| #
277317 |
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18-Jan-2015 |
kib |
Fix known issues which blow up the process after dlopen("libthr.so")
(or loading a dso linked to libthr.so into process which was not
linked against threading library).
MFC r276630:
Remove interposing, fix malloc, reinstall signal handlers wrappers on
libthr load.
MFC r276681:
Avoid calling internal libc function through PLT or accessing data
though GOT.
MFC r277032:
Reduce the size of the interposing table and amount of
cancellation-handling code in the libthr.
MFC note:
r276646 ("do not erronously export 'openat' symbol from rtld") is not
applicable to stable/10 yet, since PATHFDS support was not merged.
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| #
276630 |
|
03-Jan-2015 |
kib |
Fix known issues which blow up the process after dlopen("libthr.so")
(or loading a dso linked to libthr.so into process which was not
linked against threading library).
- Remove libthr interposers of the libc functions, including
__error(). Instead, functions calls are indirected through the
interposing table, similar to how pthread stubs in libc are already
done. Libc by default points either to syscall trampolines or to
existing libc implementations. On libthr load, libthr rewrites the
pointers to the cancellable implementations already in libthr. The
interposition table is separate from pthreads stubs indirection
table to not pull pthreads stubs into static binaries.
- Postpone the malloc(3) internal mutexes initialization until libthr
is loaded. This avoids recursion between calloc(3) and static
pthread_mutex_t initialization.
- Reinstall signal handlers with wrapper on libthr load. The
_rtld_is_dlopened(3) is used to avoid useless calls to sigaction(2)
when libthr is statically referenced from the main binary.
In the process, fix openat(2), swapcontext(2) and setcontext(2)
interposing. The libc symbols were exported at different versions
than libthr interposers. Export both libc and libthr versions from
libc now, with default set to the higher version from libthr.
Remove unused and disconnected swapcontext(3) userspace implementation
from libc/gen.
No objections from: deischen
Tested by: pho, antoine (exp-run) (previous versions)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
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