T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Remove global state for trap registration (#909)

Browse Source 
* Remove global state for trap registration

There's a number of changes brought about in this commit, motivated by a
few things. One motivation was to remove an instance of using
`lazy_static!` in an effort to remove global state and encapsulate it
wherever possible. A second motivation came when investigating a
slowly-compiling wasm module (a bit too slowly) where a good chunk of
time was spent in managing trap registrations.

The specific change made here is that `TrapRegistry` is now stored
inside of a `Compiler` instead of inside a global. Additionally traps
are "bulk registered" for a module rather than one-by-one. This form of
bulk-registration allows optimizing the locks used here, where a lock is
only held for a module at-a-time instead of once-per-function.

With these changes the "unregister" logic has also been tweaked a bit
here and there to continue to work. As a nice side effect the `Compiler`
type now has one fewer field that requires actual mutability and has
been updated for multi-threaded compilation, nudging us closer to a
world where we can support multi-threaded compilation. Yay!

In terms of performance improvements, a local wasm test file that
previously took 3 seconds to compile is now 10% faster to compile,
taking ~2.7 seconds now.

* Perform trap resolution after unwinding

This avoids taking locks in signal handlers which feels a bit iffy...

* Remove `TrapRegistration::dummy()`

Avoid an case where you're trying to lookup trap information from a
dummy module for something that happened in a different module.

* Tweak some comments
This commit is contained in:
Alex Crichton
2020-02-06 12:40:50 -06:00
committed by GitHub
parent 9dffaf9d57
commit 348c597a8e
14 changed files with 233 additions and 131 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
crates/api/src/externals.rs
View File

@@ -181,7 +181,7 @@ impl Global {
if val.ty() != *ty.content() {
bail!("value provided does not match the type of this global");
}
let (wasmtime_export, wasmtime_state) = generate_global_export(&ty, val)?;
let (wasmtime_export, wasmtime_state) = generate_global_export(store, &ty, val)?;
Ok(Global {
inner: Rc::new(GlobalInner {
_store: store.clone(),
@@ -321,7 +321,7 @@ impl Table {
/// Returns an error if `init` does not match the element type of the table.
pub fn new(store: &Store, ty: TableType, init: Val) -> Result<Table> {
let item = into_checked_anyfunc(init, store)?;
let (mut wasmtime_handle, wasmtime_export) = generate_table_export(&ty)?;
let (mut wasmtime_handle, wasmtime_export) = generate_table_export(store, &ty)?;
// Initialize entries with the init value.
match wasmtime_export {
@@ -473,7 +473,7 @@ impl Memory {
/// type's configuration. All WebAssembly memory is initialized to zero.
pub fn new(store: &Store, ty: MemoryType) -> Memory {
let (wasmtime_handle, wasmtime_export) =
generate_memory_export(&ty).expect("generated memory");
generate_memory_export(store, &ty).expect("generated memory");
Memory {
_store: store.clone(),
ty,

11
crates/api/src/trampoline/create_handle.rs
View File

@@ -12,7 +12,7 @@ use wasmtime_runtime::{Imports, InstanceHandle, VMFunctionBody};
pub(crate) fn create_handle(
module: Module,
store: Option<&Store>,
store: &Store,
finished_functions: PrimaryMap<DefinedFuncIndex, *const VMFunctionBody>,
state: Box<dyn Any>,
) -> Result<InstanceHandle> {
@@ -26,19 +26,16 @@ pub(crate) fn create_handle(
let data_initializers = Vec::new();
// Compute indices into the shared signature table.
let signatures = store
.map(|store| {
module
let signatures = module
.signatures
.values()
.map(|sig| store.compiler().signatures().register(sig))
.collect::<PrimaryMap<_, _>>()
})
.unwrap_or_else(PrimaryMap::new);
.collect::<PrimaryMap<_, _>>();
unsafe {
Ok(InstanceHandle::new(
Arc::new(module),
store.compiler().trap_registry().register_traps(Vec::new()),
finished_functions.into_boxed_slice(),
imports,
&data_initializers,

4
crates/api/src/trampoline/func.rs
View File

@@ -287,7 +287,7 @@ pub fn create_handle_with_function(
create_handle(
module,
Some(store),
store,
finished_functions,
Box::new(trampoline_state),
)
@@ -322,5 +322,5 @@ pub unsafe fn create_handle_with_raw_function(
.insert("trampoline".to_string(), Export::Function(func_id));
finished_functions.push(func);
create_handle(module, Some(store), finished_functions, state)
create_handle(module, store, finished_functions, state)
}

9
crates/api/src/trampoline/global.rs
View File

@@ -1,4 +1,5 @@
use super::create_handle::create_handle;
use crate::Store;
use crate::{GlobalType, Mutability, Val};
use anyhow::{bail, Result};
use wasmtime_environ::entity::PrimaryMap;
@@ -11,7 +12,11 @@ pub struct GlobalState {
handle: InstanceHandle,
}
pub fn create_global(gt: &GlobalType, val: Val) -> Result<(wasmtime_runtime::Export, GlobalState)> {
pub fn create_global(
store: &Store,
gt: &GlobalType,
val: Val,
) -> Result<(wasmtime_runtime::Export, GlobalState)> {
let mut definition = Box::new(VMGlobalDefinition::new());
unsafe {
match val {
@@ -35,7 +40,7 @@ pub fn create_global(gt: &GlobalType, val: Val) -> Result<(wasmtime_runtime::Exp
initializer: wasm::GlobalInit::Import, // TODO is it right?
};
let handle =
create_handle(Module::new(), None, PrimaryMap::new(), Box::new(())).expect("handle");
create_handle(Module::new(), store, PrimaryMap::new(), Box::new(())).expect("handle");
Ok((
wasmtime_runtime::Export::Global {
definition: definition.as_mut(),

7
crates/api/src/trampoline/memory.rs
View File

@@ -1,13 +1,12 @@
use super::create_handle::create_handle;
use crate::MemoryType;
use crate::Store;
use anyhow::Result;
use wasmtime_environ::entity::PrimaryMap;
use wasmtime_environ::{wasm, Module};
use wasmtime_runtime::InstanceHandle;
#[allow(dead_code)]
pub fn create_handle_with_memory(memory: &MemoryType) -> Result<InstanceHandle> {
pub fn create_handle_with_memory(store: &Store, memory: &MemoryType) -> Result<InstanceHandle> {
let mut module = Module::new();
let memory = wasm::Memory {
@@ -24,5 +23,5 @@ pub fn create_handle_with_memory(memory: &MemoryType) -> Result<InstanceHandle>
wasmtime_environ::Export::Memory(memory_id),
);
create_handle(module, None, PrimaryMap::new(), Box::new(()))
create_handle(module, store, PrimaryMap::new(), Box::new(()))
}

9
crates/api/src/trampoline/mod.rs
View File

@@ -43,24 +43,27 @@ pub unsafe fn generate_raw_func_export(
}
pub fn generate_global_export(
store: &Store,
gt: &GlobalType,
val: Val,
) -> Result<(wasmtime_runtime::Export, GlobalState)> {
create_global(gt, val)
create_global(store, gt, val)
}
pub fn generate_memory_export(
store: &Store,
m: &MemoryType,
) -> Result<(wasmtime_runtime::InstanceHandle, wasmtime_runtime::Export)> {
let instance = create_handle_with_memory(m)?;
let instance = create_handle_with_memory(store, m)?;
let export = instance.lookup("memory").expect("memory export");
Ok((instance, export))
}
pub fn generate_table_export(
store: &Store,
t: &TableType,
) -> Result<(wasmtime_runtime::InstanceHandle, wasmtime_runtime::Export)> {
let instance = create_handle_with_table(t)?;
let instance = create_handle_with_table(store, t)?;
let export = instance.lookup("table").expect("table export");
Ok((instance, export))
}

5
crates/api/src/trampoline/table.rs
View File

@@ -1,11 +1,12 @@
use super::create_handle::create_handle;
use crate::Store;
use crate::{TableType, ValType};
use anyhow::{bail, Result};
use wasmtime_environ::entity::PrimaryMap;
use wasmtime_environ::{wasm, Module};
use wasmtime_runtime::InstanceHandle;
pub fn create_handle_with_table(table: &TableType) -> Result<InstanceHandle> {
pub fn create_handle_with_table(store: &Store, table: &TableType) -> Result<InstanceHandle> {
let mut module = Module::new();
let table = wasm::Table {
@@ -25,5 +26,5 @@ pub fn create_handle_with_table(table: &TableType) -> Result<InstanceHandle> {
wasmtime_environ::Export::Table(table_id),
);
create_handle(module, None, PrimaryMap::new(), Box::new(()))
create_handle(module, store, PrimaryMap::new(), Box::new(()))
}

6
crates/api/tests/traps.rs
View File

@@ -63,7 +63,11 @@ fn test_trap_trace() -> Result<()> {
assert_eq!(trace[1].module_name().unwrap(), "hello_mod");
assert_eq!(trace[1].func_index(), 0);
assert_eq!(trace[1].func_name(), None);
assert!(e.message().contains("unreachable"));
assert!(
e.message().contains("unreachable"),
"wrong message: {}",
e.message()
);
Ok(())
}

60
crates/jit/src/compiler.rs
View File

@@ -21,8 +21,8 @@ use wasmtime_environ::{
VMOffsets,
};
use wasmtime_runtime::{
get_mut_trap_registry, jit_function_registry, InstantiationError, SignatureRegistry,
TrapRegistrationGuard, VMFunctionBody,
jit_function_registry, InstantiationError, SignatureRegistry, TrapRegistration, TrapRegistry,
VMFunctionBody,
};
/// Select which kind of compilation to use.
@@ -51,8 +51,8 @@ pub struct Compiler {
isa: Box<dyn TargetIsa>,
code_memory: CodeMemory,
trap_registration_guards: Vec<TrapRegistrationGuard>,
jit_function_ranges: Vec<(usize, usize)>,
trap_registry: TrapRegistry,
trampoline_park: HashMap<*const VMFunctionBody, *const VMFunctionBody>,
signatures: SignatureRegistry,
strategy: CompilationStrategy,
@@ -67,28 +67,18 @@ impl Compiler {
Self {
isa,
code_memory: CodeMemory::new(),
trap_registration_guards: Vec::new(),
jit_function_ranges: Vec::new(),
trampoline_park: HashMap::new(),
signatures: SignatureRegistry::new(),
fn_builder_ctx: FunctionBuilderContext::new(),
strategy,
trap_registry: TrapRegistry::default(),
}
}
}
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();
for (start, end) in self.jit_function_ranges.iter() {
jit_function_registry::unregister(*start, *end);
}
@@ -119,6 +109,7 @@ impl Compiler {
PrimaryMap<DefinedFuncIndex, ir::JumpTableOffsets>,
Relocations,
Option<Vec<u8>>,
TrapRegistration,
),
SetupError,
> {
@@ -156,11 +147,7 @@ impl Compiler {
)))
})?;
register_traps(
&allocated_functions,
&traps,
&mut self.trap_registration_guards,
);
let trap_registration = register_traps(&allocated_functions, &traps, &self.trap_registry);
for (i, allocated) in allocated_functions.iter() {
let ptr = (*allocated) as *const VMFunctionBody;
@@ -217,7 +204,13 @@ impl Compiler {
let jt_offsets = compilation.get_jt_offsets();
Ok((allocated_functions, jt_offsets, relocations, dbg))
Ok((
allocated_functions,
jt_offsets,
relocations,
dbg,
trap_registration,
))
}
/// Create a trampoline for invoking a function.
@@ -267,6 +260,11 @@ impl Compiler {
pub fn signatures(&self) -> &SignatureRegistry {
&self.signatures
}
/// Shared registration of trap information
pub fn trap_registry(&self) -> &TrapRegistry {
&self.trap_registry
}
}
/// Create a trampoline for invoking a function.
@@ -408,19 +406,21 @@ fn allocate_functions(
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() {
registry: &TrapRegistry,
) -> TrapRegistration {
let traps =
allocated_functions
.values()
.zip(traps.values())
.flat_map(|(func_addr, func_traps)| {
func_traps.iter().map(move |trap_desc| {
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);
}
}
(trap_addr, trap_desc.source_loc, trap_desc.trap_code)
})
});
registry.register_traps(traps)
}
/// We don't expect trampoline compilation to produce any relocations, so

12
crates/jit/src/instantiate.rs
View File

@@ -18,7 +18,7 @@ use wasmtime_environ::{
CompileError, DataInitializer, DataInitializerLocation, Module, ModuleEnvironment,
};
use wasmtime_runtime::{
GdbJitImageRegistration, InstanceHandle, InstantiationError, VMFunctionBody,
GdbJitImageRegistration, InstanceHandle, InstantiationError, TrapRegistration, VMFunctionBody,
VMSharedSignatureIndex,
};
@@ -52,6 +52,7 @@ struct RawCompiledModule<'data> {
data_initializers: Box<[DataInitializer<'data>]>,
signatures: BoxedSlice<SignatureIndex, VMSharedSignatureIndex>,
dbg_jit_registration: Option<GdbJitImageRegistration>,
trap_registration: TrapRegistration,
}
impl<'data> RawCompiledModule<'data> {
@@ -73,7 +74,8 @@ impl<'data> RawCompiledModule<'data> {
None
};
let (allocated_functions, jt_offsets, relocations, dbg_image) = compiler.compile(
let (allocated_functions, jt_offsets, relocations, dbg_image, trap_registration) = compiler
.compile(
&translation.module,
translation.module_translation.as_ref().unwrap(),
translation.function_body_inputs,
@@ -127,6 +129,7 @@ impl<'data> RawCompiledModule<'data> {
data_initializers: translation.data_initializers.into_boxed_slice(),
signatures: signatures.into_boxed_slice(),
dbg_jit_registration,
trap_registration,
})
}
}
@@ -138,6 +141,7 @@ pub struct CompiledModule {
data_initializers: Box<[OwnedDataInitializer]>,
signatures: BoxedSlice<SignatureIndex, VMSharedSignatureIndex>,
dbg_jit_registration: Option<Rc<GdbJitImageRegistration>>,
trap_registration: TrapRegistration,
}
impl CompiledModule {
@@ -159,6 +163,7 @@ impl CompiledModule {
.into_boxed_slice(),
raw.signatures.clone(),
raw.dbg_jit_registration,
raw.trap_registration,
))
}
@@ -169,6 +174,7 @@ impl CompiledModule {
data_initializers: Box<[OwnedDataInitializer]>,
signatures: BoxedSlice<SignatureIndex, VMSharedSignatureIndex>,
dbg_jit_registration: Option<GdbJitImageRegistration>,
trap_registration: TrapRegistration,
) -> Self {
Self {
module: Arc::new(module),
@@ -176,6 +182,7 @@ impl CompiledModule {
data_initializers,
signatures,
dbg_jit_registration: dbg_jit_registration.map(Rc::new),
trap_registration,
}
}
@@ -203,6 +210,7 @@ impl CompiledModule {
let imports = resolve_imports(&self.module, resolver)?;
InstanceHandle::new(
Arc::clone(&self.module),
self.trap_registration.clone(),
self.finished_functions.clone(),
imports,
&data_initializers,

7
crates/runtime/src/instance.rs
View File

@@ -15,6 +15,7 @@ use crate::vmcontext::{
VMGlobalDefinition, VMGlobalImport, VMMemoryDefinition, VMMemoryImport, VMSharedSignatureIndex,
VMTableDefinition, VMTableImport,
};
use crate::TrapRegistration;
use memoffset::offset_of;
use more_asserts::assert_lt;
use std::any::Any;
@@ -100,6 +101,10 @@ pub(crate) struct Instance {
/// Handler run when `SIGBUS`, `SIGFPE`, `SIGILL`, or `SIGSEGV` are caught by the instance thread.
pub(crate) signal_handler: Cell<Option<Box<SignalHandler>>>,
/// Handle to our registration of traps so signals know what trap to return
/// when a segfault/sigill happens.
pub(crate) trap_registration: TrapRegistration,
/// Additional context used by compiled wasm code. This field is last, and
/// represents a dynamically-sized array that extends beyond the nominal
/// end of the struct (similar to a flexible array member).
@@ -534,6 +539,7 @@ impl InstanceHandle {
/// safety.
pub unsafe fn new(
module: Arc<Module>,
trap_registration: TrapRegistration,
finished_functions: BoxedSlice<DefinedFuncIndex, *const VMFunctionBody>,
imports: Imports,
data_initializers: &[DataInitializer<'_>],
@@ -582,6 +588,7 @@ impl InstanceHandle {
dbg_jit_registration,
host_state,
signal_handler: Cell::new(None),
trap_registration,
vmctx: VMContext {},
};
ptr::write(instance_ptr, instance);

3
crates/runtime/src/lib.rs
View File

@@ -43,8 +43,7 @@ pub use crate::instance::{InstanceHandle, InstantiationError, LinkError};
pub use crate::jit_int::GdbJitImageRegistration;
pub use crate::mmap::Mmap;
pub use crate::sig_registry::SignatureRegistry;
pub use crate::trap_registry::TrapDescription;
pub use crate::trap_registry::{get_mut_trap_registry, get_trap_registry, TrapRegistrationGuard};
pub use crate::trap_registry::{TrapDescription, TrapRegistration, TrapRegistry};
pub use crate::traphandlers::resume_panic;
pub use crate::traphandlers::{raise_user_trap, wasmtime_call, wasmtime_call_trampoline, Trap};
pub use crate::vmcontext::{

144
crates/runtime/src/trap_registry.rs
View File

@@ -1,19 +1,64 @@
use lazy_static::lazy_static;
use std::collections::HashMap;
use std::collections::{BTreeMap, HashMap};
use std::fmt;
use std::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
use std::sync::{Arc, RwLock};
use wasmtime_environ::ir;
lazy_static! {
static ref REGISTRY: RwLock<TrapRegistry> = RwLock::new(TrapRegistry::default());
}
/// The registry maintains descriptions of traps in currently allocated functions.
#[derive(Default)]
pub struct TrapRegistry {
// This data structure is intended to be safe to use across many threads
// since this is stored inside of a `Compiler` which, eventually, will be
// used across many threads. To that end this is internally use an `Arc`
// plus an `RwLock`.
//
// The problem that this data structure is solving is that when a
// segfault/illegal instruction happens we need to answer "given this
// hardware program counter what is the wasm reason this trap is being
// raised"?
//
// The way this is answered here is done to minimize the amount of
// synchronization (in theory) and have something like so:
//
// * Each module bulk-registers a list of in-memory pc addresses that have
// traps. We assume that the range of traps for each module are always
// disjoint.
// * Each key in this `BTreeMap` is the highest trapping address and the
// value contains the lowest address as well as all the individual
// addresses in their own `HashMap`.
// * Registration then looks by calculating the start/end and inserting
// into this map (with some assertions about disjointed-ness)
// * Lookup is done in two layers. First we find the corresponding entry
// in the map and verify that a program counter falls in the start/end
// range. Next we look up the address in the `traps` hash map below.
//
// The `register_traps` function works by returning an RAII guard that owns
// a handle to this `Arc` as well, and when that type is dropped it will
// automatically remove all trap information from this `ranges` list.
ranges: Arc<RwLock<BTreeMap<usize, TrapGroup>>>,
}
#[derive(Debug)]
struct TrapGroup {
/// The lowest key in the `trap` field.
///
/// This represents the start of the range of this group of traps, and the
/// end of the range for this group of traps is stored as the key in the
/// `ranges` struct above in `TrapRegistry`.
start: usize,
/// All known traps in this group, mapped from program counter to the
/// description of the trap itself.
traps: HashMap<usize, TrapDescription>,
}
/// RAII structure returned from `TrapRegistry::register_trap` to unregister
/// trap information on drop.
#[derive(Clone)]
pub struct TrapRegistration {
ranges: Arc<RwLock<BTreeMap<usize, TrapGroup>>>,
end: Option<usize>,
}
/// Description of a trap.
#[derive(Clone, Copy, PartialEq, Debug)]
pub struct TrapDescription {
@@ -52,50 +97,77 @@ fn trap_code_to_expected_string(trap_code: ir::TrapCode) -> String {
}
}
/// RAII guard for deregistering traps
pub struct TrapRegistrationGuard(usize);
impl TrapRegistry {
/// Registers a new trap.
/// Returns a RAII guard that deregisters the trap when dropped.
pub fn register_trap(
&mut self,
address: usize,
source_loc: ir::SourceLoc,
trap_code: ir::TrapCode,
) -> TrapRegistrationGuard {
let entry = TrapDescription {
/// Registers a list of traps.
///
/// Returns a RAII guard that deregisters all traps when dropped.
pub fn register_traps(
&self,
list: impl IntoIterator<Item = (usize, ir::SourceLoc, ir::TrapCode)>,
) -> TrapRegistration {
let mut start = usize::max_value();
let mut end = 0;
let mut traps = HashMap::new();
for (addr, source_loc, trap_code) in list.into_iter() {
traps.insert(
addr,
TrapDescription {
source_loc,
trap_code,
},
);
if addr < start {
start = addr;
}
if addr > end {
end = addr;
}
}
if traps.len() == 0 {
return TrapRegistration {
ranges: self.ranges.clone(),
end: None,
};
let previous_trap = self.traps.insert(address, entry);
assert!(previous_trap.is_none());
TrapRegistrationGuard(address)
}
let mut ranges = self.ranges.write().unwrap();
// Sanity check that no other group of traps overlaps with our
// registration...
if let Some((_, prev)) = ranges.range(end..).next() {
assert!(prev.start > end);
}
if let Some((prev_end, _)) = ranges.range(..=start).next_back() {
assert!(*prev_end < start);
}
fn deregister_trap(&mut self, address: usize) {
assert!(self.traps.remove(&address).is_some());
// ... and then register ourselves
assert!(ranges.insert(end, TrapGroup { start, traps }).is_none());
TrapRegistration {
ranges: self.ranges.clone(),
end: Some(end),
}
}
}
impl TrapRegistration {
/// Gets a trap description at given address.
pub fn get_trap(&self, address: usize) -> Option<TrapDescription> {
self.traps.get(&address).copied()
let ranges = self.ranges.read().ok()?;
let (end, group) = ranges.range(address..).next()?;
if group.start <= address && address <= *end {
group.traps.get(&address).copied()
} else {
None
}
}
}
impl Drop for TrapRegistrationGuard {
impl Drop for TrapRegistration {
fn drop(&mut self) {
let mut registry = get_mut_trap_registry();
registry.deregister_trap(self.0);
if let Some(end) = self.end {
if let Ok(mut ranges) = self.ranges.write() {
ranges.remove(&end);
}
}
/// Gets guarded writable reference to traps registry
pub fn get_mut_trap_registry() -> RwLockWriteGuard<'static, TrapRegistry> {
REGISTRY.write().expect("trap registry lock got poisoned")
}
/// Gets guarded readable reference to traps registry
pub fn get_trap_registry() -> RwLockReadGuard<'static, TrapRegistry> {
REGISTRY.read().expect("trap registry lock got poisoned")
}

45
crates/runtime/src/traphandlers.rs
View File

@@ -2,7 +2,6 @@
//! signalhandling mechanisms.
use crate::instance::{InstanceHandle, SignalHandler};
use crate::trap_registry::get_trap_registry;
use crate::trap_registry::TrapDescription;
use crate::vmcontext::{VMContext, VMFunctionBody};
use backtrace::Backtrace;
@@ -78,8 +77,7 @@ cfg_if::cfg_if! {
/// Only safe to call when wasm code is on the stack, aka `wasmtime_call` or
/// `wasmtime_call_trampoline` must have been previously called.
pub unsafe fn raise_user_trap(data: Box<dyn Error + Send + Sync>) -> ! {
let trap = Trap::User(data);
tls::with(|info| info.unwrap().unwind_with(UnwindReason::Trap(trap)))
tls::with(|info| info.unwrap().unwind_with(UnwindReason::UserTrap(data)))
}
/// Carries a Rust panic across wasm code and resumes the panic on the other
@@ -187,7 +185,8 @@ pub struct CallThreadState {
enum UnwindReason {
None,
Panic(Box<dyn Any + Send>),
Trap(Trap),
UserTrap(Box<dyn Error + Send + Sync>),
Trap { backtrace: Backtrace, pc: usize },
}
impl CallThreadState {
@@ -210,9 +209,25 @@ impl CallThreadState {
debug_assert_eq!(ret, 1);
Ok(())
}
UnwindReason::Trap(trap) => {
UnwindReason::UserTrap(data) => {
debug_assert_eq!(ret, 0);
Err(trap)
Err(Trap::User(data))
}
UnwindReason::Trap { backtrace, pc } => {
debug_assert_eq!(ret, 0);
let instance = unsafe { InstanceHandle::from_vmctx(self.vmctx) };
Err(Trap::Wasm {
desc: instance
.instance()
.trap_registration
.get_trap(pc)
.unwrap_or_else(|| TrapDescription {
source_loc: ir::SourceLoc::default(),
trap_code: ir::TrapCode::StackOverflow,
}),
backtrace,
})
}
UnwindReason::Panic(panic) => {
debug_assert_eq!(ret, 0);
@@ -289,20 +304,12 @@ impl CallThreadState {
if self.jmp_buf.get().is_null() {
return ptr::null();
}
let registry = get_trap_registry();
let trap = Trap::Wasm {
desc: registry
.get_trap(pc as usize)
.unwrap_or_else(|| TrapDescription {
source_loc: ir::SourceLoc::default(),
trap_code: ir::TrapCode::StackOverflow,
}),
backtrace: Backtrace::new_unresolved(),
};
let backtrace = Backtrace::new_unresolved();
self.reset_guard_page.set(reset_guard_page);
self.unwind.replace(UnwindReason::Trap(trap));
self.unwind.replace(UnwindReason::Trap {
backtrace,
pc: pc as usize,
});
self.jmp_buf.get()
}
}