diff --git a/Cargo.lock b/Cargo.lock
index 5d50ac69e6fa..a819a215db3d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3277,6 +3277,33 @@ version = "0.2.80"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "d554b7f530dee5964d9a9468d95c1f8b8acae4f282807e7d27d4b03099a46744"
+[[package]]
+name = "wasm-coredump-builder"
+version = "0.1.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "158180f35c9ba89a3e7763f20be93e77d5e41535c18e22c85d6dd5b5bce18108"
+dependencies = [
+ "wasm-coredump-encoder",
+ "wasm-coredump-types",
+ "wasm-encoder",
+]
+
+[[package]]
+name = "wasm-coredump-encoder"
+version = "0.1.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2f0c99cdf3a88363570f1027e2f337de6647cac9fed5d474f86103d7c45c8700"
+dependencies = [
+ "leb128",
+ "wasm-coredump-types",
+]
+
+[[package]]
+name = "wasm-coredump-types"
+version = "0.1.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10e35729a021e44c20511e23ac2b215df05da243bdc4bad336fd3686552539fc"
+
[[package]]
name = "wasm-encoder"
version = "0.23.0"
@@ -3515,6 +3542,7 @@ dependencies = [
"tempfile",
"test-programs",
"tokio",
+ "wasm-coredump-builder",
"wasmparser",
"wasmtime",
"wasmtime-cache",
diff --git a/Cargo.toml b/Cargo.toml
index f052cbe1d628..407ab2fd0554 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -42,6 +42,7 @@ wat = { workspace = true }
serde = "1.0.94"
serde_json = "1.0.26"
wasmparser = { workspace = true }
+wasm-coredump-builder = { version = "0.1.11" }
[target.'cfg(unix)'.dependencies]
rustix = { workspace = true, features = ["mm", "param"] }
diff --git a/docs/examples-coredump.md b/docs/examples-coredump.md
new file mode 100644
index 000000000000..6a78dd5176f2
--- /dev/null
+++ b/docs/examples-coredump.md
@@ -0,0 +1,62 @@
+# Using Wasm coredump
+
+The following steps describe how to debug using Wasm coredump in Wasmtime:
+
+1. Compile your WebAssembly with debug info enabled; for example:
+
+ ```sh
+ $ rustc foo.rs --target=wasm32-wasi -C debuginfo=2
+ ```
+
+
+ foo.rs
+
+ fn c(v: usize) {
+ a(v - 3);
+ }
+
+ fn b(v: usize) {
+ c(v - 3);
+ }
+
+ fn a(v: usize) {
+ b(v - 3);
+ }
+
+ pub fn main() {
+ a(10);
+ }
+
+
+2. Run with Wasmtime and Wasm coredump enabled:
+
+ ```sh
+ $ wasmtime --coredump-on-trap=/tmp/coredump foo.wasm
+
+ thread 'main' panicked at 'attempt to subtract with overflow', foo.rs:10:7
+ note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+ Error: failed to run main module `foo.wasm`
+
+ Caused by:
+ 0: Core dumped at /tmp/coredump
+ 1: failed to invoke command default
+ 2: error while executing at wasm backtrace:
+ ...
+ ```
+
+3. Use [wasmgdb] to debug:
+ ```sh
+ $ wasmgdb foo.wasm /tmp/coredump
+
+ wasmgdb> bt
+ ...
+ #13 000175 as panic () at library/core/src/panicking.rs
+ #12 000010 as a (v=???) at /path/to/foo.rs
+ #11 000009 as c (v=???) at /path/to/foo.rs
+ #10 000011 as b (v=???) at /path/to/foo.rs
+ #9 000010 as a (v=???) at /path/to/foo.rs
+ #8 000012 as main () at /path/to/foo.rs
+ ...
+ ```
+
+[wasmgdb]: https://crates.io/crates/wasmgdb
diff --git a/src/commands/run.rs b/src/commands/run.rs
index 4f5751c3befe..cea3ef741021 100644
--- a/src/commands/run.rs
+++ b/src/commands/run.rs
@@ -4,6 +4,8 @@ use anyhow::{anyhow, bail, Context as _, Result};
use clap::Parser;
use once_cell::sync::Lazy;
use std::ffi::OsStr;
+use std::fs::File;
+use std::io::Write;
use std::path::{Component, Path, PathBuf};
use std::thread;
use std::time::Duration;
@@ -151,6 +153,10 @@ pub struct RunCommand {
)]
wasm_timeout: Option,
+ /// Enable coredump generation after a WebAssembly trap.
+ #[clap(long = "coredump-on-trap", value_name = "PATH")]
+ coredump_on_trap: Option,
+
// NOTE: this must come last for trailing varargs
/// The arguments to pass to the module
#[clap(value_name = "ARGS")]
@@ -170,6 +176,13 @@ impl RunCommand {
let preopen_sockets = self.compute_preopen_sockets()?;
+ // Validate coredump-on-trap argument
+ if let Some(coredump_path) = self.coredump_on_trap.as_ref() {
+ if coredump_path.contains("%") {
+ bail!("the coredump-on-trap path does not support patterns yet.")
+ }
+ }
+
// Make wasi available by default.
let preopen_dirs = self.compute_preopen_dirs()?;
let argv = self.compute_argv();
@@ -376,13 +389,35 @@ impl RunCommand {
// Invoke the function and then afterwards print all the results that came
// out, if there are any.
let mut results = vec![Val::null(); ty.results().len()];
- func.call(store, &values, &mut results).with_context(|| {
+ let invoke_res = func.call(store, &values, &mut results).with_context(|| {
if let Some(name) = name {
format!("failed to invoke `{}`", name)
} else {
format!("failed to invoke command default")
}
- })?;
+ });
+
+ if let Err(err) = invoke_res {
+ let err = if err.is::() {
+ if let Some(coredump_path) = self.coredump_on_trap.as_ref() {
+ let source_name = self.module.to_str().unwrap_or_else(|| "unknown");
+
+ if let Err(coredump_err) = generate_coredump(&err, &source_name, coredump_path)
+ {
+ eprintln!("warning: coredump failed to generate: {}", coredump_err);
+ err
+ } else {
+ err.context(format!("core dumped at {}", coredump_path))
+ }
+ } else {
+ err
+ }
+ } else {
+ err
+ };
+ return Err(err);
+ }
+
if !results.is_empty() {
eprintln!(
"warning: using `--invoke` with a function that returns values \
@@ -557,3 +592,37 @@ fn ctx_set_listenfd(num_fd: usize, builder: WasiCtxBuilder) -> Result<(usize, Wa
Ok((num_fd, builder))
}
+
+fn generate_coredump(err: &anyhow::Error, source_name: &str, coredump_path: &str) -> Result<()> {
+ let bt = err
+ .downcast_ref::()
+ .ok_or_else(|| anyhow!("no wasm backtrace found to generate coredump with"))?;
+
+ let mut coredump_builder =
+ wasm_coredump_builder::CoredumpBuilder::new().executable_name(source_name);
+
+ {
+ let mut thread_builder = wasm_coredump_builder::ThreadBuilder::new().thread_name("main");
+
+ for frame in bt.frames() {
+ let coredump_frame = wasm_coredump_builder::FrameBuilder::new()
+ .codeoffset(frame.func_offset().unwrap_or(0) as u32)
+ .funcidx(frame.func_index())
+ .build();
+ thread_builder.add_frame(coredump_frame);
+ }
+
+ coredump_builder.add_thread(thread_builder.build());
+ }
+
+ let coredump = coredump_builder
+ .serialize()
+ .map_err(|err| anyhow!("failed to serialize coredump: {}", err))?;
+
+ let mut f = File::create(coredump_path)
+ .context(format!("failed to create file at `{}`", coredump_path))?;
+ f.write_all(&coredump)
+ .with_context(|| format!("failed to write coredump file at `{}`", coredump_path))?;
+
+ Ok(())
+}