/*
 * Copyright (c) 2015, 2018, 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.
 *
 * 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 "gc/z/zAddress.inline.hpp"
#include "gc/z/zErrno.hpp"
#include "gc/z/zErrno.hpp"
#include "gc/z/zLargePages.inline.hpp"
#include "gc/z/zMemory.hpp"
#include "gc/z/zNUMA.hpp"
#include "gc/z/zPhysicalMemory.inline.hpp"
#include "gc/z/zPhysicalMemoryBacking_linux_aarch64.hpp"
#include "logging/log.hpp"
#include "runtime/os.hpp"
#include "utilities/align.hpp"
#include "utilities/debug.hpp"

#include <stdio.h>
#include <sys/mman.h>
#include <sys/types.h>

// Support for building on older Linux systems
#ifndef MADV_HUGEPAGE
#define MADV_HUGEPAGE                        14
#endif

// Proc file entry for max map mount
#define ZFILENAME_PROC_MAX_MAP_COUNT         "/proc/sys/vm/max_map_count"

ZPhysicalMemoryBacking::ZPhysicalMemoryBacking(size_t max_capacity) {
  // Check and warn if max map count is too low
  check_max_map_count(max_capacity);
}

void ZPhysicalMemoryBacking::check_max_map_count(size_t max_capacity) const {
  const char* const filename = ZFILENAME_PROC_MAX_MAP_COUNT;
  FILE* const file = fopen(filename, "r");
  if (file == NULL) {
    // Failed to open file, skip check
    log_debug(gc, init)("Failed to open %s", filename);
    return;
  }

  size_t actual_max_map_count = 0;
  const int result = fscanf(file, SIZE_FORMAT, &actual_max_map_count);
  fclose(file);
  if (result != 1) {
    // Failed to read file, skip check
    log_debug(gc, init)("Failed to read %s", filename);
    return;
  }

  // The required max map count is impossible to calculate exactly since subsystems
  // other than ZGC are also creating memory mappings, and we have no control over that.
  // However, ZGC tends to create the most mappings and dominate the total count.
  // In the worst cases, We speculate that we need another 20% to allow for
  // non-ZGC subsystems to map memory.
  const size_t required_max_map_count = (max_capacity / ZGranuleSize) * 1.2;
  if (actual_max_map_count < required_max_map_count) {
    log_warning(gc, init)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
    log_warning(gc, init)("The system limit on number of memory mappings per process might be too low "
                          "for the given");
    log_warning(gc, init)("max Java heap size (" SIZE_FORMAT "M). Please adjust %s to allow for at",
                          max_capacity / M, filename);
    log_warning(gc, init)("least " SIZE_FORMAT " mappings (current limit is " SIZE_FORMAT "). Continuing "
                          "execution with the current", required_max_map_count, actual_max_map_count);
    log_warning(gc, init)("limit could lead to a fatal error, due to failure to map memory.");
  }
}

size_t ZPhysicalMemoryBacking::try_expand(size_t old_capacity, size_t new_capacity) {
  assert(old_capacity < new_capacity, "Invalid old/new capacity");
  return new_capacity;
}

ZPhysicalMemory ZPhysicalMemoryBacking::alloc(size_t size) {
  assert(is_aligned(size, ZGranuleSize), "Invalid size");
   return ZPhysicalMemory(size);
}

void ZPhysicalMemoryBacking::free(ZPhysicalMemory pmem) {
  assert(pmem.nsegments() == 1, "Invalid number of segments");
}

void ZPhysicalMemoryBacking::map_failed(ZErrno err) const {
  if (err == ENOMEM) {
    fatal("Failed to map memory. Please check the system limit on number of "
          "memory mappings allowed per process (see %s)", ZFILENAME_PROC_MAX_MAP_COUNT);
  } else {
    fatal("Failed to map memory (%s)", err.to_string());
  }
}

uintptr_t ZPhysicalMemoryBacking::nmt_address(uintptr_t offset) const {
  // We only have one heap mapping, so just convert the offset to a heap address
  return ZAddress::address(offset);
}

void ZPhysicalMemoryBacking::map(ZPhysicalMemory pmem, uintptr_t offset) const {
  assert(pmem.nsegments() == 1, "Invalid number of segments");
  uintptr_t addr = ZAddress::address(offset);

  const size_t size = pmem.size();
  int flags =  MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE;

  if (ZLargePages::is_explicit()) {
    flags |= MAP_HUGETLB;
  }

  const void* const res = mmap((void*)addr, size, PROT_READ|PROT_WRITE, flags, 0, 0);

  if (res == MAP_FAILED) {
    ZErrno err;
    map_failed(err);
  }

  // Advise on use of transparent huge pages before touching it
  if (ZLargePages::is_transparent()) {
    if (madvise((void*)addr, size, MADV_HUGEPAGE) == -1) {
      ZErrno err;
      log_error(gc)("Failed to advise use of transparent huge pages (%s)", err.to_string());
    }
  }

  // NUMA interleave memory before touching it
  ZNUMA::memory_interleave(addr, size);

  if (AlwaysPreTouch) {
      const size_t page_size = ZLargePages::is_explicit() ? os::large_page_size() : os::vm_page_size();
      os::pretouch_memory((void*)addr, (void*)(addr + size), page_size);
  }
}

void ZPhysicalMemoryBacking::unmap(ZPhysicalMemory pmem, uintptr_t offset) const {
  const size_t size = pmem.size();
  const uintptr_t addr = ZAddress::address(offset);

  const void* const res = mmap((void*)addr, size, PROT_NONE, MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0);
  if (res == MAP_FAILED) {
    ZErrno err;
    map_failed(err);
  }
}

void ZPhysicalMemoryBacking::flip(ZPhysicalMemory pmem, uintptr_t offset) const {
  // Does nothing when using VA-masking
}