add system for resetting TLS to initial values

this is needed for reused threads in the SIGEV_THREAD timer
notification system, and could be reused elsewhere in the future if
needed, though it should be refactored for such use.

for static linking, __init_tls.c is simply modified to export the TLS
info in a structure with external linkage, rather than using statics.
this perhaps makes the code more clear, since the statics were poorly
named for statics. the new __reset_tls.c is only linked if it is used.

for dynamic linking, the code is in dynlink.c. sharing code with
__copy_tls is not practical since __reset_tls must also re-zero
thread-local bss.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index d689f96e..fa5ad004 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -783,6 +783,19 @@ void _dl_debug_state(void)
 {
 }
 
+void __reset_tls()
+{
+	pthread_t self = __pthread_self();
+	struct dso *p;
+	for (p=head; p; p=p->next) {
+		if (!p->tls_id || !self->dtv[p->tls_id]) continue;
+		memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
+		memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
+			p->tls_size - p->tls_len);
+		if (p->tls_id == (size_t)self->dtv[0]) break;
+	}
+}
+
 void *__copy_tls(unsigned char *mem)
 {
 	pthread_t td;