scripts/gdb: port to python3 / gdb7.7

I tried to use these scripts in an ubuntu 14.04 host (gdb 7.7 compiled
against python 3.3) but there were several errors.

I believe this patch fixes these issues so that the commands now work (I
tested lx-symbols, lx-dmesg, lx-lsmod).

Main issues that needed to be resolved:

* In python 2 iterators have a "next()" method. In python 3 it is
__next__() instead (so let's just add both).

* In older python versions there was an implicit conversion
in object.__format__() (used when an object is in string.format())
where it was converting the object to str first and then
calling str's __format__(). This has now been removed so
we must explicitly convert to str the objects for which
we need to keep this behavior.

* In dmesg.py: in python 3 log_buf is now a "memoryview" object
which needs to be converted to a string in order to use string
methods like "splitlines()". Luckily memoryview exists in
python 2.7.6 as well, so we can convert log_buf to memoryview
and use the same code in both python 2 and python 3.

This version of the patch has now been tested with gdb 7.7 and both python
3.4 and python 2.7.6 (I think asking for at least python 2.7.6 is a
reasonable requirement instead of complicating the code with version
checks etc).

Signed-off-by: Pantelis Koukousoulas <[e-mail]>
Signed-off-by: Jan Kiszka <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Jason Wessel <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Ben Widawsky <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

scripts/gdb/linux/cpus.py

···
     def __iter__(self):
         return self
 
-    def next(self):
+    def __next__(self):
         while self.bits == 0:
             self.entry += 1
             if self.entry == self.num_entries:
···
         self.bit += 1
 
         return cpu
+
+    def next(self):
+        return self.__next__()
 
 
 class PerCpu(gdb.Function):

scripts/gdb/linux/dmesg.py

···
                 continue
 
             text_len = utils.read_u16(log_buf[pos + 10:pos + 12])
+            text = log_buf[pos + 16:pos + 16 + text_len]
             time_stamp = utils.read_u64(log_buf[pos:pos + 8])
 
-            for line in log_buf[pos + 16:pos + 16 + text_len].splitlines():
+            for line in memoryview(text).tobytes().splitlines():
                 gdb.write("[{time:12.6f}] {line}\n".format(
                     time=time_stamp / 1000000000.0,
                     line=line))

scripts/gdb/linux/modules.py

···
     def __iter__(self):
         return self
 
-    def next(self):
+    def __next__(self):
         entry = self.curr_entry
         if entry != self.end_of_list:
             self.curr_entry = entry['next']
             return utils.container_of(entry, self.module_ptr_type, "list")
         else:
             raise StopIteration
+
+    def next(self):
+        return self.__next__()
 
 
 def find_module_by_name(name):
···
             gdb.write("{address} {name:<19} {size:>8}  {ref}".format(
                 address=str(module['module_core']).split()[0],
                 name=module['name'].string(),
-                size=module['core_size'],
-                ref=ref))
+                size=str(module['core_size']),
+                ref=str(ref)))
 
             source_list = module['source_list']
             t = self._module_use_type.get_type().pointer()

scripts/gdb/linux/symbols.py

···
 
     def _get_module_file(self, module_name):
         module_pattern = ".*/{0}\.ko$".format(
-            string.replace(module_name, "_", r"[_\-]"))
+            module_name.replace("_", r"[_\-]"))
         for name in self.module_files:
             if re.match(module_pattern, name) and os.path.exists(name):
                 return name
···
         attrs = sect_attrs['attrs']
         section_name_to_address = {
             attrs[n]['name'].string() : attrs[n]['address']
-            for n in range(sect_attrs['nsections'])}
+            for n in range(int(sect_attrs['nsections']))}
         args = []
         for section_name in [".data", ".data..read_mostly", ".rodata", ".bss"]:
             address = section_name_to_address.get(section_name)

scripts/gdb/linux/tasks.py

···
     def __iter__(self):
         return self
 
-    def next(self):
+    def __next__(self):
         t = self.curr_task
         if not t or t == self.curr_group:
             self.curr_group = \
···
                                    self.task_ptr_type, "thread_group")
         return t
 
+    def next(self):
+        return self.__next__()
 
 def get_task_by_pid(pid):
     for task in TaskList():

scripts/gdb/linux/utils.py

···
         elif "big endian" in endian:
             target_endianness = BIG_ENDIAN
         else:
-            raise gdb.GdgError("unknown endianness '{0}'".format(endian))
+            raise gdb.GdgError("unknown endianness '{0}'".format(str(endian)))
     return target_endianness