pub use crate::backing::{ImportBacking, LocalBacking, INTERNALS_SIZE}; use crate::{ memory::{Memory, MemoryType}, module::{ModuleInfo, ModuleInner}, structures::TypedIndex, types::{LocalOrImport, MemoryIndex}, vmcalls, }; use std::{ cell::UnsafeCell, ffi::c_void, mem, ptr, sync::atomic::{AtomicUsize, Ordering}, sync::Once, }; use hashbrown::HashMap; /// The context of the currently running WebAssembly instance. /// /// This is implicitly passed to every WebAssembly function. /// Since this is per-instance, each field has a statically /// (as in after compiling the wasm) known size, so no /// runtime checks are necessary. /// /// While the runtime currently just passes this around /// as the first, implicit parameter of every function, /// it may someday be pinned to a register (especially /// on arm, which has a ton of registers) to reduce /// register shuffling. #[derive(Debug)] #[repr(C)] pub struct Ctx { // `internal` must be the first field of `Ctx`. pub internal: InternalCtx, pub(crate) local_functions: *const *const Func, /// These are pointers to things that are known to be owned /// by the owning `Instance`. pub local_backing: *mut LocalBacking, pub import_backing: *mut ImportBacking, pub module: *const ModuleInner, //// This is intended to be user-supplied, per-instance /// contextual data. There are currently some issue with it, /// notably that it cannot be set before running the `start` /// function in a WebAssembly module. /// /// [#219](https://github.com/wasmerio/wasmer/pull/219) fixes that /// issue, as well as allowing the user to have *per-function* /// context, instead of just per-instance. pub data: *mut c_void, /// If there's a function set in this field, it gets called /// when the context is destructed, e.g. when an `Instance` /// is dropped. pub data_finalizer: Option, } /// The internal context of the currently running WebAssembly instance. /// /// #[doc(hidden)] #[derive(Debug)] #[repr(C)] pub struct InternalCtx { /// A pointer to an array of locally-defined memories, indexed by `MemoryIndex`. pub memories: *mut *mut LocalMemory, /// A pointer to an array of locally-defined tables, indexed by `TableIndex`. pub tables: *mut *mut LocalTable, /// A pointer to an array of locally-defined globals, indexed by `GlobalIndex`. pub globals: *mut *mut LocalGlobal, /// A pointer to an array of imported memories, indexed by `MemoryIndex, pub imported_memories: *mut *mut LocalMemory, /// A pointer to an array of imported tables, indexed by `TableIndex`. pub imported_tables: *mut *mut LocalTable, /// A pointer to an array of imported globals, indexed by `GlobalIndex`. pub imported_globals: *mut *mut LocalGlobal, /// A pointer to an array of imported functions, indexed by `FuncIndex`. pub imported_funcs: *mut ImportedFunc, /// A pointer to an array of signature ids. Conceptually, this maps /// from a static, module-local signature id to a runtime-global /// signature id. This is used to allow call-indirect to other /// modules safely. pub dynamic_sigindices: *const SigId, pub intrinsics: *const Intrinsics, pub stack_lower_bound: *mut u8, pub memory_base: *mut u8, pub memory_bound: usize, pub internals: *mut [u64; INTERNALS_SIZE], // TODO: Make this dynamic? pub interrupt_signal_mem: *mut u8, } static INTERNAL_FIELDS: AtomicUsize = AtomicUsize::new(0); pub struct InternalField { init: Once, inner: UnsafeCell, } unsafe impl Send for InternalField {} unsafe impl Sync for InternalField {} impl InternalField { pub const fn allocate() -> InternalField { InternalField { init: Once::new(), inner: UnsafeCell::new(::std::usize::MAX), } } pub fn index(&self) -> usize { let inner: *mut usize = self.inner.get(); self.init.call_once(|| { let idx = INTERNAL_FIELDS.fetch_add(1, Ordering::SeqCst); if idx >= INTERNALS_SIZE { INTERNAL_FIELDS.fetch_sub(1, Ordering::SeqCst); panic!("at most {} internal fields are supported", INTERNALS_SIZE); } else { unsafe { *inner = idx; } } }); unsafe { *inner } } } #[repr(C)] pub struct Intrinsics { pub memory_grow: *const Func, pub memory_size: *const Func, /*pub memory_grow: unsafe extern "C" fn( ctx: &mut Ctx, memory_index: usize, delta: Pages, ) -> i32, pub memory_size: unsafe extern "C" fn( ctx: &Ctx, memory_index: usize, ) -> Pages,*/ } unsafe impl Send for Intrinsics {} unsafe impl Sync for Intrinsics {} impl Intrinsics { #[allow(clippy::erasing_op)] pub fn offset_memory_grow() -> u8 { (0 * ::std::mem::size_of::()) as u8 } pub fn offset_memory_size() -> u8 { (1 * ::std::mem::size_of::()) as u8 } } pub static INTRINSICS_LOCAL_STATIC_MEMORY: Intrinsics = Intrinsics { memory_grow: vmcalls::local_static_memory_grow as _, memory_size: vmcalls::local_static_memory_size as _, }; pub static INTRINSICS_LOCAL_DYNAMIC_MEMORY: Intrinsics = Intrinsics { memory_grow: vmcalls::local_dynamic_memory_grow as _, memory_size: vmcalls::local_dynamic_memory_size as _, }; pub static INTRINSICS_IMPORTED_STATIC_MEMORY: Intrinsics = Intrinsics { memory_grow: vmcalls::imported_static_memory_grow as _, memory_size: vmcalls::imported_static_memory_size as _, }; pub static INTRINSICS_IMPORTED_DYNAMIC_MEMORY: Intrinsics = Intrinsics { memory_grow: vmcalls::imported_dynamic_memory_grow as _, memory_size: vmcalls::imported_dynamic_memory_size as _, }; fn get_intrinsics_for_module(m: &ModuleInfo) -> *const Intrinsics { if m.memories.len() == 0 && m.imported_memories.len() == 0 { ::std::ptr::null() } else { match MemoryIndex::new(0).local_or_import(m) { LocalOrImport::Local(local_mem_index) => { let mem_desc = &m.memories[local_mem_index]; match mem_desc.memory_type() { MemoryType::Dynamic => &INTRINSICS_LOCAL_DYNAMIC_MEMORY, MemoryType::Static => &INTRINSICS_LOCAL_STATIC_MEMORY, MemoryType::SharedStatic => unimplemented!(), } } LocalOrImport::Import(import_mem_index) => { let mem_desc = &m.imported_memories[import_mem_index].1; match mem_desc.memory_type() { MemoryType::Dynamic => &INTRINSICS_IMPORTED_DYNAMIC_MEMORY, MemoryType::Static => &INTRINSICS_IMPORTED_STATIC_MEMORY, MemoryType::SharedStatic => unimplemented!(), } } } } } #[cfg(all(unix, target_arch = "x86_64"))] fn get_interrupt_signal_mem() -> *mut u8 { unsafe { crate::alternative_stack::get_wasm_interrupt_signal_mem() } } #[cfg(not(all(unix, target_arch = "x86_64")))] fn get_interrupt_signal_mem() -> *mut u8 { static mut REGION: u64 = 0; unsafe { &mut REGION as *mut u64 as *mut u8 } } impl Ctx { #[doc(hidden)] pub unsafe fn new( local_backing: &mut LocalBacking, import_backing: &mut ImportBacking, module: &ModuleInner, ) -> Self { let (mem_base, mem_bound): (*mut u8, usize) = if module.info.memories.len() == 0 && module.info.imported_memories.len() == 0 { (::std::ptr::null_mut(), 0) } else { let mem = match MemoryIndex::new(0).local_or_import(&module.info) { LocalOrImport::Local(index) => local_backing.vm_memories[index], LocalOrImport::Import(index) => import_backing.vm_memories[index], }; ((*mem).base, (*mem).bound) }; Self { internal: InternalCtx { memories: local_backing.vm_memories.as_mut_ptr(), tables: local_backing.vm_tables.as_mut_ptr(), globals: local_backing.vm_globals.as_mut_ptr(), imported_memories: import_backing.vm_memories.as_mut_ptr(), imported_tables: import_backing.vm_tables.as_mut_ptr(), imported_globals: import_backing.vm_globals.as_mut_ptr(), imported_funcs: import_backing.vm_functions.as_mut_ptr(), dynamic_sigindices: local_backing.dynamic_sigindices.as_ptr(), intrinsics: get_intrinsics_for_module(&module.info), stack_lower_bound: ::std::ptr::null_mut(), memory_base: mem_base, memory_bound: mem_bound, internals: &mut local_backing.internals.0, interrupt_signal_mem: get_interrupt_signal_mem(), }, local_functions: local_backing.local_functions.as_ptr(), local_backing, import_backing, module, data: ptr::null_mut(), data_finalizer: None, } } #[doc(hidden)] pub unsafe fn new_with_data( local_backing: &mut LocalBacking, import_backing: &mut ImportBacking, module: &ModuleInner, data: *mut c_void, data_finalizer: fn(*mut c_void), ) -> Self { let (mem_base, mem_bound): (*mut u8, usize) = if module.info.memories.len() == 0 && module.info.imported_memories.len() == 0 { (::std::ptr::null_mut(), 0) } else { let mem = match MemoryIndex::new(0).local_or_import(&module.info) { LocalOrImport::Local(index) => local_backing.vm_memories[index], LocalOrImport::Import(index) => import_backing.vm_memories[index], }; ((*mem).base, (*mem).bound) }; Self { internal: InternalCtx { memories: local_backing.vm_memories.as_mut_ptr(), tables: local_backing.vm_tables.as_mut_ptr(), globals: local_backing.vm_globals.as_mut_ptr(), imported_memories: import_backing.vm_memories.as_mut_ptr(), imported_tables: import_backing.vm_tables.as_mut_ptr(), imported_globals: import_backing.vm_globals.as_mut_ptr(), imported_funcs: import_backing.vm_functions.as_mut_ptr(), dynamic_sigindices: local_backing.dynamic_sigindices.as_ptr(), intrinsics: get_intrinsics_for_module(&module.info), stack_lower_bound: ::std::ptr::null_mut(), memory_base: mem_base, memory_bound: mem_bound, internals: &mut local_backing.internals.0, interrupt_signal_mem: get_interrupt_signal_mem(), }, local_functions: local_backing.local_functions.as_ptr(), local_backing, import_backing, module, data, data_finalizer: Some(data_finalizer), } } /// This exposes the specified memory of the WebAssembly instance /// as a immutable slice. /// /// WebAssembly will soon support multiple linear memories, so this /// forces the user to specify. /// /// # Usage: /// /// ``` /// # use wasmer_runtime_core::{ /// # vm::Ctx, /// # }; /// fn read_memory(ctx: &Ctx) -> u8 { /// let first_memory = ctx.memory(0); /// // Read the first byte of that linear memory. /// first_memory.view()[0].get() /// } /// ``` pub fn memory(&self, mem_index: u32) -> &Memory { let module = unsafe { &*self.module }; let mem_index = MemoryIndex::new(mem_index as usize); match mem_index.local_or_import(&module.info) { LocalOrImport::Local(local_mem_index) => unsafe { let local_backing = &*self.local_backing; &local_backing.memories[local_mem_index] }, LocalOrImport::Import(import_mem_index) => unsafe { let import_backing = &*self.import_backing; &import_backing.memories[import_mem_index] }, } } /// Gives access to the emscripten symbol map, used for debugging pub unsafe fn borrow_symbol_map(&self) -> &Option> { &(*self.module).info.em_symbol_map } /// Returns the number of dynamic sigindices. pub fn dynamic_sigindice_count(&self) -> usize { unsafe { (*self.local_backing).dynamic_sigindices.len() } } /// Returns the value of the specified internal field. pub fn get_internal(&self, field: &InternalField) -> u64 { unsafe { (*self.internal.internals)[field.index()] } } /// Writes the value to the specified internal field. pub fn set_internal(&mut self, field: &InternalField, value: u64) { unsafe { (*self.internal.internals)[field.index()] = value; } } } #[doc(hidden)] impl Ctx { #[allow(clippy::erasing_op)] // TODO pub fn offset_memories() -> u8 { 0 * (mem::size_of::() as u8) } pub fn offset_tables() -> u8 { 1 * (mem::size_of::() as u8) } pub fn offset_globals() -> u8 { 2 * (mem::size_of::() as u8) } pub fn offset_imported_memories() -> u8 { 3 * (mem::size_of::() as u8) } pub fn offset_imported_tables() -> u8 { 4 * (mem::size_of::() as u8) } pub fn offset_imported_globals() -> u8 { 5 * (mem::size_of::() as u8) } pub fn offset_imported_funcs() -> u8 { 6 * (mem::size_of::() as u8) } pub fn offset_signatures() -> u8 { 7 * (mem::size_of::() as u8) } pub fn offset_intrinsics() -> u8 { 8 * (mem::size_of::() as u8) } pub fn offset_stack_lower_bound() -> u8 { 9 * (mem::size_of::() as u8) } pub fn offset_memory_base() -> u8 { 10 * (mem::size_of::() as u8) } pub fn offset_memory_bound() -> u8 { 11 * (mem::size_of::() as u8) } pub fn offset_internals() -> u8 { 12 * (mem::size_of::() as u8) } pub fn offset_interrupt_signal_mem() -> u8 { 13 * (mem::size_of::() as u8) } pub fn offset_local_functions() -> u8 { 14 * (mem::size_of::() as u8) } } enum InnerFunc {} /// Used to provide type safety (ish) for passing around function pointers. /// The typesystem ensures this cannot be dereferenced since an /// empty enum cannot actually exist. #[repr(C)] pub struct Func(InnerFunc); /// An imported function, which contains the vmctx that owns this function. #[derive(Debug, Clone)] #[repr(C)] pub struct ImportedFunc { pub func: *const Func, pub vmctx: *mut Ctx, } impl ImportedFunc { #[allow(clippy::erasing_op)] // TODO pub fn offset_func() -> u8 { 0 * (mem::size_of::() as u8) } pub fn offset_vmctx() -> u8 { 1 * (mem::size_of::() as u8) } pub fn size() -> u8 { mem::size_of::() as u8 } } /// Definition of a table used by the VM. (obviously) #[derive(Debug, Clone, Copy)] #[repr(C)] pub struct LocalTable { /// pointer to the elements in the table. pub base: *mut u8, /// Number of elements in the table (NOT necessarily the size of the table in bytes!). pub count: usize, /// The table that this represents. At the moment, this can only be `*mut AnyfuncTable`. pub table: *mut (), } impl LocalTable { #[allow(clippy::erasing_op)] // TODO pub fn offset_base() -> u8 { 0 * (mem::size_of::() as u8) } pub fn offset_count() -> u8 { 1 * (mem::size_of::() as u8) } pub fn size() -> u8 { mem::size_of::() as u8 } } /// Definition of a memory used by the VM. #[derive(Debug, Clone, Copy)] #[repr(C)] pub struct LocalMemory { /// Pointer to the bottom of this linear memory. pub base: *mut u8, /// Current size of this linear memory in bytes. pub bound: usize, /// The actual memory that this represents. /// This is either `*mut DynamicMemory`, `*mut StaticMemory`, /// or `*mut SharedStaticMemory`. pub memory: *mut (), } impl LocalMemory { #[allow(clippy::erasing_op)] // TODO pub fn offset_base() -> u8 { 0 * (mem::size_of::() as u8) } pub fn offset_bound() -> u8 { 1 * (mem::size_of::() as u8) } pub fn size() -> u8 { mem::size_of::() as u8 } } /// Definition of a global used by the VM. #[derive(Debug, Clone, Copy)] #[repr(C)] pub struct LocalGlobal { pub data: u64, } impl LocalGlobal { #[allow(clippy::erasing_op)] // TODO pub fn offset_data() -> u8 { 0 * (mem::size_of::() as u8) } pub fn null() -> Self { Self { data: 0 } } pub fn size() -> u8 { mem::size_of::() as u8 } } #[derive(Debug, Clone, Copy)] #[repr(transparent)] pub struct SigId(pub u32); /// Caller-checked anyfunc #[derive(Debug, Clone, Copy)] #[repr(C)] pub struct Anyfunc { pub func: *const Func, pub ctx: *mut Ctx, pub sig_id: SigId, } impl Anyfunc { pub fn null() -> Self { Self { func: ptr::null(), ctx: ptr::null_mut(), sig_id: SigId(u32::max_value()), } } #[allow(clippy::erasing_op)] // TODO pub fn offset_func() -> u8 { 0 * (mem::size_of::() as u8) } pub fn offset_vmctx() -> u8 { 1 * (mem::size_of::() as u8) } pub fn offset_sig_id() -> u8 { 2 * (mem::size_of::() as u8) } pub fn size() -> u8 { mem::size_of::() as u8 } } #[cfg(test)] mod vm_offset_tests { use super::{Anyfunc, Ctx, ImportedFunc, InternalCtx, LocalGlobal, LocalMemory, LocalTable}; #[test] fn vmctx() { assert_eq!(0usize, offset_of!(Ctx => internal).get_byte_offset(),); assert_eq!( Ctx::offset_memories() as usize, offset_of!(InternalCtx => memories).get_byte_offset(), ); assert_eq!( Ctx::offset_tables() as usize, offset_of!(InternalCtx => tables).get_byte_offset(), ); assert_eq!( Ctx::offset_globals() as usize, offset_of!(InternalCtx => globals).get_byte_offset(), ); assert_eq!( Ctx::offset_imported_memories() as usize, offset_of!(InternalCtx => imported_memories).get_byte_offset(), ); assert_eq!( Ctx::offset_imported_tables() as usize, offset_of!(InternalCtx => imported_tables).get_byte_offset(), ); assert_eq!( Ctx::offset_imported_globals() as usize, offset_of!(InternalCtx => imported_globals).get_byte_offset(), ); assert_eq!( Ctx::offset_imported_funcs() as usize, offset_of!(InternalCtx => imported_funcs).get_byte_offset(), ); assert_eq!( Ctx::offset_intrinsics() as usize, offset_of!(InternalCtx => intrinsics).get_byte_offset(), ); assert_eq!( Ctx::offset_stack_lower_bound() as usize, offset_of!(InternalCtx => stack_lower_bound).get_byte_offset(), ); assert_eq!( Ctx::offset_memory_base() as usize, offset_of!(InternalCtx => memory_base).get_byte_offset(), ); assert_eq!( Ctx::offset_memory_bound() as usize, offset_of!(InternalCtx => memory_bound).get_byte_offset(), ); assert_eq!( Ctx::offset_internals() as usize, offset_of!(InternalCtx => internals).get_byte_offset(), ); assert_eq!( Ctx::offset_interrupt_signal_mem() as usize, offset_of!(InternalCtx => interrupt_signal_mem).get_byte_offset(), ); assert_eq!( Ctx::offset_local_functions() as usize, offset_of!(Ctx => local_functions).get_byte_offset(), ); } #[test] fn imported_func() { assert_eq!( ImportedFunc::offset_func() as usize, offset_of!(ImportedFunc => func).get_byte_offset(), ); assert_eq!( ImportedFunc::offset_vmctx() as usize, offset_of!(ImportedFunc => vmctx).get_byte_offset(), ); } #[test] fn local_table() { assert_eq!( LocalTable::offset_base() as usize, offset_of!(LocalTable => base).get_byte_offset(), ); assert_eq!( LocalTable::offset_count() as usize, offset_of!(LocalTable => count).get_byte_offset(), ); } #[test] fn local_memory() { assert_eq!( LocalMemory::offset_base() as usize, offset_of!(LocalMemory => base).get_byte_offset(), ); assert_eq!( LocalMemory::offset_bound() as usize, offset_of!(LocalMemory => bound).get_byte_offset(), ); } #[test] fn local_global() { assert_eq!( LocalGlobal::offset_data() as usize, offset_of!(LocalGlobal => data).get_byte_offset(), ); } #[test] fn cc_anyfunc() { assert_eq!( Anyfunc::offset_func() as usize, offset_of!(Anyfunc => func).get_byte_offset(), ); assert_eq!( Anyfunc::offset_vmctx() as usize, offset_of!(Anyfunc => ctx).get_byte_offset(), ); assert_eq!( Anyfunc::offset_sig_id() as usize, offset_of!(Anyfunc => sig_id).get_byte_offset(), ); } } #[cfg(test)] mod vm_ctx_tests { use super::{Ctx, ImportBacking, LocalBacking}; use crate::module::{ModuleInfo, ModuleInner, StringTable}; use crate::structures::Map; use std::ffi::c_void; struct TestData { x: u32, y: bool, str: String, } fn test_data_finalizer(data: *mut c_void) { let test_data: &mut TestData = unsafe { &mut *(data as *mut TestData) }; assert_eq!(test_data.x, 10); assert_eq!(test_data.y, true); assert_eq!(test_data.str, "Test".to_string()); println!("hello from finalizer"); drop(test_data); } #[test] fn test_callback_on_drop() { let mut data = TestData { x: 10, y: true, str: "Test".to_string(), }; let mut local_backing = LocalBacking { memories: Map::new().into_boxed_map(), tables: Map::new().into_boxed_map(), globals: Map::new().into_boxed_map(), vm_memories: Map::new().into_boxed_map(), vm_tables: Map::new().into_boxed_map(), vm_globals: Map::new().into_boxed_map(), dynamic_sigindices: Map::new().into_boxed_map(), local_functions: Map::new().into_boxed_map(), internals: crate::backing::Internals([0; crate::backing::INTERNALS_SIZE]), }; let mut import_backing = ImportBacking { memories: Map::new().into_boxed_map(), tables: Map::new().into_boxed_map(), globals: Map::new().into_boxed_map(), vm_functions: Map::new().into_boxed_map(), vm_memories: Map::new().into_boxed_map(), vm_tables: Map::new().into_boxed_map(), vm_globals: Map::new().into_boxed_map(), }; let module = generate_module(); let data = &mut data as *mut _ as *mut c_void; let ctx = unsafe { Ctx::new_with_data( &mut local_backing, &mut import_backing, &module, data, test_data_finalizer, ) }; let ctx_test_data = cast_test_data(ctx.data); assert_eq!(ctx_test_data.x, 10); assert_eq!(ctx_test_data.y, true); assert_eq!(ctx_test_data.str, "Test".to_string()); drop(ctx); } fn cast_test_data(data: *mut c_void) -> &'static mut TestData { let test_data: &mut TestData = unsafe { &mut *(data as *mut TestData) }; test_data } fn generate_module() -> ModuleInner { use super::Func; use crate::backend::{sys::Memory, Backend, CacheGen, RunnableModule}; use crate::cache::Error as CacheError; use crate::typed_func::Wasm; use crate::types::{LocalFuncIndex, SigIndex}; use hashbrown::HashMap; use std::any::Any; use std::ptr::NonNull; struct Placeholder; impl RunnableModule for Placeholder { fn get_func( &self, _module: &ModuleInfo, _local_func_index: LocalFuncIndex, ) -> Option> { None } fn get_trampoline(&self, _module: &ModuleInfo, _sig_index: SigIndex) -> Option { unimplemented!() } unsafe fn do_early_trap(&self, _: Box) -> ! { unimplemented!() } } impl CacheGen for Placeholder { fn generate_cache(&self) -> Result<(Box<[u8]>, Memory), CacheError> { unimplemented!() } } ModuleInner { runnable_module: Box::new(Placeholder), cache_gen: Box::new(Placeholder), info: ModuleInfo { memories: Map::new(), globals: Map::new(), tables: Map::new(), // These are strictly imported and the typesystem ensures that. imported_functions: Map::new(), imported_memories: Map::new(), imported_tables: Map::new(), imported_globals: Map::new(), exports: HashMap::new(), data_initializers: Vec::new(), elem_initializers: Vec::new(), start_func: None, func_assoc: Map::new(), signatures: Map::new(), backend: Backend::Cranelift, namespace_table: StringTable::new(), name_table: StringTable::new(), em_symbol_map: None, custom_sections: HashMap::new(), }, } } }