Re: [Valgrind-developers] Debugging guest code

[Peter B. <be...@vn...>]

On Thu, 2014-02-06 at 19:35 +0100, Julian Seward wrote:
> Carl
> 
> > regards to function calls.  Specifically they used to store the function
> > entry address at in the first location of the function, followed by the
> > code.  The first address of the function in the new API no longer has
> > the start address.
> 
> Can you clarify what you mean?  For ppc64-linux, I remember the ABI requires
> that taking the address of a function gives a pointer to a three word
> descriptor, the first word of which points to the code itself, the second
> is the TOC pointer, and the third I am not sure what it is for.  Dealing
> with these descriptors is a lot of hassle in various bits of the code.
> 
> Is this what has changed?  If so, what did it change to?

That is correct.  In the old ELFv1 ABI, a function pointer was the
address of the 3 element function descriptor you describe.  In the
new ELFv2 ABI, the function pointer is now just the address of the
function code like most other architectures/ABIs.

Peter