When using WASM_WORKERS: make sure sbrk ptr is aligned properly for t…

…ls space, and malloc needs to be thread safe (emscripten-core#18157)

* emscripten_wasm_worker_main_thread_initialize: make sure sbrk ptr is aligned properly when account for tls space

* dlmalloc.c: define USE_LOCKS when __EMSCRIPTEN_WASM_WORKERS__ is true, so that memory allocation is thread safe

* emscripten_wasm_worker_main_thread_initialize: make sure sbrk ptr is aligned properly when account for tls space

* emscripten_wasm_worker_main_thread_initialize: make sure sbrk ptr is aligned properly when account for tls space

Co-authored-by: kme <none>

system/lib/dlmalloc.c

@@ -21,6 +21,10 @@
 /* XXX Emscripten Tracing API. This defines away the code if tracing is disabled. */
 #include <emscripten/trace.h>
 
+#ifdef __EMSCRIPTEN_WASM_WORKERS__
+#define USE_LOCKS 1
+#endif
+
 /* Make malloc() and free() threadsafe by securing the memory allocations with pthread mutexes. */
 #if __EMSCRIPTEN_PTHREADS__
 #define USE_LOCKS 1

system/lib/wasm_worker/library_wasm_worker.c

@@ -21,8 +21,10 @@ void __wasm_init_tls(void *memory);
 __attribute__((constructor(48)))
 static void emscripten_wasm_worker_main_thread_initialize() {
 	uintptr_t* sbrk_ptr = emscripten_get_sbrk_ptr();
+	assert((*sbrk_ptr & 15) == 0);
+	assert(__builtin_wasm_tls_align() <= 16);
 	__wasm_init_tls((void*)*sbrk_ptr);
-	*sbrk_ptr += __builtin_wasm_tls_size();
+	*sbrk_ptr += (__builtin_wasm_tls_size() + 15) & -16;
 }
 
 emscripten_wasm_worker_t emscripten_create_wasm_worker(void *stackLowestAddress, uint32_t stackSize)