Add general fuzzing support for custom page sizes

crates/fuzzing/src/generators/config.rs

@@ -176,6 +176,7 @@ impl Config {
             .wasm_threads(self.module_config.config.threads_enabled)
             .wasm_function_references(self.module_config.config.gc_enabled)
             .wasm_gc(self.module_config.config.gc_enabled)
+            .wasm_custom_page_sizes(self.module_config.config.custom_page_sizes_enabled)
             .wasm_wide_arithmetic(self.module_config.config.wide_arithmetic_enabled)
             .native_unwind_info(cfg!(target_os = "windows") || self.wasmtime.native_unwind_info)
             .cranelift_nan_canonicalization(self.wasmtime.canonicalize_nans)

crates/fuzzing/src/generators/module.rs

@@ -36,14 +36,13 @@ impl<'a> Arbitrary<'a> for ModuleConfig {
         let _ = config.tail_call_enabled;
         config.exceptions_enabled = false;
         config.gc_enabled = false;
+        config.custom_page_sizes_enabled = u.arbitrary()?;
         config.wide_arithmetic_enabled = u.arbitrary()?;
         config.memory64_enabled = u.ratio(1, 20)?;
         // Allow the threads proposal if memory64 is not already enabled. FIXME:
         // to allow threads and memory64 to coexist, see
         // https://github.com/bytecodealliance/wasmtime/issues/4267.
         config.threads_enabled = !config.memory64_enabled && u.ratio(1, 20)?;
-        // FIXME: this may be safe to enable
-        config.custom_page_sizes_enabled = false;
         // Allow multi-memory but make it unlikely
         if u.ratio(1, 20)? {
             config.max_memories = config.max_memories.max(2);

crates/fuzzing/src/oracles/diff_spec.rs

@@ -25,6 +25,7 @@ impl SpecInterpreter {
         config.reference_types_enabled = false;
         config.tail_call_enabled = false;
         config.relaxed_simd_enabled = false;
+        config.custom_page_sizes_enabled = false;
         config.wide_arithmetic_enabled = false;
 
         Self

crates/fuzzing/src/oracles/diff_v8.rs

@@ -32,6 +32,7 @@ impl V8Engine {
         config.min_memories = config.min_memories.min(1);
         config.max_memories = config.max_memories.min(1);
         config.memory64_enabled = false;
+        config.custom_page_sizes_enabled = false;
         config.wide_arithmetic_enabled = false;
 
         Self {

crates/fuzzing/src/oracles/diff_wasmi.rs

@@ -20,6 +20,7 @@ impl WasmiEngine {
         config.threads_enabled = false;
         config.exceptions_enabled = false;
         config.gc_enabled = false;
+        config.custom_page_sizes_enabled = false;
         config.wide_arithmetic_enabled = false;
 
         let mut wasmi_config = wasmi::Config::default();

docs/stability-wasm-proposals.md

@@ -46,16 +46,14 @@ column is below.
 | [`function-references`]  | ✅      | ✅    | ❌       | ❌     | ✅  | ❌    |
 | [`gc`] [^6]              | ✅      | ✅    | ❌[^7]   | ❌     | ✅  | ❌    |
 | [`wide-arithmetic`]      | ❌      | ✅    | ✅       | ✅     | ✅  | ✅    |
-| [`custom-page-sizes`]    | ❌      | ✅    | ❌       | ⚠️[^8]  | ✅  | ❌    |
+| [`custom-page-sizes`]    | ❌      | ✅    | ✅       | ✅     | ✅  | ❌    |
 
 [^6]: There is also a [tracking
     issue](https://github.com/bytecodealliance/wasmtime/issues/5032) for the
     GC proposal.
 [^7]: The implementation of GC has [known performance
     issues](https://github.com/bytecodealliance/wasmtime/issues/9351) which can
     affect non-GC code when the GC proposal is enabled.
-[^8]: A custom fuzzer exists but this isn't enabled yet for general-purpose
-    fuzzing.
 
 ## Unsupported proposals