Merge pull request #306 from gwsystems/dynamically-size-global-table

feat: Dynamically size runtime globals

awsm

@@ -1 +1 @@
-Subproject commit 9732a7b02712e8c7b5e80daaf6493b372c5b43a9
+Subproject commit 669c1889008f15fccaf4693708de847053489aa4

libsledge/README.md

@@ -144,6 +144,7 @@ The path to the JSON file is passed to `module_alloc_from_json`, which uses the
 `module.abi.entrypoint` -> `SLEDGE_ABI__ENTRYPOINT` -> `wasmf__start`
 `module.abi.starting_pages` -> `SLEDGE_ABI__STARTING_PAGES` -> `starting_pages`
 `module.abi.max_pages` -> `SLEDGE_ABI__MAX_PAGES` -> `max_pages`
+`module.abi.globals_len` -> `SLEDGE_ABI__GLOBALS_LEN` -> `globals_len`
 
 `module init` then calls `module.abi.initialize_table`, which populates the indirect function table with the actual functions. This is performed once during module initialization because this table does not actually vary between instances of a module.
 

libsledge/include/sledge_abi.h

@@ -92,6 +92,9 @@ typedef uint32_t (*sledge_abi__wasm_memory_starting_pages_fn_t)(void);
 typedef uint32_t (*sledge_abi__wasm_memory_max_pages_fn_t)(void);
 #define SLEDGE_ABI__MAX_PAGES "sledge_abi__wasm_memory_max_pages"
 
+typedef uint32_t (*sledge_abi__wasm_memory_globals_len_fn_t)(void);
+#define SLEDGE_ABI__GLOBALS_LEN "sledge_abi__wasm_globals_len"
+
 typedef uint32_t __wasi_clockid_t;
 typedef uint64_t __wasi_dircookie_t;
 typedef uint32_t __wasi_exitcode_t;

libsledge/src/instantiation.c

@@ -20,6 +20,7 @@ extern void     populate_table(void);
 extern int32_t  wasmf__start(void);
 extern uint32_t starting_pages;
 extern uint32_t max_pages;
+extern uint32_t globals_len;
 
 WEAK void populate_globals(){};
 
@@ -58,3 +59,9 @@ sledge_abi__wasm_memory_max_pages(void)
 {
 	return max_pages;
 }
+
+EXPORT uint32_t
+sledge_abi__wasm_globals_len(void)
+{
+	return globals_len;
+}

runtime/include/sledge_abi_symbols.h

@@ -16,6 +16,7 @@ struct sledge_abi_symbols {
 	sledge_abi__entrypoint_fn_t   entrypoint;
 	uint32_t                      starting_pages;
 	uint32_t                      max_pages;
+	uint32_t                      globals_len;
 };
 
 /* Initializes the ABI object using the *.so file at path */
@@ -78,6 +79,14 @@ sledge_abi_symbols_init(struct sledge_abi_symbols *abi, char *path)
 	}
 	abi->max_pages = get_max_pages();
 
+	sledge_abi__wasm_memory_globals_len_fn_t get_globals_len = dlsym(abi->handle, SLEDGE_ABI__GLOBALS_LEN);
+	if (get_globals_len == NULL) {
+		fprintf(stderr, "Failed to resolve symbol %s in %s with error: %s\n", SLEDGE_ABI__GLOBALS_LEN, path,
+		        dlerror());
+		goto dl_error;
+	}
+	abi->globals_len = get_globals_len();
+
 done:
 	return rc;
 dl_error:

runtime/src/sandbox.c

@@ -59,7 +59,7 @@ sandbox_allocate_globals(struct sandbox *sandbox)
 	assert(sandbox);
 	assert(sandbox->module);
 
-	return wasm_globals_init(&sandbox->globals, 50);
+	return wasm_globals_init(&sandbox->globals, sandbox->module->abi.globals_len);
 }
 
 static inline void