Re: [PING 5][PATCH PR gdb/18071] TLS variables can't be resolved on aarch64-linux-gnu

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

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));
>>>>
>>>
>>
>