Re: [PING 2][PATCH PR gdb/18071] TLS variables can't be resolved on aarch64-linux-gnu

Weimin Pan
2018-01-12T23:59:28Z

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));
>