Implement the pooling instance allocator.

.github/workflows/main.yml

@@ -73,14 +73,11 @@ jobs:
     - uses: actions/checkout@v2
       with:
         submodules: true
-    # Note that we use nightly Rust here to get intra-doc links which are a
-    # nightly-only feature right now.
+    # Note that we use nightly Rust for the doc_cfg feature (enabled via `nightlydoc` above)
+    # This version is an older nightly for the new x64 backend (see below)
     - uses: ./.github/actions/install-rust
       with:
-        # TODO (rust-lang/rust#79661): We are seeing an internal compiler error when
-        # building with the latest (2020-12-06) nightly; pin on a slightly older
-        # version for now.
-        toolchain: nightly-2020-11-29
+        toolchain: nightly-2020-12-26
     - run: cargo doc --no-deps --all --exclude wasmtime-cli --exclude test-programs --exclude cranelift-codegen-meta
     - run: cargo doc --package cranelift-codegen-meta --document-private-items
     - uses: actions/upload-artifact@v1
@@ -122,6 +119,7 @@ jobs:
     - run: cargo check --manifest-path crates/wasmtime/Cargo.toml --features jitdump
     - run: cargo check --manifest-path crates/wasmtime/Cargo.toml --features cache
     - run: cargo check --manifest-path crates/wasmtime/Cargo.toml --features async
+    - run: cargo check --manifest-path crates/wasmtime/Cargo.toml --features uffd
 
     # Check some feature combinations of the `wasmtime-c-api` crate
     - run: cargo check --manifest-path crates/c-api/Cargo.toml --no-default-features
@@ -167,7 +165,7 @@ jobs:
     # flags to rustc.
     - uses: ./.github/actions/install-rust
       with:
-        toolchain: nightly-2020-11-29
+        toolchain: nightly
     - run: cargo install cargo-fuzz --vers "^0.8"
     - run: cargo fetch
       working-directory: ./fuzz
@@ -224,7 +222,7 @@ jobs:
             rust: beta
           - build: nightly
             os: ubuntu-latest
-            rust: nightly-2020-11-29
+            rust: nightly
           - build: macos
             os: macos-latest
             rust: stable
@@ -303,6 +301,15 @@ jobs:
       env:
         RUST_BACKTRACE: 1
 
+    # Test uffd functionality on Linux
+    - run: |
+        cargo test --features uffd -p wasmtime-runtime instance::allocator::pooling
+        cargo test --features uffd -p wasmtime-cli pooling_allocator
+        cargo test --features uffd -p wasmtime-cli wast::Cranelift
+      if: matrix.os == 'ubuntu-latest'
+      env:
+        RUST_BACKTRACE: 1
+
     # Build and test lightbeam. Note that
     # Lightbeam tests fail right now, but we don't want to block on that.
     - run: cargo build --package lightbeam
@@ -312,8 +319,10 @@ jobs:
         RUST_BACKTRACE: 1
 
   # Perform all tests (debug mode) for `wasmtime` with the experimental x64
-  # backend. This runs on the nightly channel of Rust (because of issues with
-  # unifying Cargo features on stable) on Ubuntu.
+  # backend. This runs on an older nightly of Rust (because of issues with
+  # unifying Cargo features on stable) on Ubuntu such that it's new enough
+  # to build Wasmtime, but old enough where the -Z options being used
+  # haven't been stabilized yet.
   test_x64:
     name: Test x64 new backend
     runs-on: ubuntu-latest
@@ -323,7 +332,7 @@ jobs:
         submodules: true
     - uses: ./.github/actions/install-rust
       with:
-        toolchain: nightly-2020-11-29
+        toolchain: nightly-2020-12-26
     - uses: ./.github/actions/define-llvm-env
 
     # Install wasm32 targets in order to build various tests throughout the
@@ -334,7 +343,7 @@ jobs:
     # Run the x64 CI script.
     - run: ./ci/run-experimental-x64-ci.sh
       env:
-        CARGO_VERSION: "+nightly-2020-11-29"
+        CARGO_VERSION: "+nightly-2020-12-26"
         RUST_BACKTRACE: 1
 
   # Build and test the wasi-nn module.
@@ -347,7 +356,7 @@ jobs:
           submodules: true
       - uses: ./.github/actions/install-rust
         with:
-          toolchain: nightly-2020-11-29
+          toolchain: nightly
       - run: rustup target add wasm32-wasi
       - uses: ./.github/actions/install-openvino
       - run: ./ci/run-wasi-nn-example.sh

Cargo.toml

@@ -89,6 +89,7 @@ jitdump = ["wasmtime/jitdump"]
 vtune = ["wasmtime/vtune"]
 wasi-crypto = ["wasmtime-wasi-crypto"]
 wasi-nn = ["wasmtime-wasi-nn"]
+uffd = ["wasmtime/uffd"]
 
 # Try the experimental, work-in-progress new x86_64 backend. This is not stable
 # as of June 2020.

README.md

@@ -11,7 +11,7 @@
   <p>
     <a href="https://github.com/bytecodealliance/wasmtime/actions?query=workflow%3ACI"><img src="https://github.com/bytecodealliance/wasmtime/workflows/CI/badge.svg" alt="build status" /></a>
     <a href="https://bytecodealliance.zulipchat.com/#narrow/stream/217126-wasmtime"><img src="https://img.shields.io/badge/zulip-join_chat-brightgreen.svg" alt="zulip chat" /></a>
-    <img src="https://img.shields.io/badge/rustc-1.37+-green.svg" alt="min rustc" />
+    <img src="https://img.shields.io/badge/rustc-stable+-green.svg" alt="supported rustc stable" />
     <a href="https://docs.rs/wasmtime"><img src="https://docs.rs/wasmtime/badge.svg" alt="Documentation Status" /></a>
   </p>
 

build.rs

@@ -111,7 +111,8 @@ fn test_directory(
 
     let testsuite = &extract_name(path);
     for entry in dir_entries.iter() {
-        write_testsuite_tests(out, entry, testsuite, strategy)?;
+        write_testsuite_tests(out, entry, testsuite, strategy, false)?;
+        write_testsuite_tests(out, entry, testsuite, strategy, true)?;
     }
 
     Ok(dir_entries.len())
@@ -148,6 +149,7 @@ fn write_testsuite_tests(
     path: impl AsRef<Path>,
     testsuite: &str,
     strategy: &str,
+    pooling: bool,
 ) -> anyhow::Result<()> {
     let path = path.as_ref();
     let testname = extract_name(path);
@@ -160,14 +162,24 @@ fn write_testsuite_tests(
         )?;
     } else if ignore(testsuite, &testname, strategy) {
         writeln!(out, "#[ignore]")?;
+    } else if pooling {
+        // Ignore on aarch64 due to using QEMU for running tests (limited memory)
+        writeln!(out, r#"#[cfg_attr(target_arch = "aarch64", ignore)]"#)?;
     }
-    writeln!(out, "fn r#{}() {{", &testname)?;
+
+    writeln!(
+        out,
+        "fn r#{}{}() {{",
+        &testname,
+        if pooling { "_pooling" } else { "" }
+    )?;
     writeln!(out, "    let _ = env_logger::try_init();")?;
     writeln!(
         out,
-        "    crate::wast::run_wast(r#\"{}\"#, crate::wast::Strategy::{}).unwrap();",
+        "    crate::wast::run_wast(r#\"{}\"#, crate::wast::Strategy::{}, {}).unwrap();",
         path.display(),
-        strategy
+        strategy,
+        pooling
     )?;
     writeln!(out, "}}")?;
     writeln!(out)?;

cranelift/wasm/src/module_translator.rs

@@ -101,6 +101,8 @@ pub fn translate_module<'data>(
 
             Payload::DataCountSection { count, range } => {
                 validator.data_count_section(count, &range)?;
+
+                // NOTE: the count here is the total segment count, not the passive segment count
                 environ.reserve_passive_data(count)?;
             }
 

cranelift/wasm/src/sections_translator.rs

@@ -401,6 +401,12 @@ pub fn parse_element_section<'data>(
                         ));
                     }
                 };
+                // Check for offset + len overflow
+                if offset.checked_add(segments.len()).is_none() {
+                    return Err(wasm_unsupported!(
+                        "element segment offset and length overflows"
+                    ));
+                }
                 environ.declare_table_elements(
                     TableIndex::from_u32(table_index),
                     base,
@@ -447,6 +453,12 @@ pub fn parse_data_section<'data>(
                         ))
                     }
                 };
+                // Check for offset + len overflow
+                if offset.checked_add(data.len()).is_none() {
+                    return Err(wasm_unsupported!(
+                        "data segment offset and length overflows"
+                    ));
+                }
                 environ.declare_data_initialization(
                     MemoryIndex::from_u32(memory_index),
                     base,

crates/c-api/src/config.rs

@@ -61,8 +61,8 @@ pub extern "C" fn wasmtime_config_consume_fuel_set(c: &mut wasm_config_t, enable
 }
 
 #[no_mangle]
-pub extern "C" fn wasmtime_config_max_wasm_stack_set(c: &mut wasm_config_t, size: usize) {
-    c.config.max_wasm_stack(size);
+pub extern "C" fn wasmtime_config_max_wasm_stack_set(c: &mut wasm_config_t, size: usize) -> bool {
+    c.config.max_wasm_stack(size).is_ok()
 }
 
 #[no_mangle]

crates/environ/Cargo.toml

@@ -13,6 +13,7 @@ edition = "2018"
 
 [dependencies]
 anyhow = "1.0"
+region = "2.2.0"
 cranelift-codegen = { path = "../../cranelift/codegen", version = "0.71.0", features = ["enable-serde"] }
 cranelift-entity = { path = "../../cranelift/entity", version = "0.71.0", features = ["enable-serde"] }
 cranelift-wasm = { path = "../../cranelift/wasm", version = "0.71.0", features = ["enable-serde"] }

crates/environ/src/data_structures.rs

@@ -20,7 +20,7 @@ pub mod isa {
 }
 
 pub mod entity {
-    pub use cranelift_entity::{packed_option, BoxedSlice, EntityRef, PrimaryMap};
+    pub use cranelift_entity::{packed_option, BoxedSlice, EntityRef, EntitySet, PrimaryMap};
 }
 
 pub mod wasm {