Commit Graph

2 Commits

Author SHA1 Message Date
Konstantin Belousov
bd6060a1c6 Switch libc from using _sig{procmask,action,suspend} symbols, which
are aliases for the syscall stubs and are plt-interposed, to the
libc-private aliases of internally interposed sigprocmask() etc.

Since e.g. _sigaction is not interposed by libthr, calling signal()
removes thr_sighandler() from the handler slot etc.  The result was
breaking signal semantic and rtld locking.

The added __libc_sigprocmask and other symbols are hidden, they are
not exported and cannot be called through PLT.  The setjmp/longjmp
functions for x86 were changed to use direct calls, and since
PIC_PROLOGUE only needed for functional PLT indirection on i386, it is
removed as well.

The PowerPC bug of calling the syscall directly in the setjmp/longjmp
implementation is kept as is.

Reported by:	Pete French <petefrench@ingresso.co.uk>
Tested by:	Michiel Boland <boland37@xs4all.nl>
Reviewed by:	jilles (previous version)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-08-29 14:25:01 +00:00
Konstantin Belousov
8495e8b1e9 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
2015-01-03 18:38:46 +00:00