Quelle systemMemoryBarrier_linux.cpp Sprache: C

/*
* Copyright (c) 2022, 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).
*
* 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.
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*/

#include "precompiled.hpp"
#include "logging/log.hpp"
#include "runtime/os.hpp"
#include "utilities/debug.hpp"
#include "utilities/systemMemoryBarrier.hpp"

#include <sys/syscall.h>

// Syscall defined in kernel 4.3
// Oracle x64 builds may use old sysroot (pre 4.3)
#ifndef SYS_membarrier
  #if defined(AMD64)
  #define SYS_membarrier 324
  #elif defined(X86)
  #define SYS_membarrier 375
  #elif defined(PPC64)
  #define SYS_membarrier 365
  #elif defined(AARCH64)
  #define SYS_membarrier 283
  #elif defined(ALPHA)
  #define SYS_membarrier 517
  #else
  #error define SYS_membarrier for the arch
  #endif
#endif // SYS_membarrier

// Expedited defined in kernel 4.14
// Therefore we define it here instead of including linux/membarrier.h
enum membarrier_cmd {
  MEMBARRIER_CMD_QUERY                      = 0,
  MEMBARRIER_CMD_PRIVATE_EXPEDITED          = (1 << 3),
  MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),
};

#define check_with_errno(check_type, cond, msg)                             \
  do {                                                                      \
    int err = errno;                                                        \
    check_type(cond, "%s: error='%s' (errno=%s)", msg, os::strerror(err),   \
               os::errno_name(err));                                        \
} while (false)

#define guarantee_with_errno(cond, msg) check_with_errno(guarantee, cond, msg)

static int membarrier(int cmd, unsigned int flags, int cpu_id) {
  return syscall(SYS_membarrier, cmd, flags, cpu_id); // cpu_id only on >= 5.10
}

bool LinuxSystemMemoryBarrier::initialize() {
  int ret = membarrier(MEMBARRIER_CMD_QUERY, 0, 0);
  if (ret < 0) {
    log_error(os)("MEMBARRIER_CMD_QUERY unsupported");
    return false;
  }
  if (!(ret & MEMBARRIER_CMD_PRIVATE_EXPEDITED) ||
      !(ret & MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED)) {
    log_error(os)("MEMBARRIER PRIVATE_EXPEDITED unsupported");
    return false;
  }
  ret = membarrier(MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED, 0, 0);
  guarantee_with_errno(ret == 0, "MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED failed");
  return true;
}

void LinuxSystemMemoryBarrier::emit() {
  int s = membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0, 0);
  guarantee_with_errno(s >= 0, "MEMBARRIER_CMD_PRIVATE_EXPEDITED failed");
}

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