Debugging: add builtin gdbstub component. (#12771)

* Debugging: add builtin gdbstub component.

This adds a debug component that makes use of the debug-main world
defined in #12756 and serves the gdbstub protocol, with Wasm
extensions, compatible with LLDB.

This component is built and included inside the Wasmtime binary, and
is loaded using the lower-level `-D debugger=...` debug-main option;
the user doesn't need to specify the `.wasm` adapter
component. Instead, the user simply runs `wasmtime run -g <PORT>
program.wasm ...` and Wasmtime will load and prepare to run
`program.wasm` as the debuggee, waiting for a gdbstub connection on
the given TCP port before continuing.

The workflow is:

```
$ wasmtime run -g 1234 program.wasm
[ wasmtime starts and waits for connection ]

$ /opt/wasi-sdk/bin/lldb  # use LLDB from wasi-sdk release 32 or later
(lldb) process connect --plugin wasm connect://localhost:1234
Process 1 stopped
* thread #1, stop reason = signal SIGTRAP
    frame #0: 0x40000000000001cc
->  0x40000000000001cc: unreachable
    0x40000000000001cd: end
    0x40000000000001ce: local.get 0
    0x40000000000001d0: call   13
(lldb) si
Process 1 stopped
* thread #1, stop reason = instruction step into
    frame #0: 0x4000000000000184
->  0x4000000000000184: block
    0x4000000000000186: block
    0x4000000000000188: global.get 1
    0x400000000000018e: i32.const 3664
[ ... ]
```

This makes use of the `gdbstub` third-party crate, into which I've
upstreamed support for the Wasm extensions in daniel5151/gdbstub#188,
daniel5151/gdbstub#189, daniel5151/gdbstub#190, and
daniel5151/gdbstub#192. (I'll add vets as part of this PR.)

* cargo vets.

* Handle Trap events as well as breakpoints.

* Review feedback.

* Fix gdbstub artifact build to make it publishable (by disabling it when isolated crates are used).

* Review feedback.

* fix published-crates list

* For now, empty gdbstub data but no compile error when artifact crate is published.

* add some more Cargo metadata: version for artifact crate dep

Author: cfallin

.github/workflows/main.yml

@@ -387,6 +387,7 @@ jobs:
               -p wasmtime-cli --no-default-features --features compile,cranelift,component-model
               -p wasmtime-cli --no-default-features --features objdump
               -p wasmtime-cli --no-default-features --features wizer
+              -p wasmtime-cli --no-default-features --features gdbstub
               -p wasmtime-cli --all-features
               -p wasmtime-cli --features component-model
 

Cargo.lock

@@ -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 }
@@ -166,6 +167,8 @@ members = [
   "crates/wasi-preview1-component-adapter",
   "crates/wasi-preview1-component-adapter/verify",
   "crates/debugger",
+  "crates/gdbstub-component",
+  "crates/gdbstub-component/artifact",
   "crates/wizer/fuzz",
   "crates/wizer/tests/regex-test",
   "crates/wizer/benches/regex-bench",
@@ -276,6 +279,7 @@ 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", version = "=44.0.0", 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
@@ -354,6 +358,9 @@ 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"
@@ -437,6 +444,8 @@ rayon = "1.5.3"
 regex = "1.9.1"
 pin-project-lite = "0.2.14"
 sha2 = { version = "0.10.2", default-features = false }
+gdbstub = "0.7.10"
+gdbstub_arch = "0.3.3"
 
 # =============================================================================
 #
@@ -523,6 +532,11 @@ component-model-async = [
 ]
 rr = ["wasmtime/rr", "component-model", "wasmtime-cli-flags/rr", "run"]
 
+# Enabled in release builds. We cannot enable the built-in gdbstub component in
+# the default build because the published-to-crates.io crates cannot build the
+# artifact (a limitation caused by lack of artifact dependencies).
+gdbstub = ["debug", "dep:gdbstub-component-artifact"]
+
 # This feature, when enabled, will statically compile out all logging statements
 # throughout Wasmtime and its dependencies.
 disable-logging = ["log/max_level_off", "tracing/max_level_off"]

Cargo.toml

@@ -59,7 +59,7 @@ if [[ "$build" = *-min ]]; then
 else
   # For release builds the CLI is built a bit more feature-ful than the Cargo
   # defaults to provide artifacts that can do as much as possible.
-  bin_flags="--features all-arch,component-model"
+  bin_flags="--features all-arch,component-model,gdbstub"
 fi
 
 if [[ "$target" = "x86_64-pc-windows-msvc" ]]; then

ci/build-release-artifacts.sh

@@ -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 }
+clap = { 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/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"
+description = "gdbstub debug-component adapter"
+
+[lints]
+workspace = true