deps/v8/src/base/platform/platform-linux.cc
// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Platform-specific code for Linux goes here. For the POSIX-compatible
// parts, the implementation is in platform-posix.cc.
#include <pthread.h>
#include <semaphore.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
// Ubuntu Dapper requires memory pages to be marked as
// executable. Otherwise, OS raises an exception when executing code
// in that page.
#include <errno.h>
#include <fcntl.h> // open
#include <stdarg.h>
#include <strings.h> // index
#include <sys/mman.h> // mmap & munmap
#include <sys/stat.h> // open
#include <sys/types.h> // mmap & munmap
#include <unistd.h> // sysconf
// GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
// Old versions of the C library <signal.h> didn't define the type.
#if defined(__ANDROID__) && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
(defined(__arm__) || defined(__aarch64__)) && \
!defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
#include <asm/sigcontext.h> // NOLINT
#endif
#if defined(LEAK_SANITIZER)
#include <sanitizer/lsan_interface.h>
#endif
#include <cmath>
#undef MAP_TYPE
#include "src/base/macros.h"
#include "src/base/platform/platform.h"
namespace v8 {
namespace base {
#ifdef __arm__
bool OS::ArmUsingHardFloat() {
// GCC versions 4.6 and above define __ARM_PCS or __ARM_PCS_VFP to specify
// the Floating Point ABI used (PCS stands for Procedure Call Standard).
// We use these as well as a couple of other defines to statically determine
// what FP ABI used.
// GCC versions 4.4 and below don't support hard-fp.
// GCC versions 4.5 may support hard-fp without defining __ARM_PCS or
// __ARM_PCS_VFP.
#define GCC_VERSION (__GNUC__ * 10000 \
+ __GNUC_MINOR__ * 100 \
+ __GNUC_PATCHLEVEL__)
#if GCC_VERSION >= 40600
#if defined(__ARM_PCS_VFP)
return true;
#else
return false;
#endif
#elif GCC_VERSION < 40500
return false;
#else
#if defined(__ARM_PCS_VFP)
return true;
#elif defined(__ARM_PCS) || defined(__SOFTFP__) || defined(__SOFTFP) || \
!defined(__VFP_FP__)
return false;
#else
#error "Your version of GCC does not report the FP ABI compiled for." \
"Please report it on this issue" \
"http://code.google.com/p/v8/issues/detail?id=2140"
#endif
#endif
#undef GCC_VERSION
}
#endif // def __arm__
const char* OS::LocalTimezone(double time, TimezoneCache* cache) {
if (std::isnan(time)) return "";
time_t tv = static_cast<time_t>(std::floor(time/msPerSecond));
struct tm* t = localtime(&tv);
if (NULL == t) return "";
return t->tm_zone;
}
double OS::LocalTimeOffset(TimezoneCache* cache) {
time_t tv = time(NULL);
struct tm* t = localtime(&tv);
// tm_gmtoff includes any daylight savings offset, so subtract it.
return static_cast<double>(t->tm_gmtoff * msPerSecond -
(t->tm_isdst > 0 ? 3600 * msPerSecond : 0));
}
void* OS::Allocate(const size_t requested,
size_t* allocated,
bool is_executable) {
const size_t msize = RoundUp(requested, AllocateAlignment());
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
void* addr = OS::GetRandomMmapAddr();
void* mbase = mmap(addr, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (mbase == MAP_FAILED) return NULL;
*allocated = msize;
return mbase;
}
class PosixMemoryMappedFile : public OS::MemoryMappedFile {
public:
PosixMemoryMappedFile(FILE* file, void* memory, int size)
: file_(file), memory_(memory), size_(size) { }
virtual ~PosixMemoryMappedFile();
virtual void* memory() { return memory_; }
virtual int size() { return size_; }
private:
FILE* file_;
void* memory_;
int size_;
};
OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
FILE* file = fopen(name, "r+");
if (file == NULL) return NULL;
fseek(file, 0, SEEK_END);
int size = ftell(file);
void* memory =
mmap(OS::GetRandomMmapAddr(),
size,
PROT_READ | PROT_WRITE,
MAP_SHARED,
fileno(file),
0);
return new PosixMemoryMappedFile(file, memory, size);
}
OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name, int size,
void* initial) {
FILE* file = fopen(name, "w+");
if (file == NULL) return NULL;
int result = fwrite(initial, size, 1, file);
if (result < 1) {
fclose(file);
return NULL;
}
void* memory =
mmap(OS::GetRandomMmapAddr(),
size,
PROT_READ | PROT_WRITE,
MAP_SHARED,
fileno(file),
0);
return new PosixMemoryMappedFile(file, memory, size);
}
PosixMemoryMappedFile::~PosixMemoryMappedFile() {
if (memory_) OS::Free(memory_, size_);
fclose(file_);
}
std::vector<OS::SharedLibraryAddress> OS::GetSharedLibraryAddresses() {
std::vector<SharedLibraryAddress> result;
// This function assumes that the layout of the file is as follows:
// hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name]
// If we encounter an unexpected situation we abort scanning further entries.
FILE* fp = fopen("/proc/self/maps", "r");
if (fp == NULL) return result;
// Allocate enough room to be able to store a full file name.
const int kLibNameLen = FILENAME_MAX + 1;
char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));
// This loop will terminate once the scanning hits an EOF.
while (true) {
uintptr_t start, end;
char attr_r, attr_w, attr_x, attr_p;
// Parse the addresses and permission bits at the beginning of the line.
if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2) break;
if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4) break;
int c;
if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') {
// Found a read-only executable entry. Skip characters until we reach
// the beginning of the filename or the end of the line.
do {
c = getc(fp);
} while ((c != EOF) && (c != '\n') && (c != '/') && (c != '['));
if (c == EOF) break; // EOF: Was unexpected, just exit.
// Process the filename if found.
if ((c == '/') || (c == '[')) {
// Push the '/' or '[' back into the stream to be read below.
ungetc(c, fp);
// Read to the end of the line. Exit if the read fails.
if (fgets(lib_name, kLibNameLen, fp) == NULL) break;
// Drop the newline character read by fgets. We do not need to check
// for a zero-length string because we know that we at least read the
// '/' or '[' character.
lib_name[strlen(lib_name) - 1] = '\0';
} else {
// No library name found, just record the raw address range.
snprintf(lib_name, kLibNameLen,
"%08" V8PRIxPTR "-%08" V8PRIxPTR, start, end);
}
result.push_back(SharedLibraryAddress(lib_name, start, end));
} else {
// Entry not describing executable data. Skip to end of line to set up
// reading the next entry.
do {
c = getc(fp);
} while ((c != EOF) && (c != '\n'));
if (c == EOF) break;
}
}
free(lib_name);
fclose(fp);
return result;
}
void OS::SignalCodeMovingGC() {
// Support for ll_prof.py.
//
// The Linux profiler built into the kernel logs all mmap's with
// PROT_EXEC so that analysis tools can properly attribute ticks. We
// do a mmap with a name known by ll_prof.py and immediately munmap
// it. This injects a GC marker into the stream of events generated
// by the kernel and allows us to synchronize V8 code log and the
// kernel log.
int size = sysconf(_SC_PAGESIZE);
FILE* f = fopen(OS::GetGCFakeMMapFile(), "w+");
if (f == NULL) {
OS::PrintError("Failed to open %s\n", OS::GetGCFakeMMapFile());
OS::Abort();
}
void* addr = mmap(OS::GetRandomMmapAddr(),
size,
#if defined(__native_client__)
// The Native Client port of V8 uses an interpreter,
// so code pages don't need PROT_EXEC.
PROT_READ,
#else
PROT_READ | PROT_EXEC,
#endif
MAP_PRIVATE,
fileno(f),
0);
DCHECK(addr != MAP_FAILED);
OS::Free(addr, size);
fclose(f);
}
// Constants used for mmap.
static const int kMmapFd = -1;
static const int kMmapFdOffset = 0;
VirtualMemory::VirtualMemory() : address_(NULL), size_(0) { }
VirtualMemory::VirtualMemory(size_t size)
: address_(ReserveRegion(size)), size_(size) { }
VirtualMemory::VirtualMemory(size_t size, size_t alignment)
: address_(NULL), size_(0) {
DCHECK(IsAligned(alignment, static_cast<intptr_t>(OS::AllocateAlignment())));
size_t request_size = RoundUp(size + alignment,
static_cast<intptr_t>(OS::AllocateAlignment()));
void* reservation = mmap(OS::GetRandomMmapAddr(),
request_size,
PROT_NONE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE,
kMmapFd,
kMmapFdOffset);
if (reservation == MAP_FAILED) return;
uint8_t* base = static_cast<uint8_t*>(reservation);
uint8_t* aligned_base = RoundUp(base, alignment);
DCHECK_LE(base, aligned_base);
// Unmap extra memory reserved before and after the desired block.
if (aligned_base != base) {
size_t prefix_size = static_cast<size_t>(aligned_base - base);
OS::Free(base, prefix_size);
request_size -= prefix_size;
}
size_t aligned_size = RoundUp(size, OS::AllocateAlignment());
DCHECK_LE(aligned_size, request_size);
if (aligned_size != request_size) {
size_t suffix_size = request_size - aligned_size;
OS::Free(aligned_base + aligned_size, suffix_size);
request_size -= suffix_size;
}
DCHECK(aligned_size == request_size);
address_ = static_cast<void*>(aligned_base);
size_ = aligned_size;
#if defined(LEAK_SANITIZER)
__lsan_register_root_region(address_, size_);
#endif
}
VirtualMemory::~VirtualMemory() {
if (IsReserved()) {
bool result = ReleaseRegion(address(), size());
DCHECK(result);
USE(result);
}
}
bool VirtualMemory::IsReserved() {
return address_ != NULL;
}
void VirtualMemory::Reset() {
address_ = NULL;
size_ = 0;
}
bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
return CommitRegion(address, size, is_executable);
}
bool VirtualMemory::Uncommit(void* address, size_t size) {
return UncommitRegion(address, size);
}
bool VirtualMemory::Guard(void* address) {
OS::Guard(address, OS::CommitPageSize());
return true;
}
void* VirtualMemory::ReserveRegion(size_t size) {
void* result = mmap(OS::GetRandomMmapAddr(),
size,
PROT_NONE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE,
kMmapFd,
kMmapFdOffset);
if (result == MAP_FAILED) return NULL;
#if defined(LEAK_SANITIZER)
__lsan_register_root_region(result, size);
#endif
return result;
}
bool VirtualMemory::CommitRegion(void* base, size_t size, bool is_executable) {
#if defined(__native_client__)
// The Native Client port of V8 uses an interpreter,
// so code pages don't need PROT_EXEC.
int prot = PROT_READ | PROT_WRITE;
#else
int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
#endif
if (MAP_FAILED == mmap(base,
size,
prot,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
kMmapFd,
kMmapFdOffset)) {
return false;
}
return true;
}
bool VirtualMemory::UncommitRegion(void* base, size_t size) {
return mmap(base,
size,
PROT_NONE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE | MAP_FIXED,
kMmapFd,
kMmapFdOffset) != MAP_FAILED;
}
bool VirtualMemory::ReleaseRegion(void* base, size_t size) {
#if defined(LEAK_SANITIZER)
__lsan_unregister_root_region(base, size);
#endif
return munmap(base, size) == 0;
}
bool VirtualMemory::HasLazyCommits() {
return true;
}
} } // namespace v8::base