Enhance XIP and add XIP document (#863)

Auto detect whether file is XIP file before loading module in posix like and
linux-sgx platforms, and if yes, mmap executable memory automatically to
run the XIP file.
Add document about XIP feature.
Enable test spec cases with XIP feature.

Author: wenyongh

README.md

@@ -29,6 +29,7 @@ iwasm VM core
 - [Thread management and pthread library](./doc/pthread_library.md), ref to [sample](samples/multi-thread)
 - [Linux SGX (Intel Software Guard Extension) support](./doc/linux_sgx.md)
 - [Source debugging](./doc/source_debugging.md)
+- [XIP (Execution In Place) support](./doc/xip.md)
 
 ### post-MVP features
 - [Non-trapping float-to-int conversions](https://github.com/WebAssembly/nontrapping-float-to-int-conversions)

core/iwasm/aot/aot_loader.c

@@ -2190,13 +2190,16 @@ load_relocation_section(const uint8 *buf, const uint8 *buf_end,
             || !strcmp(group->section_name, ".text")
 #endif
         ) {
+#if !defined(BH_PLATFORM_LINUX) && !defined(BH_PLATFORM_LINUX_SGX) \
+    && !defined(BH_PLATFORM_DARWIN)
             if (module->native_symbol_count > 0) {
                 set_error_buf(error_buf, error_buf_size,
                               "cannot apply relocation to text section "
                               "for aot file generated with "
                               "\"--enable-indirect-mode\" flag");
                 goto fail;
             }
+#endif
             if (!do_text_relocation(module, group, error_buf, error_buf_size))
                 goto fail;
         }

core/iwasm/common/wasm_runtime_common.c

@@ -294,6 +294,64 @@ get_package_type(const uint8 *buf, uint32 size)
     return Package_Type_Unknown;
 }
 
+#if WASM_ENABLE_AOT != 0
+static uint8 *
+align_ptr(const uint8 *p, uint32 b)
+{
+    uintptr_t v = (uintptr_t)p;
+    uintptr_t m = b - 1;
+    return (uint8 *)((v + m) & ~m);
+}
+
+#define CHECK_BUF(buf, buf_end, length)                   \
+    do {                                                  \
+        if (buf + length < buf || buf + length > buf_end) \
+            return false;                                 \
+    } while (0)
+
+#define read_uint32(p, p_end, res)                 \
+    do {                                           \
+        p = (uint8 *)align_ptr(p, sizeof(uint32)); \
+        CHECK_BUF(p, p_end, sizeof(uint32));       \
+        res = *(uint32 *)p;                        \
+        p += sizeof(uint32);                       \
+    } while (0)
+
+bool
+wasm_runtime_is_xip_file(const uint8 *buf, uint32 size)
+{
+    const uint8 *p = buf, *p_end = buf + size;
+    uint32 section_type, sub_section_type, section_size;
+
+    if (get_package_type(buf, size) != Wasm_Module_AoT)
+        return false;
+
+    CHECK_BUF(p, p_end, 8);
+    p += 8;
+    while (p < p_end) {
+        read_uint32(p, p_end, section_type);
+        read_uint32(p, p_end, section_size);
+        CHECK_BUF(p, p_end, section_size);
+
+        if (section_type == AOT_SECTION_TYPE_CUSTOM) {
+            read_uint32(p, p_end, sub_section_type);
+            if (sub_section_type == AOT_CUSTOM_SECTION_NATIVE_SYMBOL) {
+                return true;
+            }
+            else {
+                p -= sizeof(uint32);
+            }
+        }
+        else if (section_type >= AOT_SECTION_TYPE_SIGANATURE) {
+            return false;
+        }
+        p += section_size;
+    }
+
+    return false;
+}
+#endif /* end of WASM_ENABLE_AOT */
+
 #if (WASM_ENABLE_THREAD_MGR != 0) && (WASM_ENABLE_DEBUG_INTERP != 0)
 uint32
 wasm_runtime_start_debug_instance(WASMExecEnv *exec_env)

core/iwasm/common/wasm_runtime_common.h

@@ -406,6 +406,10 @@ wasm_runtime_destroy(void);
 WASM_RUNTIME_API_EXTERN PackageType
 get_package_type(const uint8 *buf, uint32 size);
 
+/* See wasm_export.h for description */
+WASM_RUNTIME_API_EXTERN bool
+wasm_runtime_is_xip_file(const uint8 *buf, uint32 size);
+
 /* See wasm_export.h for description */
 WASM_RUNTIME_API_EXTERN WASMModuleCommon *
 wasm_runtime_load(const uint8 *buf, uint32 size, char *error_buf,

core/iwasm/include/wasm_export.h

@@ -235,6 +235,17 @@ wasm_runtime_free(void *ptr);
 WASM_RUNTIME_API_EXTERN package_type_t
 get_package_type(const uint8_t *buf, uint32_t size);
 
+/**
+ * Check whether a file is an AOT XIP (Execution In Place) file
+ *
+ * @param buf the package buffer
+ * @param size the package buffer size
+ *
+ * @return true if success, false otherwise
+ */
+WASM_RUNTIME_API_EXTERN bool
+wasm_runtime_is_xip_file(const uint8_t *buf, uint32_t size);
+
 /**
  * It is a callback for WAMR providing by embedding to load a module file
  * into a buffer

doc/xip.md

@@ -0,0 +1,14 @@
+# WAMR XIP (Execution In Place) feature introduction
+
+Some IoT devices may require to run the AOT file from flash or ROM which is read-only, so as to reduce the memory consumption, or resolve the issue that there is no executable memory available to run AOT code. In such case, the AOT code inside the AOT file shouldn't be duplicated into memory and shouldn't be modified (or patched) by the AOT relocations. To address this, WAMR implements the XIP (Execution In Place) feature, which generates the AOT relocations as few as possible:
+- In the AOT code, an AOT function calls other functions with indirect mode: it doesn't call other functions directly, but looks up their pointers from the function pointer table passed by its first argument exec_env, and then calls the function pointer found. By this way the relocations to other functions are eliminated.
+- Eliminate the calls to the LLVM intrinsic functions, or, replace calling them with calling runtime self implemented functions instead, e.g. the calling to `llvm.experimental.constrained.fadd.f32` is replaced by the calling to `aot_intrinsic_fadd_f32`.
+
+The XIP file is an AOT file without (or with few) relocations to patch the AOT code (or text section). Developer can use the option `--enable-indirect-mode --disable-llvm-intrinsics` for wamrc to generate the AOT file, e.g.:
+```bash
+wamrc --enable-indirect-mode --disable-llvm-intrinsics -o <aot_file> <wasm_file>
+```
+
+## Known issues
+
+There may be some relocations to the ".rodata" like sections which require to patch the AOT code. More work will be done to resolve it in the future.

product-mini/platforms/linux-sgx/enclave-sample/Enclave/Enclave.cpp

@@ -52,6 +52,8 @@ typedef struct EnclaveModule {
     uint32 wasi_env_list_size;
     char **wasi_argv;
     uint32 wasi_argc;
+    bool is_xip_file;
+    uint32 total_size_mapped;
 } EnclaveModule;
 
 #if WASM_ENABLE_SPEC_TEST == 0
@@ -127,28 +129,57 @@ handle_cmd_load_module(uint64 *args, uint32 argc)
     uint32 error_buf_size = *(uint32 *)args++;
     uint64 total_size = sizeof(EnclaveModule) + (uint64)wasm_file_size;
     EnclaveModule *enclave_module;
+    bool is_xip_file = false;
 
     bh_assert(argc == 4);
 
-    if (total_size >= UINT32_MAX
-        || !(enclave_module =
-                 (EnclaveModule *)wasm_runtime_malloc((uint32)total_size))) {
-        set_error_buf(error_buf, error_buf_size,
-                      "WASM module load failed: "
-                      "allocate memory failed.");
-        *(void **)args_org = NULL;
-        return;
+#if WASM_ENABLE_AOT != 0
+    is_xip_file = wasm_runtime_is_xip_file((uint8 *)wasm_file, wasm_file_size);
+#endif
+
+    if (!is_xip_file) {
+        if (total_size >= UINT32_MAX
+            || !(enclave_module = (EnclaveModule *)wasm_runtime_malloc(
+                     (uint32)total_size))) {
+            set_error_buf(error_buf, error_buf_size,
+                          "WASM module load failed: "
+                          "allocate memory failed.");
+            *(void **)args_org = NULL;
+            return;
+        }
+        memset(enclave_module, 0, (uint32)total_size);
+    }
+    else {
+        int map_prot = MMAP_PROT_READ | MMAP_PROT_WRITE | MMAP_PROT_EXEC;
+        int map_flags = MMAP_MAP_NONE;
+
+        if (total_size >= UINT32_MAX
+            || !(enclave_module = (EnclaveModule *)os_mmap(
+                     NULL, (uint32)total_size, map_prot, map_flags))) {
+            set_error_buf(error_buf, error_buf_size,
+                          "WASM module load failed: mmap memory failed.");
+            *(void **)args_org = NULL;
+            return;
+        }
+        memset(enclave_module, 0, (uint32)total_size);
+        enclave_module->is_xip_file = true;
+        enclave_module->total_size_mapped = (uint32)total_size;
     }
 
-    memset(enclave_module, 0, (uint32)total_size);
     enclave_module->wasm_file = (uint8 *)enclave_module + sizeof(EnclaveModule);
     bh_memcpy_s(enclave_module->wasm_file, wasm_file_size, wasm_file,
                 wasm_file_size);
+    if (is_xip_file) {
+        enclave_module->is_xip_file = true;
+    }
 
     if (!(enclave_module->module =
               wasm_runtime_load(enclave_module->wasm_file, wasm_file_size,
                                 error_buf, error_buf_size))) {
-        wasm_runtime_free(enclave_module);
+        if (!is_xip_file)
+            wasm_runtime_free(enclave_module);
+        else
+            os_munmap(enclave_module, (uint32)total_size);
         *(void **)args_org = NULL;
         return;
     }
@@ -170,7 +201,10 @@ handle_cmd_unload_module(uint64 *args, uint32 argc)
         wasm_runtime_free(enclave_module->wasi_arg_buf);
 
     wasm_runtime_unload(enclave_module->module);
-    wasm_runtime_free(enclave_module);
+    if (!enclave_module->is_xip_file)
+        wasm_runtime_free(enclave_module);
+    else
+        os_munmap(enclave_module, enclave_module->total_size_mapped);
 
     LOG_VERBOSE("Unload module success.\n");
 }

product-mini/platforms/posix/main.c

@@ -34,8 +34,6 @@ print_help()
     printf("  --heap-size=n          Set maximum heap size in bytes, default is 16 KB\n");
     printf("  --repl                 Start a very simple REPL (read-eval-print-loop) mode\n"
            "                         that runs commands in the form of \"FUNC ARG...\"\n");
-    printf("  --xip                  Enable XIP (Execution In Place) mode to run AOT file\n"
-           "                         generated with \"--enable-indirect-mode\" flag\n");
 #if WASM_ENABLE_LIBC_WASI != 0
     printf("  --env=<env>            Pass wasi environment variables with \"key=value\"\n");
     printf("                         to the program, for example:\n");
@@ -240,7 +238,7 @@ main(int argc, char *argv[])
     int log_verbose_level = 2;
 #endif
     bool is_repl_mode = false;
-    bool is_xip_mode = false;
+    bool is_xip_file = false;
 #if WASM_ENABLE_LIBC_WASI != 0
     const char *dir_list[8] = { NULL };
     uint32 dir_list_size = 0;
@@ -273,9 +271,6 @@ main(int argc, char *argv[])
         else if (!strcmp(argv[0], "--repl")) {
             is_repl_mode = true;
         }
-        else if (!strcmp(argv[0], "--xip")) {
-            is_xip_mode = true;
-        }
         else if (!strncmp(argv[0], "--stack-size=", 13)) {
             if (argv[0][13] == '\0')
                 return print_help();
@@ -392,10 +387,11 @@ main(int argc, char *argv[])
               (uint8 *)bh_read_file_to_buffer(wasm_file, &wasm_file_size)))
         goto fail1;
 
-    if (is_xip_mode) {
+#if WASM_ENABLE_AOT != 0
+    if (wasm_runtime_is_xip_file(wasm_file_buf, wasm_file_size)) {
         uint8 *wasm_file_mapped;
         int map_prot = MMAP_PROT_READ | MMAP_PROT_WRITE | MMAP_PROT_EXEC;
-        int map_flags = MMAP_MAP_NONE;
+        int map_flags = MMAP_MAP_32BIT;
 
         if (!(wasm_file_mapped =
                   os_mmap(NULL, (uint32)wasm_file_size, map_prot, map_flags))) {
@@ -408,7 +404,9 @@ main(int argc, char *argv[])
                     wasm_file_size);
         wasm_runtime_free(wasm_file_buf);
         wasm_file_buf = wasm_file_mapped;
+        is_xip_file = true;
     }
+#endif
 
 #if WASM_ENABLE_MULTI_MODULE != 0
     wasm_runtime_set_module_reader(module_reader_callback, moudle_destroyer);
@@ -450,7 +448,7 @@ main(int argc, char *argv[])
 
 fail2:
     /* free the file buffer */
-    if (!is_xip_mode)
+    if (!is_xip_file)
         wasm_runtime_free(wasm_file_buf);
     else
         os_munmap(wasm_file_buf, wasm_file_size);

tests/wamr-test-suites/spec-test-script/all.py

@@ -51,6 +51,7 @@ def ignore_the_case(
     multi_module_flag=False,
     multi_thread_flag=False,
     simd_flag=False,
+    xip_flag=False,
 ):
     if case_name in ["comments", "inline-module", "names"]:
         return True
@@ -100,6 +101,7 @@ def test_case(
     multi_module_flag=False,
     multi_thread_flag=False,
     simd_flag=False,
+    xip_flag=False,
     clean_up_flag=True,
     verbose_flag=True,
 ):
@@ -114,6 +116,7 @@ def test_case(
         multi_module_flag,
         multi_thread_flag,
         simd_flag,
+        xip_flag,
     ):
         return True
 
@@ -139,6 +142,9 @@ def test_case(
     if simd_flag:
         CMD.append("--simd")
 
+    if xip_flag:
+        CMD.append("--xip")
+
     if not clean_up_flag:
         CMD.append("--no_cleanup")
 
@@ -195,6 +201,7 @@ def test_suite(
     multi_module_flag=False,
     multi_thread_flag=False,
     simd_flag=False,
+    xip_flag=False,
     clean_up_flag=True,
     verbose_flag=True,
 ):
@@ -217,6 +224,7 @@ def test_suite(
                 multi_module_flag,
                 multi_thread_flag,
                 simd_flag,
+                xip_flag,
                 clean_up_flag,
                 verbose_flag,
             )
@@ -239,6 +247,7 @@ def test_suite_parallelly(
     multi_module_flag=False,
     multi_thread_flag=False,
     simd_flag=False,
+    xip_flag=False,
     clean_up_flag=False,
     verbose_flag=False,
 ):
@@ -266,6 +275,7 @@ def test_suite_parallelly(
                     multi_module_flag,
                     multi_thread_flag,
                     simd_flag,
+                    xip_flag,
                     clean_up_flag,
                     verbose_flag,
                 ],
@@ -323,6 +333,13 @@ def main():
         dest="simd_flag",
         help="Running with the SIMD feature",
     )
+    parser.add_argument(
+        "-X",
+        action="store_true",
+        default=False,
+        dest="xip_flag",
+        help="Running with the XIP feature",
+    )
     parser.add_argument(
         "-t",
         action="store_true",
@@ -387,6 +404,7 @@ def main():
                 options.multi_module_flag,
                 options.multi_thread_flag,
                 options.simd_flag,
+                options.xip_flag,
                 options.clean_up_flag,
                 options.verbose_flag,
             )
@@ -403,6 +421,7 @@ def main():
                 options.multi_module_flag,
                 options.multi_thread_flag,
                 options.simd_flag,
+                options.xip_flag,
                 options.clean_up_flag,
                 options.verbose_flag,
             )
@@ -419,6 +438,7 @@ def main():
                     options.multi_module_flag,
                     options.multi_thread_flag,
                     options.simd_flag,
+                    options.xip_flag,
                     options.clean_up_flag,
                     options.verbose_flag,
                 )