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Make module information lookup from runtime safe.

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This commit uses a two-phase lookup of stack map information from modules
rather than giving back raw pointers to stack maps.

First the runtime looks up information about a module from a pc value, which
returns an `Arc` it keeps a reference on while completing the stack map lookup.

Second it then queries the module information for the stack map from a pc
value, getting a reference to the stack map (which is now safe because of the
`Arc` held by the runtime).
This commit is contained in:
Peter Huene
2021-04-16 12:05:38 -07:00
parent 6ac1321162
commit b775b68cfb
15 changed files with 116 additions and 112 deletions
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8
crates/runtime/src/instance/allocator.rs
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@@ -1,4 +1,4 @@
use crate::externref::{StackMapLookup, VMExternRefActivationsTable, EMPTY_STACK_MAP_LOOKUP};
use crate::externref::{ModuleInfoLookup, VMExternRefActivationsTable, EMPTY_MODULE_LOOKUP};
use crate::imports::Imports;
use crate::instance::{Instance, InstanceHandle, RuntimeMemoryCreator};
use crate::memory::{DefaultMemoryCreator, Memory};
@@ -57,8 +57,8 @@ pub struct InstanceAllocationRequest<'a> {
/// The pointer to the reference activations table to use for the instance.
pub externref_activations_table: *mut VMExternRefActivationsTable,
/// The pointer to the stack map lookup to use for the instance.
pub stack_map_lookup: Option<*const dyn StackMapLookup>,
/// The pointer to the module info lookup to use for the instance.
pub module_info_lookup: Option<*const dyn ModuleInfoLookup>,
}
/// An link error while instantiating a module.
@@ -447,7 +447,7 @@ unsafe fn initialize_vmcontext(instance: &Instance, req: InstanceAllocationReque
*instance.interrupts() = req.interrupts;
*instance.externref_activations_table() = req.externref_activations_table;
*instance.stack_map_lookup() = req.stack_map_lookup.unwrap_or(&EMPTY_STACK_MAP_LOOKUP);
*instance.module_info_lookup() = req.module_info_lookup.unwrap_or(&EMPTY_MODULE_LOOKUP);
// Initialize shared signatures
let mut ptr = instance.signature_ids_ptr();