Debugging: add builtin gdbstub component.

Cargo.toml

@@ -61,6 +61,7 @@ wasmtime-wasi-http = { workspace = true, optional = true }
 wasmtime-unwinder = { workspace = true }
 wasmtime-wizer = { workspace = true, optional = true, features = ['clap', 'wasmtime'] }
 wasmtime-debugger = { workspace = true, optional = true }
+gdbstub-component-artifact = { workspace = true, optional = true }
 clap = { workspace = true }
 clap_complete = { workspace = true, optional = true }
 target-lexicon = { workspace = true }
@@ -168,6 +169,8 @@ members = [
   "crates/wasi-tls-nativetls",
   "crates/wasi-tls-openssl",
   "crates/debugger",
+  "crates/gdbstub-component",
+  "crates/gdbstub-component/artifact",
   "crates/wizer/fuzz",
   "crates/wizer/tests/regex-test",
   "crates/wizer/benches/regex-bench",
@@ -280,6 +283,7 @@ wasmtime-jit-icache-coherence = { path = "crates/jit-icache-coherence", version
 wasmtime-wit-bindgen = { path = "crates/wit-bindgen", version = "=44.0.0", package = 'wasmtime-internal-wit-bindgen' }
 wasmtime-unwinder = { path = "crates/unwinder", version = "=44.0.0", package = 'wasmtime-internal-unwinder' }
 wasmtime-debugger = { path = "crates/debugger", version = "=44.0.0", package = "wasmtime-internal-debugger" }
+gdbstub-component-artifact = { path = "crates/gdbstub-component/artifact", package = "wasmtime-internal-gdbstub-component-artifact" }
 wasmtime-wizer = { path = "crates/wizer", version = "44.0.0" }
 
 # Miscellaneous crates without a `wasmtime-*` prefix in their name but still
@@ -358,6 +362,9 @@ wasm-wave = "0.245.0"
 wasm-compose = "0.245.0"
 json-from-wast = "0.245.0"
 
+wstd = "0.6.5"
+wasip2 = "1.0"
+
 # Non-Bytecode Alliance maintained dependencies:
 # --------------------------
 arbitrary = "1.4.2"
@@ -441,6 +448,9 @@ rayon = "1.5.3"
 regex = "1.9.1"
 pin-project-lite = "0.2.14"
 sha2 = { version = "0.10.2", default-features = false }
+structopt = "0.3.26"
+gdbstub = "0.7.10"
+gdbstub_arch = "0.3.3"
 
 # =============================================================================
 #
@@ -566,7 +576,7 @@ gc-drc = ["gc", "wasmtime/gc-drc", "wasmtime-cli-flags/gc-drc"]
 gc-null = ["gc", "wasmtime/gc-null", "wasmtime-cli-flags/gc-null"]
 pulley = ["wasmtime-cli-flags/pulley"]
 stack-switching = ["wasmtime/stack-switching", "wasmtime-cli-flags/stack-switching"]
-debug = ["wasmtime-cli-flags/debug", "wasmtime/debug", "component-model"]
+debug = ["wasmtime-cli-flags/debug", "wasmtime/debug", "component-model", "dep:gdbstub-component-artifact"]
 
 # CLI subcommands for the `wasmtime` executable. See `wasmtime $cmd --help`
 # for more information on each subcommand.

crates/gdbstub-component/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "wasmtime-internal-gdbstub-component"
+version.workspace = true
+authors.workspace = true
+edition.workspace = true
+license = "Apache-2.0 WITH LLVM-exception"
+description = "gdbstub debug-component adapter"
+publish = false
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+wit-bindgen = { workspace = true, features = ["macros"] }
+anyhow = { workspace = true }
+structopt = { workspace = true }
+wstd = { workspace = true }
+wasip2 = { workspace = true }
+futures = { workspace = true, default-features = true }
+gdbstub = { workspace = true }
+gdbstub_arch = { workspace = true }
+log = { workspace = true }
+env_logger = { workspace = true }
+
+[lints]
+workspace = true

crates/gdbstub-component/artifact/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "wasmtime-internal-gdbstub-component-artifact"
+version.workspace = true
+authors.workspace = true
+edition.workspace = true
+license = "Apache-2.0 WITH LLVM-exception"
+publish = false
+
+[lints]
+workspace = true

crates/gdbstub-component/artifact/build.rs

@@ -0,0 +1,63 @@
+use std::env;
+use std::path::PathBuf;
+use std::process::Command;
+
+fn main() {
+    let out_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+
+    let mut cmd = cargo();
+    cmd.arg("build")
+        .arg("--release")
+        .arg("--target=wasm32-wasip2")
+        .arg("--package=wasmtime-internal-gdbstub-component")
+        .env("CARGO_TARGET_DIR", &out_dir)
+        .env("RUSTFLAGS", rustflags())
+        .env_remove("CARGO_ENCODED_RUSTFLAGS");
+    eprintln!("running: {cmd:?}");
+    let status = cmd.status().unwrap();
+    assert!(status.success());
+
+    let wasm = out_dir
+        .join("wasm32-wasip2")
+        .join("release")
+        .join("wasmtime_internal_gdbstub_component.wasm");
+
+    // Read dep-info to get proper rerun-if-changed directives.
+    let deps_file = wasm.with_extension("d");
+    if let Ok(contents) = std::fs::read_to_string(&deps_file) {
+        for line in contents.lines() {
+            let Some(pos) = line.find(": ") else {
+                continue;
+            };
+            let line = &line[pos + 2..];
+            let mut parts = line.split_whitespace();
+            while let Some(part) = parts.next() {
+                let mut file = part.to_string();
+                while file.ends_with('\\') {
+                    file.pop();
+                    file.push(' ');
+                    file.push_str(parts.next().unwrap());
+                }
+                println!("cargo:rerun-if-changed={file}");
+            }
+        }
+    }
+
+    let generated = format!("pub const GDBSTUB_COMPONENT: &[u8] = include_bytes!({wasm:?});\n");
+    std::fs::write(out_dir.join("gen.rs"), generated).unwrap();
+}
+
+fn cargo() -> Command {
+    let mut cargo = Command::new("cargo");
+    if std::env::var("CARGO_CFG_MIRI").is_ok() {
+        cargo.env_remove("RUSTC").env_remove("RUSTC_WRAPPER");
+    }
+    cargo
+}
+
+fn rustflags() -> &'static str {
+    match option_env!("RUSTFLAGS") {
+        Some(s) if s.contains("-D warnings") => "-D warnings",
+        _ => "",
+    }
+}

crates/gdbstub-component/artifact/src/lib.rs

@@ -0,0 +1 @@
+include!(concat!(env!("OUT_DIR"), "/gen.rs"));

crates/gdbstub-component/src/addr.rs

@@ -0,0 +1,186 @@
+//! Synthetic Wasm address space expected by the gdbstub Wasm
+//! extensions.
+
+use crate::api::{Debuggee, Frame, Memory, Module};
+use anyhow::Result;
+use gdbstub_arch::wasm::addr::{WasmAddr, WasmAddrType};
+use std::collections::{HashMap, hash_map::Entry};
+
+/// Representation of the synthesized Wasm address space.
+pub struct AddrSpace {
+    module_ids: HashMap<u64, u32>,
+    memory_ids: HashMap<u64, u32>,
+    modules: Vec<Module>,
+    module_bytecode: Vec<Vec<u8>>,
+    memories: Vec<Memory>,
+}
+
+/// The result of a lookup in the address space.
+pub enum AddrSpaceLookup<'a> {
+    Module {
+        module: &'a Module,
+        bytecode: &'a [u8],
+        offset: u32,
+    },
+    Memory {
+        memory: &'a Memory,
+        offset: u32,
+    },
+    Empty,
+}
+
+impl AddrSpace {
+    pub fn new() -> Self {
+        AddrSpace {
+            module_ids: HashMap::new(),
+            modules: vec![],
+            module_bytecode: vec![],
+            memory_ids: HashMap::new(),
+            memories: vec![],
+        }
+    }
+
+    fn module_id(&mut self, m: &Module) -> u32 {
+        match self.module_ids.entry(m.unique_id()) {
+            Entry::Occupied(o) => *o.get(),
+            Entry::Vacant(v) => {
+                let id = u32::try_from(self.modules.len()).unwrap();
+                let bytecode = m.bytecode().unwrap_or(vec![]);
+                self.module_bytecode.push(bytecode);
+                self.modules.push(m.clone());
+                *v.insert(id)
+            }
+        }
+    }
+
+    fn memory_id(&mut self, m: &Memory) -> u32 {
+        match self.memory_ids.entry(m.unique_id()) {
+            Entry::Occupied(o) => *o.get(),
+            Entry::Vacant(v) => {
+                let id = u32::try_from(self.memories.len()).unwrap();
+                self.memories.push(m.clone());
+                *v.insert(id)
+            }
+        }
+    }
+
+    /// Update/create new mappings so that all modules and instances'
+    /// memories in the debuggee have mappings.
+    pub fn update(&mut self, d: &Debuggee) -> Result<()> {
+        for module in d.all_modules() {
+            let _ = self.module_id(&module);
+        }
+        for instance in d.all_instances() {
+            let mut idx = 0;
+            loop {
+                if let Ok(m) = instance.get_memory(d, idx) {
+                    let _ = self.memory_id(&m);
+                    idx += 1;
+                } else {
+                    break;
+                }
+            }
+        }
+        Ok(())
+    }
+
+    /// Iterate over the base `WasmAddr` of every registered module.
+    pub fn module_base_addrs(&self) -> impl Iterator<Item = WasmAddr> + '_ {
+        (0..self.modules.len())
+            .map(|idx| WasmAddr::new(WasmAddrType::Object, u32::try_from(idx).unwrap(), 0).unwrap())
+    }
+
+    /// Build the GDB memory-map XML describing all known regions.
+    ///
+    /// Module bytecode regions are reported as `rom` (read-only), and
+    /// linear memories as `ram` (read-write).
+    pub fn memory_map_xml(&self, debuggee: &Debuggee) -> String {
+        use std::fmt::Write;
+        let mut xml = String::from(
+            "<?xml version=\"1.0\"?><!DOCTYPE memory-map SYSTEM \"memory-map.dtd\"><memory-map>",
+        );
+        for (idx, bc) in self.module_bytecode.iter().enumerate() {
+            let start =
+                WasmAddr::new(WasmAddrType::Object, u32::try_from(idx).unwrap(), 0).unwrap();
+            let len = bc.len();
+            if len > 0 {
+                write!(
+                    xml,
+                    "<memory type=\"rom\" start=\"0x{:x}\" length=\"0x{:x}\"/>",
+                    start.as_raw(),
+                    len
+                )
+                .unwrap();
+            }
+        }
+        for (idx, mem) in self.memories.iter().enumerate() {
+            let start =
+                WasmAddr::new(WasmAddrType::Memory, u32::try_from(idx).unwrap(), 0).unwrap();
+            let len = mem.size_bytes(debuggee);
+            if len > 0 {
+                write!(
+                    xml,
+                    "<memory type=\"ram\" start=\"0x{:x}\" length=\"0x{:x}\"/>",
+                    start.as_raw(),
+                    len
+                )
+                .unwrap();
+            }
+        }
+        xml.push_str("</memory-map>");
+        xml
+    }
+
+    pub fn frame_to_pc(&self, frame: &Frame, debuggee: &Debuggee) -> WasmAddr {
+        let module = frame.get_instance(debuggee).unwrap().get_module(debuggee);
+        let &module_id = self
+            .module_ids
+            .get(&module.unique_id())
+            .expect("module not found in addr space");
+        let pc = frame.get_pc(debuggee).unwrap();
+        WasmAddr::new(WasmAddrType::Object, module_id, pc).unwrap()
+    }
+
+    pub fn frame_to_return_addr(&self, frame: &Frame, debuggee: &Debuggee) -> Option<WasmAddr> {
+        let module = frame.get_instance(debuggee).unwrap().get_module(debuggee);
+        let &module_id = self
+            .module_ids
+            .get(&module.unique_id())
+            .expect("module not found in addr space");
+        let ret_pc = frame.get_pc(debuggee).ok()?;
+        Some(WasmAddr::new(WasmAddrType::Object, module_id, ret_pc).unwrap())
+    }
+
+    pub fn lookup(&self, addr: WasmAddr, d: &Debuggee) -> AddrSpaceLookup<'_> {
+        let index = usize::try_from(addr.module_index()).unwrap();
+        match addr.addr_type() {
+            WasmAddrType::Object => {
+                if index >= self.modules.len() {
+                    return AddrSpaceLookup::Empty;
+                }
+                let bytecode = &self.module_bytecode[index];
+                if addr.offset() >= u32::try_from(bytecode.len()).unwrap() {
+                    return AddrSpaceLookup::Empty;
+                }
+                AddrSpaceLookup::Module {
+                    module: &self.modules[index],
+                    bytecode,
+                    offset: addr.offset(),
+                }
+            }
+            WasmAddrType::Memory => {
+                if index >= self.memories.len() {
+                    return AddrSpaceLookup::Empty;
+                }
+                let size = self.memories[index].size_bytes(d);
+                if u64::from(addr.offset()) >= size {
+                    return AddrSpaceLookup::Empty;
+                }
+                AddrSpaceLookup::Memory {
+                    memory: &self.memories[index],
+                    offset: addr.offset(),
+                }
+            }
+        }
+    }
+}

crates/gdbstub-component/src/api.rs

@@ -0,0 +1,44 @@
+//! Bindings for Wasmtime's debugger API.
+
+use wstd::runtime::AsyncPollable;
+
+wit_bindgen::generate!({
+    world: "bytecodealliance:wasmtime/debug-main",
+    path: "../debugger/wit",
+    with: {
+        "wasi:io/poll@0.2.6": wasip2::io::poll,
+    }
+});
+pub(crate) use bytecodealliance::wasmtime::debuggee::*;
+
+/// One "resumption", or period of execution, in the debuggee.
+pub struct Resumption {
+    future: EventFuture,
+    pollable: Option<AsyncPollable>,
+}
+
+impl Resumption {
+    pub fn continue_(d: &Debuggee, r: ResumptionValue) -> Self {
+        let future = d.continue_(r);
+        let pollable = Some(AsyncPollable::new(future.subscribe()));
+        Resumption { future, pollable }
+    }
+
+    pub fn single_step(d: &Debuggee, r: ResumptionValue) -> Self {
+        let future = d.single_step(r);
+        let pollable = Some(AsyncPollable::new(future.subscribe()));
+        Resumption { future, pollable }
+    }
+
+    pub async fn wait(&mut self) {
+        if let Some(pollable) = self.pollable.as_mut() {
+            pollable.wait_for().await;
+        }
+    }
+
+    pub fn result(mut self, d: &Debuggee) -> std::result::Result<Event, Error> {
+        // Drop the pollable first, since it's a child resource.
+        let _ = self.pollable.take();
+        EventFuture::finish(self.future, d)
+    }
+}