0e9a48afd5
This change adds a basic coredump generation after a WebAssembly trap was entered. The coredump includes rudimentary stack / process debugging information. A new CLI argument is added to enable coredump generation: ``` wasmtime --coredump-on-trap=/path/to/coredump/file module.wasm ``` See ./docs/examples-coredump.md for a working example. Refs https://github.com/bytecodealliance/wasmtime/issues/5732
63 lines
1.4 KiB
Markdown
63 lines
1.4 KiB
Markdown
# Using Wasm coredump
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The following steps describe how to debug using Wasm coredump in Wasmtime:
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1. Compile your WebAssembly with debug info enabled; for example:
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```sh
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$ rustc foo.rs --target=wasm32-wasi -C debuginfo=2
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```
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<details>
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<summary>foo.rs</summary>
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fn c(v: usize) {
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a(v - 3);
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}
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fn b(v: usize) {
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c(v - 3);
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}
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fn a(v: usize) {
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b(v - 3);
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}
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pub fn main() {
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a(10);
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}
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</details>
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2. Run with Wasmtime and Wasm coredump enabled:
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```sh
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$ wasmtime --coredump-on-trap=/tmp/coredump foo.wasm
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thread 'main' panicked at 'attempt to subtract with overflow', foo.rs:10:7
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note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
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Error: failed to run main module `foo.wasm`
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Caused by:
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0: Core dumped at /tmp/coredump
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1: failed to invoke command default
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2: error while executing at wasm backtrace:
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...
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```
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3. Use [wasmgdb] to debug:
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```sh
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$ wasmgdb foo.wasm /tmp/coredump
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wasmgdb> bt
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...
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#13 000175 as panic () at library/core/src/panicking.rs
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#12 000010 as a (v=???) at /path/to/foo.rs
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#11 000009 as c (v=???) at /path/to/foo.rs
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#10 000011 as b (v=???) at /path/to/foo.rs
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#9 000010 as a (v=???) at /path/to/foo.rs
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#8 000012 as main () at /path/to/foo.rs
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...
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```
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[wasmgdb]: https://crates.io/crates/wasmgdb
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