os_linux_x86.hpp

/*
 * Copyright (c) 1999, 2019, Oracle and/or its affiliates. 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#ifndef OS_CPU_LINUX_X86_OS_LINUX_X86_HPP
#define OS_CPU_LINUX_X86_OS_LINUX_X86_HPP

  static void setup_fpu();
  static bool supports_sse();
  static juint cpu_microcode_revision();

  static jlong rdtsc();

  // Used to register dynamic code cache area with the OS
  // Note: Currently only used in 64 bit Windows implementations
  static bool register_code_area(char *low, char *high) { return true; }

  /*
   * Work-around for broken NX emulation using CS limit, Red Hat patch "Exec-Shield"
   * (IA32 only).
   *
   * Map and execute at a high VA to prevent CS lazy updates race with SMP MM
   * invalidation.Further code generation by the JVM will no longer cause CS limit
   * updates.
   *
   * Affects IA32: RHEL 5 & 6, Ubuntu 10.04 (LTS), 10.10, 11.04, 11.10, 12.04.
   * @see JDK-8023956
   */
  static void workaround_expand_exec_shield_cs_limit();

#endif // OS_CPU_LINUX_X86_OS_LINUX_X86_HPP