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Check may-leave flags in trampolines, not Rust #12427

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Check may-leave flags in trampolines, not Rust #12427

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106 changes: 89 additions & 17 deletions crates/cranelift/src/compiler/component.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -119,6 +119,8 @@ impl<'a> TrampolineCompiler<'a> {
}

fn translate(&mut self, trampoline: &Trampoline) {
self.check_may_leave(trampoline);

match trampoline {
Trampoline::Transcoder {
op,
Expand Down Expand Up @@ -1202,23 +1204,7 @@ impl<'a> TrampolineCompiler<'a> {
// calling itself.
let old_may_block = if let Some(def) = resource_def {
if self.types[resource].unwrap_concrete_instance() != def.instance {
let flags = self.builder.ins().load(
ir::types::I32,
trusted,
vmctx,
i32::try_from(
self.offsets
.instance_flags(self.types[resource].unwrap_concrete_instance()),
)
.unwrap(),
);
let masked = self
.builder
.ins()
.band_imm(flags, i64::from(FLAG_MAY_LEAVE));
self.builder
.ins()
.trapz(masked, TRAP_CANNOT_LEAVE_COMPONENT);
self.check_may_leave_instance(self.types[resource].unwrap_concrete_instance());

if self.compiler.tunables.concurrency_support {
// Stash the old value of `may_block` and then set it to false.
Expand Down Expand Up @@ -1471,6 +1457,92 @@ impl<'a> TrampolineCompiler<'a> {
self.compiler
.call_indirect_host(&mut self.builder, index, host_sig, host_fn, args)
}

fn check_may_leave(&mut self, trampoline: &Trampoline) {
let instance = match trampoline {
// These intrinsics explicitly do not check the may-leave flag.
Trampoline::ResourceRep { .. }
| Trampoline::ThreadIndex
| Trampoline::BackpressureInc { .. }
| Trampoline::BackpressureDec { .. }
| Trampoline::ContextGet { .. }
| Trampoline::ContextSet { .. } => return,

// Intrinsics used in adapters generated by FACT that aren't called
// directly from guest wasm, so no check is needed.
Trampoline::ResourceTransferOwn
| Trampoline::ResourceTransferBorrow
| Trampoline::ResourceEnterCall
| Trampoline::ResourceExitCall
| Trampoline::PrepareCall { .. }
| Trampoline::SyncStartCall { .. }
| Trampoline::AsyncStartCall { .. }
| Trampoline::FutureTransfer
| Trampoline::StreamTransfer
| Trampoline::ErrorContextTransfer
| Trampoline::Trap
| Trampoline::EnterSyncCall
| Trampoline::ExitSyncCall
| Trampoline::Transcoder { .. } => return,

Trampoline::LowerImport { options, .. } => self.component.options[*options].instance,

Trampoline::ResourceNew { instance, .. }
| Trampoline::ResourceDrop { instance, .. }
| Trampoline::TaskReturn { instance, .. }
| Trampoline::TaskCancel { instance }
| Trampoline::WaitableSetNew { instance }
| Trampoline::WaitableSetWait { instance, .. }
| Trampoline::WaitableSetPoll { instance, .. }
| Trampoline::WaitableSetDrop { instance }
| Trampoline::WaitableJoin { instance }
| Trampoline::ThreadYield { instance, .. }
| Trampoline::ThreadSwitchTo { instance, .. }
| Trampoline::ThreadNewIndirect { instance, .. }
| Trampoline::ThreadSuspend { instance, .. }
| Trampoline::ThreadResumeLater { instance }
| Trampoline::ThreadYieldTo { instance, .. }
| Trampoline::SubtaskDrop { instance }
| Trampoline::SubtaskCancel { instance, .. }
| Trampoline::ErrorContextNew { instance, .. }
| Trampoline::ErrorContextDebugMessage { instance, .. }
| Trampoline::ErrorContextDrop { instance, .. }
| Trampoline::StreamNew { instance, .. }
| Trampoline::StreamRead { instance, .. }
| Trampoline::StreamWrite { instance, .. }
| Trampoline::StreamCancelRead { instance, .. }
| Trampoline::StreamCancelWrite { instance, .. }
| Trampoline::StreamDropReadable { instance, .. }
| Trampoline::StreamDropWritable { instance, .. }
| Trampoline::FutureNew { instance, .. }
| Trampoline::FutureRead { instance, .. }
| Trampoline::FutureWrite { instance, .. }
| Trampoline::FutureCancelRead { instance, .. }
| Trampoline::FutureCancelWrite { instance, .. }
| Trampoline::FutureDropReadable { instance, .. }
| Trampoline::FutureDropWritable { instance, .. } => *instance,
};

self.check_may_leave_instance(instance)
}

fn check_may_leave_instance(&mut self, instance: RuntimeComponentInstanceIndex) {
let vmctx = self.builder.func.dfg.block_params(self.block0)[0];

let flags = self.builder.ins().load(
ir::types::I32,
ir::MemFlags::trusted(),
vmctx,
i32::try_from(self.offsets.instance_flags(instance)).unwrap(),
);
let may_leave_bit = self
.builder
.ins()
.band_imm(flags, i64::from(FLAG_MAY_LEAVE));
self.builder
.ins()
.trapz(may_leave_bit, TRAP_CANNOT_LEAVE_COMPONENT);
}
}

impl ComponentCompiler for Compiler {
Expand Down
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