Re: [PING 6][PATCH PR gdb/18071] TLS variables can't be resolved on aarch64-linux-gnu

Weimin Pan
2018-03-13T18:56:58Z

On 3/5/2018 5:19 PM, Weimin Pan wrote:
>
>
> On 2/5/2018 5:21 PM, Weimin Pan wrote:
>> On 1/23/2018 5:11 PM, Weimin Pan wrote:
>>> While this problem shows up in aarch64, the fix is actually
>>> in gdb core. Pedro, would you please review the patch when
>>> you get a chance?
>>>
>>> Thanks.
>>>
>>> On 1/11/2018 4:32 PM, Wei-min Pan wrote:
>>>>
>>>> On 11/15/2017 5:51 PM, Wei-min Pan wrote:
>>>>>
>>>>> On 11/2/2017 8:32 AM, Weimin Pan wrote:
>>>>>> Running the test case with upstream gdb shows two failures:
>>>>>>
>>>>>> (1) Receiving different error messages when printing TLS variable
>>>>>> before
>>>>>> Â Â Â Â  program runs - because the ARM compiler does not emit dwarf
>>>>>> attribute
>>>>>> Â Â Â Â  DW_AT_location for TLS, the result is expected and the
>>>>>> baseline may
>>>>>> Â Â Â Â  need to be changed for aarch64.
>>>>>>
>>>>>> (2) Using "info address" command on C++ static TLS object
>>>>>> resulted in
>>>>>> Â Â Â Â  "symbol unresolved" error - below is a snippet from the test
>>>>>> case:
>>>>>>
>>>>>> class K {
>>>>>> Â  public:
>>>>>> Â Â  static __thread int another_thread_local;
>>>>>> };
>>>>>>
>>>>>> __thread int K::another_thread_local;
>>>>>>
>>>>>> (gdb) info address K::another_thread_local
>>>>>> Symbol "K::another_thread_local" is unresolved.
>>>>>>
>>>>>> This patch contains fix for (2).
>>>>>>
>>>>>> Function info_address_command() handles the "info address"
>>>>>> command and
>>>>>> calls lookup_minimal_symbol_and_objfile() to find sym's symbol
>>>>>> entry in
>>>>>> mininal symbol table if SYMBOL_COMPUTED_OPS (sym) is false.
>>>>>> Problem is
>>>>>> that function lookup_minimal_symbol_and_objfile() only looked up an
>>>>>> objfile's minsym ordinary hash table, not its demangled hash
>>>>>> table, which
>>>>>> was the reason why the C++ name was not found.
>>>>>>
>>>>>> The fix is to call lookup_minimal_symbol(), which already looks
>>>>>> up entries
>>>>>> in both minsym's hash tables, to find names when traversing the
>>>>>> object file
>>>>>> list in lookup_minimal_symbol_and_objfile().
>>>>>>
>>>>>> Tested in both aarch64-linux-gnu and amd64-linux-gnu. No
>>>>>> regressions.
>>>>>> ---
>>>>>> Â  gdb/ChangeLog |Â Â Â  5 +++++
>>>>>> Â  gdb/minsyms.c |Â Â  17 +++--------------
>>>>>> Â  2 files changed, 8 insertions(+), 14 deletions(-)
>>>>>>
>>>>>> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
>>>>>> index 4b292e0..2f630bc 100644
>>>>>> --- a/gdb/ChangeLog
>>>>>> +++ b/gdb/ChangeLog
>>>>>> @@ -1,3 +1,8 @@
>>>>>> +2017-11-01Â  Weimin PanÂ  <weimin.pan@oracle.com>
>>>>>> +
>>>>>> +Â Â Â  * minsyms.c (lookup_minimal_symbol_and_objfile): Use
>>>>>> +Â Â Â  lookup_minimal_symbol() to find symbol entry.
>>>>>> +
>>>>>> Â  2017-10-27Â  Keith SeitzÂ  <keiths@redhat.com>
>>>>>> Â  Â Â Â Â Â  * breakpoint.c (print_breakpoint_location): Use the
>>>>>> symbol saved
>>>>>> diff --git a/gdb/minsyms.c b/gdb/minsyms.c
>>>>>> index 37edbd8..4edd8b1 100644
>>>>>> --- a/gdb/minsyms.c
>>>>>> +++ b/gdb/minsyms.c
>>>>>> @@ -881,23 +881,12 @@ lookup_minimal_symbol_and_objfile (const
>>>>>> char *name)
>>>>>> Â  {
>>>>>> Â Â Â  struct bound_minimal_symbol result;
>>>>>> Â Â Â  struct objfile *objfile;
>>>>>> -Â  unsigned int hash = msymbol_hash (name) %
>>>>>> MINIMAL_SYMBOL_HASH_SIZE;
>>>>>> Â  Â Â Â  ALL_OBJFILES (objfile)
>>>>>> Â Â Â Â Â  {
>>>>>> -Â Â Â Â Â  struct minimal_symbol *msym;
>>>>>> -
>>>>>> -Â Â Â Â Â  for (msym = objfile->per_bfd->msymbol_hash[hash];
>>>>>> -Â Â Â Â Â Â  msym != NULL;
>>>>>> -Â Â Â Â Â Â  msym = msym->hash_next)
>>>>>> -Â Â Â  {
>>>>>> -Â Â Â Â Â  if (strcmp (MSYMBOL_LINKAGE_NAME (msym), name) == 0)
>>>>>> -Â Â Â Â Â Â Â  {
>>>>>> -Â Â Â Â Â Â Â Â Â  result.minsym = msym;
>>>>>> -Â Â Â Â Â Â Â Â Â  result.objfile = objfile;
>>>>>> -Â Â Â Â Â Â Â Â Â  return result;
>>>>>> -Â Â Â Â Â Â Â  }
>>>>>> -Â Â Â  }
>>>>>> +Â Â Â Â Â  result = lookup_minimal_symbol (name, NULL, objfile);
>>>>>> +Â Â Â Â Â  if (result.minsym != NULL)
>>>>>> +Â Â Â Â Â Â Â  return result;
>>>>>> Â Â Â Â Â  }
>>>>>> Â  Â Â Â  memset (&result, 0, sizeof (result));
>>>>>
>>>>
>>>
>>
>