Fix profiling for shared libraries on Linux loaded at negative addresses...

src/platform-linux.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 206 matching lines @@
 }
 
 
 PosixMemoryMappedFile::~PosixMemoryMappedFile() {
   if (memory_) munmap(memory_, size_);
   fclose(file_);
 }
 
 
 #ifdef ENABLE_LOGGING_AND_PROFILING
-static unsigned StringToLong(char* buffer) {
-  return static_cast<unsigned>(strtol(buffer, NULL, 16));  // NOLINT
+static uintptr_t StringToULong(char* buffer) {
+  return strtoul(buffer, NULL, 16);  // NOLINT
 }
 #endif
 
 
 void OS::LogSharedLibraryAddresses() {
 #ifdef ENABLE_LOGGING_AND_PROFILING
   static const int MAP_LENGTH = 1024;
   int fd = open("/proc/self/maps", O_RDONLY);
   if (fd < 0) return;
   while (true) {
     char addr_buffer[11];
     addr_buffer[0] = '0';
     addr_buffer[1] = 'x';
     addr_buffer[10] = 0;
     int result = read(fd, addr_buffer + 2, 8);
     if (result < 8) break;
-    unsigned start = StringToLong(addr_buffer);
+    uintptr_t start = StringToULong(addr_buffer);
     result = read(fd, addr_buffer + 2, 1);
     if (result < 1) break;
     if (addr_buffer[2] != '-') break;
     result = read(fd, addr_buffer + 2, 8);
     if (result < 8) break;
-    unsigned end = StringToLong(addr_buffer);
+    uintptr_t end = StringToULong(addr_buffer);
     char buffer[MAP_LENGTH];
     int bytes_read = -1;
     do {
       bytes_read++;
       if (bytes_read >= MAP_LENGTH - 1)
         break;
       result = read(fd, buffer + bytes_read, 1);
       if (result < 1) break;
     } while (buffer[bytes_read] != '\n');
     buffer[bytes_read] = 0;
     // Ignore mappings that are not executable.
     if (buffer[3] != 'x') continue;
     char* start_of_path = index(buffer, '/');
-    // There may be no filename in this line.  Skip to next.
-    if (start_of_path == NULL) continue;
-    buffer[bytes_read] = 0;
-    LOG(SharedLibraryEvent(start_of_path, start, end));
+    // If there is no filename for this line then log it as an anonymous
+    // mapping and use the address as its name.
+    if (start_of_path == NULL) {
+      // 40 is enough to print a 64 bit address range.
+      ASSERT(sizeof(buffer) > 40);
+      snprintf(buffer,
+               sizeof(buffer),
+               "%08" V8PRIxPTR "-%08" V8PRIxPTR,
+               start,
+               end);
+      LOG(SharedLibraryEvent(buffer, start, end));
+    } else {
+      buffer[bytes_read] = 0;
+      LOG(SharedLibraryEvent(start_of_path, start, end));
+    }
   }
   close(fd);
 #endif
 }
 
 
 int OS::StackWalk(Vector<OS::StackFrame> frames) {
   // backtrace is a glibc extension.
 #ifdef __GLIBC__
   int frames_size = frames.length();
@@ skipping 417 matching lines @@
   }
 
   // This sampler is no longer the active sampler.
   active_sampler_ = NULL;
   active_ = false;
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal