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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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16
crates/environ/src/vmoffsets.rs
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@@ -6,7 +6,7 @@
// struct VMContext {
// interrupts: *const VMInterrupts,
// externref_activations_table: *mut VMExternRefActivationsTable,
// stack_map_lookup: *const dyn StackMapLookup,
// module_info_lookup: *const dyn ModuleInfoLookup,
// signature_ids: [VMSharedSignatureIndex; module.num_signature_ids],
// imported_functions: [VMFunctionImport; module.num_imported_functions],
// imported_tables: [VMTableImport; module.num_imported_tables],
@@ -77,7 +77,7 @@ pub struct VMOffsets {
// precalculated offsets of various member fields
interrupts: u32,
externref_activations_table: u32,
stack_map_lookup: u32,
module_info_lookup: u32,
signature_ids: u32,
imported_functions: u32,
imported_tables: u32,
@@ -149,7 +149,7 @@ impl From<VMOffsetsFields> for VMOffsets {
num_defined_globals: fields.num_defined_globals,
interrupts: 0,
externref_activations_table: 0,
stack_map_lookup: 0,
module_info_lookup: 0,
signature_ids: 0,
imported_functions: 0,
imported_tables: 0,
@@ -168,12 +168,12 @@ impl From<VMOffsetsFields> for VMOffsets {
.interrupts
.checked_add(u32::from(fields.pointer_size))
.unwrap();
ret.stack_map_lookup = ret
ret.module_info_lookup = ret
.externref_activations_table
.checked_add(u32::from(fields.pointer_size))
.unwrap();
ret.signature_ids = ret
.stack_map_lookup
.module_info_lookup
.checked_add(u32::from(fields.pointer_size * 2))
.unwrap();
ret.imported_functions = ret
@@ -507,10 +507,10 @@ impl VMOffsets {
self.externref_activations_table
}
/// The offset of the `*const dyn StackMapLookup` member.
/// The offset of the `*const dyn ModuleInfoLookup` member.
#[inline]
pub fn vmctx_stack_map_lookup(&self) -> u32 {
self.stack_map_lookup
pub fn vmctx_module_info_lookup(&self) -> u32 {
self.module_info_lookup
}
/// The offset of the `signature_ids` array.