Implemented shared memory for Wasmer in preparation for multithreading

lib/api/src/js/externals/memory.rs

@@ -6,7 +6,6 @@ use crate::js::{MemoryAccessError, MemoryType};
 use std::marker::PhantomData;
 use std::mem::MaybeUninit;
 use std::slice;
-use thiserror::Error;
 #[cfg(feature = "tracing")]
 use tracing::warn;
 
@@ -16,22 +15,7 @@ use wasmer_types::Pages;
 
 use super::MemoryView;
 
-/// Error type describing things that can go wrong when operating on Wasm Memories.
-#[derive(Error, Debug, Clone, PartialEq, Hash)]
-pub enum MemoryError {
-    /// The operation would cause the size of the memory to exceed the maximum or would cause
-    /// an overflow leading to unindexable memory.
-    #[error("The memory could not grow: current size {} pages, requested increase: {} pages", current.0, attempted_delta.0)]
-    CouldNotGrow {
-        /// The current size in pages.
-        current: Pages,
-        /// The attempted amount to grow by in pages.
-        attempted_delta: Pages,
-    },
-    /// A user defined error value, used for error cases not listed above.
-    #[error("A user-defined error occurred: {0}")]
-    Generic(String),
-}
+pub use wasmer_types::MemoryError;
 
 #[wasm_bindgen]
 extern "C" {
@@ -116,6 +100,17 @@ impl Memory {
         Ok(Self::from_vm_export(store, vm_memory))
     }
 
+    /// Creates a new host `Memory` from provided JavaScript memory.
+    pub fn new_raw(store: &mut impl AsStoreMut, js_memory: js_sys::WebAssembly::Memory, ty: MemoryType) -> Result<Self, MemoryError> {
+        let vm_memory = VMMemory::new(js_memory, ty);
+        Ok(Self::from_vm_export(store, vm_memory))
+    }
+
+    /// Create a memory object from an existing memory and attaches it to the store
+    pub fn new_from_existing(new_store: &mut impl AsStoreMut, memory: VMMemory) -> Self {
+        Self::from_vm_export(new_store, memory)
+    }
+
     /// Returns the [`MemoryType`] of the `Memory`.
     ///
     /// # Example

lib/api/src/js/function_env.rs

@@ -36,7 +36,7 @@ impl<T> FunctionEnv<T> {
     }
 
     /// Get the data as reference
-    pub fn as_ref<'a>(&self, store: &'a impl AsStoreMut) -> &'a T
+    pub fn as_ref<'a>(&self, store: &'a impl AsStoreRef) -> &'a T
     where
         T: Any + Send + 'static + Sized,
     {
@@ -112,6 +112,11 @@ impl<T: Send + 'static> FunctionEnvMut<'_, T> {
         self.func_env.as_mut(&mut self.store_mut)
     }
 
+    /// Borrows a new immmutable reference
+    pub fn as_ref(&self) -> FunctionEnv<T> {
+        self.func_env.clone()
+    }
+
     /// Borrows a new mutable reference
     pub fn as_mut<'a>(&'a mut self) -> FunctionEnvMut<'a, T> {
         FunctionEnvMut {

lib/api/src/js/imports.rs

@@ -174,6 +174,36 @@ impl Imports {
         }
         imports
     }
+
+    /// Iterates through all the imports in this structure
+    pub fn iter<'a>(&'a self) -> ImportsIterator<'a> {
+        ImportsIterator::new(self)
+    }
+}
+
+pub struct ImportsIterator<'a> {
+    iter: std::collections::hash_map::Iter<'a, (String, String), Extern>
+}
+
+impl<'a> ImportsIterator<'a>
+{
+    fn new(imports: &'a Imports) -> Self {
+        let iter = imports.map.iter();
+        Self { iter }
+    }
+}
+
+impl<'a> Iterator
+for ImportsIterator<'a> {
+    type Item = (&'a str, &'a str, &'a Extern);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.iter
+            .next()
+            .map(|(k, v)| {
+                (k.0.as_str(), k.1.as_str(), v)
+            })
+    }
 }
 
 impl IntoIterator for &Imports {

lib/api/src/js/store.rs

@@ -263,6 +263,11 @@ mod objects {
             self.id
         }
 
+        /// Sets the ID of this store
+        pub fn set_id(&mut self, id: StoreId) {
+            self.id = id;
+        }
+
         /// Returns a pair of mutable references from two handles.
         ///
         /// Panics if both handles point to the same object.

lib/api/src/sys/externals/memory.rs

@@ -10,7 +10,7 @@ use std::mem::MaybeUninit;
 use std::slice;
 #[cfg(feature = "tracing")]
 use tracing::warn;
-use wasmer_types::Pages;
+use wasmer_types::{Pages, LinearMemory};
 use wasmer_vm::{InternalStoreHandle, MemoryError, StoreHandle, VMExtern, VMMemory};
 
 use super::MemoryView;
@@ -60,6 +60,13 @@ impl Memory {
         })
     }
 
+    /// Create a memory object from an existing memory and attaches it to the store
+    pub fn new_from_existing(new_store: &mut impl AsStoreMut, memory: VMMemory) -> Self {
+        Self {
+            handle: StoreHandle::new(new_store.objects_mut(), memory)
+        }
+    }
+
     /// Returns the [`MemoryType`] of the `Memory`.
     ///
     /// # Example

lib/api/src/sys/externals/memory_view.rs

@@ -4,7 +4,7 @@ use std::convert::TryInto;
 use std::marker::PhantomData;
 use std::mem::MaybeUninit;
 use std::slice;
-use wasmer_types::Pages;
+use wasmer_types::{Pages, LinearMemory};
 
 use super::memory::MemoryBuffer;
 use super::Memory;

lib/api/src/sys/imports.rs

@@ -1,11 +1,12 @@
 //! The import module contains the implementation data structures and helper functions used to
 //! manipulate and access a wasm module's imports including memories, tables, globals, and
 //! functions.
-use crate::{Exports, Extern, Module};
+use crate::{Exports, Extern, Module, AsStoreMut, Memory};
 use std::collections::HashMap;
 use std::fmt;
 use wasmer_compiler::LinkError;
 use wasmer_types::ImportError;
+use wasmer_vm::{VMMemory, VMSharedMemory};
 
 /// All of the import data used when instantiating.
 ///
@@ -111,6 +112,32 @@ impl Imports {
             .insert((ns.to_string(), name.to_string()), val.into());
     }
 
+    /// Imports (any) shared memory into the imports.
+    /// (if the module does not import memory then this function is ignored)
+    pub fn import_shared_memory(&mut self, module: &Module, store: &mut impl AsStoreMut) -> Option<VMSharedMemory> {
+        // Determine if shared memory needs to be created and imported
+        let shared_memory = module
+            .imports()
+            .memories()
+            .next()
+            .map(|a| *a.ty())
+            .map(|ty| {
+                let style = store
+                    .as_store_ref()
+                    .tunables()
+                    .memory_style(&ty);
+                VMSharedMemory::new(&ty, &style)
+                    .unwrap()
+            });
+
+        if let Some(memory) = shared_memory {
+            self.define("env", "memory", Memory::new_from_existing(store, VMMemory::from_custom(memory.clone())));
+            Some(memory)
+        } else {
+            None
+        }
+    }
+
     /// Returns the contents of a namespace as an `Exports`.
     ///
     /// Returns `None` if the namespace doesn't exist.

lib/cli/src/commands/run/wasi.rs

@@ -96,7 +96,8 @@ impl Wasi {
             is_wasix_module(module),
             std::sync::atomic::Ordering::Release,
         );
-        let import_object = import_object_for_all_wasi_versions(store, &wasi_env.env);
+        let mut import_object = import_object_for_all_wasi_versions(store, &wasi_env.env);
+        import_object.import_shared_memory(module, store);
         let instance = Instance::new(store, module, &import_object)?;
         let memory = instance.exports.get_memory("memory")?;
         wasi_env.data_mut(store).set_memory(memory.clone());

lib/compiler-cranelift/src/translator/code_translator.rs

@@ -1063,25 +1063,44 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
             assert!(builder.func.dfg.value_type(expected) == implied_ty);
             // `fn translate_atomic_wait` can inspect the type of `expected` to figure out what
             // code it needs to generate, if it wants.
-            let res = environ.translate_atomic_wait(
+            match environ.translate_atomic_wait(
                 builder.cursor(),
                 heap_index,
                 heap,
                 addr,
                 expected,
                 timeout,
-            )?;
-            state.push1(res);
+            ) {
+                Ok(res) => {
+                    state.push1(res);
+                },
+                Err(wasmer_types::WasmError::Unsupported(_err)) => {
+                    // If multiple threads hit a mutex then the function will fail
+                    builder.ins().trap(ir::TrapCode::UnreachableCodeReached);
+                    state.reachable = false;
+                },
+                Err(err) => { return Err(err); }
+            };
         }
         Operator::MemoryAtomicNotify { memarg } => {
             let heap_index = MemoryIndex::from_u32(memarg.memory);
             let heap = state.get_heap(builder.func, memarg.memory, environ)?;
             let count = state.pop1(); // 32 (fixed)
             let addr = state.pop1(); // 32 (fixed)
             let addr = fold_atomic_mem_addr(addr, memarg, I32, builder);
-            let res =
-                environ.translate_atomic_notify(builder.cursor(), heap_index, heap, addr, count)?;
-            state.push1(res);
+            match environ.translate_atomic_notify(builder.cursor(), heap_index, heap, addr, count)
+            {
+                Ok(res) => {
+                    state.push1(res);
+                },
+                Err(wasmer_types::WasmError::Unsupported(_err)) => {
+                    // Simple return a zero as this function is needed for the __wasi_init_memory function
+                    // but the equivalent notify.wait will not be called (as only one thread calls __start)
+                    // hence these atomic operations are not needed
+                    state.push1(builder.ins().iconst(I32, i64::from(0)));
+                },
+                Err(err) => { return Err(err); }
+            };
         }
         Operator::I32AtomicLoad { memarg } => {
             translate_atomic_load(I32, I32, memarg, builder, state, environ)?

lib/compiler/src/engine/resolver.rs

@@ -4,7 +4,7 @@ use crate::LinkError;
 use more_asserts::assert_ge;
 use wasmer_types::entity::{BoxedSlice, EntityRef, PrimaryMap};
 use wasmer_types::{
-    ExternType, FunctionIndex, ImportError, ImportIndex, MemoryIndex, ModuleInfo, TableIndex,
+    ExternType, FunctionIndex, ImportError, ImportIndex, MemoryIndex, ModuleInfo, TableIndex, LinearMemory,
 };
 
 use wasmer_vm::{

lib/compiler/src/translator/environ.rs

@@ -1,7 +1,6 @@
 // This file contains code from external sources.
 // Attributions: https://github.com/wasmerio/wasmer/blob/master/ATTRIBUTIONS.md
 use super::state::ModuleTranslationState;
-use crate::lib::std::borrow::ToOwned;
 use crate::lib::std::string::ToString;
 use crate::lib::std::{boxed::Box, string::String, vec::Vec};
 use crate::translate_module;
@@ -15,7 +14,7 @@ use wasmer_types::{
     LocalFunctionIndex, MemoryIndex, MemoryType, ModuleInfo, SignatureIndex, TableIndex,
     TableInitializer, TableType,
 };
-use wasmer_types::{WasmError, WasmResult};
+use wasmer_types::WasmResult;
 
 /// Contains function data: bytecode and its offset in the module.
 #[derive(Hash)]
@@ -254,11 +253,6 @@ impl<'data> ModuleEnvironment<'data> {
     }
 
     pub(crate) fn declare_memory(&mut self, memory: MemoryType) -> WasmResult<()> {
-        if memory.shared {
-            return Err(WasmError::Unsupported(
-                "shared memories are not supported yet".to_owned(),
-            ));
-        }
         self.module.memories.push(memory);
         Ok(())
     }

lib/types/Cargo.toml

@@ -21,6 +21,9 @@ enum-iterator = "0.7.0"
 target-lexicon = { version = "0.12.2", default-features = false }
 enumset = "1.0"
 
+[dev-dependencies]
+memoffset = "0.6"
+
 [features]
 default = ["std"]
 std = []

lib/types/src/error.rs

@@ -1,5 +1,5 @@
 //! The WebAssembly possible errors
-use crate::ExternType;
+use crate::{ExternType, Pages};
 use std::io;
 use thiserror::Error;
 
@@ -37,6 +37,48 @@ pub enum DeserializeError {
     Compiler(#[from] CompileError),
 }
 
+/// Error type describing things that can go wrong when operating on Wasm Memories.
+#[derive(Error, Debug, Clone, PartialEq, Hash)]
+pub enum MemoryError {
+    /// Low level error with mmap.
+    #[error("Error when allocating memory: {0}")]
+    Region(String),
+    /// The operation would cause the size of the memory to exceed the maximum or would cause
+    /// an overflow leading to unindexable memory.
+    #[error("The memory could not grow: current size {} pages, requested increase: {} pages", current.0, attempted_delta.0)]
+    CouldNotGrow {
+        /// The current size in pages.
+        current: Pages,
+        /// The attempted amount to grow by in pages.
+        attempted_delta: Pages,
+    },
+    /// The operation would cause the size of the memory size exceed the maximum.
+    #[error("The memory is invalid because {}", reason)]
+    InvalidMemory {
+        /// The reason why the provided memory is invalid.
+        reason: String,
+    },
+    /// Caller asked for more minimum memory than we can give them.
+    #[error("The minimum requested ({} pages) memory is greater than the maximum allowed memory ({} pages)", min_requested.0, max_allowed.0)]
+    MinimumMemoryTooLarge {
+        /// The number of pages requested as the minimum amount of memory.
+        min_requested: Pages,
+        /// The maximum amount of memory we can allocate.
+        max_allowed: Pages,
+    },
+    /// Caller asked for a maximum memory greater than we can give them.
+    #[error("The maximum requested memory ({} pages) is greater than the maximum allowed memory ({} pages)", max_requested.0, max_allowed.0)]
+    MaximumMemoryTooLarge {
+        /// The number of pages requested as the maximum amount of memory.
+        max_requested: Pages,
+        /// The number of pages requested as the maximum amount of memory.
+        max_allowed: Pages,
+    },
+    /// A user defined error value, used for error cases not listed above.
+    #[error("A user-defined error occurred: {0}")]
+    Generic(String),
+}
+
 /// An ImportError.
 ///
 /// Note: this error is not standard to WebAssembly, but it's
@@ -52,6 +94,10 @@ pub enum ImportError {
     /// This error occurs when an import was expected but not provided.
     #[error("unknown import. Expected {0:?}")]
     UnknownImport(ExternType),
+
+    /// Memory Error
+    #[error("memory error. {0}")]
+    MemoryError(String),
 }
 
 /// An error while preinstantiating a module.