Add support for ELF indirect functions. These are symbols of
type STT_GNU_IFUNC which, instead of pointing directly at the
function, point at a routine which will return the address of
the real function. Redirection of indirect functions is handled
by valgrind as follows:
- When a redirection specification matches an indirect
function symbol an active redirection is added in the
normal way, but with the isIFunc flag set.
- When a call is made to an address which matches an
active redirection with the isIFunc flag set the call
is redirected, but not to the target address of the
redirection - instead it is sent to a small wrapper
routine that is preloaded into the client.
- The wrapper routine calls the original client routine
and collects the result, which it reports to valgrind
using a client request, and then returns the result to
the caller.
- When valgrind gets the client request it looks up the
active redirection for the indirect function and then
adds a new active redirection which redirects from the
address returned by the indirection function to the
redirection target. This new redirection does not have
the isIFunc flag set so behaves as a normal redirection.
In addition to the above we also add a few new redirections to
memcheck to capture internal calls made by glibc to things like
strlen, as these internal calls do not go through the indirect
function and instead go direct to the chosen implementation.
Based on a patch from Dodji Seketeli and comments from Jakub
Jelinek, this commit closes bug 206013.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@10920 a5019735-40e9-0310-863c-91ae7b9d1cf9
10 files changed