wasm2c: Cleanup/separate code for heap and stack signal handlers

.github/workflows/build.yml

@@ -172,7 +172,7 @@ jobs:
     runs-on: ubuntu-latest
     env:
       USE_NINJA: "1"
-      WASM2C_CFLAGS: "-DWASM_RT_USE_MMAP=1 -DWASM_RT_SKIP_SIGNAL_RECOVERY=1 -DWASM_RT_USE_STACK_DEPTH_COUNT=0 -DWASM2C_TEST_EMBEDDER_SIGNAL_HANDLING"
+      WASM2C_CFLAGS: "-DWASM_RT_USE_MMAP=1 -DWASM_RT_SKIP_SIGNAL_RECOVERY=1 -DWASM2C_TEST_EMBEDDER_SIGNAL_HANDLING"
     steps:
     - uses: actions/setup-python@v1
       with:
@@ -182,4 +182,5 @@ jobs:
         submodules: true
     - run: sudo apt-get install ninja-build
     - run: make clang-debug
-    - run: ./test/run-tests.py --exclude-dir memory64
+    - name: tests (excluding memory64)
+      run: ./test/run-tests.py --exclude-dir memory64

src/prebuilt/wasm2c_source_declarations.cc

@@ -43,7 +43,7 @@ R"w2c_template(
 #define TRAP(x) (wasm_rt_trap(WASM_RT_TRAP_##x), 0)
 )w2c_template"
 R"w2c_template(
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 )w2c_template"
 R"w2c_template(#define FUNC_PROLOGUE                                            \
 )w2c_template"

src/template/wasm2c.declarations.c

@@ -22,7 +22,7 @@
 
 #define TRAP(x) (wasm_rt_trap(WASM_RT_TRAP_##x), 0)
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 #define FUNC_PROLOGUE                                            \
   if (++wasm_rt_call_stack_depth > WASM_RT_MAX_CALL_STACK_DEPTH) \
     TRAP(EXHAUSTION);

test/wasm2c/add.txt

@@ -89,7 +89,7 @@ u32 w2c_test_add(w2c_test*, u32, u32);
 
 #define TRAP(x) (wasm_rt_trap(WASM_RT_TRAP_##x), 0)
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 #define FUNC_PROLOGUE                                            \
   if (++wasm_rt_call_stack_depth > WASM_RT_MAX_CALL_STACK_DEPTH) \
     TRAP(EXHAUSTION);

test/wasm2c/check-imports.txt

@@ -112,7 +112,7 @@ extern const u8 wasm2c_test_is64_env_0x5F_linear_memory;
 
 #define TRAP(x) (wasm_rt_trap(WASM_RT_TRAP_##x), 0)
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 #define FUNC_PROLOGUE                                            \
   if (++wasm_rt_call_stack_depth > WASM_RT_MAX_CALL_STACK_DEPTH) \
     TRAP(EXHAUSTION);

test/wasm2c/export-names.txt

@@ -112,7 +112,7 @@ void w2c_test_0xE20x9D0xA40xEF0xB80x8F(w2c_test*);
 
 #define TRAP(x) (wasm_rt_trap(WASM_RT_TRAP_##x), 0)
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 #define FUNC_PROLOGUE                                            \
   if (++wasm_rt_call_stack_depth > WASM_RT_MAX_CALL_STACK_DEPTH) \
     TRAP(EXHAUSTION);

test/wasm2c/hello.txt

@@ -120,7 +120,7 @@ void w2c_test_0x5Fstart(w2c_test*);
 
 #define TRAP(x) (wasm_rt_trap(WASM_RT_TRAP_##x), 0)
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 #define FUNC_PROLOGUE                                            \
   if (++wasm_rt_call_stack_depth > WASM_RT_MAX_CALL_STACK_DEPTH) \
     TRAP(EXHAUSTION);

test/wasm2c/minimal.txt

@@ -83,7 +83,7 @@ wasm_rt_func_type_t wasm2c_test_get_func_type(uint32_t param_count, uint32_t res
 
 #define TRAP(x) (wasm_rt_trap(WASM_RT_TRAP_##x), 0)
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 #define FUNC_PROLOGUE                                            \
   if (++wasm_rt_call_stack_depth > WASM_RT_MAX_CALL_STACK_DEPTH) \
     TRAP(EXHAUSTION);

test/wasm2c/tail-calls.txt

@@ -113,7 +113,7 @@ void wasm_tailcall_w2c_test_tailcaller(void **instance_ptr, void *tail_call_stac
 
 #define TRAP(x) (wasm_rt_trap(WASM_RT_TRAP_##x), 0)
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 #define FUNC_PROLOGUE                                            \
   if (++wasm_rt_call_stack_depth > WASM_RT_MAX_CALL_STACK_DEPTH) \
     TRAP(EXHAUSTION);

wasm2c/examples/fac/fac.c

@@ -20,7 +20,7 @@
 
 #define TRAP(x) (wasm_rt_trap(WASM_RT_TRAP_##x), 0)
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 #define FUNC_PROLOGUE                                            \
   if (++wasm_rt_call_stack_depth > WASM_RT_MAX_CALL_STACK_DEPTH) \
     TRAP(EXHAUSTION);

wasm2c/wasm-rt-impl.c

@@ -25,8 +25,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#if (WASM_RT_INSTALL_SIGNAL_HANDLER || !WASM_RT_USE_STACK_DEPTH_COUNT) && \
-    !defined(_WIN32)
+#if WASM_RT_INSTALL_SIGNAL_HANDLER && !defined(_WIN32)
 #include <signal.h>
 #include <unistd.h>
 #endif
@@ -39,17 +38,23 @@
 
 #define PAGE_SIZE 65536
 
+#ifndef NDEBUG
+#define DEBUG_PRINTF(...) fprintf(stderr, __VA_ARGS__);
+#else
+#define DEBUG_PRINTF(...)
+#endif
+
 #if WASM_RT_INSTALL_SIGNAL_HANDLER
 static bool g_signal_handler_installed = false;
 #ifdef _WIN32
 static void* g_sig_handler_handle = 0;
 #endif
 #endif
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 WASM_RT_THREAD_LOCAL uint32_t wasm_rt_call_stack_depth;
 WASM_RT_THREAD_LOCAL uint32_t wasm_rt_saved_call_stack_depth;
-#elif WASM_RT_INSTALL_SIGNAL_HANDLER
+#elif WASM_RT_STACK_EXHAUSTION_HANDLER
 static WASM_RT_THREAD_LOCAL void* g_alt_stack = NULL;
 #endif
 
@@ -65,7 +70,7 @@ extern void WASM_RT_GROW_FAILED_HANDLER();
 
 void wasm_rt_trap(wasm_rt_trap_t code) {
   assert(code != WASM_RT_TRAP_NONE);
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
   wasm_rt_call_stack_depth = wasm_rt_saved_call_stack_depth;
 #endif
 
@@ -164,7 +169,45 @@ static void os_print_last_error(const char* msg) {
   perror(msg);
 }
 
-#if !WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_INSTALL_SIGNAL_HANDLER
+static void os_signal_handler(int sig, siginfo_t* si, void* unused) {
+  if (si->si_code == SEGV_ACCERR) {
+    wasm_rt_trap(WASM_RT_TRAP_OOB);
+  } else {
+    wasm_rt_trap(WASM_RT_TRAP_EXHAUSTION);
+  }
+}
+
+static void os_install_signal_handler(void) {
+  struct sigaction sa;
+  memset(&sa, '\0', sizeof(sa));
+  sa.sa_flags = SA_SIGINFO;
+#if WASM_RT_STACK_EXHAUSTION_HANDLER
+  sa.sa_flags |= SA_ONSTACK;
+#endif
+  sigemptyset(&sa.sa_mask);
+  sa.sa_sigaction = os_signal_handler;
+
+  /* Install SIGSEGV and SIGBUS handlers, since macOS seems to use SIGBUS. */
+  if (sigaction(SIGSEGV, &sa, NULL) != 0 || sigaction(SIGBUS, &sa, NULL) != 0) {
+    perror("sigaction failed");
+    abort();
+  }
+}
+
+static void os_cleanup_signal_handler(void) {
+  /* Undo what was done in os_install_signal_handler */
+  struct sigaction sa;
+  memset(&sa, '\0', sizeof(sa));
+  sa.sa_handler = SIG_DFL;
+  if (sigaction(SIGSEGV, &sa, NULL) != 0 || sigaction(SIGBUS, &sa, NULL)) {
+    perror("sigaction failed");
+    abort();
+  }
+}
+#endif
+
+#if WASM_RT_STACK_EXHAUSTION_HANDLER
 static bool os_has_altstack_installed() {
   /* check for altstack already in place */
   stack_t ss;
@@ -175,18 +218,7 @@ static bool os_has_altstack_installed() {
 
   return !(ss.ss_flags & SS_DISABLE);
 }
-#endif
-
-#if WASM_RT_INSTALL_SIGNAL_HANDLER
-static void os_signal_handler(int sig, siginfo_t* si, void* unused) {
-  if (si->si_code == SEGV_ACCERR) {
-    wasm_rt_trap(WASM_RT_TRAP_OOB);
-  } else {
-    wasm_rt_trap(WASM_RT_TRAP_EXHAUSTION);
-  }
-}
 
-#if !WASM_RT_USE_STACK_DEPTH_COUNT
 /* These routines set up an altstack to handle SIGSEGV from stack overflow. */
 static void os_allocate_and_install_altstack(void) {
   /* verify altstack not already allocated */
@@ -229,10 +261,8 @@ static void os_disable_and_deallocate_altstack(void) {
 
   if ((!g_alt_stack) || (ss.ss_flags & SS_DISABLE) ||
       (ss.ss_sp != g_alt_stack) || (ss.ss_size != SIGSTKSZ)) {
-#ifndef NDEBUG
-    fprintf(stderr,
-            "wasm-rt warning: alternate stack was modified unexpectedly\n");
-#endif
+    DEBUG_PRINTF(
+        "wasm-rt warning: alternate stack was modified unexpectedly\n");
     return;
   }
 
@@ -247,35 +277,6 @@ static void os_disable_and_deallocate_altstack(void) {
 }
 #endif
 
-static void os_install_signal_handler(void) {
-  struct sigaction sa;
-  memset(&sa, '\0', sizeof(sa));
-  sa.sa_flags = SA_SIGINFO;
-#if !WASM_RT_USE_STACK_DEPTH_COUNT
-  sa.sa_flags |= SA_ONSTACK;
-#endif
-  sigemptyset(&sa.sa_mask);
-  sa.sa_sigaction = os_signal_handler;
-
-  /* Install SIGSEGV and SIGBUS handlers, since macOS seems to use SIGBUS. */
-  if (sigaction(SIGSEGV, &sa, NULL) != 0 || sigaction(SIGBUS, &sa, NULL) != 0) {
-    perror("sigaction failed");
-    abort();
-  }
-}
-
-static void os_cleanup_signal_handler(void) {
-  /* Undo what was done in os_install_signal_handler */
-  struct sigaction sa;
-  memset(&sa, '\0', sizeof(sa));
-  sa.sa_handler = SIG_DFL;
-  if (sigaction(SIGSEGV, &sa, NULL) != 0 || sigaction(SIGBUS, &sa, NULL)) {
-    perror("sigaction failed");
-    abort();
-  }
-}
-#endif
-
 #endif
 
 void wasm_rt_init(void) {
@@ -290,7 +291,7 @@ void wasm_rt_init(void) {
 }
 
 bool wasm_rt_is_initialized(void) {
-#if !WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_EXHAUSTION_HANDLER
   if (!os_has_altstack_installed()) {
     return false;
   }
@@ -312,13 +313,13 @@ void wasm_rt_free(void) {
 }
 
 void wasm_rt_init_thread(void) {
-#if WASM_RT_INSTALL_SIGNAL_HANDLER && !WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_EXHAUSTION_HANDLER
   os_allocate_and_install_altstack();
 #endif
 }
 
 void wasm_rt_free_thread(void) {
-#if WASM_RT_INSTALL_SIGNAL_HANDLER && !WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_EXHAUSTION_HANDLER
   os_disable_and_deallocate_altstack();
 #endif
 }

wasm2c/wasm-rt-impl.h

@@ -30,7 +30,7 @@ extern "C" {
 /** A setjmp buffer used for handling traps. */
 extern WASM_RT_THREAD_LOCAL wasm_rt_jmp_buf g_wasm_rt_jmp_buf;
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 /** Saved call stack depth that will be restored in case a trap occurs. */
 extern WASM_RT_THREAD_LOCAL uint32_t wasm_rt_saved_call_stack_depth;
 #define WASM_RT_SAVE_STACK_DEPTH() \

wasm2c/wasm-rt.h

@@ -166,17 +166,42 @@ extern "C" {
 #define WASM_RT_INSTALL_SIGNAL_HANDLER 0
 #endif
 
-#ifndef WASM_RT_USE_STACK_DEPTH_COUNT
-/* The signal handler on POSIX can detect call stack overflows. On windows, or
- * platforms without a signal handler, we use stack depth counting. */
+/* We need to detect and trap stack overflows. If we use a signal handler on
+ * POSIX systems, this can detect call stack overflows. On windows, or platforms
+ * without a signal handler, we use stack depth counting. */
+#if !defined(WASM_RT_STACK_DEPTH_COUNT) && \
+    !defined(WASM_RT_STACK_EXHAUSTION_HANDLER)
+
 #if WASM_RT_INSTALL_SIGNAL_HANDLER && !defined(_WIN32)
-#define WASM_RT_USE_STACK_DEPTH_COUNT 0
+#define WASM_RT_STACK_EXHAUSTION_HANDLER 1
 #else
-#define WASM_RT_USE_STACK_DEPTH_COUNT 1
+#define WASM_RT_STACK_DEPTH_COUNT 1
+#endif
+
+#endif
+
+// Ensure the stack macros are defined
+#ifndef WASM_RT_STACK_DEPTH_COUNT
+#define WASM_RT_STACK_DEPTH_COUNT 0
+#endif
+#ifndef WASM_RT_STACK_EXHAUSTION_HANDLER
+#define WASM_RT_STACK_EXHAUSTION_HANDLER 0
 #endif
+
+#if (WASM_RT_STACK_EXHAUSTION_HANDLER + WASM_RT_STACK_DEPTH_COUNT) > 1
+#error \
+    "Cannot specify multiple options from WASM_RT_STACK_EXHAUSTION_HANDLER , WASM_RT_STACK_DEPTH_COUNT"
+#elif (WASM_RT_STACK_EXHAUSTION_HANDLER + WASM_RT_STACK_DEPTH_COUNT) == 0
+#error \
+    "Must specify one of WASM_RT_STACK_EXHAUSTION_HANDLER , WASM_RT_STACK_DEPTH_COUNT"
+#endif
+
+#if WASM_RT_STACK_EXHAUSTION_HANDLER && !WASM_RT_INSTALL_SIGNAL_HANDLER
+#error \
+    "WASM_RT_STACK_EXHAUSTION_HANDLER  can only be used if WASM_RT_INSTALL_SIGNAL_HANDLER is enabled"
 #endif
 
-#if WASM_RT_USE_STACK_DEPTH_COUNT
+#if WASM_RT_STACK_DEPTH_COUNT
 /**
  * When the signal handler cannot be used to detect stack overflows, stack depth
  * is limited explicitly. The maximum stack depth before trapping can be
@@ -202,7 +227,7 @@ extern WASM_RT_THREAD_LOCAL uint32_t wasm_rt_call_stack_depth;
 #define WASM_RT_NO_RETURN __attribute__((noreturn))
 #endif
 
-#if defined(__APPLE__) && !WASM_RT_USE_STACK_DEPTH_COUNT
+#if defined(__APPLE__) && WASM_RT_STACK_EXHAUSTION_HANDLER
 #define WASM_RT_MERGED_OOB_AND_EXHAUSTION_TRAPS 1
 #else
 #define WASM_RT_MERGED_OOB_AND_EXHAUSTION_TRAPS 0
@@ -279,7 +304,8 @@ typedef struct {
 } wasm_rt_funcref_t;
 
 /** Default (null) value of a funcref */
-#define wasm_rt_funcref_null_value ((wasm_rt_funcref_t){NULL, NULL, {NULL}, NULL})
+#define wasm_rt_funcref_null_value \
+  ((wasm_rt_funcref_t){NULL, NULL, {NULL}, NULL})
 
 /** The type of an external reference (opaque to WebAssembly). */
 typedef void* wasm_rt_externref_t;
@@ -354,8 +380,7 @@ typedef struct {
   jmp_buf buffer;
 } wasm_rt_jmp_buf;
 
-#if (WASM_RT_INSTALL_SIGNAL_HANDLER || (!WASM_RT_USE_STACK_DEPTH_COUNT)) && \
-    !defined(_WIN32)
+#ifndef _WIN32
 #define WASM_RT_SETJMP_SETBUF(buf) sigsetjmp(buf, 1)
 #else
 #define WASM_RT_SETJMP_SETBUF(buf) setjmp(buf)
@@ -364,8 +389,7 @@ typedef struct {
 #define WASM_RT_SETJMP(buf) \
   ((buf).initialized = true, WASM_RT_SETJMP_SETBUF((buf).buffer))
 
-#if (WASM_RT_INSTALL_SIGNAL_HANDLER || (!WASM_RT_USE_STACK_DEPTH_COUNT)) && \
-    !defined(_WIN32)
+#ifndef _WIN32
 #define WASM_RT_LONGJMP_UNCHECKED(buf, val) siglongjmp(buf, val)
 #else
 #define WASM_RT_LONGJMP_UNCHECKED(buf, val) longjmp(buf, val)