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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -8,4 +8,15 @@ authors = ["The Wasmer Engineering Team <[email protected]>"] | |
| edition = "2018" | ||
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| [dependencies] | ||
| wasmer-runtime-core = { path = "../runtime-core", version = "0.4.2" } | ||
| wasmer-runtime-core = { path = "../runtime-core" } | ||
| wasmer-clif-backend = { path = "../clif-backend", version = "0.4.2" } | ||
| wasmer-llvm-backend = { path = "../llvm-backend", version = "0.4.2", optional = true } | ||
| wasmer-singlepass-backend = { path = "../singlepass-backend", version = "0.4.2", optional = true } | ||
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|
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| [dev-dependencies] | ||
| wabt = "0.7.4" | ||
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| [features] | ||
| clif = [] | ||
| llvm = ["wasmer-llvm-backend"] | ||
| singlepass = ["wasmer-singlepass-backend"] | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,3 +1,4 @@ | ||
| #![deny(unused_imports, unused_variables, unused_unsafe, unreachable_patterns)] | ||
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| pub mod call_trace; | ||
| pub mod metering; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,281 @@ | ||
| use wasmer_runtime_core::{ | ||
| codegen::{Event, EventSink, FunctionMiddleware, InternalEvent}, | ||
| module::ModuleInfo, | ||
| vm::InternalField, | ||
| wasmparser::{Operator, Type as WpType}, | ||
| Instance, | ||
| }; | ||
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| static INTERNAL_FIELD: InternalField = InternalField::allocate(); | ||
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| /// Metering is a compiler middleware that calculates the cost of WebAssembly instructions at compile | ||
| /// time and will count the cost of executed instructions at runtime. Within the Metering functionality, | ||
| /// this instruction cost is called `points`. | ||
| /// | ||
| /// The Metering struct takes a `limit` parameter which is the maximum number of points which can be | ||
| /// used by an instance during a function call. If this limit is exceeded, the function call will | ||
| /// trap. Each instance has a `points_used` field which can be used to track points used during | ||
| /// a function call and should be set back to zero after a function call. | ||
| /// | ||
| /// Each compiler backend with Metering enabled should produce the same cost used at runtime for | ||
| /// the same function calls so we can say that the metering is deterministic. | ||
| /// | ||
| pub struct Metering { | ||
| limit: u64, | ||
| current_block: u64, | ||
| } | ||
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|
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| impl Metering { | ||
| pub fn new(limit: u64) -> Metering { | ||
| Metering { | ||
| limit, | ||
| current_block: 0, | ||
| } | ||
| } | ||
| } | ||
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| #[derive(Copy, Clone, Debug)] | ||
| pub struct ExecutionLimitExceededError; | ||
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| impl FunctionMiddleware for Metering { | ||
| type Error = String; | ||
| fn feed_event<'a, 'b: 'a>( | ||
| &mut self, | ||
| op: Event<'a, 'b>, | ||
| _module_info: &ModuleInfo, | ||
| sink: &mut EventSink<'a, 'b>, | ||
| ) -> Result<(), Self::Error> { | ||
| match op { | ||
| Event::Internal(InternalEvent::FunctionBegin(_)) => { | ||
| self.current_block = 0; | ||
| } | ||
| Event::Wasm(&ref op) | Event::WasmOwned(ref op) => { | ||
| self.current_block += 1; | ||
| match *op { | ||
| Operator::Loop { .. } | ||
| | Operator::Block { .. } | ||
| | Operator::End | ||
| | Operator::If { .. } | ||
| | Operator::Else | ||
| | Operator::Unreachable | ||
| | Operator::Br { .. } | ||
| | Operator::BrTable { .. } | ||
| | Operator::BrIf { .. } | ||
| | Operator::Call { .. } | ||
| | Operator::CallIndirect { .. } | ||
| | Operator::Return => { | ||
| sink.push(Event::Internal(InternalEvent::GetInternal( | ||
| INTERNAL_FIELD.index() as _, | ||
| ))); | ||
| sink.push(Event::WasmOwned(Operator::I64Const { | ||
| value: self.current_block as i64, | ||
| })); | ||
| sink.push(Event::WasmOwned(Operator::I64Add)); | ||
| sink.push(Event::Internal(InternalEvent::SetInternal( | ||
| INTERNAL_FIELD.index() as _, | ||
| ))); | ||
| self.current_block = 0; | ||
| } | ||
| _ => {} | ||
| } | ||
| match *op { | ||
| Operator::Br { .. } | ||
| | Operator::BrTable { .. } | ||
| | Operator::BrIf { .. } | ||
| | Operator::Call { .. } | ||
| | Operator::CallIndirect { .. } => { | ||
| sink.push(Event::Internal(InternalEvent::GetInternal( | ||
| INTERNAL_FIELD.index() as _, | ||
| ))); | ||
| sink.push(Event::WasmOwned(Operator::I64Const { | ||
| value: self.limit as i64, | ||
| })); | ||
| sink.push(Event::WasmOwned(Operator::I64GeU)); | ||
| sink.push(Event::WasmOwned(Operator::If { | ||
| ty: WpType::EmptyBlockType, | ||
| })); | ||
| sink.push(Event::Internal(InternalEvent::Breakpoint(Box::new( | ||
| move |ctx| unsafe { | ||
| (ctx.throw)(Box::new(ExecutionLimitExceededError)); | ||
| }, | ||
| )))); | ||
| sink.push(Event::WasmOwned(Operator::End)); | ||
| } | ||
| _ => {} | ||
| } | ||
| } | ||
| _ => {} | ||
| } | ||
| sink.push(op); | ||
| Ok(()) | ||
| } | ||
| } | ||
|
|
||
| /// Returns the number of points used by a function call for metering | ||
| pub fn get_points_used(instance: &Instance) -> u64 { | ||
| instance.get_internal(&INTERNAL_FIELD) | ||
| } | ||
|
|
||
| /// Sets the value of points used | ||
| pub fn set_points_used(instance: &mut Instance, value: u64) { | ||
| instance.set_internal(&INTERNAL_FIELD, value); | ||
| } | ||
|
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||
| #[cfg(all(test, feature = "singlepass"))] | ||
| mod tests { | ||
| use super::*; | ||
| use wabt::wat2wasm; | ||
|
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||
| use wasmer_runtime_core::{backend::Compiler, compile_with, imports, Func}; | ||
|
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| #[cfg(feature = "llvm")] | ||
| fn get_compiler(limit: u64) -> impl Compiler { | ||
| use wasmer_llvm_backend::code::LLVMModuleCodeGenerator; | ||
| use wasmer_runtime_core::codegen::{MiddlewareChain, StreamingCompiler}; | ||
| let c: StreamingCompiler<LLVMModuleCodeGenerator, _, _, _, _> = | ||
| StreamingCompiler::new(move || { | ||
| let mut chain = MiddlewareChain::new(); | ||
| chain.push(Metering::new(limit)); | ||
| chain | ||
| }); | ||
| c | ||
| } | ||
|
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||
| #[cfg(feature = "singlepass")] | ||
| fn get_compiler(limit: u64) -> impl Compiler { | ||
| use wasmer_runtime_core::codegen::{MiddlewareChain, StreamingCompiler}; | ||
| use wasmer_singlepass_backend::ModuleCodeGenerator as SinglePassMCG; | ||
| let c: StreamingCompiler<SinglePassMCG, _, _, _, _> = StreamingCompiler::new(move || { | ||
| let mut chain = MiddlewareChain::new(); | ||
| chain.push(Metering::new(limit)); | ||
| chain | ||
| }); | ||
| c | ||
| } | ||
|
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| #[cfg(not(any(feature = "llvm", feature = "clif", feature = "singlepass")))] | ||
| fn get_compiler(_limit: u64) -> impl Compiler { | ||
| panic!("compiler not specified, activate a compiler via features"); | ||
| use wasmer_clif_backend::CraneliftCompiler; | ||
| CraneliftCompiler::new() | ||
| } | ||
|
|
||
| #[cfg(feature = "clif")] | ||
| fn get_compiler(_limit: u64) -> impl Compiler { | ||
| panic!("cranelift does not implement metering"); | ||
| use wasmer_clif_backend::CraneliftCompiler; | ||
| CraneliftCompiler::new() | ||
| } | ||
|
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| // Assemblyscript | ||
| // export function add_to(x: i32, y: i32): i32 { | ||
| // for(var i = 0; i < x; i++){ | ||
| // if(i % 1 == 0){ | ||
| // y += i; | ||
| // } else { | ||
| // y *= i | ||
| // } | ||
| // } | ||
| // return y; | ||
| // } | ||
| static WAT: &'static str = r#" | ||
| (module | ||
| (type $t0 (func (param i32 i32) (result i32))) | ||
| (type $t1 (func)) | ||
| (func $add_to (export "add_to") (type $t0) (param $p0 i32) (param $p1 i32) (result i32) | ||
| (local $l0 i32) | ||
| block $B0 | ||
| i32.const 0 | ||
| set_local $l0 | ||
| loop $L1 | ||
| get_local $l0 | ||
| get_local $p0 | ||
| i32.lt_s | ||
| i32.eqz | ||
| br_if $B0 | ||
| get_local $l0 | ||
| i32.const 1 | ||
| i32.rem_s | ||
| i32.const 0 | ||
| i32.eq | ||
| if $I2 | ||
| get_local $p1 | ||
| get_local $l0 | ||
| i32.add | ||
| set_local $p1 | ||
| else | ||
| get_local $p1 | ||
| get_local $l0 | ||
| i32.mul | ||
| set_local $p1 | ||
| end | ||
| get_local $l0 | ||
| i32.const 1 | ||
| i32.add | ||
| set_local $l0 | ||
| br $L1 | ||
| unreachable | ||
| end | ||
| unreachable | ||
| end | ||
| get_local $p1) | ||
| (func $f1 (type $t1)) | ||
| (table $table (export "table") 1 anyfunc) | ||
| (memory $memory (export "memory") 0) | ||
| (global $g0 i32 (i32.const 8)) | ||
| (elem (i32.const 0) $f1)) | ||
| "#; | ||
|
|
||
| #[test] | ||
| fn test_points_reduced_after_call() { | ||
| let wasm_binary = wat2wasm(WAT).unwrap(); | ||
|
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| let limit = 100u64; | ||
|
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| let module = compile_with(&wasm_binary, &get_compiler(limit)).unwrap(); | ||
|
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| let import_object = imports! {}; | ||
| let mut instance = module.instantiate(&import_object).unwrap(); | ||
|
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| set_points_used(&mut instance, 0u64); | ||
|
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| let add_to: Func<(i32, i32), i32> = instance.func("add_to").unwrap(); | ||
| let value = add_to.call(3, 4).unwrap(); | ||
|
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| // verify it returns the correct value | ||
| assert_eq!(value, 7); | ||
|
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| // verify is uses the correct number of points | ||
| assert_eq!(get_points_used(&instance), 74); | ||
| } | ||
|
|
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| #[test] | ||
| fn test_traps_after_costly_call() { | ||
| use wasmer_runtime_core::error::RuntimeError; | ||
| let wasm_binary = wat2wasm(WAT).unwrap(); | ||
|
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| let limit = 100u64; | ||
|
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| let module = compile_with(&wasm_binary, &get_compiler(limit)).unwrap(); | ||
|
|
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| let import_object = imports! {}; | ||
| let mut instance = module.instantiate(&import_object).unwrap(); | ||
|
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| set_points_used(&mut instance, 0u64); | ||
|
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| let add_to: Func<(i32, i32), i32> = instance.func("add_to").unwrap(); | ||
| let result = add_to.call(10_000_000, 4); | ||
|
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| let err = result.unwrap_err(); | ||
| match err { | ||
| RuntimeError::Error { data } => { | ||
| assert!(data.downcast_ref::<ExecutionLimitExceededError>().is_some()); | ||
| } | ||
| _ => unreachable!(), | ||
| } | ||
|
|
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| // verify is uses the correct number of points | ||
| assert_eq!(get_points_used(&instance), 109); // Used points will be slightly more than `limit` because of the way we do gas checking. | ||
| } | ||
|
|
||
| } |
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