Re: [PATCH] perf: Fix symbol resolution on old ppc64 ABI

[Anton Blanchard]

Hi Ingo,

> > The synthetic symbol creation code has an issue with the old ppc64 
> > ABI. We end up with duplicate symbols of different sizes that 
> > overlap.
> > 
> > To fix this, walk all of the symbols and remove any duplicates that 
> > are the length of a function descriptor.
> 
> > I'd prefer not to add a ppc64 specific hack here, but I'm not sure 
> > how we can fix this in a simpler way.
> 
> Symbol space problems are common on other architectures as well.
> 
> We could use a heuristic: when symbols are overlapping then we could 
> throw away the one that is smaller. This would implicitly cover the 
> ppc64 case, right?
> 
> I'd also suggest we warn somewhere that a symbol has been thrown 
> away, if verbosity is turned off. (i.e. don't warn by default.)

It would cover most cases. There would be an issue with functions that
are less than 24 bytes in length (ie 6 instructions). Tiny functions
are probably rare enough that we can live with it.

Anton
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