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/*
* 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.
*/
#include "mem_map.h"
#include <inttypes.h>
#include <backtrace/BacktraceMap.h>
#include "UniquePtr.h"
#include "base/stringprintf.h"
#include "ScopedFd.h"
#include "utils.h"
#define USE_ASHMEM 1
#ifdef USE_ASHMEM
#include <cutils/ashmem.h>
#endif
namespace art {
#if !defined(NDEBUG)
static std::ostream& operator<<(
std::ostream& os,
std::pair<BacktraceMap::const_iterator, BacktraceMap::const_iterator> iters) {
for (BacktraceMap::const_iterator it = iters.first; it != iters.second; ++it) {
os << StringPrintf("0x%08x-0x%08x %c%c%c %s\n",
static_cast<uint32_t>(it->start),
static_cast<uint32_t>(it->end),
(it->flags & PROT_READ) ? 'r' : '-',
(it->flags & PROT_WRITE) ? 'w' : '-',
(it->flags & PROT_EXEC) ? 'x' : '-', it->name.c_str());
}
return os;
}
static void CheckMapRequest(byte* addr, size_t byte_count) {
if (addr == NULL) {
return;
}
uintptr_t base = reinterpret_cast<uintptr_t>(addr);
uintptr_t limit = base + byte_count;
UniquePtr<BacktraceMap> map(BacktraceMap::Create(getpid()));
if (!map->Build()) {
PLOG(WARNING) << "Failed to build process map";
return;
}
for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) {
CHECK(!(base >= it->start && base < it->end) // start of new within old
&& !(limit > it->start && limit < it->end) // end of new within old
&& !(base <= it->start && limit > it->end)) // start/end of new includes all of old
<< StringPrintf("Requested region 0x%08" PRIxPTR "-0x%08" PRIxPTR " overlaps with "
"existing map 0x%08" PRIxPTR "-0x%08" PRIxPTR " (%s)\n",
base, limit,
static_cast<uintptr_t>(it->start), static_cast<uintptr_t>(it->end),
it->name.c_str())
<< std::make_pair(it, map->end());
}
}
#else
static void CheckMapRequest(byte*, size_t) { }
#endif
MemMap* MemMap::MapAnonymous(const char* name, byte* addr, size_t byte_count, int prot,
std::string* error_msg) {
if (byte_count == 0) {
return new MemMap(name, NULL, 0, NULL, 0, prot);
}
size_t page_aligned_byte_count = RoundUp(byte_count, kPageSize);
CheckMapRequest(addr, page_aligned_byte_count);
#ifdef USE_ASHMEM
// android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are
// prefixed "dalvik-".
std::string debug_friendly_name("dalvik-");
debug_friendly_name += name;
ScopedFd fd(ashmem_create_region(debug_friendly_name.c_str(), page_aligned_byte_count));
int flags = MAP_PRIVATE;
if (fd.get() == -1) {
*error_msg = StringPrintf("ashmem_create_region failed for '%s': %s", name, strerror(errno));
return nullptr;
}
#else
ScopedFd fd(-1);
int flags = MAP_PRIVATE | MAP_ANONYMOUS;
#endif
byte* actual = reinterpret_cast<byte*>(mmap(addr, page_aligned_byte_count, prot, flags, fd.get(), 0));
if (actual == MAP_FAILED) {
std::string maps;
ReadFileToString("/proc/self/maps", &maps);
*error_msg = StringPrintf("anonymous mmap(%p, %zd, %x, %x, %d, 0) failed\n%s",
addr, page_aligned_byte_count, prot, flags, fd.get(),
maps.c_str());
return nullptr;
}
return new MemMap(name, actual, byte_count, actual, page_aligned_byte_count, prot);
}
MemMap* MemMap::MapFileAtAddress(byte* addr, size_t byte_count, int prot, int flags, int fd,
off_t start, bool reuse, const char* filename,
std::string* error_msg) {
CHECK_NE(0, prot);
CHECK_NE(0, flags & (MAP_SHARED | MAP_PRIVATE));
if (byte_count == 0) {
return new MemMap(filename, NULL, 0, NULL, 0, prot);
}
// Adjust 'offset' to be page-aligned as required by mmap.
int page_offset = start % kPageSize;
off_t page_aligned_offset = start - page_offset;
// Adjust 'byte_count' to be page-aligned as we will map this anyway.
size_t page_aligned_byte_count = RoundUp(byte_count + page_offset, kPageSize);
// The 'addr' is modified (if specified, ie non-null) to be page aligned to the file but not
// necessarily to virtual memory. mmap will page align 'addr' for us.
byte* page_aligned_addr = (addr == NULL) ? NULL : (addr - page_offset);
if (!reuse) {
// reuse means it is okay that it overlaps an existing page mapping.
// Only use this if you actually made the page reservation yourself.
CheckMapRequest(page_aligned_addr, page_aligned_byte_count);
} else {
CHECK(addr != NULL);
}
byte* actual = reinterpret_cast<byte*>(mmap(page_aligned_addr,
page_aligned_byte_count,
prot,
flags,
fd,
page_aligned_offset));
if (actual == MAP_FAILED) {
std::string strerr(strerror(errno));
std::string maps;
ReadFileToString("/proc/self/maps", &maps);
*error_msg = StringPrintf("mmap(%p, %zd, %x, %x, %d, %" PRId64 ") of file '%s' failed: %s\n%s",
page_aligned_addr, page_aligned_byte_count, prot, flags, fd,
static_cast<int64_t>(page_aligned_offset), filename, strerr.c_str(),
maps.c_str());
return NULL;
}
return new MemMap(filename, actual + page_offset, byte_count, actual, page_aligned_byte_count,
prot);
}
MemMap::~MemMap() {
if (base_begin_ == NULL && base_size_ == 0) {
return;
}
int result = munmap(base_begin_, base_size_);
if (result == -1) {
PLOG(FATAL) << "munmap failed";
}
}
MemMap::MemMap(const std::string& name, byte* begin, size_t size, void* base_begin,
size_t base_size, int prot)
: name_(name), begin_(begin), size_(size), base_begin_(base_begin), base_size_(base_size),
prot_(prot) {
if (size_ == 0) {
CHECK(begin_ == NULL);
CHECK(base_begin_ == NULL);
CHECK_EQ(base_size_, 0U);
} else {
CHECK(begin_ != NULL);
CHECK(base_begin_ != NULL);
CHECK_NE(base_size_, 0U);
}
};
MemMap* MemMap::RemapAtEnd(byte* new_end, const char* tail_name, int tail_prot,
std::string* error_msg) {
DCHECK_GE(new_end, Begin());
DCHECK_LE(new_end, End());
DCHECK_LE(begin_ + size_, reinterpret_cast<byte*>(base_begin_) + base_size_);
DCHECK(IsAligned<kPageSize>(begin_));
DCHECK(IsAligned<kPageSize>(base_begin_));
DCHECK(IsAligned<kPageSize>(reinterpret_cast<byte*>(base_begin_) + base_size_));
DCHECK(IsAligned<kPageSize>(new_end));
byte* old_end = begin_ + size_;
byte* old_base_end = reinterpret_cast<byte*>(base_begin_) + base_size_;
byte* new_base_end = new_end;
DCHECK_LE(new_base_end, old_base_end);
if (new_base_end == old_base_end) {
return new MemMap(tail_name, NULL, 0, NULL, 0, tail_prot);
}
size_ = new_end - reinterpret_cast<byte*>(begin_);
base_size_ = new_base_end - reinterpret_cast<byte*>(base_begin_);
DCHECK_LE(begin_ + size_, reinterpret_cast<byte*>(base_begin_) + base_size_);
size_t tail_size = old_end - new_end;
byte* tail_base_begin = new_base_end;
size_t tail_base_size = old_base_end - new_base_end;
DCHECK_EQ(tail_base_begin + tail_base_size, old_base_end);
DCHECK(IsAligned<kPageSize>(tail_base_size));
#ifdef USE_ASHMEM
// android_os_Debug.cpp read_mapinfo assumes all ashmem regions associated with the VM are
// prefixed "dalvik-".
std::string debug_friendly_name("dalvik-");
debug_friendly_name += tail_name;
ScopedFd fd(ashmem_create_region(debug_friendly_name.c_str(), tail_base_size));
int flags = MAP_PRIVATE;
if (fd.get() == -1) {
*error_msg = StringPrintf("ashmem_create_region failed for '%s': %s",
tail_name, strerror(errno));
return nullptr;
}
#else
ScopedFd fd(-1);
int flags = MAP_PRIVATE | MAP_ANONYMOUS;
#endif
// Unmap/map the tail region.
int result = munmap(tail_base_begin, tail_base_size);
if (result == -1) {
std::string maps;
ReadFileToString("/proc/self/maps", &maps);
*error_msg = StringPrintf("munmap(%p, %zd) failed for '%s'\n%s",
tail_base_begin, tail_base_size, name_.c_str(),
maps.c_str());
return nullptr;
}
// Don't cause memory allocation between the munmap and the mmap
// calls. Otherwise, libc (or something else) might take this memory
// region. Note this isn't perfect as there's no way to prevent
// other threads to try to take this memory region here.
byte* actual = reinterpret_cast<byte*>(mmap(tail_base_begin, tail_base_size, tail_prot,
flags, fd.get(), 0));
if (actual == MAP_FAILED) {
std::string maps;
ReadFileToString("/proc/self/maps", &maps);
*error_msg = StringPrintf("anonymous mmap(%p, %zd, %x, %x, %d, 0) failed\n%s",
tail_base_begin, tail_base_size, tail_prot, flags, fd.get(),
maps.c_str());
return nullptr;
}
return new MemMap(tail_name, actual, tail_size, actual, tail_base_size, tail_prot);
}
bool MemMap::Protect(int prot) {
if (base_begin_ == NULL && base_size_ == 0) {
prot_ = prot;
return true;
}
if (mprotect(base_begin_, base_size_, prot) == 0) {
prot_ = prot;
return true;
}
PLOG(ERROR) << "mprotect(" << reinterpret_cast<void*>(base_begin_) << ", " << base_size_ << ", "
<< prot << ") failed";
return false;
}
std::ostream& operator<<(std::ostream& os, const MemMap& mem_map) {
os << StringPrintf("[MemMap: %s prot=%x %p-%p]",
mem_map.GetName().c_str(), mem_map.GetProtect(),
mem_map.BaseBegin(), mem_map.BaseEnd());
return os;
}
} // namespace art