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Initial reorg.

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This is largely the same as #305, but updated for the current tree.
This commit is contained in:
Dan Gohman
2019-11-07 17:11:06 -08:00
parent 2c69546a24
commit 22641de629
351 changed files with 52 additions and 52 deletions
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[package]
name = "wasmtime-jit"
version = "0.2.0"
authors = ["The Wasmtime Project Developers"]
description = "JIT-style execution for WebAsssembly code in Cranelift"
categories = ["wasm"]
keywords = ["webassembly", "wasm"]
repository = "https://github.com/CraneStation/wasmtime"
license = "Apache-2.0 WITH LLVM-exception"
readme = "README.md"
edition = "2018"
[dependencies]
cranelift-codegen = { version = "0.49", features = ["enable-serde"] }
cranelift-entity = { version = "0.49", features = ["enable-serde"] }
cranelift-wasm = { version = "0.49", features = ["enable-serde"] }
cranelift-frontend = { version = "0.49" }
wasmtime-environ = { path = "../environ", default-features = false }
wasmtime-runtime = { path = "../runtime", default-features = false }
wasmtime-debug = { path = "../debug", default-features = false }
region = "2.0.0"
failure = { version = "0.1.3", default-features = false }
thiserror = "1.0.4"
target-lexicon = { version = "0.9.0", default-features = false }
hashbrown = { version = "0.6.0", optional = true }
wasmparser = { version = "0.39.2", default-features = false }
[target.'cfg(target_os = "windows")'.dependencies]
winapi = { version = "0.3.7", features = ["winnt", "impl-default"] }
[features]
default = ["std"]
std = ["cranelift-codegen/std", "cranelift-wasm/std", "wasmtime-environ/std", "wasmtime-debug/std", "wasmtime-runtime/std", "wasmparser/std"]
core = ["hashbrown/nightly", "cranelift-codegen/core", "cranelift-wasm/core", "wasmtime-environ/core", "wasmtime-debug/core", "wasmparser/core"]
lightbeam = ["wasmtime-environ/lightbeam"]
[badges]
maintenance = { status = "experimental" }
travis-ci = { repository = "CraneStation/wasmtime" }

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This is the `wasmtime-jit` crate, which contains JIT-based execution
for wasm, using the wasm ABI defined by [`wasmtime-environ`] and the
runtime support provided by [`wasmtime-runtime`].
[`wasmtime-environ`]: https://crates.io/crates/wasmtime-environ
[`wasmtime-runtime`]: https://crates.io/crates/wasmtime-runtime

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//! Support for performing actions with a wasm module from the outside.
use crate::compiler::Compiler;
use crate::instantiate::SetupError;
use alloc::string::String;
use alloc::vec::Vec;
use core::cmp::max;
use core::{fmt, mem, ptr, slice};
use cranelift_codegen::ir;
use thiserror::Error;
use wasmtime_runtime::{wasmtime_call_trampoline, Export, InstanceHandle, VMInvokeArgument};
/// A runtime value.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum RuntimeValue {
/// A runtime value with type i32.
I32(i32),
/// A runtime value with type i64.
I64(i64),
/// A runtime value with type f32.
F32(u32),
/// A runtime value with type f64.
F64(u64),
/// A runtime value with type v128
V128([u8; 16]),
}
impl RuntimeValue {
/// Return the type of this `RuntimeValue`.
pub fn value_type(self) -> ir::Type {
match self {
Self::I32(_) => ir::types::I32,
Self::I64(_) => ir::types::I64,
Self::F32(_) => ir::types::F32,
Self::F64(_) => ir::types::F64,
Self::V128(_) => ir::types::I8X16,
}
}
/// Assuming this `RuntimeValue` holds an `i32`, return that value.
pub fn unwrap_i32(self) -> i32 {
match self {
Self::I32(x) => x,
_ => panic!("unwrapping value of type {} as i32", self.value_type()),
}
}
/// Assuming this `RuntimeValue` holds an `i64`, return that value.
pub fn unwrap_i64(self) -> i64 {
match self {
Self::I64(x) => x,
_ => panic!("unwrapping value of type {} as i64", self.value_type()),
}
}
/// Assuming this `RuntimeValue` holds an `f32`, return that value.
pub fn unwrap_f32(self) -> f32 {
f32::from_bits(self.unwrap_f32_bits())
}
/// Assuming this `RuntimeValue` holds an `f32`, return the bits of that value as a `u32`.
pub fn unwrap_f32_bits(self) -> u32 {
match self {
Self::F32(x) => x,
_ => panic!("unwrapping value of type {} as f32", self.value_type()),
}
}
/// Assuming this `RuntimeValue` holds an `f64`, return that value.
pub fn unwrap_f64(self) -> f64 {
f64::from_bits(self.unwrap_f64_bits())
}
/// Assuming this `RuntimeValue` holds an `f64`, return the bits of that value as a `u64`.
pub fn unwrap_f64_bits(self) -> u64 {
match self {
Self::F64(x) => x,
_ => panic!("unwrapping value of type {} as f64", self.value_type()),
}
}
}
impl fmt::Display for RuntimeValue {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::I32(x) => write!(f, "{}: i32", x),
Self::I64(x) => write!(f, "{}: i64", x),
Self::F32(x) => write!(f, "{}: f32", x),
Self::F64(x) => write!(f, "{}: f64", x),
Self::V128(x) => write!(f, "{:?}: v128", x.to_vec()),
}
}
}
/// The result of invoking a wasm function or reading a wasm global.
#[derive(Debug)]
pub enum ActionOutcome {
/// The action returned normally. Its return values are provided.
Returned {
/// The return values.
values: Vec<RuntimeValue>,
},
/// A trap occurred while the action was executing.
Trapped {
/// The trap message.
message: String,
},
}
/// An error detected while invoking a wasm function or reading a wasm global.
/// Note that at this level, traps are not reported errors, but are rather
/// returned through `ActionOutcome`.
#[derive(Error, Debug)]
pub enum ActionError {
/// An internal implementation error occurred.
#[error("{0}")]
Setup(#[from] SetupError),
/// No field with the specified name was present.
#[error("Unknown field: {0}")]
Field(String),
/// The field was present but was the wrong kind (eg. function, table, global, or memory).
#[error("Kind error: {0}")]
Kind(String),
/// The field was present but was the wrong type (eg. i32, i64, f32, or f64).
#[error("Type error: {0}")]
Type(String),
}
/// Invoke a function through an `InstanceHandle` identified by an export name.
pub fn invoke(
compiler: &mut Compiler,
instance: &mut InstanceHandle,
function_name: &str,
args: &[RuntimeValue],
) -> Result<ActionOutcome, ActionError> {
let (address, signature, callee_vmctx) = match instance.lookup(function_name) {
Some(Export::Function {
address,
signature,
vmctx,
}) => (address, signature, vmctx),
Some(_) => {
return Err(ActionError::Kind(format!(
"exported item \"{}\" is not a function",
function_name
)));
}
None => {
return Err(ActionError::Field(format!(
"no export named \"{}\"",
function_name
)));
}
};
for (index, value) in args.iter().enumerate() {
// Add one to account for the leading vmctx argument.
assert_eq!(value.value_type(), signature.params[index + 1].value_type);
}
// TODO: Support values larger than v128. And pack the values into memory
// instead of just using fixed-sized slots.
// Subtract one becase we don't pass the vmctx argument in `values_vec`.
let value_size = mem::size_of::<VMInvokeArgument>();
let mut values_vec: Vec<VMInvokeArgument> =
vec![VMInvokeArgument::new(); max(signature.params.len() - 1, signature.returns.len())];
// Store the argument values into `values_vec`.
for (index, arg) in args.iter().enumerate() {
unsafe {
let ptr = values_vec.as_mut_ptr().add(index);
match arg {
RuntimeValue::I32(x) => ptr::write(ptr as *mut i32, *x),
RuntimeValue::I64(x) => ptr::write(ptr as *mut i64, *x),
RuntimeValue::F32(x) => ptr::write(ptr as *mut u32, *x),
RuntimeValue::F64(x) => ptr::write(ptr as *mut u64, *x),
RuntimeValue::V128(x) => ptr::write(ptr as *mut [u8; 16], *x),
}
}
}
// Get the trampoline to call for this function.
let exec_code_buf = compiler
.get_trampoline(address, &signature, value_size)
.map_err(ActionError::Setup)?;
// Make all JIT code produced thus far executable.
compiler.publish_compiled_code();
// Call the trampoline.
if let Err(message) = unsafe {
wasmtime_call_trampoline(
callee_vmctx,
exec_code_buf,
values_vec.as_mut_ptr() as *mut u8,
)
} {
return Ok(ActionOutcome::Trapped { message });
}
// Load the return values out of `values_vec`.
let values = signature
.returns
.iter()
.enumerate()
.map(|(index, abi_param)| unsafe {
let ptr = values_vec.as_ptr().add(index);
match abi_param.value_type {
ir::types::I32 => RuntimeValue::I32(ptr::read(ptr as *const i32)),
ir::types::I64 => RuntimeValue::I64(ptr::read(ptr as *const i64)),
ir::types::F32 => RuntimeValue::F32(ptr::read(ptr as *const u32)),
ir::types::F64 => RuntimeValue::F64(ptr::read(ptr as *const u64)),
ir::types::I8X16 => RuntimeValue::V128(ptr::read(ptr as *const [u8; 16])),
other => panic!("unsupported value type {:?}", other),
}
})
.collect();
Ok(ActionOutcome::Returned { values })
}
/// Returns a slice of the contents of allocated linear memory.
pub fn inspect_memory<'instance>(
instance: &'instance InstanceHandle,
memory_name: &str,
start: usize,
len: usize,
) -> Result<&'instance [u8], ActionError> {
let definition = match unsafe { instance.lookup_immutable(memory_name) } {
Some(Export::Memory {
definition,
memory: _memory,
vmctx: _vmctx,
}) => definition,
Some(_) => {
return Err(ActionError::Kind(format!(
"exported item \"{}\" is not a linear memory",
memory_name
)));
}
None => {
return Err(ActionError::Field(format!(
"no export named \"{}\"",
memory_name
)));
}
};
Ok(unsafe {
let memory_def = &*definition;
&slice::from_raw_parts(memory_def.base, memory_def.current_length)[start..start + len]
})
}
/// Read a global in the given instance identified by an export name.
pub fn get(instance: &InstanceHandle, global_name: &str) -> Result<RuntimeValue, ActionError> {
let (definition, global) = match unsafe { instance.lookup_immutable(global_name) } {
Some(Export::Global {
definition,
vmctx: _,
global,
}) => (definition, global),
Some(_) => {
return Err(ActionError::Kind(format!(
"exported item \"{}\" is not a global variable",
global_name
)));
}
None => {
return Err(ActionError::Field(format!(
"no export named \"{}\"",
global_name
)));
}
};
unsafe {
let global_def = &*definition;
Ok(match global.ty {
ir::types::I32 => RuntimeValue::I32(*global_def.as_i32()),
ir::types::I64 => RuntimeValue::I64(*global_def.as_i64()),
ir::types::F32 => RuntimeValue::F32(*global_def.as_f32_bits()),
ir::types::F64 => RuntimeValue::F64(*global_def.as_f64_bits()),
other => {
return Err(ActionError::Type(format!(
"global with type {} not supported",
other
)));
}
})
}
}

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//! Memory management for executable code.
use crate::function_table::FunctionTable;
use alloc::boxed::Box;
use alloc::string::String;
use alloc::vec::Vec;
use core::{cmp, mem};
use region;
use wasmtime_environ::{Compilation, CompiledFunction};
use wasmtime_runtime::{Mmap, VMFunctionBody};
/// Memory manager for executable code.
pub struct CodeMemory {
current: (Mmap, FunctionTable),
mmaps: Vec<(Mmap, FunctionTable)>,
position: usize,
published: usize,
}
impl CodeMemory {
/// Create a new `CodeMemory` instance.
pub fn new() -> Self {
Self {
current: (Mmap::new(), FunctionTable::new()),
mmaps: Vec::new(),
position: 0,
published: 0,
}
}
/// Allocate a continuous memory block for a single compiled function.
/// TODO: Reorganize the code that calls this to emit code directly into the
/// mmap region rather than into a Vec that we need to copy in.
pub fn allocate_for_function(
&mut self,
func: &CompiledFunction,
) -> Result<&mut [VMFunctionBody], String> {
let size = Self::function_allocation_size(func);
let start = self.position as u32;
let (buf, table) = self.allocate(size)?;
let (_, _, _, vmfunc) = Self::copy_function(func, start, buf, table);
Ok(vmfunc)
}
/// Allocate a continuous memory block for a compilation.
///
/// Allocates memory for both the function bodies as well as function unwind data.
pub fn allocate_for_compilation(
&mut self,
compilation: &Compilation,
) -> Result<Box<[&mut [VMFunctionBody]]>, String> {
let total_len = compilation
.into_iter()
.fold(0, |acc, func| acc + Self::function_allocation_size(func));
let mut start = self.position as u32;
let (mut buf, mut table) = self.allocate(total_len)?;
let mut result = Vec::with_capacity(compilation.len());
for func in compilation.into_iter() {
let (next_start, next_buf, next_table, vmfunc) =
Self::copy_function(func, start, buf, table);
result.push(vmfunc);
start = next_start;
buf = next_buf;
table = next_table;
}
Ok(result.into_boxed_slice())
}
/// Make all allocated memory executable.
pub fn publish(&mut self) {
self.push_current(0)
.expect("failed to push current memory map");
for (m, t) in &mut self.mmaps[self.published..] {
if m.len() != 0 {
unsafe {
region::protect(m.as_mut_ptr(), m.len(), region::Protection::ReadExecute)
}
.expect("unable to make memory readonly and executable");
}
t.publish(m.as_ptr() as u64)
.expect("failed to publish function table");
}
self.published = self.mmaps.len();
}
/// Allocate `size` bytes of memory which can be made executable later by
/// calling `publish()`. Note that we allocate the memory as writeable so
/// that it can be written to and patched, though we make it readonly before
/// actually executing from it.
///
/// TODO: Add an alignment flag.
fn allocate(&mut self, size: usize) -> Result<(&mut [u8], &mut FunctionTable), String> {
if self.current.0.len() - self.position < size {
self.push_current(cmp::max(0x10000, size))?;
}
let old_position = self.position;
self.position += size;
Ok((
&mut self.current.0.as_mut_slice()[old_position..self.position],
&mut self.current.1,
))
}
/// Calculates the allocation size of the given compiled function.
fn function_allocation_size(func: &CompiledFunction) -> usize {
if func.unwind_info.is_empty() {
func.body.len()
} else {
// Account for necessary unwind information alignment padding (32-bit)
((func.body.len() + 3) & !3) + func.unwind_info.len()
}
}
/// Copies the data of the compiled function to the given buffer.
///
/// This will also add the function to the current function table.
fn copy_function<'a>(
func: &CompiledFunction,
func_start: u32,
buf: &'a mut [u8],
table: &'a mut FunctionTable,
) -> (
u32,
&'a mut [u8],
&'a mut FunctionTable,
&'a mut [VMFunctionBody],
) {
let func_end = func_start + (func.body.len() as u32);
let (body, remainder) = buf.split_at_mut(func.body.len());
body.copy_from_slice(&func.body);
let vmfunc = Self::view_as_mut_vmfunc_slice(body);
if func.unwind_info.is_empty() {
return (func_end, remainder, table, vmfunc);
}
// Keep unwind information 32-bit aligned (round up to the nearest 4 byte boundary)
let padding = ((func.body.len() + 3) & !3) - func.body.len();
let (unwind, remainder) = remainder.split_at_mut(padding + func.unwind_info.len());
unwind[padding..].copy_from_slice(&func.unwind_info);
let unwind_start = func_end + (padding as u32);
let unwind_end = unwind_start + (func.unwind_info.len() as u32);
table.add_function(func_start, func_end, unwind_start);
(unwind_end, remainder, table, vmfunc)
}
/// Convert mut a slice from u8 to VMFunctionBody.
fn view_as_mut_vmfunc_slice(slice: &mut [u8]) -> &mut [VMFunctionBody] {
let byte_ptr: *mut [u8] = slice;
let body_ptr = byte_ptr as *mut [VMFunctionBody];
unsafe { &mut *body_ptr }
}
/// Pushes the current Mmap (and function table) and allocates a new Mmap of the given size.
fn push_current(&mut self, new_size: usize) -> Result<(), String> {
let previous = mem::replace(
&mut self.current,
(
if new_size == 0 {
Mmap::new()
} else {
Mmap::with_at_least(cmp::max(0x10000, new_size))?
},
FunctionTable::new(),
),
);
if previous.0.len() > 0 {
self.mmaps.push(previous);
} else {
assert!(previous.1.len() == 0);
}
self.position = 0;
Ok(())
}
}

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//! JIT compilation.
use super::HashMap;
use crate::code_memory::CodeMemory;
use crate::instantiate::SetupError;
use crate::target_tunables::target_tunables;
use alloc::boxed::Box;
use alloc::string::String;
use alloc::vec::Vec;
use core::convert::TryFrom;
use cranelift_codegen::ir::InstBuilder;
use cranelift_codegen::isa::{TargetFrontendConfig, TargetIsa};
use cranelift_codegen::Context;
use cranelift_codegen::{binemit, ir};
use cranelift_entity::{EntityRef, PrimaryMap};
use cranelift_frontend::{FunctionBuilder, FunctionBuilderContext};
use cranelift_wasm::{DefinedFuncIndex, DefinedMemoryIndex, ModuleTranslationState};
use wasmtime_debug::{emit_debugsections_image, DebugInfoData};
use wasmtime_environ::{
Compilation, CompileError, CompiledFunction, Compiler as _C, FunctionBodyData, Module,
ModuleVmctxInfo, Relocations, Traps, Tunables, VMOffsets,
};
use wasmtime_runtime::{
get_mut_trap_registry, InstantiationError, SignatureRegistry, TrapRegistrationGuard,
VMFunctionBody,
};
/// Select which kind of compilation to use.
#[derive(Copy, Clone, Debug)]
pub enum CompilationStrategy {
/// Let Wasmtime pick the strategy.
Auto,
/// Compile all functions with Cranelift.
Cranelift,
/// Compile all functions with Lightbeam.
#[cfg(feature = "lightbeam")]
Lightbeam,
}
/// A WebAssembly code JIT compiler.
///
/// A `Compiler` instance owns the executable memory that it allocates.
///
/// TODO: Evolve this to support streaming rather than requiring a `&[u8]`
/// containing a whole wasm module at once.
///
/// TODO: Consider using cranelift-module.
pub struct Compiler {
isa: Box<dyn TargetIsa>,
code_memory: CodeMemory,
trap_registration_guards: Vec<TrapRegistrationGuard>,
trampoline_park: HashMap<*const VMFunctionBody, *const VMFunctionBody>,
signatures: SignatureRegistry,
strategy: CompilationStrategy,
/// The `FunctionBuilderContext`, shared between trampline function compilations.
fn_builder_ctx: FunctionBuilderContext,
}
impl Compiler {
/// Construct a new `Compiler`.
pub fn new(isa: Box<dyn TargetIsa>, strategy: CompilationStrategy) -> Self {
Self {
isa,
code_memory: CodeMemory::new(),
trap_registration_guards: Vec::new(),
trampoline_park: HashMap::new(),
signatures: SignatureRegistry::new(),
fn_builder_ctx: FunctionBuilderContext::new(),
strategy,
}
}
}
impl Drop for Compiler {
fn drop(&mut self) {
// We must deregister traps before freeing the code memory.
// Otherwise, we have a race:
// - Compiler #1 dropped code memory, but hasn't deregistered the trap yet
// - Compiler #2 allocated code memory and tries to register a trap,
// but the trap at certain address happens to be already registered,
// since Compiler #1 hasn't deregistered it yet => assertion in trap registry fails.
// Having a custom drop implementation we are independent from the field order
// in the struct what reduces potential human error.
self.trap_registration_guards.clear();
}
}
impl Compiler {
/// Return the target's frontend configuration settings.
pub fn frontend_config(&self) -> TargetFrontendConfig {
self.isa.frontend_config()
}
/// Return the tunables in use by this engine.
pub fn tunables(&self) -> Tunables {
target_tunables(self.isa.triple())
}
/// Compile the given function bodies.
pub(crate) fn compile<'data>(
&mut self,
module: &Module,
module_translation: &ModuleTranslationState,
function_body_inputs: PrimaryMap<DefinedFuncIndex, FunctionBodyData<'data>>,
debug_data: Option<DebugInfoData>,
) -> Result<
(
PrimaryMap<DefinedFuncIndex, *mut [VMFunctionBody]>,
PrimaryMap<DefinedFuncIndex, ir::JumpTableOffsets>,
Relocations,
Option<Vec<u8>>,
),
SetupError,
> {
let (compilation, relocations, address_transform, value_ranges, stack_slots, traps) =
match self.strategy {
// For now, interpret `Auto` as `Cranelift` since that's the most stable
// implementation.
CompilationStrategy::Auto | CompilationStrategy::Cranelift => {
wasmtime_environ::cranelift::Cranelift::compile_module(
module,
module_translation,
function_body_inputs,
&*self.isa,
debug_data.is_some(),
)
}
#[cfg(feature = "lightbeam")]
CompilationStrategy::Lightbeam => {
wasmtime_environ::lightbeam::Lightbeam::compile_module(
module,
module_translation,
function_body_inputs,
&*self.isa,
debug_data.is_some(),
)
}
}
.map_err(SetupError::Compile)?;
let allocated_functions =
allocate_functions(&mut self.code_memory, &compilation).map_err(|message| {
SetupError::Instantiate(InstantiationError::Resource(format!(
"failed to allocate memory for functions: {}",
message
)))
})?;
register_traps(
&allocated_functions,
&traps,
&mut self.trap_registration_guards,
);
let dbg = if let Some(debug_data) = debug_data {
let target_config = self.isa.frontend_config();
let triple = self.isa.triple().clone();
let mut funcs = Vec::new();
for (i, allocated) in allocated_functions.into_iter() {
let ptr = (*allocated) as *const u8;
let body_len = compilation.get(i).body.len();
funcs.push((ptr, body_len));
}
let module_vmctx_info = {
let ofs = VMOffsets::new(target_config.pointer_bytes(), &module);
let memory_offset =
ofs.vmctx_vmmemory_definition_base(DefinedMemoryIndex::new(0)) as i64;
ModuleVmctxInfo {
memory_offset,
stack_slots,
}
};
let bytes = emit_debugsections_image(
triple,
&target_config,
&debug_data,
&module_vmctx_info,
&address_transform,
&value_ranges,
&funcs,
)
.map_err(|e| SetupError::DebugInfo(e))?;
Some(bytes)
} else {
None
};
let jt_offsets = compilation.get_jt_offsets();
Ok((allocated_functions, jt_offsets, relocations, dbg))
}
/// Create a trampoline for invoking a function.
pub(crate) fn get_trampoline(
&mut self,
callee_address: *const VMFunctionBody,
signature: &ir::Signature,
value_size: usize,
) -> Result<*const VMFunctionBody, SetupError> {
use super::hash_map::Entry::{Occupied, Vacant};
Ok(match self.trampoline_park.entry(callee_address) {
Occupied(entry) => *entry.get(),
Vacant(entry) => {
let body = make_trampoline(
&*self.isa,
&mut self.code_memory,
&mut self.fn_builder_ctx,
callee_address,
signature,
value_size,
)?;
entry.insert(body);
body
}
})
}
/// Create and publish a trampoline for invoking a function.
pub fn get_published_trampoline(
&mut self,
callee_address: *const VMFunctionBody,
signature: &ir::Signature,
value_size: usize,
) -> Result<*const VMFunctionBody, SetupError> {
let result = self.get_trampoline(callee_address, signature, value_size)?;
self.publish_compiled_code();
Ok(result)
}
/// Make memory containing compiled code executable.
pub(crate) fn publish_compiled_code(&mut self) {
self.code_memory.publish();
}
/// Shared signature registry.
pub fn signatures(&mut self) -> &mut SignatureRegistry {
&mut self.signatures
}
}
/// Create a trampoline for invoking a function.
fn make_trampoline(
isa: &dyn TargetIsa,
code_memory: &mut CodeMemory,
fn_builder_ctx: &mut FunctionBuilderContext,
callee_address: *const VMFunctionBody,
signature: &ir::Signature,
value_size: usize,
) -> Result<*const VMFunctionBody, SetupError> {
let pointer_type = isa.pointer_type();
let mut wrapper_sig = ir::Signature::new(isa.frontend_config().default_call_conv);
// Add the `vmctx` parameter.
wrapper_sig.params.push(ir::AbiParam::special(
pointer_type,
ir::ArgumentPurpose::VMContext,
));
// Add the `values_vec` parameter.
wrapper_sig.params.push(ir::AbiParam::new(pointer_type));
let mut context = Context::new();
context.func = ir::Function::with_name_signature(ir::ExternalName::user(0, 0), wrapper_sig);
{
let mut builder = FunctionBuilder::new(&mut context.func, fn_builder_ctx);
let block0 = builder.create_ebb();
builder.append_ebb_params_for_function_params(block0);
builder.switch_to_block(block0);
builder.seal_block(block0);
let (vmctx_ptr_val, values_vec_ptr_val) = {
let params = builder.func.dfg.ebb_params(block0);
(params[0], params[1])
};
// Load the argument values out of `values_vec`.
let mflags = ir::MemFlags::trusted();
let callee_args = signature
.params
.iter()
.enumerate()
.map(|(i, r)| {
match r.purpose {
// i - 1 because vmctx isn't passed through `values_vec`.
ir::ArgumentPurpose::Normal => builder.ins().load(
r.value_type,
mflags,
values_vec_ptr_val,
((i - 1) * value_size) as i32,
),
ir::ArgumentPurpose::VMContext => vmctx_ptr_val,
other => panic!("unsupported argument purpose {}", other),
}
})
.collect::<Vec<_>>();
let new_sig = builder.import_signature(signature.clone());
// TODO: It's possible to make this a direct call. We just need Cranelift
// to support functions declared with an immediate integer address.
// ExternalName::Absolute(u64). Let's do it.
let callee_value = builder.ins().iconst(pointer_type, callee_address as i64);
let call = builder
.ins()
.call_indirect(new_sig, callee_value, &callee_args);
let results = builder.func.dfg.inst_results(call).to_vec();
// Store the return values into `values_vec`.
let mflags = ir::MemFlags::trusted();
for (i, r) in results.iter().enumerate() {
builder
.ins()
.store(mflags, *r, values_vec_ptr_val, (i * value_size) as i32);
}
builder.ins().return_(&[]);
builder.finalize()
}
let mut code_buf = Vec::new();
let mut unwind_info = Vec::new();
let mut reloc_sink = RelocSink {};
let mut trap_sink = binemit::NullTrapSink {};
let mut stackmap_sink = binemit::NullStackmapSink {};
context
.compile_and_emit(
isa,
&mut code_buf,
&mut reloc_sink,
&mut trap_sink,
&mut stackmap_sink,
)
.map_err(|error| SetupError::Compile(CompileError::Codegen(error)))?;
context.emit_unwind_info(isa, &mut unwind_info);
Ok(code_memory
.allocate_for_function(&CompiledFunction {
body: code_buf,
jt_offsets: context.func.jt_offsets,
unwind_info,
})
.map_err(|message| SetupError::Instantiate(InstantiationError::Resource(message)))?
.as_ptr())
}
fn allocate_functions(
code_memory: &mut CodeMemory,
compilation: &Compilation,
) -> Result<PrimaryMap<DefinedFuncIndex, *mut [VMFunctionBody]>, String> {
let fat_ptrs = code_memory.allocate_for_compilation(compilation)?;
// Second, create a PrimaryMap from result vector of pointers.
let mut result = PrimaryMap::with_capacity(compilation.len());
for i in 0..fat_ptrs.len() {
let fat_ptr: *mut [VMFunctionBody] = fat_ptrs[i];
result.push(fat_ptr);
}
Ok(result)
}
fn register_traps(
allocated_functions: &PrimaryMap<DefinedFuncIndex, *mut [VMFunctionBody]>,
traps: &Traps,
trap_registration_guards: &mut Vec<TrapRegistrationGuard>,
) {
let mut trap_registry = get_mut_trap_registry();
for (func_addr, func_traps) in allocated_functions.values().zip(traps.values()) {
for trap_desc in func_traps.iter() {
let func_addr = *func_addr as *const u8 as usize;
let offset = usize::try_from(trap_desc.code_offset).unwrap();
let trap_addr = func_addr + offset;
let guard =
trap_registry.register_trap(trap_addr, trap_desc.source_loc, trap_desc.trap_code);
trap_registration_guards.push(guard);
}
}
}
/// We don't expect trampoline compilation to produce any relocations, so
/// this `RelocSink` just asserts that it doesn't recieve any.
struct RelocSink {}
impl binemit::RelocSink for RelocSink {
fn reloc_ebb(
&mut self,
_offset: binemit::CodeOffset,
_reloc: binemit::Reloc,
_ebb_offset: binemit::CodeOffset,
) {
panic!("trampoline compilation should not produce ebb relocs");
}
fn reloc_external(
&mut self,
_offset: binemit::CodeOffset,
_reloc: binemit::Reloc,
_name: &ir::ExternalName,
_addend: binemit::Addend,
) {
panic!("trampoline compilation should not produce external symbol relocs");
}
fn reloc_constant(
&mut self,
_code_offset: binemit::CodeOffset,
_reloc: binemit::Reloc,
_constant_offset: ir::ConstantOffset,
) {
panic!("trampoline compilation should not produce constant relocs");
}
fn reloc_jt(
&mut self,
_offset: binemit::CodeOffset,
_reloc: binemit::Reloc,
_jt: ir::JumpTable,
) {
panic!("trampoline compilation should not produce jump table relocs");
}
}

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use crate::action::{get, inspect_memory, invoke};
use crate::HashMap;
use crate::{
instantiate, ActionError, ActionOutcome, CompilationStrategy, CompiledModule, Compiler,
InstanceHandle, Namespace, RuntimeValue, SetupError,
};
use alloc::boxed::Box;
use alloc::rc::Rc;
use alloc::string::{String, ToString};
use core::cell::RefCell;
use cranelift_codegen::isa::TargetIsa;
use thiserror::Error;
use wasmparser::{validate, OperatorValidatorConfig, ValidatingParserConfig};
/// Indicates an unknown instance was specified.
#[derive(Error, Debug)]
#[error("no instance {instance_name} present")]
pub struct UnknownInstance {
instance_name: String,
}
/// Error message used by `WastContext`.
#[derive(Error, Debug)]
pub enum ContextError {
/// An unknown instance name was used.
#[error("{0}")]
Instance(#[from] UnknownInstance),
/// An error occured while performing an action.
#[error("{0}")]
Action(#[from] ActionError),
}
/// The collection of features configurable during compilation
#[derive(Clone, Default)]
pub struct Features {
/// marks whether the proposed thread feature is enabled or disabled
pub threads: bool,
/// marks whether the proposed reference type feature is enabled or disabled
pub reference_types: bool,
/// marks whether the proposed SIMD feature is enabled or disabled
pub simd: bool,
/// marks whether the proposed bulk memory feature is enabled or disabled
pub bulk_memory: bool,
/// marks whether the proposed multi-value feature is enabled or disabled
pub multi_value: bool,
}
impl Into<ValidatingParserConfig> for Features {
fn into(self) -> ValidatingParserConfig {
ValidatingParserConfig {
operator_config: OperatorValidatorConfig {
enable_threads: self.threads,
enable_reference_types: self.reference_types,
enable_bulk_memory: self.bulk_memory,
enable_simd: self.simd,
enable_multi_value: self.multi_value,
},
}
}
}
/// A convenient context for compiling and executing WebAssembly instances.
pub struct Context {
namespace: Namespace,
compiler: Box<Compiler>,
global_exports: Rc<RefCell<HashMap<String, Option<wasmtime_runtime::Export>>>>,
debug_info: bool,
features: Features,
}
impl Context {
/// Construct a new instance of `Context`.
pub fn new(compiler: Box<Compiler>) -> Self {
Self {
namespace: Namespace::new(),
compiler,
global_exports: Rc::new(RefCell::new(HashMap::new())),
debug_info: false,
features: Default::default(),
}
}
/// Get debug_info settings.
pub fn debug_info(&self) -> bool {
self.debug_info
}
/// Set debug_info settings.
pub fn set_debug_info(&mut self, value: bool) {
self.debug_info = value;
}
/// Construct a new instance of `Context` with the given target.
pub fn with_isa(isa: Box<dyn TargetIsa>, strategy: CompilationStrategy) -> Self {
Self::new(Box::new(Compiler::new(isa, strategy)))
}
/// Retrieve the context features
pub fn features(&self) -> &Features {
&self.features
}
/// Construct a new instance with the given features from the current `Context`
pub fn with_features(self, features: Features) -> Self {
Self { features, ..self }
}
fn validate(&mut self, data: &[u8]) -> Result<(), String> {
// TODO: Fix Cranelift to be able to perform validation itself, rather
// than calling into wasmparser ourselves here.
validate(data, Some(self.features.clone().into()))
.map_err(|e| format!("module did not validate: {}", e.to_string()))
}
fn instantiate(&mut self, data: &[u8]) -> Result<InstanceHandle, SetupError> {
self.validate(&data).map_err(SetupError::Validate)?;
let debug_info = self.debug_info();
instantiate(
&mut *self.compiler,
&data,
&mut self.namespace,
Rc::clone(&self.global_exports),
debug_info,
)
}
/// Return the instance associated with the given name.
pub fn get_instance(
&mut self,
instance_name: &str,
) -> Result<&mut InstanceHandle, UnknownInstance> {
self.namespace
.get_instance(instance_name)
.ok_or_else(|| UnknownInstance {
instance_name: instance_name.to_string(),
})
}
/// Instantiate a module instance and register the instance.
pub fn instantiate_module(
&mut self,
instance_name: Option<String>,
data: &[u8],
) -> Result<InstanceHandle, ActionError> {
let instance = self.instantiate(data).map_err(ActionError::Setup)?;
self.optionally_name_instance(instance_name, instance.clone());
Ok(instance)
}
/// Compile a module.
pub fn compile_module(&mut self, data: &[u8]) -> Result<CompiledModule, SetupError> {
self.validate(&data).map_err(SetupError::Validate)?;
let debug_info = self.debug_info();
CompiledModule::new(
&mut *self.compiler,
data,
&mut self.namespace,
Rc::clone(&self.global_exports),
debug_info,
)
}
/// If `name` isn't None, register it for the given instance.
pub fn optionally_name_instance(&mut self, name: Option<String>, instance: InstanceHandle) {
if let Some(name) = name {
self.namespace.name_instance(name, instance);
}
}
/// Register a name for the given instance.
pub fn name_instance(&mut self, name: String, instance: InstanceHandle) {
self.namespace.name_instance(name, instance);
}
/// Register an additional name for an existing registered instance.
pub fn alias(&mut self, name: &str, as_name: String) -> Result<(), UnknownInstance> {
let instance = self.get_instance(&name)?.clone();
self.name_instance(as_name, instance);
Ok(())
}
/// Invoke an exported function from a named instance.
pub fn invoke_named(
&mut self,
instance_name: &str,
field: &str,
args: &[RuntimeValue],
) -> Result<ActionOutcome, ContextError> {
let mut instance = self
.get_instance(&instance_name)
.map_err(ContextError::Instance)?
.clone();
self.invoke(&mut instance, field, args)
.map_err(ContextError::Action)
}
/// Invoke an exported function from an instance.
pub fn invoke(
&mut self,
instance: &mut InstanceHandle,
field: &str,
args: &[RuntimeValue],
) -> Result<ActionOutcome, ActionError> {
invoke(&mut *self.compiler, instance, field, &args)
}
/// Get the value of an exported global variable from an instance.
pub fn get_named(
&mut self,
instance_name: &str,
field: &str,
) -> Result<ActionOutcome, ContextError> {
let instance = self
.get_instance(&instance_name)
.map_err(ContextError::Instance)?
.clone();
self.get(&instance, field).map_err(ContextError::Action)
}
/// Get the value of an exported global variable from an instance.
pub fn get(
&mut self,
instance: &InstanceHandle,
field: &str,
) -> Result<ActionOutcome, ActionError> {
get(instance, field).map(|value| ActionOutcome::Returned {
values: vec![value],
})
}
/// Get a slice of memory from an instance.
pub fn inspect_memory<'instance>(
&self,
instance: &'instance InstanceHandle,
field_name: &str,
start: usize,
len: usize,
) -> Result<&'instance [u8], ActionError> {
inspect_memory(instance, field_name, start, len)
}
/// Return a handle to the global_exports mapping, needed by some modules
/// for instantiation.
pub fn get_global_exports(
&mut self,
) -> Rc<RefCell<HashMap<String, Option<wasmtime_runtime::Export>>>> {
Rc::clone(&mut self.global_exports)
}
}

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//! Runtime function table.
//!
//! This module is primarily used to track JIT functions on Windows for stack walking and unwind.
/// Represents a runtime function table.
///
/// The runtime function table is not implemented for non-Windows target platforms.
#[cfg(not(target_os = "windows"))]
pub(crate) struct FunctionTable;
#[cfg(not(target_os = "windows"))]
impl FunctionTable {
/// Creates a new function table.
pub fn new() -> Self {
Self
}
/// Returns the number of functions in the table, also referred to as its 'length'.
///
/// For non-Windows platforms, the table will always be empty.
pub fn len(&self) -> usize {
0
}
/// Adds a function to the table based off of the start offset, end offset, and unwind offset.
///
/// The offsets are from the "module base", which is provided when the table is published.
///
/// For non-Windows platforms, this is a no-op.
pub fn add_function(&mut self, _start: u32, _end: u32, _unwind: u32) {}
/// Publishes the function table using the given base address.
///
/// A published function table will automatically be deleted when it is dropped.
///
/// For non-Windows platforms, this is a no-op.
pub fn publish(&mut self, _base_address: u64) -> Result<(), String> {
Ok(())
}
}
/// Represents a runtime function table.
///
/// This is used to register JIT code with the operating system to enable stack walking and unwinding.
#[cfg(all(target_os = "windows", target_arch = "x86_64"))]
pub(crate) struct FunctionTable {
functions: Vec<winapi::um::winnt::RUNTIME_FUNCTION>,
published: bool,
}
#[cfg(all(target_os = "windows", target_arch = "x86_64"))]
impl FunctionTable {
/// Creates a new function table.
pub fn new() -> Self {
Self {
functions: Vec::new(),
published: false,
}
}
/// Returns the number of functions in the table, also referred to as its 'length'.
pub fn len(&self) -> usize {
self.functions.len()
}
/// Adds a function to the table based off of the start offset, end offset, and unwind offset.
///
/// The offsets are from the "module base", which is provided when the table is published.
pub fn add_function(&mut self, start: u32, end: u32, unwind: u32) {
use winapi::um::winnt;
assert!(!self.published, "table has already been published");
let mut entry = winnt::RUNTIME_FUNCTION::default();
entry.BeginAddress = start;
entry.EndAddress = end;
unsafe {
*entry.u.UnwindInfoAddress_mut() = unwind;
}
self.functions.push(entry);
}
/// Publishes the function table using the given base address.
///
/// A published function table will automatically be deleted when it is dropped.
pub fn publish(&mut self, base_address: u64) -> Result<(), String> {
use winapi::um::winnt;
if self.published {
return Err("function table was already published".into());
}
self.published = true;
if self.functions.is_empty() {
return Ok(());
}
unsafe {
// Windows heap allocations are 32-bit aligned, but assert just in case
assert!(
(self.functions.as_mut_ptr() as u64) % 4 == 0,
"function table allocation was not aligned"
);
if winnt::RtlAddFunctionTable(
self.functions.as_mut_ptr(),
self.functions.len() as u32,
base_address,
) == 0
{
return Err("failed to add function table".into());
}
}
Ok(())
}
}
#[cfg(target_os = "windows")]
impl Drop for FunctionTable {
fn drop(&mut self) {
use winapi::um::winnt;
if self.published {
unsafe {
winnt::RtlDeleteFunctionTable(self.functions.as_mut_ptr());
}
}
}
}

282
crates/jit/src/instantiate.rs Normal file
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//! Define the `instantiate` function, which takes a byte array containing an
//! encoded wasm module and returns a live wasm instance. Also, define
//! `CompiledModule` to allow compiling and instantiating to be done as separate
//! steps.
use super::HashMap;
use crate::compiler::Compiler;
use crate::link::link_module;
use crate::resolver::Resolver;
use alloc::boxed::Box;
use alloc::rc::Rc;
use alloc::string::String;
use alloc::vec::Vec;
use core::cell::RefCell;
use cranelift_entity::{BoxedSlice, PrimaryMap};
use cranelift_wasm::{DefinedFuncIndex, SignatureIndex};
#[cfg(feature = "std")]
use std::io::Write;
use thiserror::Error;
use wasmtime_debug::read_debuginfo;
use wasmtime_environ::{
CompileError, DataInitializer, DataInitializerLocation, Module, ModuleEnvironment,
};
use wasmtime_runtime::{
Export, GdbJitImageRegistration, Imports, InstanceHandle, InstantiationError, VMFunctionBody,
VMSharedSignatureIndex,
};
/// An error condition while setting up a wasm instance, be it validation,
/// compilation, or instantiation.
#[derive(Error, Debug)]
pub enum SetupError {
/// The module did not pass validation.
#[error("Validation error: {0}")]
Validate(String),
/// A wasm translation error occured.
#[error("WebAssembly compilation error: {0}")]
Compile(#[from] CompileError),
/// Some runtime resource was unavailable or insufficient, or the start function
/// trapped.
#[error("Instantiation error: {0}")]
Instantiate(#[from] InstantiationError),
/// Debug information generation error occured.
#[error("Debug information error: {0}")]
DebugInfo(failure::Error),
}
/// This is similar to `CompiledModule`, but references the data initializers
/// from the wasm buffer rather than holding its own copy.
struct RawCompiledModule<'data> {
module: Module,
finished_functions: BoxedSlice<DefinedFuncIndex, *const VMFunctionBody>,
imports: Imports,
data_initializers: Box<[DataInitializer<'data>]>,
signatures: BoxedSlice<SignatureIndex, VMSharedSignatureIndex>,
dbg_jit_registration: Option<GdbJitImageRegistration>,
}
impl<'data> RawCompiledModule<'data> {
/// Create a new `RawCompiledModule` by compiling the wasm module in `data` and instatiating it.
fn new(
compiler: &mut Compiler,
data: &'data [u8],
resolver: &mut dyn Resolver,
debug_info: bool,
) -> Result<Self, SetupError> {
let environ = ModuleEnvironment::new(compiler.frontend_config(), compiler.tunables());
let translation = environ
.translate(data)
.map_err(|error| SetupError::Compile(CompileError::Wasm(error)))?;
let debug_data = if debug_info {
Some(read_debuginfo(&data))
} else {
None
};
let (allocated_functions, jt_offsets, relocations, dbg_image) = compiler.compile(
&translation.module,
translation.module_translation.as_ref().unwrap(),
translation.function_body_inputs,
debug_data,
)?;
let imports = link_module(
&translation.module,
&allocated_functions,
&jt_offsets,
relocations,
resolver,
)
.map_err(|err| SetupError::Instantiate(InstantiationError::Link(err)))?;
// Gather up the pointers to the compiled functions.
let finished_functions: BoxedSlice<DefinedFuncIndex, *const VMFunctionBody> =
allocated_functions
.into_iter()
.map(|(_index, allocated)| {
let fatptr: *const [VMFunctionBody] = *allocated;
fatptr as *const VMFunctionBody
})
.collect::<PrimaryMap<_, _>>()
.into_boxed_slice();
// Compute indices into the shared signature table.
let signatures = {
let signature_registry = compiler.signatures();
translation
.module
.signatures
.values()
.map(|sig| signature_registry.register(sig))
.collect::<PrimaryMap<_, _>>()
};
// Make all code compiled thus far executable.
compiler.publish_compiled_code();
#[cfg(feature = "std")]
let dbg_jit_registration = if let Some(img) = dbg_image {
let mut bytes = Vec::new();
bytes.write_all(&img).expect("all written");
let reg = GdbJitImageRegistration::register(bytes);
Some(reg)
} else {
None
};
Ok(Self {
module: translation.module,
finished_functions,
imports,
data_initializers: translation.data_initializers.into_boxed_slice(),
signatures: signatures.into_boxed_slice(),
dbg_jit_registration,
})
}
}
/// A compiled wasm module, ready to be instantiated.
pub struct CompiledModule {
module: Rc<Module>,
finished_functions: BoxedSlice<DefinedFuncIndex, *const VMFunctionBody>,
imports: Imports,
data_initializers: Box<[OwnedDataInitializer]>,
signatures: BoxedSlice<SignatureIndex, VMSharedSignatureIndex>,
global_exports: Rc<RefCell<HashMap<String, Option<Export>>>>,
dbg_jit_registration: Option<Rc<GdbJitImageRegistration>>,
}
impl CompiledModule {
/// Compile a data buffer into a `CompiledModule`, which may then be instantiated.
pub fn new<'data>(
compiler: &mut Compiler,
data: &'data [u8],
resolver: &mut dyn Resolver,
global_exports: Rc<RefCell<HashMap<String, Option<Export>>>>,
debug_info: bool,
) -> Result<Self, SetupError> {
let raw = RawCompiledModule::<'data>::new(compiler, data, resolver, debug_info)?;
Ok(Self::from_parts(
raw.module,
global_exports,
raw.finished_functions,
raw.imports,
raw.data_initializers
.iter()
.map(OwnedDataInitializer::new)
.collect::<Vec<_>>()
.into_boxed_slice(),
raw.signatures.clone(),
raw.dbg_jit_registration,
))
}
/// Construct a `CompiledModule` from component parts.
pub fn from_parts(
module: Module,
global_exports: Rc<RefCell<HashMap<String, Option<Export>>>>,
finished_functions: BoxedSlice<DefinedFuncIndex, *const VMFunctionBody>,
imports: Imports,
data_initializers: Box<[OwnedDataInitializer]>,
signatures: BoxedSlice<SignatureIndex, VMSharedSignatureIndex>,
dbg_jit_registration: Option<GdbJitImageRegistration>,
) -> Self {
Self {
module: Rc::new(module),
global_exports: Rc::clone(&global_exports),
finished_functions,
imports,
data_initializers,
signatures,
dbg_jit_registration: dbg_jit_registration.map(|r| Rc::new(r)),
}
}
/// Crate an `Instance` from this `CompiledModule`.
///
/// Note that if only one instance of this module is needed, it may be more
/// efficient to call the top-level `instantiate`, since that avoids copying
/// the data initializers.
pub fn instantiate(&mut self) -> Result<InstanceHandle, InstantiationError> {
let data_initializers = self
.data_initializers
.iter()
.map(|init| DataInitializer {
location: init.location.clone(),
data: &*init.data,
})
.collect::<Vec<_>>();
InstanceHandle::new(
Rc::clone(&self.module),
Rc::clone(&self.global_exports),
self.finished_functions.clone(),
self.imports.clone(),
&data_initializers,
self.signatures.clone(),
self.dbg_jit_registration.as_ref().map(|r| Rc::clone(&r)),
Box::new(()),
)
}
/// Return a reference-counting pointer to a module.
pub fn module(&self) -> Rc<Module> {
self.module.clone()
}
/// Return a reference to a module.
pub fn module_ref(&self) -> &Module {
&self.module
}
}
/// Similar to `DataInitializer`, but owns its own copy of the data rather
/// than holding a slice of the original module.
pub struct OwnedDataInitializer {
/// The location where the initialization is to be performed.
location: DataInitializerLocation,
/// The initialization data.
data: Box<[u8]>,
}
impl OwnedDataInitializer {
fn new(borrowed: &DataInitializer<'_>) -> Self {
Self {
location: borrowed.location.clone(),
data: borrowed.data.to_vec().into_boxed_slice(),
}
}
}
/// Create a new wasm instance by compiling the wasm module in `data` and instatiating it.
///
/// This is equivalent to createing a `CompiledModule` and calling `instantiate()` on it,
/// but avoids creating an intermediate copy of the data initializers.
pub fn instantiate(
compiler: &mut Compiler,
data: &[u8],
resolver: &mut dyn Resolver,
global_exports: Rc<RefCell<HashMap<String, Option<Export>>>>,
debug_info: bool,
) -> Result<InstanceHandle, SetupError> {
let raw = RawCompiledModule::new(compiler, data, resolver, debug_info)?;
InstanceHandle::new(
Rc::new(raw.module),
global_exports,
raw.finished_functions,
raw.imports,
&*raw.data_initializers,
raw.signatures,
raw.dbg_jit_registration.map(|r| Rc::new(r)),
Box::new(()),
)
.map_err(SetupError::Instantiate)
}

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//! JIT-style runtime for WebAssembly using Cranelift.
#![deny(missing_docs, trivial_numeric_casts, unused_extern_crates)]
#![warn(unused_import_braces)]
#![cfg_attr(feature = "std", deny(unstable_features))]
#![cfg_attr(feature = "clippy", plugin(clippy(conf_file = "../../clippy.toml")))]
#![cfg_attr(
feature = "cargo-clippy",
allow(clippy::new_without_default, clippy::new_without_default_derive)
)]
#![cfg_attr(
feature = "cargo-clippy",
warn(
clippy::float_arithmetic,
clippy::mut_mut,
clippy::nonminimal_bool,
clippy::option_map_unwrap_or,
clippy::option_map_unwrap_or_else,
clippy::print_stdout,
clippy::unicode_not_nfc,
clippy::use_self
)
)]
#[macro_use]
extern crate alloc;
#[cfg(not(feature = "std"))]
use hashbrown::{hash_map, HashMap, HashSet};
#[cfg(feature = "std")]
use std::collections::{hash_map, HashMap, HashSet};
mod action;
mod code_memory;
mod compiler;
mod context;
mod function_table;
mod instantiate;
mod link;
mod namespace;
mod resolver;
mod target_tunables;
pub use crate::action::{ActionError, ActionOutcome, RuntimeValue};
pub use crate::code_memory::CodeMemory;
pub use crate::compiler::{CompilationStrategy, Compiler};
pub use crate::context::{Context, ContextError, Features, UnknownInstance};
pub use crate::instantiate::{instantiate, CompiledModule, SetupError};
pub use crate::link::link_module;
pub use crate::namespace::Namespace;
pub use crate::resolver::{NullResolver, Resolver};
pub use crate::target_tunables::target_tunables;
// Re-export `InstanceHandle` so that users won't need to separately depend on
// wasmtime-runtime in common cases.
pub use wasmtime_runtime::{InstanceHandle, InstantiationError};
/// Version number of this crate.
pub const VERSION: &str = env!("CARGO_PKG_VERSION");

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//! Linking for JIT-compiled code.
use crate::resolver::Resolver;
use crate::HashSet;
use alloc::vec::Vec;
use core::ptr::write_unaligned;
use cranelift_codegen::binemit::Reloc;
use cranelift_codegen::ir::JumpTableOffsets;
use cranelift_entity::PrimaryMap;
use cranelift_wasm::{DefinedFuncIndex, Global, GlobalInit, Memory, Table, TableElementType};
use wasmtime_environ::{
MemoryPlan, MemoryStyle, Module, Relocation, RelocationTarget, Relocations, TablePlan,
};
use wasmtime_runtime::libcalls;
use wasmtime_runtime::{
Export, Imports, InstanceHandle, LinkError, VMFunctionBody, VMFunctionImport, VMGlobalImport,
VMMemoryImport, VMTableImport,
};
/// Links a module that has been compiled with `compiled_module` in `wasmtime-environ`.
pub fn link_module(
module: &Module,
allocated_functions: &PrimaryMap<DefinedFuncIndex, *mut [VMFunctionBody]>,
jt_offsets: &PrimaryMap<DefinedFuncIndex, JumpTableOffsets>,
relocations: Relocations,
resolver: &mut dyn Resolver,
) -> Result<Imports, LinkError> {
let mut dependencies = HashSet::new();
let mut function_imports = PrimaryMap::with_capacity(module.imported_funcs.len());
for (index, (ref module_name, ref field)) in module.imported_funcs.iter() {
match resolver.resolve(module_name, field) {
Some(export_value) => match export_value {
Export::Function {
address,
signature,
vmctx,
} => {
let import_signature = &module.signatures[module.functions[index]];
if signature != *import_signature {
// TODO: If the difference is in the calling convention,
// we could emit a wrapper function to fix it up.
return Err(LinkError(
format!("{}/{}: incompatible import type: exported function with signature {} incompatible with function import with signature {}",
module_name, field,
signature, import_signature)
));
}
dependencies.insert(unsafe { InstanceHandle::from_vmctx(vmctx) });
function_imports.push(VMFunctionImport {
body: address,
vmctx,
});
}
Export::Table { .. } | Export::Memory { .. } | Export::Global { .. } => {
return Err(LinkError(format!(
"{}/{}: incompatible import type: export incompatible with function import",
module_name, field
)));
}
},
None => {
return Err(LinkError(format!(
"{}/{}: unknown import function: function not provided",
module_name, field
)));
}
}
}
let mut table_imports = PrimaryMap::with_capacity(module.imported_tables.len());
for (index, (ref module_name, ref field)) in module.imported_tables.iter() {
match resolver.resolve(module_name, field) {
Some(export_value) => match export_value {
Export::Table {
definition,
vmctx,
table,
} => {
let import_table = &module.table_plans[index];
if !is_table_compatible(&table, import_table) {
return Err(LinkError(format!(
"{}/{}: incompatible import type: exported table incompatible with table import",
module_name, field,
)));
}
dependencies.insert(unsafe { InstanceHandle::from_vmctx(vmctx) });
table_imports.push(VMTableImport {
from: definition,
vmctx,
});
}
Export::Global { .. } | Export::Memory { .. } | Export::Function { .. } => {
return Err(LinkError(format!(
"{}/{}: incompatible import type: export incompatible with table import",
module_name, field
)));
}
},
None => {
return Err(LinkError(format!(
"unknown import: no provided import table for {}/{}",
module_name, field
)));
}
}
}
let mut memory_imports = PrimaryMap::with_capacity(module.imported_memories.len());
for (index, (ref module_name, ref field)) in module.imported_memories.iter() {
match resolver.resolve(module_name, field) {
Some(export_value) => match export_value {
Export::Memory {
definition,
vmctx,
memory,
} => {
let import_memory = &module.memory_plans[index];
if !is_memory_compatible(&memory, import_memory) {
return Err(LinkError(format!(
"{}/{}: incompatible import type: exported memory incompatible with memory import",
module_name, field
)));
}
// Sanity-check: Ensure that the imported memory has at least
// guard-page protections the importing module expects it to have.
match (memory.style, &import_memory.style) {
(
MemoryStyle::Static { bound },
MemoryStyle::Static {
bound: import_bound,
},
) => {
assert!(bound >= *import_bound);
}
_ => (),
}
assert!(memory.offset_guard_size >= import_memory.offset_guard_size);
dependencies.insert(unsafe { InstanceHandle::from_vmctx(vmctx) });
memory_imports.push(VMMemoryImport {
from: definition,
vmctx,
});
}
Export::Table { .. } | Export::Global { .. } | Export::Function { .. } => {
return Err(LinkError(format!(
"{}/{}: incompatible import type: export incompatible with memory import",
module_name, field
)));
}
},
None => {
return Err(LinkError(format!(
"unknown import: no provided import memory for {}/{}",
module_name, field
)));
}
}
}
let mut global_imports = PrimaryMap::with_capacity(module.imported_globals.len());
for (index, (ref module_name, ref field)) in module.imported_globals.iter() {
match resolver.resolve(module_name, field) {
Some(export_value) => match export_value {
Export::Table { .. } | Export::Memory { .. } | Export::Function { .. } => {
return Err(LinkError(format!(
"{}/{}: incompatible import type: exported global incompatible with global import",
module_name, field
)));
}
Export::Global {
definition,
vmctx,
global,
} => {
let imported_global = module.globals[index];
if !is_global_compatible(&global, &imported_global) {
return Err(LinkError(format!(
"{}/{}: incompatible import type: exported global incompatible with global import",
module_name, field
)));
}
dependencies.insert(unsafe { InstanceHandle::from_vmctx(vmctx) });
global_imports.push(VMGlobalImport { from: definition });
}
},
None => {
return Err(LinkError(format!(
"unknown import: no provided import global for {}/{}",
module_name, field
)));
}
}
}
// Apply relocations, now that we have virtual addresses for everything.
relocate(allocated_functions, jt_offsets, relocations, module);
Ok(Imports::new(
dependencies,
function_imports,
table_imports,
memory_imports,
global_imports,
))
}
fn is_global_compatible(exported: &Global, imported: &Global) -> bool {
match imported.initializer {
GlobalInit::Import => (),
_ => panic!("imported Global should have an Imported initializer"),
}
let Global {
ty: exported_ty,
mutability: exported_mutability,
initializer: _exported_initializer,
} = exported;
let Global {
ty: imported_ty,
mutability: imported_mutability,
initializer: _imported_initializer,
} = imported;
exported_ty == imported_ty && imported_mutability == exported_mutability
}
fn is_table_element_type_compatible(
exported_type: TableElementType,
imported_type: TableElementType,
) -> bool {
match exported_type {
TableElementType::Func => match imported_type {
TableElementType::Func => true,
_ => false,
},
TableElementType::Val(exported_val_ty) => match imported_type {
TableElementType::Val(imported_val_ty) => exported_val_ty == imported_val_ty,
_ => false,
},
}
}
fn is_table_compatible(exported: &TablePlan, imported: &TablePlan) -> bool {
let TablePlan {
table:
Table {
ty: exported_ty,
minimum: exported_minimum,
maximum: exported_maximum,
},
style: _exported_style,
} = exported;
let TablePlan {
table:
Table {
ty: imported_ty,
minimum: imported_minimum,
maximum: imported_maximum,
},
style: _imported_style,
} = imported;
is_table_element_type_compatible(*exported_ty, *imported_ty)
&& imported_minimum <= exported_minimum
&& (imported_maximum.is_none()
|| (!exported_maximum.is_none()
&& imported_maximum.unwrap() >= exported_maximum.unwrap()))
}
fn is_memory_compatible(exported: &MemoryPlan, imported: &MemoryPlan) -> bool {
let MemoryPlan {
memory:
Memory {
minimum: exported_minimum,
maximum: exported_maximum,
shared: exported_shared,
},
style: _exported_style,
offset_guard_size: _exported_offset_guard_size,
} = exported;
let MemoryPlan {
memory:
Memory {
minimum: imported_minimum,
maximum: imported_maximum,
shared: imported_shared,
},
style: _imported_style,
offset_guard_size: _imported_offset_guard_size,
} = imported;
imported_minimum <= exported_minimum
&& (imported_maximum.is_none()
|| (!exported_maximum.is_none()
&& imported_maximum.unwrap() >= exported_maximum.unwrap()))
&& exported_shared == imported_shared
}
/// Performs the relocations inside the function bytecode, provided the necessary metadata.
fn relocate(
allocated_functions: &PrimaryMap<DefinedFuncIndex, *mut [VMFunctionBody]>,
jt_offsets: &PrimaryMap<DefinedFuncIndex, JumpTableOffsets>,
relocations: PrimaryMap<DefinedFuncIndex, Vec<Relocation>>,
module: &Module,
) {
for (i, function_relocs) in relocations.into_iter() {
for r in function_relocs {
use self::libcalls::*;
let target_func_address: usize = match r.reloc_target {
RelocationTarget::UserFunc(index) => match module.defined_func_index(index) {
Some(f) => {
let fatptr: *const [VMFunctionBody] = allocated_functions[f];
fatptr as *const VMFunctionBody as usize
}
None => panic!("direct call to import"),
},
RelocationTarget::Memory32Grow => wasmtime_memory32_grow as usize,
RelocationTarget::Memory32Size => wasmtime_memory32_size as usize,
RelocationTarget::ImportedMemory32Grow => wasmtime_imported_memory32_grow as usize,
RelocationTarget::ImportedMemory32Size => wasmtime_imported_memory32_size as usize,
RelocationTarget::LibCall(libcall) => {
use cranelift_codegen::ir::LibCall::*;
match libcall {
CeilF32 => wasmtime_f32_ceil as usize,
FloorF32 => wasmtime_f32_floor as usize,
TruncF32 => wasmtime_f32_trunc as usize,
NearestF32 => wasmtime_f32_nearest as usize,
CeilF64 => wasmtime_f64_ceil as usize,
FloorF64 => wasmtime_f64_floor as usize,
TruncF64 => wasmtime_f64_trunc as usize,
NearestF64 => wasmtime_f64_nearest as usize,
#[cfg(not(target_os = "windows"))]
Probestack => __rust_probestack as usize,
#[cfg(all(target_os = "windows", target_env = "gnu"))]
Probestack => ___chkstk as usize,
#[cfg(all(
target_os = "windows",
target_env = "msvc",
target_pointer_width = "64"
))]
Probestack => __chkstk as usize,
other => panic!("unexpected libcall: {}", other),
}
}
RelocationTarget::JumpTable(func_index, jt) => {
match module.defined_func_index(func_index) {
Some(f) => {
let offset = *jt_offsets
.get(f)
.and_then(|ofs| ofs.get(jt))
.expect("func jump table");
let fatptr: *const [VMFunctionBody] = allocated_functions[f];
fatptr as *const VMFunctionBody as usize + offset as usize
}
None => panic!("func index of jump table"),
}
}
};
let fatptr: *const [VMFunctionBody] = allocated_functions[i];
let body = fatptr as *const VMFunctionBody;
match r.reloc {
#[cfg(target_pointer_width = "64")]
Reloc::Abs8 => unsafe {
let reloc_address = body.add(r.offset as usize) as usize;
let reloc_addend = r.addend as isize;
let reloc_abs = (target_func_address as u64)
.checked_add(reloc_addend as u64)
.unwrap();
write_unaligned(reloc_address as *mut u64, reloc_abs);
},
#[cfg(target_pointer_width = "32")]
Reloc::X86PCRel4 => unsafe {
let reloc_address = body.add(r.offset as usize) as usize;
let reloc_addend = r.addend as isize;
let reloc_delta_u32 = (target_func_address as u32)
.wrapping_sub(reloc_address as u32)
.checked_add(reloc_addend as u32)
.unwrap();
write_unaligned(reloc_address as *mut u32, reloc_delta_u32);
},
#[cfg(target_pointer_width = "32")]
Reloc::X86CallPCRel4 => {
// ignore
}
Reloc::X86PCRelRodata4 => {
// ignore
}
_ => panic!("unsupported reloc kind"),
}
}
}
}
/// A declaration for the stack probe function in Rust's standard library, for
/// catching callstack overflow.
extern "C" {
#[cfg(not(target_os = "windows"))]
pub fn __rust_probestack();
#[cfg(all(
target_os = "windows",
target_env = "msvc",
target_pointer_width = "64"
))]
pub fn __chkstk();
// ___chkstk (note the triple underscore) is implemented in compiler-builtins/src/x86_64.rs
// by the Rust compiler for the MinGW target
#[cfg(all(target_os = "windows", target_env = "gnu",))]
pub fn ___chkstk();
}

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//! The core WebAssembly spec does not specify how imports are to be resolved
//! to exports. This file provides one possible way to manage multiple instances
//! and resolve imports to exports among them.
use super::HashMap;
use crate::resolver::Resolver;
use alloc::string::String;
use wasmtime_runtime::{Export, InstanceHandle};
/// A namespace containing instances keyed by name.
///
/// Note that `Namespace` implements the `Resolver` trait, so it can resolve
/// imports using defined exports.
pub struct Namespace {
/// Mapping from identifiers to indices in `self.instances`.
names: HashMap<String, InstanceHandle>,
}
impl Namespace {
/// Construct a new `Namespace`.
pub fn new() -> Self {
Self {
names: HashMap::new(),
}
}
/// Install a new `InstanceHandle` in this `Namespace`, optionally with the
/// given name.
pub fn name_instance(&mut self, name: String, instance: InstanceHandle) {
self.names.insert(name, instance);
}
/// Get the instance registered with the given `instance_name`.
pub fn get_instance(&mut self, name: &str) -> Option<&mut InstanceHandle> {
self.names.get_mut(name)
}
}
impl Resolver for Namespace {
fn resolve(&mut self, name: &str, field: &str) -> Option<Export> {
if let Some(instance) = self.names.get_mut(name) {
instance.lookup(field)
} else {
None
}
}
}

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crates/jit/src/resolver.rs Normal file
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//! Define the `Resolver` trait, allowing custom resolution for external
//! references.
use wasmtime_runtime::Export;
/// Import resolver connects imports with available exported values.
pub trait Resolver {
/// Resolve the given module/field combo.
fn resolve(&mut self, module: &str, field: &str) -> Option<Export>;
}
/// `Resolver` implementation that always resolves to `None`.
pub struct NullResolver {}
impl Resolver for NullResolver {
fn resolve(&mut self, _module: &str, _field: &str) -> Option<Export> {
None
}
}

22
crates/jit/src/target_tunables.rs Normal file
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use core::cmp::min;
use target_lexicon::{OperatingSystem, Triple};
use wasmtime_environ::Tunables;
/// Return a `Tunables` instance tuned for the given target platform.
pub fn target_tunables(triple: &Triple) -> Tunables {
let mut result = Tunables::default();
match triple.operating_system {
OperatingSystem::Windows => {
// For now, use a smaller footprint on Windows so that we don't
// don't outstrip the paging file.
// TODO: Make this configurable.
result.static_memory_bound = min(result.static_memory_bound, 0x100);
result.static_memory_offset_guard_size =
min(result.static_memory_offset_guard_size, 0x10000);
}
_ => {}
}
result
}