Expose libc_shared_globals to libc.so with symbol
Previously, the address of the global variable was communicated from the
dynamic linker to libc.so using a field of KernelArgumentBlock, which is
communicated using the TLS_SLOT_BIONIC_PREINIT slot.
As long as this function isn't called during relocations (i.e. while
executing an ifunc), it always return a non-NULL value. If it's called
before its PLT entry is relocated, I expect a crash.
I removed the __libc_init_shared_globals function. It's currently empty,
and I don't think there's one point in libc's initialization where
shared globals should be initialized.
Bug: http://b/25751302
Test: bionic unit tests
Change-Id: I614d25e7ef5e0d2ccc40d5c821dee10f1ec61c2e
diff --git a/linker/dlfcn.cpp b/linker/dlfcn.cpp
index 45ae6ed..5ae7b9b 100644
--- a/linker/dlfcn.cpp
+++ b/linker/dlfcn.cpp
@@ -38,6 +38,7 @@
#include <android/api-level.h>
#include <bionic/pthread_internal.h>
+#include "private/bionic_globals.h"
#include "private/bionic_tls.h"
#include "private/ScopedPthreadMutexLocker.h"
@@ -86,6 +87,7 @@
const void* caller_addr) __LINKER_PUBLIC__;
void __loader_add_thread_local_dtor(void* dso_handle) __LINKER_PUBLIC__;
void __loader_remove_thread_local_dtor(void* dso_handle) __LINKER_PUBLIC__;
+libc_shared_globals* __loader_shared_globals() __LINKER_PUBLIC__;
#if defined(__arm__)
_Unwind_Ptr __loader_dl_unwind_find_exidx(_Unwind_Ptr pc, int* pcount) __LINKER_PUBLIC__;
#endif
@@ -299,6 +301,10 @@
decrement_dso_handle_reference_counter(dso_handle);
}
+libc_shared_globals* __loader_shared_globals() {
+ return __libc_shared_globals();
+}
+
static uint8_t __libdl_info_buf[sizeof(soinfo)] __attribute__((aligned(8)));
static soinfo* __libdl_info = nullptr;