Re: [Xen-devel] livepatch-build-tools regression

["Wieczorkiewicz, Pawel" <wipawel@xxxxxxxxx>]

> On 27. Nov 2019, at 16:56, Sergey Dyasli <sergey.dyasli@xxxxxxxxxx> wrote:
> 
> On 27/11/2019 15:22, Wieczorkiewicz, Pawel wrote:
>> 
>> 
>>> On 27. Nov 2019, at 12:16, Sergey Dyasli <sergey.dyasli@xxxxxxxxxx> wrote:
>>> 
>>> On 26/11/2019 18:37, Wieczorkiewicz, Pawel wrote:
>>>> It looks like gcc plays the usual dirty tricks with local variables 
>>>> renaming:
>>>> 
>>>> - xen-syms
>>>> 7529: ffff82d0805fed50     8 OBJECT  LOCAL  DEFAULT 4230 lastpage.22857
>>>> - livepatch
>>>> 289: 0000000000000000     8 OBJECT  GLOBAL DEFAULT  UND 
>>>> hvm.c#lastpage.22856
>>>> 
>>>> Then, symbols resolution by name fails..
>>>> 
>>>> Can you please try to build the livepatch module with additional option 
>>>> '—prelink' and give it a try ?
>>> 
>>> My LP loading error is:
>>> 
>>>  (XEN) livepatch: lp: Unknown symbol: .LC7
>>> 
>>> When I pass --prelink to livepatch-build, it complains in a similar way:
>>> 
>>>  livepatch-build-tools/prelink: ERROR: output.o: livepatch_resolve_symbols: 
>>> 80: lookup_local_symbol .LC7 (p2m.c)
>>> 
>> 
>> Could you give this testing patch a try?
>> 
>> diff --git a/create-diff-object.c b/create-diff-object.c
>> index 8d63940..10807d2 100644
>> --- a/create-diff-object.c
>> +++ b/create-diff-object.c
>> @@ -839,8 +839,10 @@ static void kpatch_compare_symbols(struct list_head 
>> *symlist)
>>       list_for_each_entry(sym, symlist, list) {
>>               if (sym->twin)
>>                       kpatch_compare_correlated_symbol(sym);
>> -               else
>> +               else {
>>                       sym->status = NEW;
>> +                       sym->include = 1;
>> +               }
>> 
>>               log_debug("symbol %s is %s\n", sym->name, 
>> status_str(sym->status));
>>       }
>> 
> 
> Looks like this change fixed the issue for me!
> One thing to notice is that the size of a stripped LP binary increased
> from 45K to 60K.
> 

Yes, this was not supposed to be a proper fix. I was merely trying to establish 
if we were looking at the same issue.
I did fix it now the proper way, though. I shall send the patches soon.

> --
> Thanks,
> Sergey

Best Regards,
Pawel Wieczorkiewicz






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