/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Eclipse Public License (EPL);
* You may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.opensource.org/licenses/eclipse-1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.mmtk.utility.heap;
import org.mmtk.utility.*;
import org.mmtk.vm.Lock;
import org.mmtk.vm.VM;
import org.vmmagic.unboxed.*;
import org.vmmagic.pragma.*;
/**
* This class implements mmapping and protection of virtual memory.
*/
@Uninterruptible public final class Mmapper implements Constants {
/****************************************************************************
* Constants
*/
public static final byte UNMAPPED = 0;
public static final byte MAPPED = 1;
public static final byte PROTECTED = 2; // mapped but not accessible
public static final int LOG_MMAP_CHUNK_BYTES = 20;
public static final int MMAP_CHUNK_BYTES = 1 << LOG_MMAP_CHUNK_BYTES; // the granularity VMResource operates at
//TODO: 64-bit: this is not OK: value does not fit in int, but should, we do not want to create such big array
private static final int MMAP_CHUNK_MASK = MMAP_CHUNK_BYTES - 1;
private static final int MMAP_NUM_CHUNKS = 1 << (Constants.LOG_BYTES_IN_ADDRESS_SPACE - LOG_MMAP_CHUNK_BYTES);
public static final boolean verbose = false;
/****************************************************************************
* Class variables
*/
public static final Lock lock = VM.newLock("Mmapper");
private static byte[] mapped;
/****************************************************************************
* Initialization
*/
/**
* Class initializer. This is executed <i>prior</i> to bootstrap
* (i.e. at "build" time).
*/
static {
mapped = new byte[MMAP_NUM_CHUNKS];
for (int c = 0; c < MMAP_NUM_CHUNKS; c++) {
mapped[c] = UNMAPPED;
}
}
/****************************************************************************
* Generic mmap and protection functionality
*/
/**
* Given an address array describing the regions of virtual memory to be used
* by MMTk, demand zero map all of them if they are not already mapped.
*
* @param spaceMap An address array containing a pairs of start and end
* addresses for each of the regions to be mappe3d
*/
public static void eagerlyMmapAllSpaces(AddressArray spaceMap) {
/*for (int i = 0; i < spaceMap.length() / 2; i++) {
Address regionStart = spaceMap.get(i * 2);
Address regionEnd = spaceMap.get(i * 2 + 1);
Log.write(regionStart); Log.write(" "); Log.writeln(regionEnd);
if (regionEnd.EQ(Address.zero()) || regionStart.EQ(Address.fromIntSignExtend(-1)) ||regionEnd.EQ(Address.fromIntSignExtend(-1)))
break;
if (VM.VERIFY_ASSERTIONS) {
VM.assertions._assert(regionStart.EQ(chunkAlignDown(regionStart)));
VM.assertions._assert(regionEnd.EQ(chunkAlignDown(regionEnd)));
}
int pages = Conversions.bytesToPages(regionEnd.diff(regionStart));
ensureMapped(regionStart, pages);
}*/
}
/**
* Mark a range of pages as having (already) been mapped. This is useful
* where the VM has performed the mapping of the pages itself.
*
* @param start The start of the range to be marked as mapped
* @param bytes The size of the range, in bytes.
*/
public static void markAsMapped(Address start, int bytes) {
int startChunk = Conversions.addressToMmapChunksDown(start);
int endChunk = Conversions.addressToMmapChunksUp(start.plus(bytes));
for (int i = startChunk; i <= endChunk; i++)
mapped[i] = MAPPED;
}
/**
* Ensure that a range of pages is mmapped (or equivalent). If the
* pages are not yet mapped, demand-zero map them. Note that mapping
* occurs at chunk granularity, not page granularity.<p>
*
* NOTE: There is a monotonicity assumption so that only updates require lock
* acquisition.
* TODO: Fix the above to support unmapping.
*
* @param start The start of the range to be mapped.
* @param pages The size of the range to be mapped, in pages
*/
public static void ensureMapped(Address start, int pages) {
int startChunk = Conversions.addressToMmapChunksDown(start);
int endChunk = Conversions.addressToMmapChunksUp(start.plus(Conversions.pagesToBytes(pages)));
for (int chunk = startChunk; chunk < endChunk; chunk++) {
if (mapped[chunk] == MAPPED) continue;
Address mmapStart = Conversions.mmapChunksToAddress(chunk);
lock.acquire();
// Log.writeln(mmapStart);
// might have become MAPPED here
if (mapped[chunk] == UNMAPPED) {
int errno = VM.memory.dzmmap(mmapStart, MMAP_CHUNK_BYTES);
if (errno != 0) {
lock.release();
Log.write("ensureMapped failed with errno "); Log.write(errno);
Log.write(" on address "); Log.writeln(mmapStart);
VM.assertions.fail("Can't get more space with mmap()");
} else {
if (verbose) {
Log.write("mmap succeeded at chunk "); Log.write(chunk); Log.write(" "); Log.write(mmapStart);
Log.write(" with len = "); Log.writeln(MMAP_CHUNK_BYTES);
}
}
}
if (mapped[chunk] == PROTECTED) {
if (!VM.memory.munprotect(mmapStart, MMAP_CHUNK_BYTES)) {
lock.release();
VM.assertions.fail("Mmapper.ensureMapped (unprotect) failed");
} else {
if (verbose) {
Log.write("munprotect succeeded at chunk "); Log.write(chunk); Log.write(" "); Log.write(mmapStart);
Log.write(" with len = "); Log.writeln(MMAP_CHUNK_BYTES);
}
}
}
mapped[chunk] = MAPPED;
lock.release();
}
}
/**
* Memory protect a range of pages (using mprotect or equivalent). Note
* that protection occurs at chunk granularity, not page granularity.
*
* @param start The start of the range to be protected.
* @param pages The size of the range to be protected, in pages
*/
public static void protect(Address start, int pages) {
int startChunk = Conversions.addressToMmapChunksDown(start);
int chunks = Conversions.pagesToMmapChunksUp(pages);
int endChunk = startChunk + chunks;
lock.acquire();
for (int chunk = startChunk; chunk < endChunk; chunk++) {
if (mapped[chunk] == MAPPED) {
Address mmapStart = Conversions.mmapChunksToAddress(chunk);
if (!VM.memory.mprotect(mmapStart, MMAP_CHUNK_BYTES)) {
lock.release();
VM.assertions.fail("Mmapper.mprotect failed");
} else {
if (verbose) {
Log.write("mprotect succeeded at chunk "); Log.write(chunk); Log.write(" "); Log.write(mmapStart);
Log.write(" with len = "); Log.writeln(MMAP_CHUNK_BYTES);
}
}
mapped[chunk] = PROTECTED;
} else {
if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(mapped[chunk] == PROTECTED);
}
}
lock.release();
}
/****************************************************************************
* Utility functions
*/
/**
* Return true if the given address has been mmapped
*
* @param addr The address in question.
* @return true if the given address has been mmapped
*/
@Uninterruptible
public static boolean addressIsMapped(Address addr) {
int chunk = Conversions.addressToMmapChunksDown(addr);
return mapped[chunk] == MAPPED;
}
/**
* Return true if the given object has been mmapped
*
* @param object The object in question.
* @return true if the given object has been mmapped
*/
@Uninterruptible
public static boolean objectIsMapped(ObjectReference object) {
return addressIsMapped(VM.objectModel.refToAddress(object));
}
/**
* Return a given address rounded up to an mmap chunk size
*
* @param addr The address to be aligned
* @return The given address rounded up to an mmap chunk size
*/
@SuppressWarnings("unused") // but might be useful someday
private static Address chunkAlignUp(Address addr) {
return chunkAlignDown(addr.plus(MMAP_CHUNK_MASK));
}
/**
* Return a given address rounded down to an mmap chunk size
*
* @param addr The address to be aligned
* @return The given address rounded down to an mmap chunk size
*/
private static Address chunkAlignDown(Address addr) {
return addr.toWord().and(Word.fromIntSignExtend(MMAP_CHUNK_MASK).not()).toAddress();
}
}