/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* VM-specific state associated with a DEX file.
*/
#include "Dalvik.h"
#include <sys/mman.h>
/*
* Create auxillary data structures.
*
* We need a 4-byte pointer for every reference to a class, method, field,
* or string constant. Summed up over all loaded DEX files (including the
* whoppers in the boostrap class path), this adds up to be quite a bit
* of native memory.
*
* For more traditional VMs these values could be stuffed into the loaded
* class file constant pool area, but we don't have that luxury since our
* classes are memory-mapped read-only.
*
* The DEX optimizer will remove the need for some of these (e.g. we won't
* use the entry for virtual methods that are only called through
* invoke-virtual-quick), creating the possibility of some space reduction
* at dexopt time.
*/
static DvmDex* allocateAuxStructures(DexFile* pDexFile)
{
DvmDex* pDvmDex;
const DexHeader* pHeader;
u4 stringSize, classSize, methodSize, fieldSize;
pHeader = pDexFile->pHeader;
stringSize = pHeader->stringIdsSize * sizeof(struct StringObject*);
classSize = pHeader->typeIdsSize * sizeof(struct ClassObject*);
methodSize = pHeader->methodIdsSize * sizeof(struct Method*);
fieldSize = pHeader->fieldIdsSize * sizeof(struct Field*);
u4 totalSize = sizeof(DvmDex) +
stringSize + classSize + methodSize + fieldSize;
u1 *blob = (u1 *)dvmAllocRegion(totalSize,
PROT_READ | PROT_WRITE, "dalvik-aux-structure");
if ((void *)blob == MAP_FAILED)
return NULL;
pDvmDex = (DvmDex*)blob;
blob += sizeof(DvmDex);
pDvmDex->pDexFile = pDexFile;
pDvmDex->pHeader = pHeader;
pDvmDex->pResStrings = (struct StringObject**)blob;
blob += stringSize;
pDvmDex->pResClasses = (struct ClassObject**)blob;
blob += classSize;
pDvmDex->pResMethods = (struct Method**)blob;
blob += methodSize;
pDvmDex->pResFields = (struct Field**)blob;
ALOGV("+++ DEX %p: allocateAux (%d+%d+%d+%d)*4 = %d bytes",
pDvmDex, stringSizei/4, classSize/4, methodSize/4, fieldSize/4,
stringSize + classSize + methodSize + fieldSize);
pDvmDex->pInterfaceCache = dvmAllocAtomicCache(DEX_INTERFACE_CACHE_SIZE);
return pDvmDex;
}
/*
* Given an open optimized DEX file, map it into read-only shared memory and
* parse the contents.
*
* Returns nonzero on error.
*/
int dvmDexFileOpenFromFd(int fd, DvmDex** ppDvmDex)
{
DvmDex* pDvmDex;
DexFile* pDexFile;
MemMapping memMap;
int parseFlags = kDexParseDefault;
int result = -1;
if (gDvm.verifyDexChecksum)
parseFlags |= kDexParseVerifyChecksum;
if (lseek(fd, 0, SEEK_SET) < 0) {
ALOGE("lseek rewind failed");
goto bail;
}
if (sysMapFileInShmemWritableReadOnly(fd, &memMap) != 0) {
ALOGE("Unable to map file");
goto bail;
}
pDexFile = dexFileParse((u1*)memMap.addr, memMap.length, parseFlags);
if (pDexFile == NULL) {
ALOGE("DEX parse failed");
sysReleaseShmem(&memMap);
goto bail;
}
pDvmDex = allocateAuxStructures(pDexFile);
if (pDvmDex == NULL) {
dexFileFree(pDexFile);
sysReleaseShmem(&memMap);
goto bail;
}
/* tuck this into the DexFile so it gets released later */
sysCopyMap(&pDvmDex->memMap, &memMap);
pDvmDex->isMappedReadOnly = true;
*ppDvmDex = pDvmDex;
result = 0;
bail:
return result;
}
/*
* Create a DexFile structure for a "partial" DEX. This is one that is in
* the process of being optimized. The optimization header isn't finished
* and we won't have any of the auxillary data tables, so we have to do
* the initialization slightly differently.
*
* Returns nonzero on error.
*/
int dvmDexFileOpenPartial(const void* addr, int len, DvmDex** ppDvmDex)
{
DvmDex* pDvmDex;
DexFile* pDexFile;
int parseFlags = kDexParseDefault;
int result = -1;
/* -- file is incomplete, new checksum has not yet been calculated
if (gDvm.verifyDexChecksum)
parseFlags |= kDexParseVerifyChecksum;
*/
pDexFile = dexFileParse((u1*)addr, len, parseFlags);
if (pDexFile == NULL) {
ALOGE("DEX parse failed");
goto bail;
}
pDvmDex = allocateAuxStructures(pDexFile);
if (pDvmDex == NULL) {
dexFileFree(pDexFile);
goto bail;
}
pDvmDex->isMappedReadOnly = false;
*ppDvmDex = pDvmDex;
result = 0;
bail:
return result;
}
/*
* Free up the DexFile and any associated data structures.
*
* Note we may be called with a partially-initialized DvmDex.
*/
void dvmDexFileFree(DvmDex* pDvmDex)
{
u4 totalSize;
if (pDvmDex == NULL)
return;
totalSize = pDvmDex->pHeader->stringIdsSize * sizeof(struct StringObject*);
totalSize += pDvmDex->pHeader->typeIdsSize * sizeof(struct ClassObject*);
totalSize += pDvmDex->pHeader->methodIdsSize * sizeof(struct Method*);
totalSize += pDvmDex->pHeader->fieldIdsSize * sizeof(struct Field*);
totalSize += sizeof(DvmDex);
dexFileFree(pDvmDex->pDexFile);
ALOGV("+++ DEX %p: freeing aux structs", pDvmDex);
dvmFreeAtomicCache(pDvmDex->pInterfaceCache);
sysReleaseShmem(&pDvmDex->memMap);
munmap(pDvmDex, totalSize);
}
/*
* Change the byte at the specified address to a new value. If the location
* already has the new value, do nothing.
*
* This requires changing the access permissions to read-write, updating
* the value, and then resetting the permissions.
*
* We need to ensure mutual exclusion at a page granularity to avoid a race
* where one threads sets read-write, another thread sets read-only, and
* then the first thread does a write. Since we don't do a lot of updates,
* and the window is small, we just use a lock across the entire DvmDex.
* We're only trying to make the page state change atomic; it's up to the
* caller to ensure that multiple threads aren't stomping on the same
* location (e.g. breakpoints and verifier/optimizer changes happening
* simultaneously).
*
* TODO: if we're back to the original state of the page, use
* madvise(MADV_DONTNEED) to release the private/dirty copy.
*
* Returns "true" on success.
*/
bool dvmDexChangeDex1(DvmDex* pDvmDex, u1* addr, u1 newVal)
{
if (*addr == newVal) {
ALOGV("+++ byte at %p is already 0x%02x", addr, newVal);
return true;
}
/*
* We're not holding this for long, so we don't bother with switching
* to VMWAIT.
*/
dvmLockMutex(&pDvmDex->modLock);
ALOGV("+++ change byte at %p from 0x%02x to 0x%02x", addr, *addr, newVal);
if (sysChangeMapAccess(addr, 1, true, &pDvmDex->memMap) != 0) {
ALOGD("NOTE: DEX page access change (->RW) failed");
/* expected on files mounted from FAT; keep going (may crash) */
}
*addr = newVal;
if (sysChangeMapAccess(addr, 1, false, &pDvmDex->memMap) != 0) {
ALOGD("NOTE: DEX page access change (->RO) failed");
/* expected on files mounted from FAT; keep going */
}
dvmUnlockMutex(&pDvmDex->modLock);
return true;
}
/*
* Change the 2-byte value at the specified address to a new value. If the
* location already has the new value, do nothing.
*
* Otherwise works like dvmDexChangeDex1.
*/
bool dvmDexChangeDex2(DvmDex* pDvmDex, u2* addr, u2 newVal)
{
if (*addr == newVal) {
ALOGV("+++ value at %p is already 0x%04x", addr, newVal);
return true;
}
/*
* We're not holding this for long, so we don't bother with switching
* to VMWAIT.
*/
dvmLockMutex(&pDvmDex->modLock);
ALOGV("+++ change 2byte at %p from 0x%04x to 0x%04x", addr, *addr, newVal);
if (sysChangeMapAccess(addr, 2, true, &pDvmDex->memMap) != 0) {
ALOGD("NOTE: DEX page access change (->RW) failed");
/* expected on files mounted from FAT; keep going (may crash) */
}
*addr = newVal;
if (sysChangeMapAccess(addr, 2, false, &pDvmDex->memMap) != 0) {
ALOGD("NOTE: DEX page access change (->RO) failed");
/* expected on files mounted from FAT; keep going */
}
dvmUnlockMutex(&pDvmDex->modLock);
return true;
}