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platform-posix.cc
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platform-posix.cc
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// 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 POSIX goes here. This is not a platform on its
// own, but contains the parts which are the same across the POSIX platforms
// Linux, MacOS, FreeBSD, OpenBSD, NetBSD and QNX.
#include <errno.h>
#include <limits.h>
#include <pthread.h>
#if defined(__DragonFly__) || defined(__FreeBSD__) || defined(__OpenBSD__)
#include <pthread_np.h> // for pthread_set_name_np
#endif
#include <fcntl.h>
#include <sched.h> // for sched_yield
#include <stdio.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#if defined(__APPLE__) || defined(__DragonFly__) || defined(__FreeBSD__) || \
defined(__NetBSD__) || defined(__OpenBSD__)
#include <sys/sysctl.h> // for sysctl
#endif
#if defined(ANDROID) && !defined(V8_ANDROID_LOG_STDOUT)
#define LOG_TAG "v8"
#include <android/log.h>
#endif
#include <cmath>
#include <cstdlib>
#include "src/base/platform/platform-posix.h"
#include "src/base/lazy-instance.h"
#include "src/base/macros.h"
#include "src/base/platform/platform.h"
#include "src/base/platform/time.h"
#include "src/base/utils/random-number-generator.h"
#ifdef V8_FAST_TLS_SUPPORTED
#include <atomic>
#endif
#if V8_OS_DARWIN || V8_OS_LINUX
#include <dlfcn.h> // for dlsym
#endif
#if V8_OS_DARWIN
#include <mach/mach.h>
#include <malloc/malloc.h>
#else
#include <malloc.h>
#endif
#if V8_OS_LINUX
#include <sys/prctl.h> // for prctl
#endif
#if defined(V8_OS_FUCHSIA)
#include <zircon/process.h>
#else
#include <sys/resource.h>
#endif
#if !defined(_AIX) && !defined(V8_OS_FUCHSIA)
#include <sys/syscall.h>
#endif
#if V8_OS_FREEBSD || V8_OS_DARWIN || V8_OS_OPENBSD || V8_OS_SOLARIS
#define MAP_ANONYMOUS MAP_ANON
#endif
#if defined(V8_OS_SOLARIS)
#if (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE > 2) || defined(__EXTENSIONS__)
extern "C" int madvise(caddr_t, size_t, int);
#else
extern int madvise(caddr_t, size_t, int);
#endif
#endif
#ifndef MADV_FREE
#define MADV_FREE MADV_DONTNEED
#endif
#if defined(V8_LIBC_GLIBC)
extern "C" void* __libc_stack_end;
#endif
namespace v8 {
namespace base {
namespace {
// 0 is never a valid thread id.
const pthread_t kNoThread = static_cast<pthread_t>(0);
bool g_hard_abort = false;
const char* g_gc_fake_mmap = nullptr;
DEFINE_LAZY_LEAKY_OBJECT_GETTER(RandomNumberGenerator,
GetPlatformRandomNumberGenerator)
static LazyMutex rng_mutex = LAZY_MUTEX_INITIALIZER;
#if !V8_OS_FUCHSIA
#if V8_OS_DARWIN
// kMmapFd is used to pass vm_alloc flags to tag the region with the user
// defined tag 255 This helps identify V8-allocated regions in memory analysis
// tools like vmmap(1).
const int kMmapFd = VM_MAKE_TAG(255);
#else // !V8_OS_DARWIN
const int kMmapFd = -1;
#endif // !V8_OS_DARWIN
#if defined(V8_TARGET_OS_MACOS) && V8_HOST_ARCH_ARM64
// During snapshot generation in cross builds, sysconf() runs on the Intel
// host and returns host page size, while the snapshot needs to use the
// target page size.
constexpr int kAppleArmPageSize = 1 << 14;
#endif
const int kMmapFdOffset = 0;
enum class PageType { kShared, kPrivate };
int GetFlagsForMemoryPermission(OS::MemoryPermission access,
PageType page_type) {
int flags = MAP_ANONYMOUS;
flags |= (page_type == PageType::kShared) ? MAP_SHARED : MAP_PRIVATE;
if (access == OS::MemoryPermission::kNoAccess) {
#if !V8_OS_AIX && !V8_OS_FREEBSD && !V8_OS_QNX
flags |= MAP_NORESERVE;
#endif // !V8_OS_AIX && !V8_OS_FREEBSD && !V8_OS_QNX
#if V8_OS_QNX
flags |= MAP_LAZY;
#endif // V8_OS_QNX
}
#if V8_OS_DARWIN
// MAP_JIT is required to obtain writable and executable pages when the
// hardened runtime/memory protection is enabled, which is optional (via code
// signing) on Intel-based Macs but mandatory on Apple silicon ones. See also
// https://developer.apple.com/documentation/apple-silicon/porting-just-in-time-compilers-to-apple-silicon.
if (access == OS::MemoryPermission::kNoAccessWillJitLater) {
flags |= MAP_JIT;
}
#endif // V8_OS_DARWIN
return flags;
}
void* Allocate(void* hint, size_t size, OS::MemoryPermission access,
PageType page_type) {
int prot = GetProtectionFromMemoryPermission(access);
int flags = GetFlagsForMemoryPermission(access, page_type);
void* result = mmap(hint, size, prot, flags, kMmapFd, kMmapFdOffset);
if (result == MAP_FAILED) return nullptr;
#if ENABLE_HUGEPAGE
if (result != nullptr && size >= kHugePageSize) {
const uintptr_t huge_start =
RoundUp(reinterpret_cast<uintptr_t>(result), kHugePageSize);
const uintptr_t huge_end =
RoundDown(reinterpret_cast<uintptr_t>(result) + size, kHugePageSize);
if (huge_end > huge_start) {
// Bail out in case the aligned addresses do not provide a block of at
// least kHugePageSize size.
madvise(reinterpret_cast<void*>(huge_start), huge_end - huge_start,
MADV_HUGEPAGE);
}
}
#endif
return result;
}
#endif // !V8_OS_FUCHSIA
} // namespace
// TODO(v8:10026): Add the right permission flag to make executable pages
// guarded.
int GetProtectionFromMemoryPermission(OS::MemoryPermission access) {
switch (access) {
case OS::MemoryPermission::kNoAccess:
case OS::MemoryPermission::kNoAccessWillJitLater:
return PROT_NONE;
case OS::MemoryPermission::kRead:
return PROT_READ;
case OS::MemoryPermission::kReadWrite:
return PROT_READ | PROT_WRITE;
case OS::MemoryPermission::kReadWriteExecute:
return PROT_READ | PROT_WRITE | PROT_EXEC;
case OS::MemoryPermission::kReadExecute:
return PROT_READ | PROT_EXEC;
}
UNREACHABLE();
}
#if V8_OS_LINUX || V8_OS_FREEBSD
#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 && !defined(__clang__)
#if defined(__ARM_PCS_VFP)
return true;
#else
return false;
#endif
#elif GCC_VERSION < 40500 && !defined(__clang__)
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 compiler 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__
#endif
void PosixInitializeCommon(bool hard_abort, const char* const gc_fake_mmap) {
g_hard_abort = hard_abort;
g_gc_fake_mmap = gc_fake_mmap;
}
#if !V8_OS_FUCHSIA
void OS::Initialize(bool hard_abort, const char* const gc_fake_mmap) {
PosixInitializeCommon(hard_abort, gc_fake_mmap);
}
#endif // !V8_OS_FUCHSIA
int OS::ActivationFrameAlignment() {
#if V8_TARGET_ARCH_ARM
// On EABI ARM targets this is required for fp correctness in the
// runtime system.
return 8;
#elif V8_TARGET_ARCH_MIPS
return 8;
#elif V8_TARGET_ARCH_S390
return 8;
#else
// Otherwise we just assume 16 byte alignment, i.e.:
// - With gcc 4.4 the tree vectorization optimizer can generate code
// that requires 16 byte alignment such as movdqa on x86.
// - Mac OS X, PPC and Solaris (64-bit) activation frames must
// be 16 byte-aligned; see "Mac OS X ABI Function Call Guide"
return 16;
#endif
}
// static
size_t OS::AllocatePageSize() {
#if defined(V8_TARGET_OS_MACOS) && V8_HOST_ARCH_ARM64
return kAppleArmPageSize;
#else
static size_t page_size = static_cast<size_t>(sysconf(_SC_PAGESIZE));
return page_size;
#endif
}
// static
size_t OS::CommitPageSize() {
// Commit and allocate page size are the same on posix.
return OS::AllocatePageSize();
}
// static
void OS::SetRandomMmapSeed(int64_t seed) {
if (seed) {
MutexGuard guard(rng_mutex.Pointer());
GetPlatformRandomNumberGenerator()->SetSeed(seed);
}
}
// static
void* OS::GetRandomMmapAddr() {
uintptr_t raw_addr;
{
MutexGuard guard(rng_mutex.Pointer());
GetPlatformRandomNumberGenerator()->NextBytes(&raw_addr, sizeof(raw_addr));
}
#if V8_HOST_ARCH_ARM64
#if defined(V8_TARGET_OS_MACOS)
DCHECK_EQ(1 << 14, AllocatePageSize());
#endif
// Keep the address page-aligned, AArch64 supports 4K, 16K and 64K
// configurations.
raw_addr = RoundDown(raw_addr, AllocatePageSize());
#endif
#if defined(V8_USE_ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
defined(THREAD_SANITIZER) || defined(LEAK_SANITIZER)
// If random hint addresses interfere with address ranges hard coded in
// sanitizers, bad things happen. This address range is copied from TSAN
// source but works with all tools.
// See crbug.com/539863.
raw_addr &= 0x007fffff0000ULL;
raw_addr += 0x7e8000000000ULL;
#else
#if V8_TARGET_ARCH_X64 || V8_TARGET_ARCH_ARM64
// Currently available CPUs have 48 bits of virtual addressing. Truncate
// the hint address to 46 bits to give the kernel a fighting chance of
// fulfilling our placement request.
raw_addr &= uint64_t{0x3FFFFFFFF000};
#elif V8_TARGET_ARCH_PPC64
#if V8_OS_AIX
// AIX: 64 bits of virtual addressing, but we limit address range to:
// a) minimize Segment Lookaside Buffer (SLB) misses and
raw_addr &= uint64_t{0x3FFFF000};
// Use extra address space to isolate the mmap regions.
raw_addr += uint64_t{0x400000000000};
#elif V8_TARGET_BIG_ENDIAN
// Big-endian Linux: 42 bits of virtual addressing.
raw_addr &= uint64_t{0x03FFFFFFF000};
#else
// Little-endian Linux: 46 bits of virtual addressing.
raw_addr &= uint64_t{0x3FFFFFFF0000};
#endif
#elif V8_TARGET_ARCH_S390X
// Linux on Z uses bits 22-32 for Region Indexing, which translates to 42 bits
// of virtual addressing. Truncate to 40 bits to allow kernel chance to
// fulfill request.
raw_addr &= uint64_t{0xFFFFFFF000};
#elif V8_TARGET_ARCH_S390
// 31 bits of virtual addressing. Truncate to 29 bits to allow kernel chance
// to fulfill request.
raw_addr &= 0x1FFFF000;
#elif V8_TARGET_ARCH_MIPS64
// 42 bits of virtual addressing. Truncate to 40 bits to allow kernel chance
// to fulfill request.
raw_addr &= uint64_t{0xFFFFFF0000};
#elif V8_TARGET_ARCH_RISCV64
// TODO(RISCV): We need more information from the kernel to correctly mask
// this address for RISC-V. https://github.com/v8-riscv/v8/issues/375
raw_addr &= uint64_t{0xFFFFFF0000};
#elif V8_TARGET_ARCH_RISCV32
// TODO(RISCV): We need more information from the kernel to correctly mask
// this address for RISC-V. https://github.com/v8-riscv/v8/issues/375
raw_addr &= 0x3FFFF000;
#elif V8_TARGET_ARCH_LOONG64
// 42 bits of virtual addressing. Truncate to 40 bits to allow kernel chance
// to fulfill request.
raw_addr &= uint64_t{0xFFFFFF0000};
#else
raw_addr &= 0x3FFFF000;
#ifdef __sun
// For our Solaris/illumos mmap hint, we pick a random address in the bottom
// half of the top half of the address space (that is, the third quarter).
// Because we do not MAP_FIXED, this will be treated only as a hint -- the
// system will not fail to mmap() because something else happens to already
// be mapped at our random address. We deliberately set the hint high enough
// to get well above the system's break (that is, the heap); Solaris and
// illumos will try the hint and if that fails allocate as if there were
// no hint at all. The high hint prevents the break from getting hemmed in
// at low values, ceding half of the address space to the system heap.
raw_addr += 0x80000000;
#elif V8_OS_AIX
// The range 0x30000000 - 0xD0000000 is available on AIX;
// choose the upper range.
raw_addr += 0x90000000;
#else
// The range 0x20000000 - 0x60000000 is relatively unpopulated across a
// variety of ASLR modes (PAE kernel, NX compat mode, etc) and on macos
// 10.6 and 10.7.
raw_addr += 0x20000000;
#endif
#endif
#endif
return reinterpret_cast<void*>(raw_addr);
}
// TODO(bbudge) Move Cygwin and Fuchsia stuff into platform-specific files.
#if !V8_OS_CYGWIN && !V8_OS_FUCHSIA
// static
void* OS::Allocate(void* hint, size_t size, size_t alignment,
MemoryPermission access) {
size_t page_size = AllocatePageSize();
DCHECK_EQ(0, size % page_size);
DCHECK_EQ(0, alignment % page_size);
hint = AlignedAddress(hint, alignment);
// Add the maximum misalignment so we are guaranteed an aligned base address.
size_t request_size = size + (alignment - page_size);
request_size = RoundUp(request_size, OS::AllocatePageSize());
void* result = base::Allocate(hint, request_size, access, PageType::kPrivate);
if (result == nullptr) return nullptr;
// Unmap memory allocated before the aligned base address.
uint8_t* base = static_cast<uint8_t*>(result);
uint8_t* aligned_base = reinterpret_cast<uint8_t*>(
RoundUp(reinterpret_cast<uintptr_t>(base), alignment));
if (aligned_base != base) {
DCHECK_LT(base, aligned_base);
size_t prefix_size = static_cast<size_t>(aligned_base - base);
Free(base, prefix_size);
request_size -= prefix_size;
}
// Unmap memory allocated after the potentially unaligned end.
if (size != request_size) {
DCHECK_LT(size, request_size);
size_t suffix_size = request_size - size;
Free(aligned_base + size, suffix_size);
request_size -= suffix_size;
}
DCHECK_EQ(size, request_size);
return static_cast<void*>(aligned_base);
}
// static
void* OS::AllocateShared(size_t size, MemoryPermission access) {
DCHECK_EQ(0, size % AllocatePageSize());
return base::Allocate(nullptr, size, access, PageType::kShared);
}
// static
void OS::Free(void* address, size_t size) {
DCHECK_EQ(0, reinterpret_cast<uintptr_t>(address) % AllocatePageSize());
DCHECK_EQ(0, size % AllocatePageSize());
CHECK_EQ(0, munmap(address, size));
}
// macOS specific implementation in platform-macos.cc.
#if !defined(V8_OS_MACOS)
// static
void* OS::AllocateShared(void* hint, size_t size, MemoryPermission access,
PlatformSharedMemoryHandle handle, uint64_t offset) {
DCHECK_EQ(0, size % AllocatePageSize());
int prot = GetProtectionFromMemoryPermission(access);
int fd = FileDescriptorFromSharedMemoryHandle(handle);
void* result = mmap(hint, size, prot, MAP_SHARED, fd, offset);
if (result == MAP_FAILED) return nullptr;
return result;
}
#endif // !defined(V8_OS_MACOS)
// static
void OS::FreeShared(void* address, size_t size) {
DCHECK_EQ(0, size % AllocatePageSize());
CHECK_EQ(0, munmap(address, size));
}
// static
void OS::Release(void* address, size_t size) {
DCHECK_EQ(0, reinterpret_cast<uintptr_t>(address) % CommitPageSize());
DCHECK_EQ(0, size % CommitPageSize());
CHECK_EQ(0, munmap(address, size));
}
// static
bool OS::SetPermissions(void* address, size_t size, MemoryPermission access) {
DCHECK_EQ(0, reinterpret_cast<uintptr_t>(address) % CommitPageSize());
DCHECK_EQ(0, size % CommitPageSize());
int prot = GetProtectionFromMemoryPermission(access);
int ret = mprotect(address, size, prot);
// Any failure that's not OOM likely indicates a bug in the caller (e.g.
// using an invalid mapping) so attempt to catch that here to facilitate
// debugging of these failures.
if (ret != 0) CHECK_EQ(ENOMEM, errno);
// MacOS 11.2 on Apple Silicon refuses to switch permissions from
// rwx to none. Just use madvise instead.
#if defined(V8_OS_DARWIN)
if (ret != 0 && access == OS::MemoryPermission::kNoAccess) {
ret = madvise(address, size, MADV_FREE_REUSABLE);
return ret == 0;
}
#endif
if (ret == 0 && access == OS::MemoryPermission::kNoAccess) {
// This is advisory; ignore errors and continue execution.
USE(DiscardSystemPages(address, size));
}
// For accounting purposes, we want to call MADV_FREE_REUSE on macOS after
// changing permissions away from OS::MemoryPermission::kNoAccess. Since this
// state is not kept at this layer, we always call this if access != kNoAccess.
// The cost is a syscall that effectively no-ops.
// TODO(erikchen): Fix this to only call MADV_FREE_REUSE when necessary.
// https://crbug.com/823915
#if defined(V8_OS_DARWIN)
if (access != OS::MemoryPermission::kNoAccess)
madvise(address, size, MADV_FREE_REUSE);
#endif
return ret == 0;
}
// static
void OS::SetDataReadOnly(void* address, size_t size) {
DCHECK_EQ(0, reinterpret_cast<uintptr_t>(address) % CommitPageSize());
DCHECK_EQ(0, size % CommitPageSize());
CHECK_EQ(0, mprotect(address, size, PROT_READ));
}
// static
bool OS::RecommitPages(void* address, size_t size, MemoryPermission access) {
DCHECK_EQ(0, reinterpret_cast<uintptr_t>(address) % CommitPageSize());
DCHECK_EQ(0, size % CommitPageSize());
#if defined(V8_OS_DARWIN)
while (madvise(address, size, MADV_FREE_REUSE) == -1 && errno == EAGAIN) {
}
return true;
#else
return SetPermissions(address, size, access);
#endif // defined(V8_OS_DARWIN)
}
// static
bool OS::DiscardSystemPages(void* address, size_t size) {
// Roughly based on PartitionAlloc's DiscardSystemPagesInternal
// (base/allocator/partition_allocator/page_allocator_internals_posix.h)
DCHECK_EQ(0, reinterpret_cast<uintptr_t>(address) % CommitPageSize());
DCHECK_EQ(0, size % CommitPageSize());
#if defined(V8_OS_DARWIN)
// On OSX, MADV_FREE_REUSABLE has comparable behavior to MADV_FREE, but also
// marks the pages with the reusable bit, which allows both Activity Monitor
// and memory-infra to correctly track the pages.
int ret;
do {
ret = madvise(address, size, MADV_FREE_REUSABLE);
} while (ret != 0 && errno == EAGAIN);
if (ret) {
// MADV_FREE_REUSABLE sometimes fails, so fall back to MADV_DONTNEED.
ret = madvise(address, size, MADV_DONTNEED);
}
#elif defined(_AIX) || defined(V8_OS_SOLARIS)
int ret = madvise(reinterpret_cast<caddr_t>(address), size, MADV_FREE);
if (ret != 0 && errno == ENOSYS)
return true; // madvise is not available on all systems.
if (ret != 0 && errno == EINVAL)
ret = madvise(reinterpret_cast<caddr_t>(address), size, MADV_DONTNEED);
#else
int ret = madvise(address, size, MADV_DONTNEED);
#endif
return ret == 0;
}
#if !defined(_AIX)
// See AIX version for details.
// static
bool OS::DecommitPages(void* address, size_t size) {
DCHECK_EQ(0, reinterpret_cast<uintptr_t>(address) % CommitPageSize());
DCHECK_EQ(0, size % CommitPageSize());
// From https://pubs.opengroup.org/onlinepubs/9699919799/functions/mmap.html:
// "If a MAP_FIXED request is successful, then any previous mappings [...] for
// those whole pages containing any part of the address range [pa,pa+len)
// shall be removed, as if by an appropriate call to munmap(), before the new
// mapping is established." As a consequence, the memory will be
// zero-initialized on next access.
void* ptr = mmap(address, size, PROT_NONE,
MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
return ptr == address;
}
#endif // !defined(_AIX)
// static
bool OS::CanReserveAddressSpace() { return true; }
// static
Optional<AddressSpaceReservation> OS::CreateAddressSpaceReservation(
void* hint, size_t size, size_t alignment,
MemoryPermission max_permission) {
// On POSIX, address space reservations are backed by private memory mappings.
MemoryPermission permission = MemoryPermission::kNoAccess;
if (max_permission == MemoryPermission::kReadWriteExecute) {
permission = MemoryPermission::kNoAccessWillJitLater;
}
void* reservation = Allocate(hint, size, alignment, permission);
if (!reservation && permission == MemoryPermission::kNoAccessWillJitLater) {
// Retry without MAP_JIT, for example in case we are running on an old OS X.
permission = MemoryPermission::kNoAccess;
reservation = Allocate(hint, size, alignment, permission);
}
if (!reservation) return {};
return AddressSpaceReservation(reservation, size);
}
// static
void OS::FreeAddressSpaceReservation(AddressSpaceReservation reservation) {
Free(reservation.base(), reservation.size());
}
// macOS specific implementation in platform-macos.cc.
#if !defined(V8_OS_MACOS)
// static
// Need to disable CFI_ICALL due to the indirect call to memfd_create.
DISABLE_CFI_ICALL
PlatformSharedMemoryHandle OS::CreateSharedMemoryHandleForTesting(size_t size) {
return kInvalidSharedMemoryHandle;
}
// static
void OS::DestroySharedMemoryHandle(PlatformSharedMemoryHandle handle) {
DCHECK_NE(kInvalidSharedMemoryHandle, handle);
int fd = FileDescriptorFromSharedMemoryHandle(handle);
CHECK_EQ(0, close(fd));
}
#endif // !defined(V8_OS_MACOS)
// static
bool OS::HasLazyCommits() {
#if V8_OS_AIX || V8_OS_LINUX || V8_OS_DARWIN
return true;
#else
// TODO(bbudge) Return true for all POSIX platforms.
return false;
#endif
}
#endif // !V8_OS_CYGWIN && !V8_OS_FUCHSIA
const char* OS::GetGCFakeMMapFile() {
return g_gc_fake_mmap;
}
void OS::Sleep(TimeDelta interval) {
usleep(static_cast<useconds_t>(interval.InMicroseconds()));
}
void OS::Abort() {
if (g_hard_abort) {
IMMEDIATE_CRASH();
}
// Redirect to std abort to signal abnormal program termination.
abort();
}
void OS::DebugBreak() {
#if V8_HOST_ARCH_ARM
asm("bkpt 0");
#elif V8_HOST_ARCH_ARM64
asm("brk 0");
#elif V8_HOST_ARCH_MIPS
asm("break");
#elif V8_HOST_ARCH_MIPS64
asm("break");
#elif V8_HOST_ARCH_LOONG64
asm("break 0");
#elif V8_HOST_ARCH_PPC || V8_HOST_ARCH_PPC64
asm("twge 2,2");
#elif V8_HOST_ARCH_IA32
asm("int $3");
#elif V8_HOST_ARCH_X64
asm("int $3");
#elif V8_HOST_ARCH_S390
// Software breakpoint instruction is 0x0001
asm volatile(".word 0x0001");
#elif V8_HOST_ARCH_RISCV64
asm("ebreak");
#elif V8_HOST_ARCH_RISCV32
asm("ebreak");
#else
#error Unsupported host architecture.
#endif
}
class PosixMemoryMappedFile final : public OS::MemoryMappedFile {
public:
PosixMemoryMappedFile(FILE* file, void* memory, size_t size)
: file_(file), memory_(memory), size_(size) {}
~PosixMemoryMappedFile() final;
void* memory() const final { return memory_; }
size_t size() const final { return size_; }
private:
FILE* const file_;
void* const memory_;
size_t const size_;
};
// static
OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name,
FileMode mode) {
const char* fopen_mode = (mode == FileMode::kReadOnly) ? "r" : "r+";
struct stat statbuf;
// Make sure path exists and is not a directory.
if (stat(name, &statbuf) == 0 && !S_ISDIR(statbuf.st_mode)) {
if (FILE* file = fopen(name, fopen_mode)) {
if (fseek(file, 0, SEEK_END) == 0) {
long size = ftell(file); // NOLINT(runtime/int)
if (size == 0) return new PosixMemoryMappedFile(file, nullptr, 0);
if (size > 0) {
int prot = PROT_READ;
int flags = MAP_PRIVATE;
if (mode == FileMode::kReadWrite) {
prot |= PROT_WRITE;
flags = MAP_SHARED;
}
void* const memory =
mmap(OS::GetRandomMmapAddr(), size, prot, flags, fileno(file), 0);
if (memory != MAP_FAILED) {
return new PosixMemoryMappedFile(file, memory, size);
}
}
}
fclose(file);
}
}
return nullptr;
}
// static
OS::MemoryMappedFile* OS::MemoryMappedFile::create(const char* name,
size_t size, void* initial) {
if (FILE* file = fopen(name, "w+")) {
if (size == 0) return new PosixMemoryMappedFile(file, nullptr, 0);
size_t result = fwrite(initial, 1, size, file);
if (result == size && !ferror(file)) {
void* memory = mmap(OS::GetRandomMmapAddr(), result,
PROT_READ | PROT_WRITE, MAP_SHARED, fileno(file), 0);
if (memory != MAP_FAILED) {
return new PosixMemoryMappedFile(file, memory, result);
}
}
fclose(file);
}
return nullptr;
}
PosixMemoryMappedFile::~PosixMemoryMappedFile() {
if (memory_) OS::Free(memory_, RoundUp(size_, OS::AllocatePageSize()));
fclose(file_);
}
int OS::GetCurrentProcessId() {
return static_cast<int>(getpid());
}
int OS::GetCurrentThreadId() {
#if V8_OS_DARWIN || (V8_OS_ANDROID && defined(__APPLE__))
return static_cast<int>(pthread_mach_thread_np(pthread_self()));
#elif V8_OS_LINUX
return static_cast<int>(syscall(__NR_gettid));
#elif V8_OS_ANDROID
return static_cast<int>(gettid());
#elif V8_OS_AIX
return static_cast<int>(thread_self());
#elif V8_OS_FUCHSIA
return static_cast<int>(zx_thread_self());
#elif V8_OS_SOLARIS
return static_cast<int>(pthread_self());
#else
return static_cast<int>(reinterpret_cast<intptr_t>(pthread_self()));
#endif
}
void OS::ExitProcess(int exit_code) {
// Use _exit instead of exit to avoid races between isolate
// threads and static destructors.
fflush(stdout);
fflush(stderr);
_exit(exit_code);
}
// ----------------------------------------------------------------------------
// POSIX date/time support.
//
#if !defined(V8_OS_FUCHSIA)
int OS::GetUserTime(uint32_t* secs, uint32_t* usecs) {
struct rusage usage;
if (getrusage(RUSAGE_SELF, &usage) < 0) return -1;
*secs = static_cast<uint32_t>(usage.ru_utime.tv_sec);
*usecs = static_cast<uint32_t>(usage.ru_utime.tv_usec);
return 0;
}
#endif
double OS::TimeCurrentMillis() {
return Time::Now().ToJsTime();
}
double PosixTimezoneCache::DaylightSavingsOffset(double time) {
if (std::isnan(time)) return std::numeric_limits<double>::quiet_NaN();
time_t tv = static_cast<time_t>(std::floor(time/msPerSecond));
struct tm tm;
struct tm* t = localtime_r(&tv, &tm);
if (nullptr == t) return std::numeric_limits<double>::quiet_NaN();
return t->tm_isdst > 0 ? 3600 * msPerSecond : 0;
}
int OS::GetLastError() {
return errno;
}
// ----------------------------------------------------------------------------
// POSIX stdio support.
//
FILE* OS::FOpen(const char* path, const char* mode) {
FILE* file = fopen(path, mode);
if (file == nullptr) return nullptr;
struct stat file_stat;
if (fstat(fileno(file), &file_stat) != 0) {
fclose(file);
return nullptr;
}
bool is_regular_file = ((file_stat.st_mode & S_IFREG) != 0);
if (is_regular_file) return file;
fclose(file);
return nullptr;
}
bool OS::Remove(const char* path) {
return (remove(path) == 0);
}
char OS::DirectorySeparator() { return '/'; }
bool OS::isDirectorySeparator(const char ch) {
return ch == DirectorySeparator();
}
FILE* OS::OpenTemporaryFile() {
return tmpfile();
}
const char* const OS::LogFileOpenMode = "w+";
void OS::Print(const char* format, ...) {
va_list args;
va_start(args, format);
VPrint(format, args);
va_end(args);
}
void OS::VPrint(const char* format, va_list args) {
#if defined(ANDROID) && !defined(V8_ANDROID_LOG_STDOUT)
__android_log_vprint(ANDROID_LOG_INFO, LOG_TAG, format, args);
#else
vprintf(format, args);
#endif
}
void OS::FPrint(FILE* out, const char* format, ...) {
va_list args;
va_start(args, format);
VFPrint(out, format, args);
va_end(args);
}
void OS::VFPrint(FILE* out, const char* format, va_list args) {
#if defined(ANDROID) && !defined(V8_ANDROID_LOG_STDOUT)
__android_log_vprint(ANDROID_LOG_INFO, LOG_TAG, format, args);
#else
vfprintf(out, format, args);
#endif
}
void OS::PrintError(const char* format, ...) {
va_list args;
va_start(args, format);
VPrintError(format, args);
va_end(args);
}
void OS::VPrintError(const char* format, va_list args) {
#if defined(ANDROID) && !defined(V8_ANDROID_LOG_STDOUT)
__android_log_vprint(ANDROID_LOG_ERROR, LOG_TAG, format, args);
#else
vfprintf(stderr, format, args);
#endif
}
int OS::SNPrintF(char* str, int length, const char* format, ...) {
va_list args;
va_start(args, format);
int result = VSNPrintF(str, length, format, args);
va_end(args);
return result;
}
int OS::VSNPrintF(char* str,
int length,
const char* format,
va_list args) {
int n = vsnprintf(str, length, format, args);
if (n < 0 || n >= length) {
// If the length is zero, the assignment fails.
if (length > 0)
str[length - 1] = '\0';
return -1;
} else {
return n;
}
}
// ----------------------------------------------------------------------------
// POSIX string support.
//
void OS::StrNCpy(char* dest, int length, const char* src, size_t n) {
strncpy(dest, src, n);
}
// ----------------------------------------------------------------------------
// POSIX Address space reservation support.
//
#if !V8_OS_CYGWIN && !V8_OS_FUCHSIA
Optional<AddressSpaceReservation> AddressSpaceReservation::CreateSubReservation(
void* address, size_t size, OS::MemoryPermission max_permission) {
DCHECK(Contains(address, size));
DCHECK_EQ(0, size % OS::AllocatePageSize());
DCHECK_EQ(0, reinterpret_cast<uintptr_t>(address) % OS::AllocatePageSize());
return AddressSpaceReservation(address, size);
}
bool AddressSpaceReservation::FreeSubReservation(
AddressSpaceReservation reservation) {
// Nothing to do.
// Pages allocated inside the reservation must've already been freed.
return true;
}
bool AddressSpaceReservation::Allocate(void* address, size_t size,
OS::MemoryPermission access) {
// The region is already mmap'ed, so it just has to be made accessible now.
DCHECK(Contains(address, size));
if (access == OS::MemoryPermission::kNoAccess) {
// Nothing to do. We don't want to call SetPermissions with kNoAccess here
// as that will for example mark the pages as discardable, which is
// probably not desired here.
return true;
}
return OS::SetPermissions(address, size, access);
}
bool AddressSpaceReservation::Free(void* address, size_t size) {
DCHECK(Contains(address, size));
return OS::DecommitPages(address, size);
}
// macOS specific implementation in platform-macos.cc.
#if !defined(V8_OS_MACOS)
bool AddressSpaceReservation::AllocateShared(void* address, size_t size,
OS::MemoryPermission access,
PlatformSharedMemoryHandle handle,
uint64_t offset) {
DCHECK(Contains(address, size));
int prot = GetProtectionFromMemoryPermission(access);
int fd = FileDescriptorFromSharedMemoryHandle(handle);
return mmap(address, size, prot, MAP_SHARED | MAP_FIXED, fd, offset) !=
MAP_FAILED;
}
#endif // !defined(V8_OS_MACOS)