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(()) +}