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 Cygwin goes here. For the POSIX-compatible
6 // parts, the implementation is in platform-posix.cc.
7
8 #include <errno.h>
9 #include <pthread.h>
10 #include <semaphore.h>
11 #include <stdarg.h>
12 #include <strings.h> // index
13 #include <sys/mman.h> // mmap & munmap
14 #include <sys/time.h>
15 #include <unistd.h> // sysconf
16
17 #include <cmath>
18
19 #undef MAP_TYPE
20
21 #include "src/base/macros.h"
22 #include "src/base/platform/platform.h"
23 #include "src/base/win32-headers.h"
24
25 namespace v8 {
26 namespace base {
27
28
LocalTimezone(double time,TimezoneCache * cache)29 const char* OS::LocalTimezone(double time, TimezoneCache* cache) {
30 if (std::isnan(time)) return "";
31 time_t tv = static_cast<time_t>(std::floor(time/msPerSecond));
32 struct tm* t = localtime(&tv); // NOLINT(runtime/threadsafe_fn)
33 if (NULL == t) return "";
34 return tzname[0]; // The location of the timezone string on Cygwin.
35 }
36
37
LocalTimeOffset(TimezoneCache * cache)38 double OS::LocalTimeOffset(TimezoneCache* cache) {
39 // On Cygwin, struct tm does not contain a tm_gmtoff field.
40 time_t utc = time(NULL);
41 DCHECK(utc != -1);
42 struct tm* loc = localtime(&utc); // NOLINT(runtime/threadsafe_fn)
43 DCHECK(loc != NULL);
44 // time - localtime includes any daylight savings offset, so subtract it.
45 return static_cast<double>((mktime(loc) - utc) * msPerSecond -
46 (loc->tm_isdst > 0 ? 3600 * msPerSecond : 0));
47 }
48
49
Allocate(const size_t requested,size_t * allocated,bool is_executable)50 void* OS::Allocate(const size_t requested,
51 size_t* allocated,
52 bool is_executable) {
53 const size_t msize = RoundUp(requested, sysconf(_SC_PAGESIZE));
54 int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
55 void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
56 if (mbase == MAP_FAILED) return NULL;
57 *allocated = msize;
58 return mbase;
59 }
60
61
GetSharedLibraryAddresses()62 std::vector<OS::SharedLibraryAddress> OS::GetSharedLibraryAddresses() {
63 std::vector<SharedLibraryAddresses> result;
64 // This function assumes that the layout of the file is as follows:
65 // hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name]
66 // If we encounter an unexpected situation we abort scanning further entries.
67 FILE* fp = fopen("/proc/self/maps", "r");
68 if (fp == NULL) return result;
69
70 // Allocate enough room to be able to store a full file name.
71 const int kLibNameLen = FILENAME_MAX + 1;
72 char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));
73
74 // This loop will terminate once the scanning hits an EOF.
75 while (true) {
76 uintptr_t start, end;
77 char attr_r, attr_w, attr_x, attr_p;
78 // Parse the addresses and permission bits at the beginning of the line.
79 if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2) break;
80 if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4) break;
81
82 int c;
83 if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') {
84 // Found a read-only executable entry. Skip characters until we reach
85 // the beginning of the filename or the end of the line.
86 do {
87 c = getc(fp);
88 } while ((c != EOF) && (c != '\n') && (c != '/'));
89 if (c == EOF) break; // EOF: Was unexpected, just exit.
90
91 // Process the filename if found.
92 if (c == '/') {
93 ungetc(c, fp); // Push the '/' back into the stream to be read below.
94
95 // Read to the end of the line. Exit if the read fails.
96 if (fgets(lib_name, kLibNameLen, fp) == NULL) break;
97
98 // Drop the newline character read by fgets. We do not need to check
99 // for a zero-length string because we know that we at least read the
100 // '/' character.
101 lib_name[strlen(lib_name) - 1] = '\0';
102 } else {
103 // No library name found, just record the raw address range.
104 snprintf(lib_name, kLibNameLen,
105 "%08" V8PRIxPTR "-%08" V8PRIxPTR, start, end);
106 }
107 result.push_back(SharedLibraryAddress(lib_name, start, end));
108 } else {
109 // Entry not describing executable data. Skip to end of line to set up
110 // reading the next entry.
111 do {
112 c = getc(fp);
113 } while ((c != EOF) && (c != '\n'));
114 if (c == EOF) break;
115 }
116 }
117 free(lib_name);
118 fclose(fp);
119 return result;
120 }
121
122
SignalCodeMovingGC()123 void OS::SignalCodeMovingGC() {
124 // Nothing to do on Cygwin.
125 }
126
127
128 // The VirtualMemory implementation is taken from platform-win32.cc.
129 // The mmap-based virtual memory implementation as it is used on most posix
130 // platforms does not work well because Cygwin does not support MAP_FIXED.
131 // This causes VirtualMemory::Commit to not always commit the memory region
132 // specified.
133
RandomizedVirtualAlloc(size_t size,int action,int protection)134 static void* RandomizedVirtualAlloc(size_t size, int action, int protection) {
135 LPVOID base = NULL;
136
137 if (protection == PAGE_EXECUTE_READWRITE || protection == PAGE_NOACCESS) {
138 // For exectutable pages try and randomize the allocation address
139 for (size_t attempts = 0; base == NULL && attempts < 3; ++attempts) {
140 base = VirtualAlloc(OS::GetRandomMmapAddr(), size, action, protection);
141 }
142 }
143
144 // After three attempts give up and let the OS find an address to use.
145 if (base == NULL) base = VirtualAlloc(NULL, size, action, protection);
146
147 return base;
148 }
149
150
VirtualMemory()151 VirtualMemory::VirtualMemory() : address_(NULL), size_(0) { }
152
153
VirtualMemory(size_t size)154 VirtualMemory::VirtualMemory(size_t size)
155 : address_(ReserveRegion(size)), size_(size) { }
156
157
VirtualMemory(size_t size,size_t alignment)158 VirtualMemory::VirtualMemory(size_t size, size_t alignment)
159 : address_(NULL), size_(0) {
160 DCHECK((alignment % OS::AllocateAlignment()) == 0);
161 size_t request_size = RoundUp(size + alignment,
162 static_cast<intptr_t>(OS::AllocateAlignment()));
163 void* address = ReserveRegion(request_size);
164 if (address == NULL) return;
165 uint8_t* base = RoundUp(static_cast<uint8_t*>(address), alignment);
166 // Try reducing the size by freeing and then reallocating a specific area.
167 bool result = ReleaseRegion(address, request_size);
168 USE(result);
169 DCHECK(result);
170 address = VirtualAlloc(base, size, MEM_RESERVE, PAGE_NOACCESS);
171 if (address != NULL) {
172 request_size = size;
173 DCHECK(base == static_cast<uint8_t*>(address));
174 } else {
175 // Resizing failed, just go with a bigger area.
176 address = ReserveRegion(request_size);
177 if (address == NULL) return;
178 }
179 address_ = address;
180 size_ = request_size;
181 }
182
183
~VirtualMemory()184 VirtualMemory::~VirtualMemory() {
185 if (IsReserved()) {
186 bool result = ReleaseRegion(address_, size_);
187 DCHECK(result);
188 USE(result);
189 }
190 }
191
192
IsReserved()193 bool VirtualMemory::IsReserved() {
194 return address_ != NULL;
195 }
196
197
Reset()198 void VirtualMemory::Reset() {
199 address_ = NULL;
200 size_ = 0;
201 }
202
203
Commit(void * address,size_t size,bool is_executable)204 bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
205 return CommitRegion(address, size, is_executable);
206 }
207
208
Uncommit(void * address,size_t size)209 bool VirtualMemory::Uncommit(void* address, size_t size) {
210 DCHECK(IsReserved());
211 return UncommitRegion(address, size);
212 }
213
214
ReserveRegion(size_t size)215 void* VirtualMemory::ReserveRegion(size_t size) {
216 return RandomizedVirtualAlloc(size, MEM_RESERVE, PAGE_NOACCESS);
217 }
218
219
CommitRegion(void * base,size_t size,bool is_executable)220 bool VirtualMemory::CommitRegion(void* base, size_t size, bool is_executable) {
221 int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
222 if (NULL == VirtualAlloc(base, size, MEM_COMMIT, prot)) {
223 return false;
224 }
225 return true;
226 }
227
228
Guard(void * address)229 bool VirtualMemory::Guard(void* address) {
230 if (NULL == VirtualAlloc(address,
231 OS::CommitPageSize(),
232 MEM_COMMIT,
233 PAGE_NOACCESS)) {
234 return false;
235 }
236 return true;
237 }
238
239
UncommitRegion(void * base,size_t size)240 bool VirtualMemory::UncommitRegion(void* base, size_t size) {
241 return VirtualFree(base, size, MEM_DECOMMIT) != 0;
242 }
243
244
ReleaseRegion(void * base,size_t size)245 bool VirtualMemory::ReleaseRegion(void* base, size_t size) {
246 return VirtualFree(base, 0, MEM_RELEASE) != 0;
247 }
248
249
HasLazyCommits()250 bool VirtualMemory::HasLazyCommits() {
251 // TODO(alph): implement for the platform.
252 return false;
253 }
254
255 } // namespace base
256 } // namespace v8
257