Unsupported Wasm Opcode after updating nightly toolchain

[atenjin]

Is there an existing issue?

• I have searched the existing issues

Experiencing problems? Have you tried our Stack Exchange first?

• This is not a support question.

Description of bug

After I update the nightly toolchain for the newest version:

   stable-x86_64-unknown-linux-gnu updated - rustc 1.68.0 (2c8cc3432 2023-03-06) (from rustc 1.66.1 (90743e729 2023-01-10))
  nightly-x86_64-unknown-linux-gnu updated - rustc 1.70.0-nightly (4a04d086c 2023-03-18) (from rustc 1.68.0-nightly (9e75dddf6 2023-01-15))

maybe the problem appears in 1.70.0, for at least 1.68.0 it's still ok.

After I compile the substrate or any substrate based blockchain, the check for the runtime will appear the following error:

-->$ ./target/debug/node-template --tmp --dev
2023-03-19 21:03:00 Substrate Node    
2023-03-19 21:03:00 ✌️  version 4.0.0-dev-d67d92de1be    
2023-03-19 21:03:00 ❤️  by Substrate DevHub <https://github.com/substrate-developer-hub>, 2017-2023    
2023-03-19 21:03:00 📋 Chain specification: Development    
2023-03-19 21:03:00 🏷  Node name: divergent-collar-5282    
2023-03-19 21:03:00 👤 Role: AUTHORITY    
2023-03-19 21:03:00 💾 Database: RocksDb at /tmp/substrateoESZmw/chains/dev/db/full    
2023-03-19 21:03:00 ⛓  Native runtime: node-template-100 (node-template-1.tx1.au1)    
Error: Service(Client(VersionInvalid("cannot deserialize module: UnknownOpcode(192)")))
2023-03-19 21:03:00 Cannot create a runtime error=Other("cannot deserialize module: UnknownOpcode(192)")

I'm familiar with substrate very well, so I know this error is caused by the crate parity-wasm that developed by parity to check and decode and etc to handle wasm file.

This error comes from

So the unknown Opcode is 0xc0 (192), while the function deserialize_buffer comes from crate parity-wasm.

And for current substrate (at least for the branch polkadot-0.9.39), the parity-wasm is using the version 0.45.0

In this version, the Opcode 0xc0 is under the control of feature sign_ext

I know that substrate runtime wasm should be limited in the most concise Wasm specification.

So I'm not sure whether the Opcode group sign_ext is under the required Wasm specification for the Substrate runtime.

If it's needed, fix this issue is very simple.

However if it's not needed, it's strange why rust toolchain need to add those group Opcode in normal Wasm file.

At least I can ensure that, for the toolchain nightly-1.70.0(2023-03-18) is will appear this problem, while night-1.68.0 not. Not sure for nightly-1.69.0

Steps to reproduce

rust toolchain version:
stable: 1.68.0 (2c8cc3432 2023-03-06)
nightly: 1.70.0-nightly (4a04d086c 2023-03-18)

substrate version: branch: polkadot-0.9.39

how to reproduce:

build any substrate project, and run the node directly. It will meet the error and exit for the error

2023-03-19 21:03:00 Cannot create a runtime error=Other("cannot deserialize module: UnknownOpcode(192)")

[bkchr]

Maybe related to this rust-lang/rust#109326?

Please test with the nightly from the 20.03 when it is available and report back! Ty.

[btwiuse]

Maybe related to this rust-lang/rust#109326?

Please test with the nightly from the 20.03 when it is available and report back! Ty.

Yesterday compiling https://github.com/gear-dapps/app also failed with error: Unknown opcode 192 when the issue was created.

Today I updated the nightly toolchain to rustc 1.70.0-nightly (da7c50c08 2023-03-19) and the error disappeared.

[atenjin]

Maybe related to this rust-lang/rust#109326?

Please test with the nightly from the 20.03 when it is available and report back! Ty.

fine, when I have updated my toolchain to:

  stable-x86_64-unknown-linux-gnu unchanged - rustc 1.68.0 (2c8cc3432 2023-03-06)
   nightly-x86_64-unknown-linux-gnu updated - rustc 1.70.0-nightly (da7c50c08 2023-03-19) (from rustc 1.70.0-nightly (4a04d086c 2023-03-18))

Anything is ok for now.

Although I am still curious whether those Wasm Opcodes are necessary for the substrate runtime @bkchr , I doubt this revert rust-lang/rust#109326 is just a temp fix, it will add it back in future? If rust toolchain still use those changes, maybe substrate need to update the check for wasm code.

Anyway, I close this issue for now.

[bkchr]

LLVM was reverted because it broke a lot of things. As long as the new LLVM isn't back and doesn't bring back these op codes I assume that it was some kind of bug. If we see that the LLVM upgrade brings this back, we will need to investigate it!

Ty for the report @atenjin!

[clearloop]

Maybe related to this rust-lang/rust#109326?
Please test with the nightly from the 20.03 when it is available and report back! Ty.

fine, when I have updated my toolchain to:

  stable-x86_64-unknown-linux-gnu unchanged - rustc 1.68.0 (2c8cc3432 2023-03-06)
   nightly-x86_64-unknown-linux-gnu updated - rustc 1.70.0-nightly (da7c50c08 2023-03-19) (from rustc 1.70.0-nightly (4a04d086c 2023-03-18))

Anything is ok for now.

Although I am still curious whether those Wasm Opcodes are necessary for the substrate runtime @bkchr , I doubt this revert rust-lang/rust#109326 is just a temp fix, it will add it back in future? If rust toolchain still use those changes, maybe substrate need to update the check for wasm code.

Anyway, I close this issue for now.

binaryen v111 enables sign_ext by default as well, mb there's any new consensus inside the mozilla team

[bkchr]

binaryen v111 enables sign_ext by default as well, mb there's any new consensus inside the mozilla team

Okay thank you! I also just checked and every major browser has enabled it, maybe time to also enable it in our executor? But for Parachains we will need to be able to support this at runtime, to be able to let the relay chain runtime decide on when to enable this feature.

WDYT @athei @koute

[koute]

binaryen v111 enables sign_ext by default as well, mb there's any new consensus inside the mozilla team

Okay thank you! I also just checked and every major browser has enabled it, maybe time to also enable it in our executor? But for Parachains we will need to be able to support this at runtime, to be able to let the relay chain runtime decide on when to enable this feature.

WDYT @athei @koute

Hmm... we could enable it, but AFAIK we'd need to add some mechanism for versioning the PVFs' execution environment so that we can enable this in a controlled fashion. (paritytech/polkadot-sdk#917) cc @s0me0ne-unkn0wn

We could also just pass -C target-cpu=mvp as a compilation flag and I think that should disable this extensions even on the most recent version of rustc/LLVM; not entirely ideal, but it would kick the can down the road for a little bit more.

[bkchr]

Hmm... we could enable it, but AFAIK we'd need to add some mechanism for versioning the PVFs' execution environment so that we can enable this in a controlled fashion

Yeah, this is what I meant with my complicated sentence :P

[s0me0ne-unkn0wn]

parity-wasm supports sign_ext if its sign_ext feature is enabled, maybe it's time to enable it? I believe It's used during the instrumentation phase only, so shouldn't affect anything.

Enabling it for Wasmtime through parametrization would be great, but I'm afraid it would require some time... First, we must add a new execution environment parameter that controls WASM features (we do not have one yet) and wait for the supermajority to upgrade. Then, I have to push with paritytech/polkadot#6805. Otherwise, we'll have to do a runtime upgrade to enable it. Sounds doable, though, the only question is how urgent it is.

[koute]

parity-wasm supports sign_ext if its sign_ext feature is enabled, maybe it's time to enable it? I believe It's used during the instrumentation phase only, so shouldn't affect anything.

No real point in enabling it if it's not going to be supported by the executor though; it'll still fail, just a little later.

Sounds doable, though, the only question is how urgent it is.

Since AFAIK we can still force rustc to emit code without this feature it's not super urgent, but time's slowly running out. I wouldn't be surprised if the mvp feature target will eventually get removed. So it'd be better to start on this sooner rather than later.

[athei]

parity-wasm supports sign_ext if its sign_ext feature is enabled, maybe it's time to enable it? I believe It's used during the instrumentation phase only, so shouldn't affect anything.

No real point in enabling it if it's not going to be supported by the executor though; it'll still fail, just a little later.

Yes. For now we should pass -C target-cpu=mvp in wasm-builder. This is what we do in cargo contract. At least it will work until they remove this CPU. And then we get a clean build error. I am not sure if they will ever remove it. Other targets still support decade old CPUs.