llext: Add filesystem based testcase to llext test suite

Extend tests with case where extension is copied from RAM buffer
into filesystem and then loaded from filesystem.

Signed-off-by: Adam Wojasinski <awojasinski@baylibre.com>

tests/subsys/llext/simple/boards/qemu_cortex_a9.conf

@@ -0,0 +1,6 @@
+CONFIG_FILE_SYSTEM=y
+CONFIG_FILE_SYSTEM_LITTLEFS=y
+CONFIG_FS_LITTLEFS_FMP_DEV=y
+CONFIG_FLASH_MAP=y
+CONFIG_FLASH=y
+CONFIG_FLASH_SIMULATOR=y

tests/subsys/llext/simple/boards/qemu_cortex_a9.overlay

@@ -0,0 +1,28 @@
+/ {
+	sim_flash_controller: sim_flash_controller {
+		compatible = "zephyr,sim-flash";
+
+		#address-cells = <1>;
+		#size-cells = <1>;
+		erase-value = <0x00>;
+
+		flash_sim0: flash_sim@0 {
+			compatible = "soc-nv-flash";
+			reg = <0x00000000 0x2000>;
+
+			erase-block-size = <1024>;
+			write-block-size = <4>;
+
+			partitions {
+				compatible = "fixed-partitions";
+				#address-cells = <1>;
+				#size-cells = <1>;
+
+				storage_partition: partition@0 {
+					label = "storage_partition";
+					reg = <0x00000000 0x2000>;
+				};
+			};
+		};
+	};
+};

tests/subsys/llext/simple/boards/qemu_cortex_r5.conf

@@ -0,0 +1,6 @@
+CONFIG_FILE_SYSTEM=y
+CONFIG_FILE_SYSTEM_LITTLEFS=y
+CONFIG_FS_LITTLEFS_FMP_DEV=y
+CONFIG_FLASH_MAP=y
+CONFIG_FLASH=y
+CONFIG_FLASH_SIMULATOR=y

tests/subsys/llext/simple/boards/qemu_cortex_r5.overlay

@@ -0,0 +1,28 @@
+/ {
+	sim_flash_controller: sim_flash_controller {
+		compatible = "zephyr,sim-flash";
+
+		#address-cells = <1>;
+		#size-cells = <1>;
+		erase-value = <0x00>;
+
+		flash_sim0: flash_sim@0 {
+			compatible = "soc-nv-flash";
+			reg = <0x00000000 0x2000>;
+
+			erase-block-size = <1024>;
+			write-block-size = <4>;
+
+			partitions {
+				compatible = "fixed-partitions";
+				#address-cells = <1>;
+				#size-cells = <1>;
+
+				storage_partition: partition@0 {
+					label = "storage_partition";
+					reg = <0x00000000 0x2000>;
+				};
+			};
+		};
+	};
+};

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

@@ -6,10 +6,16 @@
 
 #include <zephyr/ztest.h>
 #include <zephyr/kernel.h>
+#include <zephyr/fs/fs.h>
+#if defined(CONFIG_FILE_SYSTEM_LITTLEFS)
+#include <zephyr/fs/littlefs.h>
+#endif
 #include <zephyr/llext/llext.h>
 #include <zephyr/llext/symbol.h>
 #include <zephyr/llext/buf_loader.h>
+#include <zephyr/llext/fs_loader.h>
 #include <zephyr/logging/log.h>
+#include <zephyr/storage/flash_map.h>
 #include <zephyr/sys/libc-hooks.h>
 #include "syscalls_ext.h"
 #include "threads_kernel_objects_ext.h"
@@ -323,6 +329,57 @@ ZTEST(llext, test_find_section)
 }
 #endif
 
+#if defined(CONFIG_FILE_SYSTEM)
+#define LLEXT_FILE "hello_world.llext"
+
+FS_LITTLEFS_DECLARE_DEFAULT_CONFIG(storage);
+static struct fs_mount_t mp = {
+	.type = FS_LITTLEFS,
+	.fs_data = &storage,
+	.storage_dev = (void *)FIXED_PARTITION_ID(storage_partition),
+	.mnt_point = "/lfs",
+};
+
+ZTEST(llext, test_fs_loader)
+{
+	int res;
+	char path[UINT8_MAX];
+	struct fs_file_t fd;
+
+	/* File system should be mounted before the testcase. If not mount it now. */
+	if (!(mp.flags & FS_MOUNT_FLAG_AUTOMOUNT)) {
+		zassert_ok(fs_mount(&mp), "Filesystem should be mounted");
+	}
+
+	snprintf(path, sizeof(path), "%s/%s", mp.mnt_point, LLEXT_FILE);
+	fs_file_t_init(&fd);
+
+	zassert_ok(fs_open(&fd, path, FS_O_CREATE | FS_O_TRUNC | FS_O_WRITE),
+		   "Failed opening file");
+
+	zassert_equal(fs_write(&fd, hello_world_ext, ARRAY_SIZE(hello_world_ext)),
+		      ARRAY_SIZE(hello_world_ext),
+		      "Full content of the buffer holding ext should be written");
+
+	zassert_ok(fs_close(&fd), "Failed closing file");
+
+	struct llext_fs_loader fs_loader = LLEXT_FS_LOADER(path);
+	struct llext_loader *loader = &fs_loader.loader;
+	struct llext_load_param ldr_parm = LLEXT_LOAD_PARAM_DEFAULT;
+	struct llext *ext = NULL;
+
+	res = llext_load(loader, "hello_world", &ext, &ldr_parm);
+	zassert_ok(res, "load should succeed");
+
+	void (*test_entry_fn)() = llext_find_sym(&ext->exp_tab, "test_entry");
+
+	zassert_not_null(test_entry_fn, "test_entry should be an exported symbol");
+
+	llext_unload(&ext);
+	fs_unmount(&mp);
+}
+#endif
+
 /*
  * Ensure that EXPORT_SYMBOL does indeed provide a symbol and a valid address
  * to it.

tests/subsys/llext/simple/testcase.yaml

@@ -45,6 +45,13 @@ tests:
     extra_configs:
       - CONFIG_USERSPACE=y
       - CONFIG_LLEXT_STORAGE_WRITABLE=n
+  llext.simple.readonly_fs_loader:
+    arch_allow: arm # Xtensa needs writable storage
+    filter: not CONFIG_MPU and not CONFIG_MMU and not CONFIG_SOC_SERIES_S32ZE
+    extra_configs:
+      - arch:arm:CONFIG_ARM_MPU=n
+      - arch:arm:CONFIG_ARM_AARCH32_MMU=n
+      - CONFIG_LLEXT_STORAGE_WRITABLE=n
   llext.simple.writable:
     arch_allow: arm xtensa
     integration_platforms: