Bug 1830962: Update wasm2c to disable Wasm exception handling code from runtime r=glandium

Differential Revision: https://phabricator.services.mozilla.com/D176949

config/external/wasm2c_sandbox_compiler/moz.yaml

@@ -9,8 +9,8 @@ origin:
   description: wasm2c fork used for rlbox sandboxing
   url: https://github.com/WebAssembly/wabt
 
-  release: 805bebffde3c41fe4f1255deccc7bcb5b7e05dfa (2023-04-26T15:06:45Z).
-  revision: 805bebffde3c41fe4f1255deccc7bcb5b7e05dfa
+  release: 5abbeaab97eb802acccf866d9c8cc021c1f7e570 (2023-05-02T18:27:21Z).
+  revision: 5abbeaab97eb802acccf866d9c8cc021c1f7e570
 
   license: Apache-2.0
   license-file: LICENSE
@@ -44,3 +44,4 @@ vendoring:
     - src/tools/wast*
     - src/tools/wat*
     - src/tools/wasm2w*
+    - wasm2c/wasm-rt-exceptions*

config/rules.mk

@@ -502,7 +502,7 @@ $(WASM_ARCHIVE): $(CWASMOBJS) $(CPPWASMOBJS) $(STATIC_LIBS) $(EXTRA_DEPS) $(GLOB
 	$(WASM_CXX) -o $@ -Wl,--export-all -Wl,--stack-first -Wl,-z,stack-size=$(if $(MOZ_OPTIMIZE),262144,1048576) -Wl,--no-entry -Wl,--growable-table -Wl,--import-memory -Wl,--import-table $(CWASMOBJS) $(CPPWASMOBJS) -lwasi-emulated-process-clocks
 
 $(addsuffix .c,$(WASM_ARCHIVE)): $(WASM_ARCHIVE) $(DIST)/host/bin/wasm2c$(HOST_BIN_SUFFIX)
-	$(DIST)/host/bin/wasm2c$(HOST_BIN_SUFFIX) -o $@ $<
+	$(DIST)/host/bin/wasm2c$(HOST_BIN_SUFFIX) -o $@ --disable-simd $<
 
 ifeq ($(OS_ARCH),WINNT)
 # Import libraries are created by the rules creating shared libraries.

third_party/wasm2c/include/wabt/c-writer.h

@@ -19,6 +19,7 @@
 
 #include <functional>
 #include "wabt/common.h"
+#include "wabt/feature.h"
 #include "wabt/ir.h"
 
 namespace wabt {
@@ -28,6 +29,8 @@ class Stream;
 
 struct WriteCOptions {
   std::string_view module_name;
+  /* Set of wasm features enabled for wasm2c */
+  Features* features;
   /*
    * name_to_output_file_index takes const iterators to begin and end of a list
    * of all functions in the module, number of imported functions, and number of

third_party/wasm2c/src/c-writer.cc

@@ -297,6 +297,7 @@ class CWriter {
   static void SerializeFuncType(const FuncType&, std::string&);
 
   std::string GetGlobalName(ModuleFieldType, const std::string&) const;
+  std::string GetLocalName(const std::string&, bool is_label) const;
 
   void Indent(int size = INDENT_SIZE);
   void Dedent(int size = INDENT_SIZE);
@@ -367,6 +368,7 @@ class CWriter {
                                   const std::string&);
   void WriteCallIndirectFuncDeclaration(const FuncDeclaration&,
                                         const std::string&);
+  void WriteFeatureMacros();
   void WriteModuleInstance();
   void WriteGlobals();
   void WriteGlobal(const Global&, const std::string&);
@@ -910,6 +912,13 @@ std::string CWriter::DefineLocalScopeName(std::string_view name,
       kLocalSymbolPrefix + MangleName(StripLeadingDollar(name)));
 }
 
+std::string CWriter::GetLocalName(const std::string& name,
+                                  bool is_label) const {
+  std::string mangled = name + (is_label ? kLabelSuffix : kParamSuffix);
+  assert(local_sym_map_.count(mangled) == 1);
+  return local_sym_map_.at(mangled);
+}
+
 std::string CWriter::DefineParamName(std::string_view name) {
   return DefineLocalScopeName(name, false);
 }
@@ -1021,21 +1030,15 @@ void CWriter::Write(std::string_view s) {
 }
 
 void CWriter::Write(const ParamName& name) {
-  std::string mangled = name.name + kParamSuffix;
-  assert(local_sym_map_.count(mangled) == 1);
-  Write(local_sym_map_[mangled]);
+  Write(GetLocalName(name.name, false));
 }
 
 void CWriter::Write(const LabelName& name) {
-  std::string mangled = name.name + kLabelSuffix;
-  assert(local_sym_map_.count(mangled) == 1);
-  Write(local_sym_map_[mangled]);
+  Write(GetLocalName(name.name, true));
 }
 
 void CWriter::Write(const GlobalName& name) {
-  std::string mangled = name.name + MangleField(name.type);
-  assert(global_sym_map_.count(mangled) == 1);
-  Write(global_sym_map_.at(mangled));
+  Write(GetGlobalName(name.type, name.name));
 }
 
 void CWriter::Write(const ExternalPtr& name) {
@@ -1787,6 +1790,15 @@ void CWriter::WriteCallIndirectFuncDeclaration(const FuncDeclaration& decl,
   Write(")");
 }
 
+void CWriter::WriteFeatureMacros() {
+  if (options_.features->exceptions_enabled()) {
+    Write("#define WASM_RT_ENABLE_EXCEPTION_HANDLING", Newline(), Newline());
+  }
+  if (options_.features->simd_enabled()) {
+    Write("#define WASM_RT_ENABLE_SIMD", Newline(), Newline());
+  }
+}
+
 void CWriter::WriteModuleInstance() {
   BeginInstance();
   WriteGlobals();
@@ -5120,6 +5132,7 @@ void CWriter::WriteCHeader() {
   Write("#ifndef ", guard, Newline());
   Write("#define ", guard, Newline());
   Write(Newline());
+  WriteFeatureMacros();
   Write(s_header_top);
   Write(Newline());
   WriteModuleInstance();

third_party/wasm2c/src/prebuilt/wasm2c_header_top.cc

@@ -4,6 +4,13 @@ R"w2c_template(
 #include "wasm-rt.h"
 )w2c_template"
 R"w2c_template(
+#if defined(WASM_RT_ENABLE_EXCEPTION_HANDLING)
+)w2c_template"
+R"w2c_template(#include "wasm-rt-exceptions.h"
+)w2c_template"
+R"w2c_template(#endif
+)w2c_template"
+R"w2c_template(
 #if defined(WASM_RT_ENABLE_SIMD)
 )w2c_template"
 R"w2c_template(#include "simde/wasm/simd128.h"

third_party/wasm2c/src/tools/wasm2c.cc

@@ -60,7 +60,7 @@ examples:
 
 static const std::string supported_features[] = {
     "multi-memory", "multi-value", "sign-extension", "saturating-float-to-int",
-    "exceptions",   "memory64",    "extended-const"};
+    "exceptions",   "memory64",    "extended-const", "simd"};
 
 static bool IsFeatureSupported(const std::string& feature) {
   return std::find(std::begin(supported_features), std::end(supported_features),
@@ -100,12 +100,13 @@ static void ParseOptions(int argc, char** argv) {
                        ConvertBackslashToSlash(&s_infile);
                      });
   parser.Parse(argc, argv);
+  s_write_c_options.features = &s_features;
 
   bool any_non_supported_feature = false;
 #define WABT_FEATURE(variable, flag, default_, help)   \
   any_non_supported_feature |=                         \
       (s_features.variable##_enabled() != default_) && \
-      !IsFeatureSupported(flag);
+      s_features.variable##_enabled() && !IsFeatureSupported(flag);
 #include "wabt/feature.def"
 #undef WABT_FEATURE
 

third_party/wasm2c/src/validator.cc

@@ -820,7 +820,7 @@ Result Validator::CheckModule() {
                                                   f->elem_segment.elem_type);
 
       // Init expr.
-      if (f->elem_segment.offset.size()) {
+      if (f->elem_segment.kind == SegmentKind::Active) {
         result_ |= validator_.BeginInitExpr(field.loc, Type::I32);
         ExprVisitor visitor(this);
         result_ |= visitor.VisitExprList(
@@ -881,7 +881,7 @@ Result Validator::CheckModule() {
                                           f->data_segment.kind);
 
       // Init expr.
-      if (f->data_segment.offset.size()) {
+      if (f->data_segment.kind == SegmentKind::Active) {
         Type offset_type = Type::I32;
         Index memory_index = module->GetMemoryIndex(f->data_segment.memory_var);
         if (memory_index < module->memories.size() &&

third_party/wasm2c/wasm2c/README.md

@@ -341,8 +341,9 @@ exhaustion.
 
 ### Runtime support for exception handling
 
-Several additional symbols must be defined if wasm2c is being run with
-support for exceptions (`--enable-exceptions`):
+Several additional symbols must be defined if wasm2c is being run with support
+for exceptions (`--enable-exceptions`). These are defined in
+`wasm-rt-exceptions.h`. These symbols are:
 
 ```c
 void wasm_rt_load_exception(const char* tag, uint32_t size, const void* values);
@@ -357,7 +358,7 @@ wasm_rt_try(target)
 ```
 
 A C implementation of these functions is also available in
-[`wasm-rt-impl.h`](wasm-rt-impl.h) and [`wasm-rt-impl.c`](wasm-rt-impl.c).
+[`wasm-rt-exceptions-impl.c`](wasm-rt-exceptions-impl.c).
 
 `wasm_rt_load_exception` sets the active exception to a given tag, size, and contents.
 

third_party/wasm2c/wasm2c/wasm-rt-impl.c

@@ -36,13 +36,7 @@
 #include <sys/mman.h>
 #endif
 
-#if _MSC_VER
-#include <malloc.h>
-#define alloca _alloca
-#endif
-
 #define PAGE_SIZE 65536
-#define MAX_EXCEPTION_SIZE PAGE_SIZE
 
 #if WASM_RT_INSTALL_SIGNAL_HANDLER
 static bool g_signal_handler_installed = false;
@@ -60,12 +54,6 @@ WASM_RT_THREAD_LOCAL uint32_t wasm_rt_saved_call_stack_depth;
 
 WASM_RT_THREAD_LOCAL wasm_rt_jmp_buf g_wasm_rt_jmp_buf;
 
-static WASM_RT_THREAD_LOCAL wasm_rt_tag_t g_active_exception_tag;
-static WASM_RT_THREAD_LOCAL uint8_t g_active_exception[MAX_EXCEPTION_SIZE];
-static WASM_RT_THREAD_LOCAL uint32_t g_active_exception_size;
-
-static WASM_RT_THREAD_LOCAL wasm_rt_jmp_buf* g_unwind_target;
-
 #ifdef WASM_RT_TRAP_HANDLER
 extern void WASM_RT_TRAP_HANDLER(wasm_rt_trap_t code);
 #endif
@@ -88,45 +76,6 @@ void wasm_rt_trap(wasm_rt_trap_t code) {
 #endif
 }
 
-void wasm_rt_load_exception(const wasm_rt_tag_t tag,
-                            uint32_t size,
-                            const void* values) {
-  if (size > MAX_EXCEPTION_SIZE) {
-    wasm_rt_trap(WASM_RT_TRAP_EXHAUSTION);
-  }
-
-  g_active_exception_tag = tag;
-  g_active_exception_size = size;
-
-  if (size) {
-    memcpy(g_active_exception, values, size);
-  }
-}
-
-WASM_RT_NO_RETURN void wasm_rt_throw(void) {
-  WASM_RT_LONGJMP(*g_unwind_target, WASM_RT_TRAP_UNCAUGHT_EXCEPTION);
-}
-
-WASM_RT_UNWIND_TARGET* wasm_rt_get_unwind_target(void) {
-  return g_unwind_target;
-}
-
-void wasm_rt_set_unwind_target(WASM_RT_UNWIND_TARGET* target) {
-  g_unwind_target = target;
-}
-
-wasm_rt_tag_t wasm_rt_exception_tag(void) {
-  return g_active_exception_tag;
-}
-
-uint32_t wasm_rt_exception_size(void) {
-  return g_active_exception_size;
-}
-
-void* wasm_rt_exception(void) {
-  return g_active_exception;
-}
-
 #ifdef _WIN32
 static void* os_mmap(size_t size) {
   void* ret = VirtualAlloc(NULL, size, MEM_RESERVE, PAGE_NOACCESS);
@@ -399,7 +348,7 @@ uint64_t wasm_rt_grow_memory(wasm_rt_memory_t* memory, uint64_t delta) {
 void wasm_rt_free_memory(wasm_rt_memory_t* memory) {
 #if WASM_RT_USE_MMAP
   const uint64_t mmap_size = get_allocation_size_for_mmap(memory);
-  os_munmap(memory->data, mmap_size); // ignore error
+  os_munmap(memory->data, mmap_size);  // ignore error
 #else
   free(memory->data);
 #endif

third_party/wasm2c/wasm2c/wasm-rt-impl.h

@@ -30,19 +30,6 @@ 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_INSTALL_SIGNAL_HANDLER && !defined(_WIN32)
-#define WASM_RT_LONGJMP_UNCHECKED(buf, val) siglongjmp(buf, val)
-#else
-#define WASM_RT_LONGJMP_UNCHECKED(buf, val) longjmp(buf, val)
-#endif
-
-#define WASM_RT_LONGJMP(buf, val)                                  \
-  /* Abort on failure as this may be called in the trap handler */ \
-  if (!((buf).initialized))                                        \
-    abort();                                                       \
-  (buf).initialized = false;                                       \
-  WASM_RT_LONGJMP_UNCHECKED((buf).buffer, val)
-
 #if WASM_RT_USE_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;

third_party/wasm2c/wasm2c/wasm-rt.h

@@ -317,6 +317,38 @@ bool wasm_rt_is_initialized(void);
 /** Free the runtime's state. */
 void wasm_rt_free(void);
 
+/**
+ * A hardened jmp_buf that allows checking for initialization before use
+ */
+typedef struct {
+  /* Is the jmp buf intialized? */
+  bool initialized;
+  /* jmp_buf contents */
+  jmp_buf buffer;
+} wasm_rt_jmp_buf;
+
+#if WASM_RT_INSTALL_SIGNAL_HANDLER && !defined(_WIN32)
+#define WASM_RT_SETJMP_SETBUF(buf) sigsetjmp(buf, 1)
+#else
+#define WASM_RT_SETJMP_SETBUF(buf) setjmp(buf)
+#endif
+
+#define WASM_RT_SETJMP(buf) \
+  ((buf).initialized = true, WASM_RT_SETJMP_SETBUF((buf).buffer))
+
+#if WASM_RT_INSTALL_SIGNAL_HANDLER && !defined(_WIN32)
+#define WASM_RT_LONGJMP_UNCHECKED(buf, val) siglongjmp(buf, val)
+#else
+#define WASM_RT_LONGJMP_UNCHECKED(buf, val) longjmp(buf, val)
+#endif
+
+#define WASM_RT_LONGJMP(buf, val)                                  \
+  /* Abort on failure as this may be called in the trap handler */ \
+  if (!((buf).initialized))                                        \
+    abort();                                                       \
+  (buf).initialized = false;                                       \
+  WASM_RT_LONGJMP_UNCHECKED((buf).buffer, val)
+
 /**
  * Stop execution immediately and jump back to the call to `wasm_rt_impl_try`.
  * The result of `wasm_rt_impl_try` will be the provided trap reason.
@@ -330,72 +362,6 @@ WASM_RT_NO_RETURN void wasm_rt_trap(wasm_rt_trap_t);
  */
 const char* wasm_rt_strerror(wasm_rt_trap_t trap);
 
-/**
- * A tag is represented as an arbitrary pointer.
- */
-typedef const void* wasm_rt_tag_t;
-
-/**
- * Set the active exception to given tag, size, and contents.
- */
-void wasm_rt_load_exception(const wasm_rt_tag_t tag,
-                            uint32_t size,
-                            const void* values);
-
-/**
- * Throw the active exception.
- */
-WASM_RT_NO_RETURN void wasm_rt_throw(void);
-
-/**
- * A hardened jmp_buf that allows us to checks if it is initialized before use
- */
-typedef struct {
-  /* Is the jmp buf intialized? */
-  bool initialized;
-  /* jmp_buf contents */
-  jmp_buf buffer;
-} wasm_rt_jmp_buf;
-
-/**
- * The type of an unwind target if an exception is thrown and caught.
- */
-#define WASM_RT_UNWIND_TARGET wasm_rt_jmp_buf
-
-/**
- * Get the current unwind target if an exception is thrown.
- */
-WASM_RT_UNWIND_TARGET* wasm_rt_get_unwind_target(void);
-
-/**
- * Set the unwind target if an exception is thrown.
- */
-void wasm_rt_set_unwind_target(WASM_RT_UNWIND_TARGET* target);
-
-/**
- * Tag of the active exception.
- */
-wasm_rt_tag_t wasm_rt_exception_tag(void);
-
-/**
- * Size of the active exception.
- */
-uint32_t wasm_rt_exception_size(void);
-
-/**
- * Contents of the active exception.
- */
-void* wasm_rt_exception(void);
-
-#if WASM_RT_INSTALL_SIGNAL_HANDLER && !defined(_WIN32)
-#define WASM_RT_SETJMP_SETBUF(buf) sigsetjmp(buf, 1)
-#else
-#define WASM_RT_SETJMP_SETBUF(buf) setjmp(buf)
-#endif
-
-#define WASM_RT_SETJMP(buf) \
-  ((buf).initialized = true, WASM_RT_SETJMP_SETBUF((buf).buffer))
-
 #define wasm_rt_try(target) WASM_RT_SETJMP(target)
 
 /**