Implement dynamic TLS accesses and allocation
Initialize a thread's DTV to an empty zeroed DTV. Allocate the DTV and
any ELF module's TLS segment on-demand in __tls_get_addr. Use a generation
counter, incremented in the linker, to signal when threads should
update/reallocate their DTV objects.
A generation count of 0 always indicates the constant zero DTV.
Once a DTV is allocated, it isn't freed until the thread exits, because
a signal handler could interrupt the fast path of __tls_get_addr between
accessing the DTV slot and reading a field of the DTV. Bionic keeps a
linked list of DTV objects so it can free them at thread-exit.
Dynamic TLS memory is allocated using a BionicAllocator instance in
libc_shared_globals. For async-signal safety, access to the
linker/libc-shared state is protected by first blocking signals, then by
acquiring the reader-writer lock, TlsModules::rwlock. A write lock is
needed to allocate or free memory.
In pthread_exit, unconditionally block signals before freeing dynamic
TLS memory or freeing the shadow call stack.
ndk_cruft.cpp: Avoid including pthread_internal.h inside an extern "C".
(The header now includes a C++ template that doesn't compile inside
extern "C".)
Bug: http://b/78026329
Bug: http://b/123094171
Test: bionic unit tests
Change-Id: I3c9b12921c9e68b33dcc1d1dd276bff364eff5d7
diff --git a/libc/bionic/__libc_init_main_thread.cpp b/libc/bionic/__libc_init_main_thread.cpp
index 6279e65..4984e38 100644
--- a/libc/bionic/__libc_init_main_thread.cpp
+++ b/libc/bionic/__libc_init_main_thread.cpp
@@ -74,6 +74,7 @@
__libc_init_sysinfo(); // uses AT_SYSINFO auxv entry
#endif
__init_tcb(temp_tcb, &main_thread);
+ __init_tcb_dtv(temp_tcb);
__set_tls(&temp_tcb->tls_slot(0));
main_thread.tid = __getpid();
main_thread.set_cached_pid(main_thread.tid);