follow up of https://github.com/paritytech/polkadot-sdk/pull/2604
closes https://github.com/paritytech/polkadot-sdk/pull/2604

- [x] take relevant changes from Marcin's PR 
- [x] extract common duplicate code for workers (low-hanging fruits)

~Some unpassed ci problems are more general and should be fixed in
master (see https://github.com/paritytech/polkadot-sdk/pull/4074)~



Proposed labels: **T0-node**, **R0-silent**, **I4-refactor**

-----

kusama address: FZXVQLqLbFV2otNXs6BMnNch54CFJ1idpWwjMb3Z8fTLQC6

---------

Co-authored-by: s0me0ne-unkn0wn <[email protected]>

@mrcnski Done the change on the prepare worker, once the prepare worker
part is good I'll do the same for the execute worker.

This is based on
https://github.com/koute/polkavm/blob/11beebd06276ce9b84f335350138479e714f6caf/crates/polkavm/src/sandbox/linux.rs#L711

.

## TODO

- [x] Add a check for this capability at startup
- [x] Add prdoc mentioning the new Secure Validator Mode (optional)
requirement.

## Related

Closes #2162

---------

Co-authored-by: Marcin S <[email protected]>

Fixes a potential memory leak.

`PR_SET_PDEATHSIG` is used to terminate children when the parent dies.
Note that this is subject to a race. There seems to be a raceless
alternative [here](https://stackoverflow.com/a/42498370/6085242), but
the concern is small enough that a bit more complexity doesn't seem
worth it. Left a bit more info in the code comment.

Co-authored-by: Javier Viola <[email protected]>

Co-authored-by: Marcin S <[email protected]>

Co-authored-by: Marcin S <[email protected]>

closes #622 

Pros:
* simpler interface, just functions:
`create_runtime_from_artifact_bytes()` and `execute_artifact()`

Cons:
* extra overhead of constructing executor semantics each time

I could make it a combination of
* `create_runtime_config(params)` (such that we could clone the
constructed semantics)
* `create_runtime(blob, config)`
* `execute_artifact(blob, config, params)`

Not sure if it's worth it though.

---------

Co-authored-by: Bastian Köcher <[email protected]>

* Use same rustfmt.toml as Substrate

Signed-off-by: Oliver Tale-Yazdi <[email protected]>

* format format file

Signed-off-by: Oliver Tale-Yazdi <[email protected]>

* Format with new config

Signed-off-by: Oliver Tale-Yazdi <[email protected]>

* Add Substrate Clippy config

Signed-off-by: Oliver Tale-Yazdi <[email protected]>

* Print Clippy version in CI

Otherwise its difficult to reproduce locally.

Signed-off-by: Oliver Tale-Yazdi <[email protected]>

* Make fmt happy

Signed-off-by: Oliver Tale-Yazdi <[email protected]>

* Update node/core/pvf/src/error.rs

Co-authored-by: Tsvetomir Dimitrov <[email protected]>

* Update node/core/pvf/src/error.rs

Co-authored-by: Tsvetomir Dimitrov <[email protected]>

---------

Signed-off-by: Oliver Tale-Yazdi <[email protected]>
Co-authored-by: Tsvetomir Dimitrov <[email protected]>

* [WIP] PVF: Split out worker binaries

* Address compilation problems and re-design a bit

* Reorganize once more, fix tests

* Reformat with new nightly to make `cargo fmt` test happy

* Address `clippy` warnings

* Add temporary trace to debug zombienet tests

* Fix zombienet node upgrade test

* Fix malus and its CI

* Fix building worker binaries with malus

* More fixes for malus

* Remove unneeded cli subcommands

* Support placing auxiliary binaries to `/usr/libexec`

* Fix spelling

* Spelling

Co-authored-by: Marcin S. <[email protected]>

* Implement review comments (mostly nits)

* Fix worker node version flag

* Rework getting the worker paths

* Address a couple of review comments

* Minor restructuring

* Fix CI error

* Add tests for worker binaries detection

* Improve tests; try to fix CI

* Move workers module into separate file

* Try to fix failing test and workers not printing latest version

- Tests were not finding the worker binaries
- Workers were not being rebuilt when the version changed
- Made some errors easier to read

* Make a bunch of fixes

* Rebuild nodes on version change

* Fix more issues

* Fix tests

* Pass node version from node into dependencies to avoid recompiles

- [X] get version in CLI
- [X] pass it in to service
- [X] pass version along to PVF
- [X] remove rerun from service
- [X] add rerun to CLI

- [X] don’t rerun pvf/worker’s (these should be built by nodes which have rerun enabled)

* Some more improvements for smoother tests

- [X] Fix tests
- [X] Make puppet workers pass None for version and remove rerun
- [X] Make test collators self-contained

* Add back rerun to PVF workers

* Move worker binaries into files in cli crate

As a final optimization I've separated out each worker binary from its own crate
into the CLI crate. Before, the worker bin shared a crate with the worker lib,
so when the binaries got recompiled so did the libs and everything transitively
depending on the libs. This commit fixes this regression that was causing
recompiles after every commit.

* Fix bug (was passing worker version for node version)

* Move workers out of cli into root src/bin/ dir

- [X] Pass in node version from top-level (polkadot)
- [X] Add build.rs with rerun-git-head to root dir

* Add some sanity checks for workers to dockerfiles

* Update malus

  + [X] Make it self-contained
  + [X] Undo multiple binary changes

* Try to fix clippy errors

* Address `cargo run` issue

- [X] Add default-run for polkadot
- [X] Add note about installation to error

* Update readme (installation instructions)

* Allow disabling external workers for local/testing setups

  + [X] cli flag to enable single-binary mode
  + [X] Add message to error

* Revert unnecessary Cargo.lock changes

* Remove unnecessary build scripts from collators

* Add back missing malus commands (should fix failing ZN job)

* Some minor fixes

* Update Cargo.lock

* Fix some build errors

* Undo self-contained binaries; cli flag to disable version check

  + [X] Remove --dont-run-external-workers
  + [X] Add --disable-worker-version-check
  + [X] Remove PVF subcommands
  + [X] Redo malus changes

* Try to fix failing job and add some docs for local tests

---------

Co-authored-by: Dmitry Sinyavin <[email protected]>
Co-authored-by: s0me0ne-unkn0wn <[email protected]>
Co-authored-by: parity-processbot <>

* Begin adding landlock + test

* Move PVF implementer's guide section to own page, document security

* Implement test

* Add some docs

* Do some cleanup

* Fix typo

* Warn on host startup if landlock is not supported

* Clarify docs a bit

* Minor improvements

* Add some docs about determinism

* Address review comments (mainly add warning on landlock error)

* Update node/core/pvf/src/host.rs

Co-authored-by: Andrei Sandu <[email protected]>

* Update node/core/pvf/src/host.rs

Co-authored-by: Andrei Sandu <[email protected]>

* Fix unused fn

* Update ABI docs to reflect latest discussions

* Remove outdated notes

* Try to trigger new test-linux-oldkernel-stable job

Job introduced in https://github.com/paritytech/polkadot/pull/7371

.

---------

Co-authored-by: Andrei Sandu <[email protected]>

* PVF: Instantiate wasm in pre-checking

* Move `runtime_construction_check` to prepare thread, use bytes

* [minor] Update comment

* Fix compile error

* Update Cargo.lock

* Update docs

* Add some missing docs!

* PVF: Refactor workers into separate crates, remove host dependency

* Fix compile error

* Remove some leftover code

* Fix compile errors

* Update Cargo.lock

* Remove worker main.rs files

I accidentally copied these from the other PR. This PR isn't intended to
introduce standalone workers yet.

* Address review comments

* cargo fmt

* Update a couple of comments

* Update log targets

* PVF: Remove `rayon` and some uses of `tokio`

1. We were using `rayon` to spawn a superfluous thread to do execution, so it was removed.

2. We were using `rayon` to set a threadpool-specific thread stack size, and AFAIK we couldn't do that with `tokio` (it's possible [per-runtime](https://docs.rs/tokio/latest/tokio/runtime/struct.Builder.html#method.thread_stack_size) but not per-thread). Since we want to remove `tokio` from the workers [anyway](https://github.com/paritytech/polkadot/issues/7117), I changed it to spawn threads with the `std::thread` API instead of `tokio`.[^1]

[^1]: NOTE: This PR does not totally remove the `tokio` dependency just yet.

3. Since `std::thread` API is not async, we could no longer `select!` on the threads as futures, so the `select!` was changed to a naive loop.

4. The order of thread selection was flipped to make (3) sound (see note in code).

I left some TODO's related to panics which I'm going to address soon as part of https://github.com/paritytech/polkadot/issues/7045.

* PVF: Vote invalid on panics in execution thread (after a retry)

Also make sure we kill the worker process on panic errors and internal errors to
potentially clear any error states independent of the candidate.

* Address a couple of TODOs

Addresses a couple of follow-up TODOs from
https://github.com/paritytech/polkadot/pull/7153

.

* Add some documentation to implementer's guide

* Fix compile error

* Fix compile errors

* Fix compile error

* Update roadmap/implementers-guide/src/node/utility/candidate-validation.md

Co-authored-by: Andrei Sandu <[email protected]>

* Address comments + couple other changes (see message)

- Measure the CPU time in the prepare thread, so the observed time is not
  affected by any delays in joining on the thread.

- Measure the full CPU time in the execute thread.

* Implement proper thread synchronization

Use condvars i.e. `Arc::new((Mutex::new(true), Condvar::new()))` as per the std
docs.

Considered also using a condvar to signal the CPU thread to end, in place of an
mpsc channel. This was not done because `Condvar::wait_timeout_while` is
documented as being imprecise, and `mpsc::Receiver::recv_timeout` is not
documented as such. Also, we would need a separate condvar, to avoid this case:
the worker thread finishes its job, notifies the condvar, the CPU thread returns
first, and we join on it and not the worker thread. So it was simpler to leave
this part as is.

* Catch panics in threads so we always notify condvar

* Use `WaitOutcome` enum instead of bool condition variable

* Fix retry timeouts to depend on exec timeout kind

* Address review comments

* Make the API for condvars in workers nicer

* Add a doc

* Use condvar for memory stats thread

* Small refactor

* Enumerate internal validation errors in an enum

* Fix comment

* Add a log

* Fix test

* Update variant naming

* Address a missed TODO

---------

Co-authored-by: Andrei Sandu <[email protected]>

* Move PVF workers into separate crate

* Fix indentation

* Fix compilation errors

* Fix more compilation errors

* Rename `worker.rs` files, make host interface to worker more clear

* Fix more compilation errors

* Fix more compilation errors

* Add link to issue

* Address review comments

* Update comment