void ICacheStubGenerator::generate_icache_flush(ICache::flush_icache_stub_t* flush_icache_stub) {
+  // Only riscv_flush_icache is supported as I-cache synchronization.
+  // We must make sure the VM can execute such without error.
+  if (!RiscvFlushIcache::test()) {
+    vm_exit_during_initialization("Unable to synchronize I-cache");
+  }
+
   address start = (address)icache_flush;
   *flush_icache_stub = (ICache::flush_icache_stub_t)start;
 

src/hotspot/os_cpu/linux_riscv/riscv_flush_icache.cpp

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, Rivos Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "logging/log.hpp"
+#include "riscv_flush_icache.hpp"
+#include "runtime/os.hpp"
+#include "runtime/vm_version.hpp"
+#include "utilities/debug.hpp"
+
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#ifndef NR_riscv_flush_icache
+#ifndef NR_arch_specific_syscall
+#define NR_arch_specific_syscall 244
+#endif
+#define NR_riscv_flush_icache (NR_arch_specific_syscall + 15)
+#endif
+
+#define SYS_RISCV_FLUSH_ICACHE_LOCAL 1UL
+#define SYS_RISCV_FLUSH_ICACHE_ALL   0UL
+
+static long sys_flush_icache(uintptr_t start, uintptr_t end , uintptr_t flags) {
+  return syscall(NR_riscv_flush_icache, start, end, flags);
+}
+
+bool RiscvFlushIcache::test() {
+  alignas(64) char memory[64];
+  long ret = sys_flush_icache((uintptr_t)&memory[0],
+                              (uintptr_t)&memory[sizeof(memory) - 1],
+                              SYS_RISCV_FLUSH_ICACHE_ALL);
+  if (ret == 0) {
+    return true;
+  }
+  int err = errno;                                                        \
+  log_error(os)("Syscall: RISCV_FLUSH_ICACHE not available; error='%s' (errno=%s)",
+                os::strerror(err), os::errno_name(err));
+  return false;
+}
+
+void RiscvFlushIcache::flush(uintptr_t start, uintptr_t end) {
+  long ret = sys_flush_icache(start, end, SYS_RISCV_FLUSH_ICACHE_ALL);
+  guarantee_with_errno(ret == 0, "riscv_flush_icache failed");
+}

src/hotspot/os_cpu/linux_riscv/riscv_flush_icache.hpp

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, Rivos Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef OS_LINUX_RISCV_FLUSH_ICACHE_LINUX_HPP
+#define OS_LINUX_RISCV_FLUSH_ICACHE_LINUX_HPP
+
+#include "memory/allStatic.hpp"
+#include "runtime/vm_version.hpp"
+#include "utilities/growableArray.hpp"
+
+class RiscvFlushIcache: public AllStatic {
+ public:
+  static bool test();
+  static void flush(uintptr_t start, uintptr_t end);
+};
+
+#endif // OS_LINUX_RISCV_FLUSH_ICACHE_LINUX_HPP