platform-linux.cc revision 9fac840a46e8b7e26894f4792ba26dde14c56b04
1// Copyright 2006-2008 the V8 project authors. All rights reserved. 2// Redistribution and use in source and binary forms, with or without 3// modification, are permitted provided that the following conditions are 4// met: 5// 6// * Redistributions of source code must retain the above copyright 7// notice, this list of conditions and the following disclaimer. 8// * Redistributions in binary form must reproduce the above 9// copyright notice, this list of conditions and the following 10// disclaimer in the documentation and/or other materials provided 11// with the distribution. 12// * Neither the name of Google Inc. nor the names of its 13// contributors may be used to endorse or promote products derived 14// from this software without specific prior written permission. 15// 16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28// Platform specific code for Linux goes here. For the POSIX comaptible parts 29// the implementation is in platform-posix.cc. 30 31#include <pthread.h> 32#include <semaphore.h> 33#include <signal.h> 34#include <sys/prctl.h> 35#include <sys/time.h> 36#include <sys/resource.h> 37#include <sys/syscall.h> 38#include <sys/types.h> 39#include <stdlib.h> 40 41// Ubuntu Dapper requires memory pages to be marked as 42// executable. Otherwise, OS raises an exception when executing code 43// in that page. 44#include <sys/types.h> // mmap & munmap 45#include <sys/mman.h> // mmap & munmap 46#include <sys/stat.h> // open 47#include <fcntl.h> // open 48#include <unistd.h> // sysconf 49#ifdef __GLIBC__ 50#include <execinfo.h> // backtrace, backtrace_symbols 51#endif // def __GLIBC__ 52#include <strings.h> // index 53#include <errno.h> 54#include <stdarg.h> 55 56#undef MAP_TYPE 57 58#include "v8.h" 59 60#include "platform.h" 61#include "top.h" 62#include "v8threads.h" 63#include "vm-state-inl.h" 64 65 66namespace v8 { 67namespace internal { 68 69// 0 is never a valid thread id on Linux since tids and pids share a 70// name space and pid 0 is reserved (see man 2 kill). 71static const pthread_t kNoThread = (pthread_t) 0; 72 73 74double ceiling(double x) { 75 return ceil(x); 76} 77 78 79void OS::Setup() { 80 // Seed the random number generator. 81 // Convert the current time to a 64-bit integer first, before converting it 82 // to an unsigned. Going directly can cause an overflow and the seed to be 83 // set to all ones. The seed will be identical for different instances that 84 // call this setup code within the same millisecond. 85 uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis()); 86 srandom(static_cast<unsigned int>(seed)); 87} 88 89 90uint64_t OS::CpuFeaturesImpliedByPlatform() { 91#if (defined(__VFP_FP__) && !defined(__SOFTFP__)) 92 // Here gcc is telling us that we are on an ARM and gcc is assuming that we 93 // have VFP3 instructions. If gcc can assume it then so can we. 94 return 1u << VFP3; 95#elif CAN_USE_ARMV7_INSTRUCTIONS 96 return 1u << ARMv7; 97#else 98 return 0; // Linux runs on anything. 99#endif 100} 101 102 103#ifdef __arm__ 104static bool CPUInfoContainsString(const char * search_string) { 105 const char* file_name = "/proc/cpuinfo"; 106 // This is written as a straight shot one pass parser 107 // and not using STL string and ifstream because, 108 // on Linux, it's reading from a (non-mmap-able) 109 // character special device. 110 FILE* f = NULL; 111 const char* what = search_string; 112 113 if (NULL == (f = fopen(file_name, "r"))) 114 return false; 115 116 int k; 117 while (EOF != (k = fgetc(f))) { 118 if (k == *what) { 119 ++what; 120 while ((*what != '\0') && (*what == fgetc(f))) { 121 ++what; 122 } 123 if (*what == '\0') { 124 fclose(f); 125 return true; 126 } else { 127 what = search_string; 128 } 129 } 130 } 131 fclose(f); 132 133 // Did not find string in the proc file. 134 return false; 135} 136 137bool OS::ArmCpuHasFeature(CpuFeature feature) { 138 const char* search_string = NULL; 139 // Simple detection of VFP at runtime for Linux. 140 // It is based on /proc/cpuinfo, which reveals hardware configuration 141 // to user-space applications. According to ARM (mid 2009), no similar 142 // facility is universally available on the ARM architectures, 143 // so it's up to individual OSes to provide such. 144 switch (feature) { 145 case VFP3: 146 search_string = "vfpv3"; 147 break; 148 case ARMv7: 149 search_string = "ARMv7"; 150 break; 151 default: 152 UNREACHABLE(); 153 } 154 155 if (CPUInfoContainsString(search_string)) { 156 return true; 157 } 158 159 if (feature == VFP3) { 160 // Some old kernels will report vfp not vfpv3. Here we make a last attempt 161 // to detect vfpv3 by checking for vfp *and* neon, since neon is only 162 // available on architectures with vfpv3. 163 // Checking neon on its own is not enough as it is possible to have neon 164 // without vfp. 165 if (CPUInfoContainsString("vfp") && CPUInfoContainsString("neon")) { 166 return true; 167 } 168 } 169 170 return false; 171} 172#endif // def __arm__ 173 174 175int OS::ActivationFrameAlignment() { 176#ifdef V8_TARGET_ARCH_ARM 177 // On EABI ARM targets this is required for fp correctness in the 178 // runtime system. 179 return 8; 180#elif V8_TARGET_ARCH_MIPS 181 return 8; 182#endif 183 // With gcc 4.4 the tree vectorization optimizer can generate code 184 // that requires 16 byte alignment such as movdqa on x86. 185 return 16; 186} 187 188 189void OS::ReleaseStore(volatile AtomicWord* ptr, AtomicWord value) { 190#if defined(V8_TARGET_ARCH_ARM) && defined(__arm__) 191 // Only use on ARM hardware. 192 MemoryBarrier(); 193#else 194 __asm__ __volatile__("" : : : "memory"); 195 // An x86 store acts as a release barrier. 196#endif 197 *ptr = value; 198} 199 200 201const char* OS::LocalTimezone(double time) { 202 if (isnan(time)) return ""; 203 time_t tv = static_cast<time_t>(floor(time/msPerSecond)); 204 struct tm* t = localtime(&tv); 205 if (NULL == t) return ""; 206 return t->tm_zone; 207} 208 209 210double OS::LocalTimeOffset() { 211 time_t tv = time(NULL); 212 struct tm* t = localtime(&tv); 213 // tm_gmtoff includes any daylight savings offset, so subtract it. 214 return static_cast<double>(t->tm_gmtoff * msPerSecond - 215 (t->tm_isdst > 0 ? 3600 * msPerSecond : 0)); 216} 217 218 219// We keep the lowest and highest addresses mapped as a quick way of 220// determining that pointers are outside the heap (used mostly in assertions 221// and verification). The estimate is conservative, ie, not all addresses in 222// 'allocated' space are actually allocated to our heap. The range is 223// [lowest, highest), inclusive on the low and and exclusive on the high end. 224static void* lowest_ever_allocated = reinterpret_cast<void*>(-1); 225static void* highest_ever_allocated = reinterpret_cast<void*>(0); 226 227 228static void UpdateAllocatedSpaceLimits(void* address, int size) { 229 lowest_ever_allocated = Min(lowest_ever_allocated, address); 230 highest_ever_allocated = 231 Max(highest_ever_allocated, 232 reinterpret_cast<void*>(reinterpret_cast<char*>(address) + size)); 233} 234 235 236bool OS::IsOutsideAllocatedSpace(void* address) { 237 return address < lowest_ever_allocated || address >= highest_ever_allocated; 238} 239 240 241size_t OS::AllocateAlignment() { 242 return sysconf(_SC_PAGESIZE); 243} 244 245 246void* OS::Allocate(const size_t requested, 247 size_t* allocated, 248 bool is_executable) { 249 // TODO(805): Port randomization of allocated executable memory to Linux. 250 const size_t msize = RoundUp(requested, sysconf(_SC_PAGESIZE)); 251 int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0); 252 void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 253 if (mbase == MAP_FAILED) { 254 LOG(StringEvent("OS::Allocate", "mmap failed")); 255 return NULL; 256 } 257 *allocated = msize; 258 UpdateAllocatedSpaceLimits(mbase, msize); 259 return mbase; 260} 261 262 263void OS::Free(void* address, const size_t size) { 264 // TODO(1240712): munmap has a return value which is ignored here. 265 int result = munmap(address, size); 266 USE(result); 267 ASSERT(result == 0); 268} 269 270 271#ifdef ENABLE_HEAP_PROTECTION 272 273void OS::Protect(void* address, size_t size) { 274 // TODO(1240712): mprotect has a return value which is ignored here. 275 mprotect(address, size, PROT_READ); 276} 277 278 279void OS::Unprotect(void* address, size_t size, bool is_executable) { 280 // TODO(1240712): mprotect has a return value which is ignored here. 281 int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0); 282 mprotect(address, size, prot); 283} 284 285#endif 286 287 288void OS::Sleep(int milliseconds) { 289 unsigned int ms = static_cast<unsigned int>(milliseconds); 290 usleep(1000 * ms); 291} 292 293 294void OS::Abort() { 295 // Redirect to std abort to signal abnormal program termination. 296 abort(); 297} 298 299 300void OS::DebugBreak() { 301// TODO(lrn): Introduce processor define for runtime system (!= V8_ARCH_x, 302// which is the architecture of generated code). 303#if (defined(__arm__) || defined(__thumb__)) 304# if defined(CAN_USE_ARMV5_INSTRUCTIONS) 305 asm("bkpt 0"); 306# endif 307#elif defined(__mips__) 308 asm("break"); 309#else 310 asm("int $3"); 311#endif 312} 313 314 315class PosixMemoryMappedFile : public OS::MemoryMappedFile { 316 public: 317 PosixMemoryMappedFile(FILE* file, void* memory, int size) 318 : file_(file), memory_(memory), size_(size) { } 319 virtual ~PosixMemoryMappedFile(); 320 virtual void* memory() { return memory_; } 321 private: 322 FILE* file_; 323 void* memory_; 324 int size_; 325}; 326 327 328OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name, int size, 329 void* initial) { 330 FILE* file = fopen(name, "w+"); 331 if (file == NULL) return NULL; 332 int result = fwrite(initial, size, 1, file); 333 if (result < 1) { 334 fclose(file); 335 return NULL; 336 } 337 void* memory = 338 mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fileno(file), 0); 339 return new PosixMemoryMappedFile(file, memory, size); 340} 341 342 343PosixMemoryMappedFile::~PosixMemoryMappedFile() { 344 if (memory_) munmap(memory_, size_); 345 fclose(file_); 346} 347 348 349void OS::LogSharedLibraryAddresses() { 350#ifdef ENABLE_LOGGING_AND_PROFILING 351 // This function assumes that the layout of the file is as follows: 352 // hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name] 353 // If we encounter an unexpected situation we abort scanning further entries. 354 FILE* fp = fopen("/proc/self/maps", "r"); 355 if (fp == NULL) return; 356 357 // Allocate enough room to be able to store a full file name. 358 const int kLibNameLen = FILENAME_MAX + 1; 359 char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen)); 360 361 // This loop will terminate once the scanning hits an EOF. 362 while (true) { 363 uintptr_t start, end; 364 char attr_r, attr_w, attr_x, attr_p; 365 // Parse the addresses and permission bits at the beginning of the line. 366 if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2) break; 367 if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4) break; 368 369 int c; 370 if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') { 371 // Found a read-only executable entry. Skip characters until we reach 372 // the beginning of the filename or the end of the line. 373 do { 374 c = getc(fp); 375 } while ((c != EOF) && (c != '\n') && (c != '/')); 376 if (c == EOF) break; // EOF: Was unexpected, just exit. 377 378 // Process the filename if found. 379 if (c == '/') { 380 ungetc(c, fp); // Push the '/' back into the stream to be read below. 381 382 // Read to the end of the line. Exit if the read fails. 383 if (fgets(lib_name, kLibNameLen, fp) == NULL) break; 384 385 // Drop the newline character read by fgets. We do not need to check 386 // for a zero-length string because we know that we at least read the 387 // '/' character. 388 lib_name[strlen(lib_name) - 1] = '\0'; 389 } else { 390 // No library name found, just record the raw address range. 391 snprintf(lib_name, kLibNameLen, 392 "%08" V8PRIxPTR "-%08" V8PRIxPTR, start, end); 393 } 394 LOG(SharedLibraryEvent(lib_name, start, end)); 395 } else { 396 // Entry not describing executable data. Skip to end of line to setup 397 // reading the next entry. 398 do { 399 c = getc(fp); 400 } while ((c != EOF) && (c != '\n')); 401 if (c == EOF) break; 402 } 403 } 404 free(lib_name); 405 fclose(fp); 406#endif 407} 408 409 410static const char kGCFakeMmap[] = "/tmp/__v8_gc__"; 411 412 413void OS::SignalCodeMovingGC() { 414#ifdef ENABLE_LOGGING_AND_PROFILING 415 // Support for ll_prof.py. 416 // 417 // The Linux profiler built into the kernel logs all mmap's with 418 // PROT_EXEC so that analysis tools can properly attribute ticks. We 419 // do a mmap with a name known by ll_prof.py and immediately munmap 420 // it. This injects a GC marker into the stream of events generated 421 // by the kernel and allows us to synchronize V8 code log and the 422 // kernel log. 423 int size = sysconf(_SC_PAGESIZE); 424 FILE* f = fopen(kGCFakeMmap, "w+"); 425 void* addr = mmap(NULL, size, PROT_READ | PROT_EXEC, MAP_PRIVATE, 426 fileno(f), 0); 427 ASSERT(addr != MAP_FAILED); 428 munmap(addr, size); 429 fclose(f); 430#endif 431} 432 433 434int OS::StackWalk(Vector<OS::StackFrame> frames) { 435 // backtrace is a glibc extension. 436#ifdef __GLIBC__ 437 int frames_size = frames.length(); 438 ScopedVector<void*> addresses(frames_size); 439 440 int frames_count = backtrace(addresses.start(), frames_size); 441 442 char** symbols = backtrace_symbols(addresses.start(), frames_count); 443 if (symbols == NULL) { 444 return kStackWalkError; 445 } 446 447 for (int i = 0; i < frames_count; i++) { 448 frames[i].address = addresses[i]; 449 // Format a text representation of the frame based on the information 450 // available. 451 SNPrintF(MutableCStrVector(frames[i].text, kStackWalkMaxTextLen), 452 "%s", 453 symbols[i]); 454 // Make sure line termination is in place. 455 frames[i].text[kStackWalkMaxTextLen - 1] = '\0'; 456 } 457 458 free(symbols); 459 460 return frames_count; 461#else // ndef __GLIBC__ 462 return 0; 463#endif // ndef __GLIBC__ 464} 465 466 467// Constants used for mmap. 468static const int kMmapFd = -1; 469static const int kMmapFdOffset = 0; 470 471 472VirtualMemory::VirtualMemory(size_t size) { 473 address_ = mmap(NULL, size, PROT_NONE, 474 MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, 475 kMmapFd, kMmapFdOffset); 476 size_ = size; 477} 478 479 480VirtualMemory::~VirtualMemory() { 481 if (IsReserved()) { 482 if (0 == munmap(address(), size())) address_ = MAP_FAILED; 483 } 484} 485 486 487bool VirtualMemory::IsReserved() { 488 return address_ != MAP_FAILED; 489} 490 491 492bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) { 493 int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0); 494 if (MAP_FAILED == mmap(address, size, prot, 495 MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, 496 kMmapFd, kMmapFdOffset)) { 497 return false; 498 } 499 500 UpdateAllocatedSpaceLimits(address, size); 501 return true; 502} 503 504 505bool VirtualMemory::Uncommit(void* address, size_t size) { 506 return mmap(address, size, PROT_NONE, 507 MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE | MAP_FIXED, 508 kMmapFd, kMmapFdOffset) != MAP_FAILED; 509} 510 511 512class ThreadHandle::PlatformData : public Malloced { 513 public: 514 explicit PlatformData(ThreadHandle::Kind kind) { 515 Initialize(kind); 516 } 517 518 void Initialize(ThreadHandle::Kind kind) { 519 switch (kind) { 520 case ThreadHandle::SELF: thread_ = pthread_self(); break; 521 case ThreadHandle::INVALID: thread_ = kNoThread; break; 522 } 523 } 524 525 pthread_t thread_; // Thread handle for pthread. 526}; 527 528 529ThreadHandle::ThreadHandle(Kind kind) { 530 data_ = new PlatformData(kind); 531} 532 533 534void ThreadHandle::Initialize(ThreadHandle::Kind kind) { 535 data_->Initialize(kind); 536} 537 538 539ThreadHandle::~ThreadHandle() { 540 delete data_; 541} 542 543 544bool ThreadHandle::IsSelf() const { 545 return pthread_equal(data_->thread_, pthread_self()); 546} 547 548 549bool ThreadHandle::IsValid() const { 550 return data_->thread_ != kNoThread; 551} 552 553 554Thread::Thread() : ThreadHandle(ThreadHandle::INVALID) { 555 set_name("v8:<unknown>"); 556} 557 558 559Thread::Thread(const char* name) : ThreadHandle(ThreadHandle::INVALID) { 560 set_name(name); 561} 562 563 564Thread::~Thread() { 565} 566 567 568static void* ThreadEntry(void* arg) { 569 Thread* thread = reinterpret_cast<Thread*>(arg); 570 // This is also initialized by the first argument to pthread_create() but we 571 // don't know which thread will run first (the original thread or the new 572 // one) so we initialize it here too. 573 prctl(PR_SET_NAME, 574 reinterpret_cast<unsigned long>(thread->name()), // NOLINT 575 0, 0, 0); 576 thread->thread_handle_data()->thread_ = pthread_self(); 577 ASSERT(thread->IsValid()); 578 thread->Run(); 579 return NULL; 580} 581 582 583void Thread::set_name(const char* name) { 584 strncpy(name_, name, sizeof(name_)); 585 name_[sizeof(name_) - 1] = '\0'; 586} 587 588 589void Thread::Start() { 590 pthread_create(&thread_handle_data()->thread_, NULL, ThreadEntry, this); 591 ASSERT(IsValid()); 592} 593 594 595void Thread::Join() { 596 pthread_join(thread_handle_data()->thread_, NULL); 597} 598 599 600Thread::LocalStorageKey Thread::CreateThreadLocalKey() { 601 pthread_key_t key; 602 int result = pthread_key_create(&key, NULL); 603 USE(result); 604 ASSERT(result == 0); 605 return static_cast<LocalStorageKey>(key); 606} 607 608 609void Thread::DeleteThreadLocalKey(LocalStorageKey key) { 610 pthread_key_t pthread_key = static_cast<pthread_key_t>(key); 611 int result = pthread_key_delete(pthread_key); 612 USE(result); 613 ASSERT(result == 0); 614} 615 616 617void* Thread::GetThreadLocal(LocalStorageKey key) { 618 pthread_key_t pthread_key = static_cast<pthread_key_t>(key); 619 return pthread_getspecific(pthread_key); 620} 621 622 623void Thread::SetThreadLocal(LocalStorageKey key, void* value) { 624 pthread_key_t pthread_key = static_cast<pthread_key_t>(key); 625 pthread_setspecific(pthread_key, value); 626} 627 628 629void Thread::YieldCPU() { 630 sched_yield(); 631} 632 633 634class LinuxMutex : public Mutex { 635 public: 636 637 LinuxMutex() { 638 pthread_mutexattr_t attrs; 639 int result = pthread_mutexattr_init(&attrs); 640 ASSERT(result == 0); 641 result = pthread_mutexattr_settype(&attrs, PTHREAD_MUTEX_RECURSIVE); 642 ASSERT(result == 0); 643 result = pthread_mutex_init(&mutex_, &attrs); 644 ASSERT(result == 0); 645 } 646 647 virtual ~LinuxMutex() { pthread_mutex_destroy(&mutex_); } 648 649 virtual int Lock() { 650 int result = pthread_mutex_lock(&mutex_); 651 return result; 652 } 653 654 virtual int Unlock() { 655 int result = pthread_mutex_unlock(&mutex_); 656 return result; 657 } 658 659 virtual bool TryLock() { 660 int result = pthread_mutex_trylock(&mutex_); 661 // Return false if the lock is busy and locking failed. 662 if (result == EBUSY) { 663 return false; 664 } 665 ASSERT(result == 0); // Verify no other errors. 666 return true; 667 } 668 669 private: 670 pthread_mutex_t mutex_; // Pthread mutex for POSIX platforms. 671}; 672 673 674Mutex* OS::CreateMutex() { 675 return new LinuxMutex(); 676} 677 678 679class LinuxSemaphore : public Semaphore { 680 public: 681 explicit LinuxSemaphore(int count) { sem_init(&sem_, 0, count); } 682 virtual ~LinuxSemaphore() { sem_destroy(&sem_); } 683 684 virtual void Wait(); 685 virtual bool Wait(int timeout); 686 virtual void Signal() { sem_post(&sem_); } 687 private: 688 sem_t sem_; 689}; 690 691 692void LinuxSemaphore::Wait() { 693 while (true) { 694 int result = sem_wait(&sem_); 695 if (result == 0) return; // Successfully got semaphore. 696 CHECK(result == -1 && errno == EINTR); // Signal caused spurious wakeup. 697 } 698} 699 700 701#ifndef TIMEVAL_TO_TIMESPEC 702#define TIMEVAL_TO_TIMESPEC(tv, ts) do { \ 703 (ts)->tv_sec = (tv)->tv_sec; \ 704 (ts)->tv_nsec = (tv)->tv_usec * 1000; \ 705} while (false) 706#endif 707 708 709bool LinuxSemaphore::Wait(int timeout) { 710 const long kOneSecondMicros = 1000000; // NOLINT 711 712 // Split timeout into second and nanosecond parts. 713 struct timeval delta; 714 delta.tv_usec = timeout % kOneSecondMicros; 715 delta.tv_sec = timeout / kOneSecondMicros; 716 717 struct timeval current_time; 718 // Get the current time. 719 if (gettimeofday(¤t_time, NULL) == -1) { 720 return false; 721 } 722 723 // Calculate time for end of timeout. 724 struct timeval end_time; 725 timeradd(¤t_time, &delta, &end_time); 726 727 struct timespec ts; 728 TIMEVAL_TO_TIMESPEC(&end_time, &ts); 729 // Wait for semaphore signalled or timeout. 730 while (true) { 731 int result = sem_timedwait(&sem_, &ts); 732 if (result == 0) return true; // Successfully got semaphore. 733 if (result > 0) { 734 // For glibc prior to 2.3.4 sem_timedwait returns the error instead of -1. 735 errno = result; 736 result = -1; 737 } 738 if (result == -1 && errno == ETIMEDOUT) return false; // Timeout. 739 CHECK(result == -1 && errno == EINTR); // Signal caused spurious wakeup. 740 } 741} 742 743 744Semaphore* OS::CreateSemaphore(int count) { 745 return new LinuxSemaphore(count); 746} 747 748 749#ifdef ENABLE_LOGGING_AND_PROFILING 750 751static Sampler* active_sampler_ = NULL; 752static int vm_tid_ = 0; 753 754 755#if !defined(__GLIBC__) && (defined(__arm__) || defined(__thumb__)) 756// Android runs a fairly new Linux kernel, so signal info is there, 757// but the C library doesn't have the structs defined. 758 759struct sigcontext { 760 uint32_t trap_no; 761 uint32_t error_code; 762 uint32_t oldmask; 763 uint32_t gregs[16]; 764 uint32_t arm_cpsr; 765 uint32_t fault_address; 766}; 767typedef uint32_t __sigset_t; 768typedef struct sigcontext mcontext_t; 769typedef struct ucontext { 770 uint32_t uc_flags; 771 struct ucontext* uc_link; 772 stack_t uc_stack; 773 mcontext_t uc_mcontext; 774 __sigset_t uc_sigmask; 775} ucontext_t; 776enum ArmRegisters {R15 = 15, R13 = 13, R11 = 11}; 777 778#endif 779 780 781static int GetThreadID() { 782 // Glibc doesn't provide a wrapper for gettid(2). 783 return syscall(SYS_gettid); 784} 785 786 787static void ProfilerSignalHandler(int signal, siginfo_t* info, void* context) { 788#ifndef V8_HOST_ARCH_MIPS 789 USE(info); 790 if (signal != SIGPROF) return; 791 if (active_sampler_ == NULL || !active_sampler_->IsActive()) return; 792 if (vm_tid_ != GetThreadID()) return; 793 794 TickSample sample_obj; 795 TickSample* sample = CpuProfiler::TickSampleEvent(); 796 if (sample == NULL) sample = &sample_obj; 797 798 // Extracting the sample from the context is extremely machine dependent. 799 ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context); 800 mcontext_t& mcontext = ucontext->uc_mcontext; 801 sample->state = Top::current_vm_state(); 802#if V8_HOST_ARCH_IA32 803 sample->pc = reinterpret_cast<Address>(mcontext.gregs[REG_EIP]); 804 sample->sp = reinterpret_cast<Address>(mcontext.gregs[REG_ESP]); 805 sample->fp = reinterpret_cast<Address>(mcontext.gregs[REG_EBP]); 806#elif V8_HOST_ARCH_X64 807 sample->pc = reinterpret_cast<Address>(mcontext.gregs[REG_RIP]); 808 sample->sp = reinterpret_cast<Address>(mcontext.gregs[REG_RSP]); 809 sample->fp = reinterpret_cast<Address>(mcontext.gregs[REG_RBP]); 810#elif V8_HOST_ARCH_ARM 811// An undefined macro evaluates to 0, so this applies to Android's Bionic also. 812#if (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ <= 3)) 813 sample->pc = reinterpret_cast<Address>(mcontext.gregs[R15]); 814 sample->sp = reinterpret_cast<Address>(mcontext.gregs[R13]); 815 sample->fp = reinterpret_cast<Address>(mcontext.gregs[R11]); 816#else 817 sample->pc = reinterpret_cast<Address>(mcontext.arm_pc); 818 sample->sp = reinterpret_cast<Address>(mcontext.arm_sp); 819 sample->fp = reinterpret_cast<Address>(mcontext.arm_fp); 820#endif 821#elif V8_HOST_ARCH_MIPS 822 // Implement this on MIPS. 823 UNIMPLEMENTED(); 824#endif 825 active_sampler_->SampleStack(sample); 826 active_sampler_->Tick(sample); 827#endif 828} 829 830 831class Sampler::PlatformData : public Malloced { 832 public: 833 enum SleepInterval { 834 FULL_INTERVAL, 835 HALF_INTERVAL 836 }; 837 838 explicit PlatformData(Sampler* sampler) 839 : sampler_(sampler), 840 signal_handler_installed_(false), 841 vm_tgid_(getpid()), 842 signal_sender_launched_(false) { 843 } 844 845 void SignalSender() { 846 while (sampler_->IsActive()) { 847 if (rate_limiter_.SuspendIfNecessary()) continue; 848 if (sampler_->IsProfiling() && RuntimeProfiler::IsEnabled()) { 849 SendProfilingSignal(); 850 Sleep(HALF_INTERVAL); 851 RuntimeProfiler::NotifyTick(); 852 Sleep(HALF_INTERVAL); 853 } else { 854 if (sampler_->IsProfiling()) SendProfilingSignal(); 855 if (RuntimeProfiler::IsEnabled()) RuntimeProfiler::NotifyTick(); 856 Sleep(FULL_INTERVAL); 857 } 858 } 859 } 860 861 void SendProfilingSignal() { 862 // Glibc doesn't provide a wrapper for tgkill(2). 863 syscall(SYS_tgkill, vm_tgid_, vm_tid_, SIGPROF); 864 } 865 866 void Sleep(SleepInterval full_or_half) { 867 // Convert ms to us and subtract 100 us to compensate delays 868 // occuring during signal delivery. 869 useconds_t interval = sampler_->interval_ * 1000 - 100; 870 if (full_or_half == HALF_INTERVAL) interval /= 2; 871 int result = usleep(interval); 872#ifdef DEBUG 873 if (result != 0 && errno != EINTR) { 874 fprintf(stderr, 875 "SignalSender usleep error; interval = %u, errno = %d\n", 876 interval, 877 errno); 878 ASSERT(result == 0 || errno == EINTR); 879 } 880#endif 881 USE(result); 882 } 883 884 Sampler* sampler_; 885 bool signal_handler_installed_; 886 struct sigaction old_signal_handler_; 887 int vm_tgid_; 888 bool signal_sender_launched_; 889 pthread_t signal_sender_thread_; 890 RuntimeProfilerRateLimiter rate_limiter_; 891}; 892 893 894static void* SenderEntry(void* arg) { 895 Sampler::PlatformData* data = 896 reinterpret_cast<Sampler::PlatformData*>(arg); 897 data->SignalSender(); 898 return 0; 899} 900 901 902Sampler::Sampler(int interval) 903 : interval_(interval), 904 profiling_(false), 905 active_(false), 906 samples_taken_(0) { 907 data_ = new PlatformData(this); 908} 909 910 911Sampler::~Sampler() { 912 ASSERT(!data_->signal_sender_launched_); 913 delete data_; 914} 915 916 917void Sampler::Start() { 918 // There can only be one active sampler at the time on POSIX 919 // platforms. 920 ASSERT(!IsActive()); 921 vm_tid_ = GetThreadID(); 922 923 // Request profiling signals. 924 struct sigaction sa; 925 sa.sa_sigaction = ProfilerSignalHandler; 926 sigemptyset(&sa.sa_mask); 927 sa.sa_flags = SA_RESTART | SA_SIGINFO; 928 if (sigaction(SIGPROF, &sa, &data_->old_signal_handler_) != 0) return; 929 data_->signal_handler_installed_ = true; 930 931 // Start a thread that sends SIGPROF signal to VM thread. 932 // Sending the signal ourselves instead of relying on itimer provides 933 // much better accuracy. 934 SetActive(true); 935 if (pthread_create( 936 &data_->signal_sender_thread_, NULL, SenderEntry, data_) == 0) { 937 data_->signal_sender_launched_ = true; 938 } 939 940 // Set this sampler as the active sampler. 941 active_sampler_ = this; 942} 943 944 945void Sampler::Stop() { 946 SetActive(false); 947 948 // Wait for signal sender termination (it will exit after setting 949 // active_ to false). 950 if (data_->signal_sender_launched_) { 951 Top::WakeUpRuntimeProfilerThreadBeforeShutdown(); 952 pthread_join(data_->signal_sender_thread_, NULL); 953 data_->signal_sender_launched_ = false; 954 } 955 956 // Restore old signal handler 957 if (data_->signal_handler_installed_) { 958 sigaction(SIGPROF, &data_->old_signal_handler_, 0); 959 data_->signal_handler_installed_ = false; 960 } 961 962 // This sampler is no longer the active sampler. 963 active_sampler_ = NULL; 964} 965 966 967#endif // ENABLE_LOGGING_AND_PROFILING 968 969} } // namespace v8::internal 970