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// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// Copyright (c) 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ---
// Author: Sanjay Ghemawat
#include <config.h>
#include <errno.h> // for EAGAIN, errno
#include <fcntl.h> // for open, O_RDWR
#include <stddef.h> // for size_t, NULL, ptrdiff_t
#if defined HAVE_STDINT_H
#include <stdint.h> // for uintptr_t, intptr_t
#elif defined HAVE_INTTYPES_H
#include <inttypes.h>
#else
#include <sys/types.h>
#endif
#ifdef HAVE_MMAP
#include <sys/mman.h> // for munmap, mmap, MADV_DONTNEED, etc
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h> // for sbrk, getpagesize, off_t
#endif
#include <new> // for operator new
#include <gperftools/malloc_extension.h>
#include "base/basictypes.h"
#include "base/commandlineflags.h"
#include "base/spinlock.h" // for SpinLockHolder, SpinLock, etc
#include "common.h"
#include "internal_logging.h"
// On systems (like freebsd) that don't define MAP_ANONYMOUS, use the old
// form of the name instead.
#ifndef MAP_ANONYMOUS
# define MAP_ANONYMOUS MAP_ANON
#endif
// MADV_FREE is specifically designed for use by malloc(), but only
// FreeBSD supports it; in linux we fall back to the somewhat inferior
// MADV_DONTNEED.
#if !defined(MADV_FREE) && defined(MADV_DONTNEED)
# define MADV_FREE MADV_DONTNEED
#endif
// Solaris has a bug where it doesn't declare madvise() for C++.
// http://www.opensolaris.org/jive/thread.jspa?threadID=21035&tstart=0
#if defined(__sun) && defined(__SVR4)
# include <sys/types.h> // for caddr_t
extern "C" { extern int madvise(caddr_t, size_t, int); }
#endif
// Set kDebugMode mode so that we can have use C++ conditionals
// instead of preprocessor conditionals.
#ifdef NDEBUG
static const bool kDebugMode = false;
#else
static const bool kDebugMode = true;
#endif
// TODO(sanjay): Move the code below into the tcmalloc namespace
using tcmalloc::kLog;
using tcmalloc::Log;
// Anonymous namespace to avoid name conflicts on "CheckAddressBits".
namespace {
// Check that no bit is set at position ADDRESS_BITS or higher.
template <int ADDRESS_BITS> bool CheckAddressBits(uintptr_t ptr) {
return (ptr >> ADDRESS_BITS) == 0;
}
// Specialize for the bit width of a pointer to avoid undefined shift.
template <> bool CheckAddressBits<8 * sizeof(void*)>(uintptr_t ptr) {
return true;
}
} // Anonymous namespace to avoid name conflicts on "CheckAddressBits".
COMPILE_ASSERT(kAddressBits <= 8 * sizeof(void*),
address_bits_larger_than_pointer_size);
// Structure for discovering alignment
union MemoryAligner {
void* p;
double d;
size_t s;
} CACHELINE_ALIGNED;
static SpinLock spinlock(SpinLock::LINKER_INITIALIZED);
#if defined(HAVE_MMAP) || defined(MADV_FREE)
// Page size is initialized on demand (only needed for mmap-based allocators)
static size_t pagesize = 0;
#endif
// The current system allocator
SysAllocator* sys_alloc = NULL;
// Number of bytes taken from system.
size_t TCMalloc_SystemTaken = 0;
// Configuration parameters.
DEFINE_int32(malloc_devmem_start,
EnvToInt("TCMALLOC_DEVMEM_START", 0),
"Physical memory starting location in MB for /dev/mem allocation."
" Setting this to 0 disables /dev/mem allocation");
DEFINE_int32(malloc_devmem_limit,
EnvToInt("TCMALLOC_DEVMEM_LIMIT", 0),
"Physical memory limit location in MB for /dev/mem allocation."
" Setting this to 0 means no limit.");
DEFINE_bool(malloc_skip_sbrk,
EnvToBool("TCMALLOC_SKIP_SBRK", false),
"Whether sbrk can be used to obtain memory.");
DEFINE_bool(malloc_skip_mmap,
EnvToBool("TCMALLOC_SKIP_MMAP", false),
"Whether mmap can be used to obtain memory.");
DEFINE_bool(malloc_disable_memory_release,
EnvToBool("TCMALLOC_DISABLE_MEMORY_RELEASE", false),
"Whether MADV_FREE/MADV_DONTNEED should be used"
" to return unused memory to the system.");
// static allocators
class SbrkSysAllocator : public SysAllocator {
public:
SbrkSysAllocator() : SysAllocator() {
}
void* Alloc(size_t size, size_t *actual_size, size_t alignment);
};
static char sbrk_space[sizeof(SbrkSysAllocator)];
class MmapSysAllocator : public SysAllocator {
public:
MmapSysAllocator() : SysAllocator() {
}
void* Alloc(size_t size, size_t *actual_size, size_t alignment);
};
static char mmap_space[sizeof(MmapSysAllocator)];
class DevMemSysAllocator : public SysAllocator {
public:
DevMemSysAllocator() : SysAllocator() {
}
void* Alloc(size_t size, size_t *actual_size, size_t alignment);
};
class DefaultSysAllocator : public SysAllocator {
public:
DefaultSysAllocator() : SysAllocator() {
for (int i = 0; i < kMaxAllocators; i++) {
failed_[i] = true;
allocs_[i] = NULL;
names_[i] = NULL;
}
}
void SetChildAllocator(SysAllocator* alloc, unsigned int index,
const char* name) {
if (index < kMaxAllocators && alloc != NULL) {
allocs_[index] = alloc;
failed_[index] = false;
names_[index] = name;
}
}
void* Alloc(size_t size, size_t *actual_size, size_t alignment);
private:
static const int kMaxAllocators = 2;
bool failed_[kMaxAllocators];
SysAllocator* allocs_[kMaxAllocators];
const char* names_[kMaxAllocators];
};
static char default_space[sizeof(DefaultSysAllocator)];
static const char sbrk_name[] = "SbrkSysAllocator";
static const char mmap_name[] = "MmapSysAllocator";
void* SbrkSysAllocator::Alloc(size_t size, size_t *actual_size,
size_t alignment) {
#if !defined(HAVE_SBRK) || defined(__UCLIBC__)
return NULL;
#else
// Check if we should use sbrk allocation.
// FLAGS_malloc_skip_sbrk starts out as false (its uninitialized
// state) and eventually gets initialized to the specified value. Note
// that this code runs for a while before the flags are initialized.
// That means that even if this flag is set to true, some (initial)
// memory will be allocated with sbrk before the flag takes effect.
if (FLAGS_malloc_skip_sbrk) {
return NULL;
}
// sbrk will release memory if passed a negative number, so we do
// a strict check here
if (static_cast<ptrdiff_t>(size + alignment) < 0) return NULL;
// This doesn't overflow because TCMalloc_SystemAlloc has already
// tested for overflow at the alignment boundary.
size = ((size + alignment - 1) / alignment) * alignment;
// "actual_size" indicates that the bytes from the returned pointer
// p up to and including (p + actual_size - 1) have been allocated.
if (actual_size) {
*actual_size = size;
}
// Check that we we're not asking for so much more memory that we'd
// wrap around the end of the virtual address space. (This seems
// like something sbrk() should check for us, and indeed opensolaris
// does, but glibc does not:
// http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libc/port/sys/sbrk.c?a=true
// http://sourceware.org/cgi-bin/cvsweb.cgi/~checkout~/libc/misc/sbrk.c?rev=1.1.2.1&content-type=text/plain&cvsroot=glibc
// Without this check, sbrk may succeed when it ought to fail.)
if (reinterpret_cast<intptr_t>(sbrk(0)) + size < size) {
return NULL;
}
void* result = sbrk(size);
if (result == reinterpret_cast<void*>(-1)) {
return NULL;
}
// Is it aligned?
uintptr_t ptr = reinterpret_cast<uintptr_t>(result);
if ((ptr & (alignment-1)) == 0) return result;
// Try to get more memory for alignment
size_t extra = alignment - (ptr & (alignment-1));
void* r2 = sbrk(extra);
if (reinterpret_cast<uintptr_t>(r2) == (ptr + size)) {
// Contiguous with previous result
return reinterpret_cast<void*>(ptr + extra);
}
// Give up and ask for "size + alignment - 1" bytes so
// that we can find an aligned region within it.
result = sbrk(size + alignment - 1);
if (result == reinterpret_cast<void*>(-1)) {
return NULL;
}
ptr = reinterpret_cast<uintptr_t>(result);
if ((ptr & (alignment-1)) != 0) {
ptr += alignment - (ptr & (alignment-1));
}
return reinterpret_cast<void*>(ptr);
#endif // HAVE_SBRK
}
void* MmapSysAllocator::Alloc(size_t size, size_t *actual_size,
size_t alignment) {
#ifndef HAVE_MMAP
return NULL;
#else
// Check if we should use mmap allocation.
// FLAGS_malloc_skip_mmap starts out as false (its uninitialized
// state) and eventually gets initialized to the specified value. Note
// that this code runs for a while before the flags are initialized.
// Chances are we never get here before the flags are initialized since
// sbrk is used until the heap is exhausted (before mmap is used).
if (FLAGS_malloc_skip_mmap) {
return NULL;
}
// Enforce page alignment
if (pagesize == 0) pagesize = getpagesize();
if (alignment < pagesize) alignment = pagesize;
size_t aligned_size = ((size + alignment - 1) / alignment) * alignment;
if (aligned_size < size) {
return NULL;
}
size = aligned_size;
// "actual_size" indicates that the bytes from the returned pointer
// p up to and including (p + actual_size - 1) have been allocated.
if (actual_size) {
*actual_size = size;
}
// Ask for extra memory if alignment > pagesize
size_t extra = 0;
if (alignment > pagesize) {
extra = alignment - pagesize;
}
// Note: size + extra does not overflow since:
// size + alignment < (1<<NBITS).
// and extra <= alignment
// therefore size + extra < (1<<NBITS)
void* result = mmap(NULL, size + extra,
PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS,
-1, 0);
if (result == reinterpret_cast<void*>(MAP_FAILED)) {
return NULL;
}
// Adjust the return memory so it is aligned
uintptr_t ptr = reinterpret_cast<uintptr_t>(result);
size_t adjust = 0;
if ((ptr & (alignment - 1)) != 0) {
adjust = alignment - (ptr & (alignment - 1));
}
// Return the unused memory to the system
if (adjust > 0) {
munmap(reinterpret_cast<void*>(ptr), adjust);
}
if (adjust < extra) {
munmap(reinterpret_cast<void*>(ptr + adjust + size), extra - adjust);
}
ptr += adjust;
return reinterpret_cast<void*>(ptr);
#endif // HAVE_MMAP
}
void* DevMemSysAllocator::Alloc(size_t size, size_t *actual_size,
size_t alignment) {
#ifndef HAVE_MMAP
return NULL;
#else
static bool initialized = false;
static off_t physmem_base; // next physical memory address to allocate
static off_t physmem_limit; // maximum physical address allowed
static int physmem_fd; // file descriptor for /dev/mem
// Check if we should use /dev/mem allocation. Note that it may take
// a while to get this flag initialized, so meanwhile we fall back to
// the next allocator. (It looks like 7MB gets allocated before
// this flag gets initialized -khr.)
if (FLAGS_malloc_devmem_start == 0) {
// NOTE: not a devmem_failure - we'd like TCMalloc_SystemAlloc to
// try us again next time.
return NULL;
}
if (!initialized) {
physmem_fd = open("/dev/mem", O_RDWR);
if (physmem_fd < 0) {
return NULL;
}
physmem_base = FLAGS_malloc_devmem_start*1024LL*1024LL;
physmem_limit = FLAGS_malloc_devmem_limit*1024LL*1024LL;
initialized = true;
}
// Enforce page alignment
if (pagesize == 0) pagesize = getpagesize();
if (alignment < pagesize) alignment = pagesize;
size_t aligned_size = ((size + alignment - 1) / alignment) * alignment;
if (aligned_size < size) {
return NULL;
}
size = aligned_size;
// "actual_size" indicates that the bytes from the returned pointer
// p up to and including (p + actual_size - 1) have been allocated.
if (actual_size) {
*actual_size = size;
}
// Ask for extra memory if alignment > pagesize
size_t extra = 0;
if (alignment > pagesize) {
extra = alignment - pagesize;
}
// check to see if we have any memory left
if (physmem_limit != 0 &&
((size + extra) > (physmem_limit - physmem_base))) {
return NULL;
}
// Note: size + extra does not overflow since:
// size + alignment < (1<<NBITS).
// and extra <= alignment
// therefore size + extra < (1<<NBITS)
void *result = mmap(0, size + extra, PROT_WRITE|PROT_READ,
MAP_SHARED, physmem_fd, physmem_base);
if (result == reinterpret_cast<void*>(MAP_FAILED)) {
return NULL;
}
uintptr_t ptr = reinterpret_cast<uintptr_t>(result);
// Adjust the return memory so it is aligned
size_t adjust = 0;
if ((ptr & (alignment - 1)) != 0) {
adjust = alignment - (ptr & (alignment - 1));
}
// Return the unused virtual memory to the system
if (adjust > 0) {
munmap(reinterpret_cast<void*>(ptr), adjust);
}
if (adjust < extra) {
munmap(reinterpret_cast<void*>(ptr + adjust + size), extra - adjust);
}
ptr += adjust;
physmem_base += adjust + size;
return reinterpret_cast<void*>(ptr);
#endif // HAVE_MMAP
}
void* DefaultSysAllocator::Alloc(size_t size, size_t *actual_size,
size_t alignment) {
for (int i = 0; i < kMaxAllocators; i++) {
if (!failed_[i] && allocs_[i] != NULL) {
void* result = allocs_[i]->Alloc(size, actual_size, alignment);
if (result != NULL) {
return result;
}
failed_[i] = true;
}
}
// After both failed, reset "failed_" to false so that a single failed
// allocation won't make the allocator never work again.
for (int i = 0; i < kMaxAllocators; i++) {
failed_[i] = false;
}
return NULL;
}
ATTRIBUTE_WEAK ATTRIBUTE_NOINLINE
SysAllocator *tc_get_sysalloc_override(SysAllocator *def)
{
return def;
}
static bool system_alloc_inited = false;
void InitSystemAllocators(void) {
MmapSysAllocator *mmap = new (mmap_space) MmapSysAllocator();
SbrkSysAllocator *sbrk = new (sbrk_space) SbrkSysAllocator();
// In 64-bit debug mode, place the mmap allocator first since it
// allocates pointers that do not fit in 32 bits and therefore gives
// us better testing of code's 64-bit correctness. It also leads to
// less false negatives in heap-checking code. (Numbers are less
// likely to look like pointers and therefore the conservative gc in
// the heap-checker is less likely to misinterpret a number as a
// pointer).
DefaultSysAllocator *sdef = new (default_space) DefaultSysAllocator();
if (kDebugMode && sizeof(void*) > 4) {
sdef->SetChildAllocator(mmap, 0, mmap_name);
sdef->SetChildAllocator(sbrk, 1, sbrk_name);
} else {
sdef->SetChildAllocator(sbrk, 0, sbrk_name);
sdef->SetChildAllocator(mmap, 1, mmap_name);
}
sys_alloc = tc_get_sysalloc_override(sdef);
}
void* TCMalloc_SystemAlloc(size_t size, size_t *actual_size,
size_t alignment) {
// Discard requests that overflow
if (size + alignment < size) return NULL;
SpinLockHolder lock_holder(&spinlock);
if (!system_alloc_inited) {
InitSystemAllocators();
system_alloc_inited = true;
}
// Enforce minimum alignment
if (alignment < sizeof(MemoryAligner)) alignment = sizeof(MemoryAligner);
size_t actual_size_storage;
if (actual_size == NULL) {
actual_size = &actual_size_storage;
}
void* result = sys_alloc->Alloc(size, actual_size, alignment);
if (result != NULL) {
CHECK_CONDITION(
CheckAddressBits<kAddressBits>(
reinterpret_cast<uintptr_t>(result) + *actual_size - 1));
TCMalloc_SystemTaken += *actual_size;
}
return result;
}
bool TCMalloc_SystemRelease(void* start, size_t length) {
#ifdef MADV_FREE
if (FLAGS_malloc_devmem_start) {
// It's not safe to use MADV_FREE/MADV_DONTNEED if we've been
// mapping /dev/mem for heap memory.
return false;
}
if (FLAGS_malloc_disable_memory_release) return false;
if (pagesize == 0) pagesize = getpagesize();
const size_t pagemask = pagesize - 1;
size_t new_start = reinterpret_cast<size_t>(start);
size_t end = new_start + length;
size_t new_end = end;
// Round up the starting address and round down the ending address
// to be page aligned:
new_start = (new_start + pagesize - 1) & ~pagemask;
new_end = new_end & ~pagemask;
ASSERT((new_start & pagemask) == 0);
ASSERT((new_end & pagemask) == 0);
ASSERT(new_start >= reinterpret_cast<size_t>(start));
ASSERT(new_end <= end);
if (new_end > new_start) {
int result;
do {
result = madvise(reinterpret_cast<char*>(new_start),
new_end - new_start, MADV_FREE);
} while (result == -1 && errno == EAGAIN);
return result != -1;
}
#endif
return false;
}
void TCMalloc_SystemCommit(void* start, size_t length) {
// Nothing to do here. TCMalloc_SystemRelease does not alter pages
// such that they need to be re-committed before they can be used by the
// application.
}