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

[Weimin Pan <weimin.pan@oracle.com>]

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
>>>>>>      program runs - because the ARM compiler does not emit dwarf 
>>>>>> attribute
>>>>>>      DW_AT_location for TLS, the result is expected and the 
>>>>>> baseline may
>>>>>>      need to be changed for aarch64.
>>>>>>
>>>>>> (2) Using "info address" command on C++ static TLS object 
>>>>>> resulted in
>>>>>>      "symbol unresolved" error - below is a snippet from the test 
>>>>>> case:
>>>>>>
>>>>>> class K {
>>>>>>   public:
>>>>>>    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.
>>>>>> ---
>>>>>>   gdb/ChangeLog |    5 +++++
>>>>>>   gdb/minsyms.c |   17 +++--------------
>>>>>>   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 @@
>>>>>> +2017-11-01  Weimin Pan  <weimin.pan@oracle.com>
>>>>>> +
>>>>>> +    * minsyms.c (lookup_minimal_symbol_and_objfile): Use
>>>>>> +    lookup_minimal_symbol() to find symbol entry.
>>>>>> +
>>>>>>   2017-10-27  Keith Seitz  <keiths@redhat.com>
>>>>>>         * 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)
>>>>>>   {
>>>>>>     struct bound_minimal_symbol result;
>>>>>>     struct objfile *objfile;
>>>>>> -  unsigned int hash = msymbol_hash (name) % 
>>>>>> MINIMAL_SYMBOL_HASH_SIZE;
>>>>>>       ALL_OBJFILES (objfile)
>>>>>>       {
>>>>>> -      struct minimal_symbol *msym;
>>>>>> -
>>>>>> -      for (msym = objfile->per_bfd->msymbol_hash[hash];
>>>>>> -       msym != NULL;
>>>>>> -       msym = msym->hash_next)
>>>>>> -    {
>>>>>> -      if (strcmp (MSYMBOL_LINKAGE_NAME (msym), name) == 0)
>>>>>> -        {
>>>>>> -          result.minsym = msym;
>>>>>> -          result.objfile = objfile;
>>>>>> -          return result;
>>>>>> -        }
>>>>>> -    }
>>>>>> +      result = lookup_minimal_symbol (name, NULL, objfile);
>>>>>> +      if (result.minsym != NULL)
>>>>>> +        return result;
>>>>>>       }
>>>>>>       memset (&result, 0, sizeof (result));
>>>>>
>>>>
>>>
>>
>