coder0xff
commented
8 months ago I cut down the p384 crate until I had a minimal reproduction. Some observations:
- The SIGSEGV is happening in LLVM
- Initially, the Xtensa toolchains appeared to be the problem because the crash could not be duplicated by building p384 using x86_64 or RISC-V target toolchains. However, after identifying the minimal reproduction, and then making the minimal reproduction very large (that will make sense shortly), crashing can be reproduced even on the x86_64 target toolchain.
- 3000 variables (give or take) is enough to trip up
xtensa-esp32s3-espidf. - 10000 variables will kill any Rust toolchain
- The original code that triggers the bug is here: https://github.com/RustCrypto/elliptic-curves/blob/master/p384/src/arithmetic/scalar/p384_scalar_32.rs#L147
- Removing the unused variables in that code (the
let mutvariables are all dead code) shortens the function enough to compile onxtensa-esp32s3-espidf.
Since this is not an esp-rs/rust bug, I'll close this ticket and open a bug report in upstream Rust. I'll also submit a patch to p384 to clean up the dead code.
Directory Structure
.
├── .cargo
│ └── config.toml
├── Cargo.toml
├── rust-toolchain.toml
└── src
└── lib.rs
2 directories, 4 filesContents of: .cargo/config.toml
[build]
target = "xtensa-esp32s3-espidf"
[target.xtensa-esp32s3-espidf]
linker = "ldproxy"
[unstable]
build-std = ["std"]Contents of: Cargo.toml
[package]
name = "p384"
version = "0.14.0-pre"
edition = "2021"Contents of: rust-toolchain.toml
[toolchain]
channel = "esp"Contents of: src/lib.rs
- This file has been truncated for readability
- The full file is at: https://pastebin.com/s72e8Akk
pub const fn break_me() { let _x1 = 0; let _x2 = 0; let _x3 = 0; let _x4 = 0; let _x5 = 0; let _x6 = 0; let _x7 = 0; let _x8 = 0; let _x9 = 0; let _x10 = 0; . . . let _x9991 = 0; let _x9992 = 0; let _x9993 = 0; let _x9994 = 0; let _x9995 = 0; let _x9996 = 0; let _x9997 = 0; let _x9998 = 0; let _x9999 = 0; }
pub const BREAK_ME: () = break_me();
I encountered this while working to make WebRTC build on Xtensa. WebRTC depends on a crate called p384. I'll try to collect more information, but figured I'd raise awareness before I go build eps-rs from sources.
Reproduction
cargo generate --vcs none esp-rs/esp-idf-template cargoand select the esp32s3 platform.p384 = "0.13"to the dependencies in the generated Cargo.tomlcargo buildMeta
Error output