Optimizated the page size wasmer

Author: john-sharratt

libc-top-half/musl/src/internal/libc.h

@@ -51,6 +51,9 @@ struct __libc {
 #ifndef PAGE_SIZE
 #define PAGE_SIZE libc.page_size
 #endif
+#ifndef LINUX_PAGE_SIZE
+#define LINUX_PAGE_SIZE 4096
+#endif
 
 extern hidden struct __libc __libc;
 #define libc __libc

libc-top-half/musl/src/thread/pthread_create.c

@@ -306,7 +306,9 @@ _Noreturn void wasi_thread_start(int tid, void *p)
  * Instead, round up to a sane alignment.
  * Note: PAGE_SIZE is rather big on WASM. (65536)
  */
-#define ROUND(x) (((x)+16-1)&-16)
+// As wasmer uses mmap on linux, rounding to a linux page size
+// makes sense
+#define ROUND(x) (((x)+LINUX_PAGE_SIZE-1)&-LINUX_PAGE_SIZE)
 #endif
 
 /* pthread_key_create.c overrides this */