llext: add a test for inter-extension linking

This test uses two LLEXT objects: one of them exports a symbol and
the other one calls the exported function.

Signed-off-by: Guennadi Liakhovetski <[email protected]>

Author: lyakh

tests/subsys/llext/simple/CMakeLists.txt

@@ -15,7 +15,16 @@ target_include_directories(app PRIVATE
   ${ZEPHYR_BASE}/arch/${ARCH}/include
 )
 
-set(ext_names hello_world logging relative_jump object syscalls threads_kernel_objects)
+set(ext_names
+	hello_world
+	logging
+	relative_jump
+	object
+	syscalls
+	threads_kernel_objects
+	export_dependent
+	export_dependency
+)
 
 if(CONFIG_ARM)
   if(NOT CONFIG_CPU_CORTEX_M0 AND NOT CONFIG_CPU_CORTEX_M0PLUS AND NOT CONFIG_CPU_CORTEX_M1)

tests/subsys/llext/simple/src/export_dependency_ext.c

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2024 Intel Corporation.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* Test exporting symbols, imported by other LLEXTs */
+
+#include <zephyr/llext/symbol.h>
+
+long test_dependency(int a, int b)
+{
+	return (long)a * b;
+}
+EXPORT_SYMBOL(test_dependency);

tests/subsys/llext/simple/src/export_dependent_ext.c

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2024 Intel Corporation.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* Test importing symbols, exported by other LLEXTs */
+
+#include <zephyr/ztest.h>
+#include <zephyr/llext/symbol.h>
+#include <zephyr/sys/util.h>
+
+extern long test_dependency(int a, int b);
+
+void test_entry(void)
+{
+	unsigned long half_ptr_bits = sizeof(uintptr_t) * 8 / 2;
+	unsigned long mask = BIT(half_ptr_bits) - 1;
+	int a = mask & (uintptr_t)test_entry;
+	int b = mask & ((uintptr_t)test_entry >> half_ptr_bits);
+
+	zassert_equal(test_dependency(a, b), (long)a * b);
+}
+EXPORT_SYMBOL(test_entry);

tests/subsys/llext/simple/src/test_llext_simple.c

@@ -320,6 +320,45 @@ static LLEXT_CONST uint8_t multi_file_ext[] ELF_ALIGN = {
 LLEXT_LOAD_UNLOAD(multi_file)
 #endif
 
+#ifndef CONFIG_USERSPACE
+static LLEXT_CONST uint8_t export_dependent_ext[] ELF_ALIGN = {
+	#include "export_dependent.inc"
+};
+
+static LLEXT_CONST uint8_t export_dependency_ext[] ELF_ALIGN = {
+	#include "export_dependency.inc"
+};
+
+ZTEST(llext, test_inter_ext)
+{
+	const void *dependency_buf = export_dependency_ext;
+	const void *dependent_buf = export_dependent_ext;
+	struct llext_buf_loader buf_loader_dependency =
+		LLEXT_BUF_LOADER(dependency_buf, sizeof(hello_world_ext));
+	struct llext_buf_loader buf_loader_dependent =
+		LLEXT_BUF_LOADER(dependent_buf, sizeof(export_dependent_ext));
+	struct llext_loader *loader_dependency = &buf_loader_dependency.loader;
+	struct llext_loader *loader_dependent = &buf_loader_dependent.loader;
+	const struct llext_load_param ldr_parm = LLEXT_LOAD_PARAM_DEFAULT;
+	struct llext *ext_dependency = NULL, *ext_dependent = NULL;
+	int ret = llext_load(loader_dependency, "inter_ext_dependency", &ext_dependency, &ldr_parm);
+
+	zassert_ok(ret, "dependency load should succeed");
+
+	ret = llext_load(loader_dependent, "export_dependent", &ext_dependent, &ldr_parm);
+
+	zassert_ok(ret, "dependent load should succeed");
+
+	int (*test_entry_fn)() = llext_find_sym(&ext_dependent->exp_tab, "test_entry");
+
+	zassert_not_null(test_entry_fn, "test_dependent should be an exported symbol");
+	test_entry_fn();
+
+	llext_unload(&ext_dependent);
+	llext_unload(&ext_dependency);
+}
+#endif
+
 #if defined(CONFIG_LLEXT_TYPE_ELF_RELOCATABLE) && defined(CONFIG_XTENSA)
 static LLEXT_CONST uint8_t pre_located_ext[] ELF_ALIGN = {
 	#include "pre_located.inc"