What's coming in glibc 2.10

It isn't a separate context. It's more like injecting code into the
implicit first call into the dynamic linker that happens the first time
any given symbol is referenced[1]. The security context is unchanged: all
the dynamic linker normally does is relocate that PLT entry. It's just
that now you can have it pick *what* to relocate first. It's no more done
in a different context than is calling a function through a function
pointer: that's all it really is.

(hm, and it looks like it might become STT_IFUNC in time and not be
GNU-specific after all. Even better.)

[1] an oversimplification: actually that implicit call happens the first
time a PLT entry is jumped to, but that's nearly the same thing...