Re: [PATCH] Lookup the JIT descriptor symbol first to avoid finding the PLT entry of the breakpoint in the wrong object file.

[Yichao Yu <yyc1992 at gmail dot com>]

And ping again.

On Fri, Feb 24, 2017 at 2:00 PM, Yichao Yu <yyc1992@gmail.com> wrote:
> Ping again.
>
> On Sun, Feb 5, 2017 at 7:46 PM, Yichao Yu <yyc1992@gmail.com> wrote:
>> Ping. Can anyone please review this? Or is there a better place to post this?
>>
>> On Thu, Jan 26, 2017 at 3:31 PM, Yichao Yu <yyc1992@gmail.com> wrote:
>>> On Thu, Jan 26, 2017 at 3:24 PM, Yichao Yu <yyc1992@gmail.com> wrote:
>>>> Fix 20633
>>>
>>>
>>> ..... I don't use git send-mail very often and missed the chance to
>>> type more comments....
>>>
>>> The link to the bug report is
>>> https://sourceware.org/bugzilla/show_bug.cgi?id=20633 . I think
>>> ideally the interface should find all the global and local symbols and
>>> breakpoint on all of them since there isn't an agreement on who will
>>> provide it AFAICT (and for example,a process can load multiple copies
>>> of statically linked LLVM each providing a jit debugging interface).
>>> However, I'm not really sure what's the right function to use for that
>>> and it'll probably be a much bigger change so I went for this smaller
>>> change that fixes the original issue.
>>>
>>> Not sure how this should be tested....... =(
>>>
>>>> ---
>>>>  gdb/jit.c | 17 ++++++++++-------
>>>>  1 file changed, 10 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/gdb/jit.c b/gdb/jit.c
>>>> index 158d6d8..d6eb800 100644
>>>> --- a/gdb/jit.c
>>>> +++ b/gdb/jit.c
>>>> @@ -1051,18 +1051,21 @@ jit_breakpoint_re_set_internal (struct gdbarch *gdbarch,
>>>>    if (ps_data->objfile == NULL)
>>>>      {
>>>>        /* Lookup the registration symbol.  If it is missing, then we
>>>> -        assume we are not attached to a JIT.  */
>>>> -      reg_symbol = lookup_minimal_symbol_and_objfile (jit_break_name);
>>>> -      if (reg_symbol.minsym == NULL
>>>> -         || BMSYMBOL_VALUE_ADDRESS (reg_symbol) == 0)
>>>> -       return 1;
>>>> +        assume we are not attached to a JIT.
>>>> +        Lookup the descriptor first since looking up the breakpoint might
>>>> +        return a PLT entry in the wrong file.  */
>>>>
>>>> -      desc_symbol = lookup_minimal_symbol (jit_descriptor_name, NULL,
>>>> -                                          reg_symbol.objfile);
>>>> +      desc_symbol = lookup_minimal_symbol_and_objfile (jit_descriptor_name);
>>>>        if (desc_symbol.minsym == NULL
>>>>           || BMSYMBOL_VALUE_ADDRESS (desc_symbol) == 0)
>>>>         return 1;
>>>>
>>>> +      reg_symbol = lookup_minimal_symbol (jit_break_name, NULL,
>>>> +                                         desc_symbol.objfile);
>>>> +      if (reg_symbol.minsym == NULL
>>>> +         || BMSYMBOL_VALUE_ADDRESS (reg_symbol) == 0)
>>>> +       return 1;
>>>> +
>>>>        objf_data = get_jit_objfile_data (reg_symbol.objfile);
>>>>        objf_data->register_code = reg_symbol.minsym;
>>>>        objf_data->descriptor = desc_symbol.minsym;
>>>> --
>>>> 2.10.2
>>>>