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      1 // Copyright 2012 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // Platform-specific code for OpenBSD and NetBSD goes here. For the
      6 // POSIX-compatible parts, the implementation is in platform-posix.cc.
      7 
      8 #include <pthread.h>
      9 #include <semaphore.h>
     10 #include <signal.h>
     11 #include <stdlib.h>
     12 #include <sys/resource.h>
     13 #include <sys/syscall.h>
     14 #include <sys/time.h>
     15 #include <sys/types.h>
     16 
     17 #include <errno.h>
     18 #include <fcntl.h>      // open
     19 #include <stdarg.h>
     20 #include <strings.h>    // index
     21 #include <sys/mman.h>   // mmap & munmap
     22 #include <sys/stat.h>   // open
     23 #include <unistd.h>     // sysconf
     24 
     25 #include <cmath>
     26 
     27 #undef MAP_TYPE
     28 
     29 #include "src/base/macros.h"
     30 #include "src/base/platform/platform.h"
     31 
     32 
     33 namespace v8 {
     34 namespace base {
     35 
     36 
     37 const char* OS::LocalTimezone(double time, TimezoneCache* cache) {
     38   if (std::isnan(time)) return "";
     39   time_t tv = static_cast<time_t>(std::floor(time/msPerSecond));
     40   struct tm* t = localtime(&tv);  // NOLINT(runtime/threadsafe_fn)
     41   if (NULL == t) return "";
     42   return t->tm_zone;
     43 }
     44 
     45 
     46 double OS::LocalTimeOffset(TimezoneCache* cache) {
     47   time_t tv = time(NULL);
     48   struct tm* t = localtime(&tv);  // NOLINT(runtime/threadsafe_fn)
     49   // tm_gmtoff includes any daylight savings offset, so subtract it.
     50   return static_cast<double>(t->tm_gmtoff * msPerSecond -
     51                              (t->tm_isdst > 0 ? 3600 * msPerSecond : 0));
     52 }
     53 
     54 
     55 void* OS::Allocate(const size_t requested,
     56                    size_t* allocated,
     57                    bool is_executable) {
     58   const size_t msize = RoundUp(requested, AllocateAlignment());
     59   int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
     60   void* addr = OS::GetRandomMmapAddr();
     61   void* mbase = mmap(addr, msize, prot, MAP_PRIVATE | MAP_ANON, -1, 0);
     62   if (mbase == MAP_FAILED) return NULL;
     63   *allocated = msize;
     64   return mbase;
     65 }
     66 
     67 
     68 std::vector<OS::SharedLibraryAddress> OS::GetSharedLibraryAddresses() {
     69   std::vector<SharedLibraryAddress> result;
     70   // This function assumes that the layout of the file is as follows:
     71   // hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name]
     72   // If we encounter an unexpected situation we abort scanning further entries.
     73   FILE* fp = fopen("/proc/self/maps", "r");
     74   if (fp == NULL) return result;
     75 
     76   // Allocate enough room to be able to store a full file name.
     77   const int kLibNameLen = FILENAME_MAX + 1;
     78   char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));
     79 
     80   // This loop will terminate once the scanning hits an EOF.
     81   while (true) {
     82     uintptr_t start, end;
     83     char attr_r, attr_w, attr_x, attr_p;
     84     // Parse the addresses and permission bits at the beginning of the line.
     85     if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2) break;
     86     if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4) break;
     87 
     88     int c;
     89     if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') {
     90       // Found a read-only executable entry. Skip characters until we reach
     91       // the beginning of the filename or the end of the line.
     92       do {
     93         c = getc(fp);
     94       } while ((c != EOF) && (c != '\n') && (c != '/'));
     95       if (c == EOF) break;  // EOF: Was unexpected, just exit.
     96 
     97       // Process the filename if found.
     98       if (c == '/') {
     99         ungetc(c, fp);  // Push the '/' back into the stream to be read below.
    100 
    101         // Read to the end of the line. Exit if the read fails.
    102         if (fgets(lib_name, kLibNameLen, fp) == NULL) break;
    103 
    104         // Drop the newline character read by fgets. We do not need to check
    105         // for a zero-length string because we know that we at least read the
    106         // '/' character.
    107         lib_name[strlen(lib_name) - 1] = '\0';
    108       } else {
    109         // No library name found, just record the raw address range.
    110         snprintf(lib_name, kLibNameLen,
    111                  "%08" V8PRIxPTR "-%08" V8PRIxPTR, start, end);
    112       }
    113       result.push_back(SharedLibraryAddress(lib_name, start, end));
    114     } else {
    115       // Entry not describing executable data. Skip to end of line to set up
    116       // reading the next entry.
    117       do {
    118         c = getc(fp);
    119       } while ((c != EOF) && (c != '\n'));
    120       if (c == EOF) break;
    121     }
    122   }
    123   free(lib_name);
    124   fclose(fp);
    125   return result;
    126 }
    127 
    128 
    129 void OS::SignalCodeMovingGC() {
    130   // Support for ll_prof.py.
    131   //
    132   // The Linux profiler built into the kernel logs all mmap's with
    133   // PROT_EXEC so that analysis tools can properly attribute ticks. We
    134   // do a mmap with a name known by ll_prof.py and immediately munmap
    135   // it. This injects a GC marker into the stream of events generated
    136   // by the kernel and allows us to synchronize V8 code log and the
    137   // kernel log.
    138   int size = sysconf(_SC_PAGESIZE);
    139   FILE* f = fopen(OS::GetGCFakeMMapFile(), "w+");
    140   if (f == NULL) {
    141     OS::PrintError("Failed to open %s\n", OS::GetGCFakeMMapFile());
    142     OS::Abort();
    143   }
    144   void* addr = mmap(NULL, size, PROT_READ | PROT_EXEC, MAP_PRIVATE,
    145                     fileno(f), 0);
    146   DCHECK(addr != MAP_FAILED);
    147   OS::Free(addr, size);
    148   fclose(f);
    149 }
    150 
    151 
    152 
    153 // Constants used for mmap.
    154 static const int kMmapFd = -1;
    155 static const int kMmapFdOffset = 0;
    156 
    157 
    158 VirtualMemory::VirtualMemory() : address_(NULL), size_(0) { }
    159 
    160 
    161 VirtualMemory::VirtualMemory(size_t size)
    162     : address_(ReserveRegion(size)), size_(size) { }
    163 
    164 
    165 VirtualMemory::VirtualMemory(size_t size, size_t alignment)
    166     : address_(NULL), size_(0) {
    167   DCHECK((alignment % OS::AllocateAlignment()) == 0);
    168   size_t request_size = RoundUp(size + alignment,
    169                                 static_cast<intptr_t>(OS::AllocateAlignment()));
    170   void* reservation = mmap(OS::GetRandomMmapAddr(),
    171                            request_size,
    172                            PROT_NONE,
    173                            MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
    174                            kMmapFd,
    175                            kMmapFdOffset);
    176   if (reservation == MAP_FAILED) return;
    177 
    178   uint8_t* base = static_cast<uint8_t*>(reservation);
    179   uint8_t* aligned_base = RoundUp(base, alignment);
    180   DCHECK_LE(base, aligned_base);
    181 
    182   // Unmap extra memory reserved before and after the desired block.
    183   if (aligned_base != base) {
    184     size_t prefix_size = static_cast<size_t>(aligned_base - base);
    185     OS::Free(base, prefix_size);
    186     request_size -= prefix_size;
    187   }
    188 
    189   size_t aligned_size = RoundUp(size, OS::AllocateAlignment());
    190   DCHECK_LE(aligned_size, request_size);
    191 
    192   if (aligned_size != request_size) {
    193     size_t suffix_size = request_size - aligned_size;
    194     OS::Free(aligned_base + aligned_size, suffix_size);
    195     request_size -= suffix_size;
    196   }
    197 
    198   DCHECK(aligned_size == request_size);
    199 
    200   address_ = static_cast<void*>(aligned_base);
    201   size_ = aligned_size;
    202 }
    203 
    204 
    205 VirtualMemory::~VirtualMemory() {
    206   if (IsReserved()) {
    207     bool result = ReleaseRegion(address(), size());
    208     DCHECK(result);
    209     USE(result);
    210   }
    211 }
    212 
    213 
    214 bool VirtualMemory::IsReserved() {
    215   return address_ != NULL;
    216 }
    217 
    218 
    219 void VirtualMemory::Reset() {
    220   address_ = NULL;
    221   size_ = 0;
    222 }
    223 
    224 
    225 bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
    226   return CommitRegion(address, size, is_executable);
    227 }
    228 
    229 
    230 bool VirtualMemory::Uncommit(void* address, size_t size) {
    231   return UncommitRegion(address, size);
    232 }
    233 
    234 
    235 bool VirtualMemory::Guard(void* address) {
    236   OS::Guard(address, OS::CommitPageSize());
    237   return true;
    238 }
    239 
    240 
    241 void* VirtualMemory::ReserveRegion(size_t size) {
    242   void* result = mmap(OS::GetRandomMmapAddr(),
    243                       size,
    244                       PROT_NONE,
    245                       MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
    246                       kMmapFd,
    247                       kMmapFdOffset);
    248 
    249   if (result == MAP_FAILED) return NULL;
    250 
    251   return result;
    252 }
    253 
    254 
    255 bool VirtualMemory::CommitRegion(void* base, size_t size, bool is_executable) {
    256   int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
    257   if (MAP_FAILED == mmap(base,
    258                          size,
    259                          prot,
    260                          MAP_PRIVATE | MAP_ANON | MAP_FIXED,
    261                          kMmapFd,
    262                          kMmapFdOffset)) {
    263     return false;
    264   }
    265   return true;
    266 }
    267 
    268 
    269 bool VirtualMemory::UncommitRegion(void* base, size_t size) {
    270   return mmap(base,
    271               size,
    272               PROT_NONE,
    273               MAP_PRIVATE | MAP_ANON | MAP_NORESERVE | MAP_FIXED,
    274               kMmapFd,
    275               kMmapFdOffset) != MAP_FAILED;
    276 }
    277 
    278 
    279 bool VirtualMemory::ReleaseRegion(void* base, size_t size) {
    280   return munmap(base, size) == 0;
    281 }
    282 
    283 
    284 bool VirtualMemory::HasLazyCommits() {
    285   // TODO(alph): implement for the platform.
    286   return false;
    287 }
    288 
    289 }  // namespace base
    290 }  // namespace v8
    291