On shared object unload, in __cxa_finalize, call and clear all installed

atexit and __cxa_atexit handlers that are either installed by unloaded
dso, or points to the functions provided by the dso.

Use _rtld_addr_phdr to locate segment information from the address of
private variable belonging to the dso, supplied by crtstuff.c. Provide
utility function __elf_phdr_match_addr to do the match of address against
dso executable segment.

Call back into libthr from __cxa_finalize using weak
__pthread_cxa_finalize symbol to remove any atfork handler which
function points into unloaded object.

The rtld needs private __pthread_cxa_finalize symbol to not require
resolution of the weak undefined symbol at initialization time. This
cannot work, since rtld is relocated before sym_zero is set up.

Idea by:	kan
Reviewed by:	kan (previous version)
MFC after:	3 weeks

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/libthr/pthread.map b/lib/libthr/pthread.map
index 6460bec..8457996 100644
--- a/lib/libthr/pthread.map
+++ b/lib/libthr/pthread.map
@@ -192,6 +192,7 @@ FBSDprivate_1.0 {
 	__poll;
 	__pthread_cond_timedwait;
 	__pthread_cond_wait;
+	__pthread_cxa_finalize;
 	__pthread_mutex_init;
 	__pthread_mutex_lock;
 	__pthread_mutex_timedlock;