Merge pull request #2305 from wasmerio/improve-traps

Improve traps

Cargo.toml

@@ -148,6 +148,9 @@ test-jit = [
 # that raise signals because that interferes with tarpaulin.
 coverage = []
 
+[profile.dev]
+split-debuginfo = "unpacked"
+
 [[bench]]
 name = "static_and_dynamic_functions"
 harness = false

lib/api/src/externals/function.rs

@@ -480,6 +480,7 @@ impl Function {
         // Call the trampoline.
         if let Err(error) = unsafe {
             wasmer_call_trampoline(
+                &self.store,
                 self.exported.vm_function.vmctx,
                 trampoline,
                 self.exported.vm_function.address,

lib/api/src/module.rs

@@ -275,7 +275,8 @@ impl Module {
             // of this steps traps, we still need to keep the instance alive
             // as some of the Instance elements may have placed in other
             // instance tables.
-            self.artifact.finish_instantiation(&instance_handle)?;
+            self.artifact
+                .finish_instantiation(&self.store, &instance_handle)?;
 
             Ok(instance_handle)
         }

lib/api/src/native.rs

@@ -131,6 +131,7 @@ macro_rules! impl_native_traits {
                     };
                     unsafe {
                         wasmer_vm::wasmer_call_trampoline(
+                            &self.store,
                             self.vmctx(),
                             trampoline,
                             self.address(),
@@ -145,8 +146,8 @@ macro_rules! impl_native_traits {
                             // TODO: we can probably remove this copy by doing some clever `transmute`s.
                             // we know it's not overlapping because `using_rets_array` is false
                             std::ptr::copy_nonoverlapping(src_pointer,
-                                                            rets_list,
-                                                            num_rets);
+                                                          rets_list,
+                                                          num_rets);
                         }
                     }
                     Ok(Rets::from_array(rets_list_array))

lib/api/src/store.rs

@@ -1,10 +1,12 @@
 use crate::tunables::BaseTunables;
 use loupe::MemoryUsage;
+use std::any::Any;
 use std::fmt;
-use std::sync::Arc;
+use std::sync::{Arc, RwLock};
 #[cfg(all(feature = "compiler", feature = "engine"))]
 use wasmer_compiler::CompilerConfig;
-use wasmer_engine::{Engine, Tunables};
+use wasmer_engine::{is_wasm_pc, Engine, Tunables};
+use wasmer_vm::{init_traps, TrapHandler, TrapHandlerFn};
 
 /// The store represents all global state that can be manipulated by
 /// WebAssembly programs. It consists of the runtime representation
@@ -20,6 +22,8 @@ use wasmer_engine::{Engine, Tunables};
 pub struct Store {
     engine: Arc<dyn Engine + Send + Sync>,
     tunables: Arc<dyn Tunables + Send + Sync>,
+    #[loupe(skip)]
+    trap_handler: Arc<RwLock<Option<Box<TrapHandlerFn>>>>,
 }
 
 impl Store {
@@ -28,20 +32,28 @@ impl Store {
     where
         E: Engine + ?Sized,
     {
-        Self {
-            engine: engine.cloned(),
-            tunables: Arc::new(BaseTunables::for_target(engine.target())),
-        }
+        Self::new_with_tunables(engine, BaseTunables::for_target(engine.target()))
+    }
+
+    /// Set the trap handler in this store.
+    pub fn set_trap_handler(&self, handler: Option<Box<TrapHandlerFn>>) {
+        let mut m = self.trap_handler.write().unwrap();
+        *m = handler;
     }
 
     /// Creates a new `Store` with a specific [`Engine`] and [`Tunables`].
     pub fn new_with_tunables<E>(engine: &E, tunables: impl Tunables + Send + Sync + 'static) -> Self
     where
         E: Engine + ?Sized,
     {
+        // Make sure the signal handlers are installed.
+        // This is required for handling traps.
+        init_traps(is_wasm_pc);
+
         Self {
             engine: engine.cloned(),
             tunables: Arc::new(tunables),
+            trap_handler: Arc::new(RwLock::new(None)),
         }
     }
 
@@ -69,6 +81,26 @@ impl PartialEq for Store {
     }
 }
 
+unsafe impl TrapHandler for Store {
+    #[inline]
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn custom_trap_handler(&self, call: &dyn Fn(&TrapHandlerFn) -> bool) -> bool {
+        if let Some(handler) = *&self.trap_handler.read().unwrap().as_ref() {
+            call(handler)
+        } else {
+            false
+        }
+    }
+}
+
+// This is required to be able to set the trap_handler in the
+// Store.
+unsafe impl Send for Store {}
+unsafe impl Sync for Store {}
+
 // We only implement default if we have assigned a default compiler and engine
 #[cfg(all(feature = "default-compiler", feature = "default-engine"))]
 impl Default for Store {
@@ -109,10 +141,7 @@ impl Default for Store {
         let config = get_config();
         let engine = get_engine(config);
         let tunables = BaseTunables::for_target(engine.target());
-        Store {
-            engine: Arc::new(engine),
-            tunables: Arc::new(tunables),
-        }
+        Self::new_with_tunables(&engine, tunables)
     }
 }
 

lib/compiler-cranelift/src/sink.rs

@@ -124,8 +124,9 @@ fn translate_ir_trapcode(trap: ir::TrapCode) -> TrapCode {
         ir::TrapCode::IntegerDivisionByZero => TrapCode::IntegerDivisionByZero,
         ir::TrapCode::BadConversionToInteger => TrapCode::BadConversionToInteger,
         ir::TrapCode::UnreachableCodeReached => TrapCode::UnreachableCodeReached,
-        ir::TrapCode::Interrupt => TrapCode::Interrupt,
+        ir::TrapCode::Interrupt => unimplemented!("Interrupts not supported"),
         ir::TrapCode::User(_user_code) => unimplemented!("User trap code not supported"),
+        // ir::TrapCode::Interrupt => TrapCode::Interrupt,
         // ir::TrapCode::User(user_code) => TrapCode::User(user_code),
     }
 }

lib/engine/src/artifact.rs

@@ -14,7 +14,7 @@ use wasmer_types::{
 };
 use wasmer_vm::{
     FuncDataRegistry, FunctionBodyPtr, InstanceAllocator, InstanceHandle, MemoryStyle, ModuleInfo,
-    TableStyle, VMSharedSignatureIndex, VMTrampoline,
+    TableStyle, TrapHandler, VMSharedSignatureIndex, VMTrampoline,
 };
 
 /// An `Artifact` is the product that the `Engine`
@@ -161,6 +161,7 @@ pub trait Artifact: Send + Sync + Upcastable + MemoryUsage {
     /// See [`InstanceHandle::finish_instantiation`].
     unsafe fn finish_instantiation(
         &self,
+        trap_handler: &dyn TrapHandler,
         handle: &InstanceHandle,
     ) -> Result<(), InstantiationError> {
         let data_initializers = self
@@ -172,7 +173,7 @@ pub trait Artifact: Send + Sync + Upcastable + MemoryUsage {
             })
             .collect::<Vec<_>>();
         handle
-            .finish_instantiation(&data_initializers)
+            .finish_instantiation(trap_handler, &data_initializers)
             .map_err(|trap| InstantiationError::Start(RuntimeError::from_trap(trap)))
     }
 }

lib/engine/src/trap/error.rs

@@ -16,6 +16,7 @@ pub struct RuntimeError {
 #[derive(Debug)]
 enum RuntimeErrorSource {
     Generic(String),
+    OOM,
     User(Box<dyn Error + Send + Sync>),
     Trap(TrapCode),
 }
@@ -25,6 +26,7 @@ impl fmt::Display for RuntimeErrorSource {
         match self {
             Self::Generic(s) => write!(f, "{}", s),
             Self::User(s) => write!(f, "{}", s),
+            Self::OOM => write!(f, "Wasmer VM out of memory"),
             Self::Trap(s) => write!(f, "{}", s.message()),
         }
     }
@@ -66,6 +68,7 @@ impl RuntimeError {
     pub fn from_trap(trap: Trap) -> Self {
         let info = FRAME_INFO.read().unwrap();
         match trap {
+            // A user error
             Trap::User(error) => {
                 match error.downcast::<Self>() {
                     // The error is already a RuntimeError, we return it directly
@@ -78,6 +81,10 @@ impl RuntimeError {
                     ),
                 }
             }
+            // A trap caused by the VM being Out of Memory
+            Trap::OOM { backtrace } => {
+                Self::new_with_trace(&info, None, RuntimeErrorSource::OOM, backtrace)
+            }
             // A trap caused by an error on the generated machine code for a Wasm function
             Trap::Wasm {
                 pc,
@@ -92,7 +99,7 @@ impl RuntimeError {
                 Self::new_with_trace(&info, Some(pc), RuntimeErrorSource::Trap(code), backtrace)
             }
             // A trap triggered manually from the Wasmer runtime
-            Trap::Runtime {
+            Trap::Lib {
                 trap_code,
                 backtrace,
             } => Self::new_with_trace(&info, None, RuntimeErrorSource::Trap(trap_code), backtrace),

lib/engine/src/trap/frame_info.rs

@@ -42,6 +42,14 @@ pub struct GlobalFrameInfo {
     ranges: BTreeMap<usize, ModuleInfoFrameInfo>,
 }
 
+/// Returns whether the `pc`, according to globally registered information,
+/// is a wasm trap or not.
+pub fn is_wasm_pc(pc: usize) -> bool {
+    let frame_info = FRAME_INFO.read().unwrap();
+    let module_info = frame_info.module_info(pc);
+    module_info.is_some()
+}
+
 /// An RAII structure used to unregister a module's frame information when the
 /// module is destroyed.
 #[derive(MemoryUsage)]

lib/engine/src/trap/mod.rs

@@ -2,6 +2,6 @@ mod error;
 mod frame_info;
 pub use error::RuntimeError;
 pub use frame_info::{
-    register as register_frame_info, FrameInfo, FunctionExtent, GlobalFrameInfoRegistration,
-    FRAME_INFO,
+    is_wasm_pc, register as register_frame_info, FrameInfo, FunctionExtent,
+    GlobalFrameInfoRegistration, FRAME_INFO,
 };

lib/vm/build.rs

@@ -1,9 +1,19 @@
 //! Runtime build script compiles C code using setjmp for trap handling.
 
+use std::env;
+
 fn main() {
-    println!("cargo:rerun-if-changed=src/trap/helpers.c");
+    println!("cargo:rerun-if-changed=src/trap/handlers.c");
+
     cc::Build::new()
         .warnings(true)
-        .file("src/trap/helpers.c")
-        .compile("helpers");
+        .define(
+            &format!(
+                "CFG_TARGET_OS_{}",
+                env::var("CARGO_CFG_TARGET_OS").unwrap().to_uppercase()
+            ),
+            None,
+        )
+        .file("src/trap/handlers.c")
+        .compile("handlers");
 }