Re: How to implement a kernel feature check in the crt* files?

[Roland McGrath <roland at redhat dot com>]

> But it would still be necessary to recognize that situation in order to
> prevent the check from being executed since accessing the ELF header field
> would segfault.  The only way I see is to compare the AT_ENTRY field with
> the _start address which basically tells you if the current auxv does belong
> to the executable or not.

I don't really see what you are talking about there.  There is nothing to
recognize.  ld.so creates the situation, so it knows what it should do.

> > That said, it seems like ld.so could fix this.  i.e., update the auxv
> > fields on the stack to point to where it's loaded the executable
> > rather than to ld.so itself.
> 
> Ok sounds reasonable.  In order to fix it completely this would mean to 
> duplicate the auxv setup from the kernel in ld.so and keep both in sync.

I don't know exactly what you have in mind, but it sounds rather off to me.
There is nothing to "duplicate".  There are a few known auxv entries that
refer to the loaded image, so ld.so needs to change those entries.


Thanks,
Roland