maurice/snix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

feat(tvix/eval): use backtrace-on-stack-overflow crate

Browse source 
The backtrace-on-stack-overflow create provides best-effort stack
traces when a stack overflow happens.  Since it's running on the
(usually tiny) signal alternate stack this isn't easy.

This is guarded by a new `backtrace_overflow` feature flag and never
enabled (even if that feature is selected) for release builds.  This
is strictly for debugging; there's crazy unsafe voodoo in there.

   https://lib.rs/crates/backtrace-on-stack-overflow

Example output:

```
Stack Overflow:
   0: backtrace_on_stack_overflow::handle_sigsegv
             at /home/amjoseph/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-on-stack-overflow-0.2.0/src/lib.rs:93:40
   1: <unknown>
   2: __rust_probestack
   3: tvix_eval::vm::VM::run_op
             at src/vm.rs:399
   4: tvix_eval::vm::VM::run
             at src/vm.rs:388:23
   5: tvix_eval::vm::VM::enter_frame
             at src/vm.rs:360:22
   6: tvix_eval::value::thunk::Thunk::force
             at src/value/thunk.rs:116:25
   7: tvix_eval::vm::VM::run_op
             at src/vm.rs:801:37
   8: tvix_eval::vm::VM::run
             at src/vm.rs:388:23
   9: tvix_eval::vm::VM::enter_frame
             at src/vm.rs:360:22
  10: tvix_eval::value::thunk::Thunk::force
             at src/value/thunk.rs:116:25
...
```

Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: I1d8a2017f836be7bf91a2223e7adacb86fa1dbb2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7354
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
This commit is contained in:
Adam Joseph 2022-11-22 19:42:06 -08:00 • committed by clbot
parent 4b09f01571
commit 56c00df710
3 changed files with 241 additions and 119 deletions
Download patch file Download diff file Expand all files Collapse all files

9
tvix/eval/src/vm.rs
View file

@ -148,6 +148,15 @@ macro_rules! cmp_op {
impl<'o> VM<'o> {
pub fn new(nix_search_path: NixSearchPath, observer: &'o mut dyn RuntimeObserver) -> Self {
// Backtrace-on-stack-overflow is some seriously weird voodoo and
// very unsafe. This double-guard prevents it from accidentally
// being enabled on release builds.
#[cfg(debug_assertions)]
#[cfg(feature = "backtrace_overflow")]
unsafe {
backtrace_on_stack_overflow::enable();
};
Self {
nix_search_path,
observer,