Upgrade toolchain and std to May 2024

[DemesneGH]

This PR upgrades the Rust toolchain and standard library to nightly-2024-05-15, and the libc crate to 0.2.153, both ported for OP-TEE targets.

Additionally, it includes various build script adjustments and code modifications necessary for this upgrade.

Changes:

• Port libc 0.2.153 and add OP-TEE implementation:

  • https://github.com/DemesneGH/libc/tree/optee

• Pin Rust src and add OP-TEE std implementation:

  • https://github.com/DemesneGH/rust/tree/optee-xargo

• No Need to Port compiler_builtins:

  • Removing the link argument link-dead-code helps avoid linking errors with math functions such as "undefined reference to log10".

• Unify OP-TEE Target Names:

  • "aarch64-unknown-optee" for AARCH64
  • "arm-unknown-optee" for ARM32

• optee-utee-rs:

  • Macros: upgrade for quote and syn.
  • Temporarily remove systest as it's not compatible with the new Rust version.

• Examples:

  • hotp-rs:
    • Workaround for the unexpected address of the slice with zero-length. For stable Rust, it's a normal address, but for nightly, it's 0x1, causing a TA panic when dereferencing.
  • tls_client-rs & tls_server-rs:
    • Upgrade to Ring 0.16.20 and Rustls 0.21.0.
    • Update TA source code to accommodate API changes.

• Fix some warnings on new version:

  • Symbolic link to .cargo/config.toml: Xargo uses .cargo.config, not .cargo/config.toml (required for the new cargo version).
  • Change build_dependencies to build-dependencies: deprecated in favor of build-dependencies and will not work in the 2024 edition.

• Polish building scripts

Discussions:

• Xargo or -Zbuild-std When building std from source:

  • cargo -Zbuild-std is the recommended feature but has a bug that [patch.crates-io] does not work. This prevents replacing all libc dependencies for Rust std. Reference: Rust compiler workspace patches are being ignored when compiling with -Zbuild-std rust-lang/wg-cargo-std-aware#78.
  • Once our target is upstream, we can use cargo -Zbuild-std since libc (with OP-TEE implementation) will be merged into the official source.
  • I have the experimental version of using cargo -Zbuild-std at https://github.com/DemesneGH/rust-optee-trustzone-sdk/tree/upgrade-std-202405.
  • Using Xargo for now, although it hasn't been updated in a long time.

• Upstream the OP-TEE Targets:

  • Benefits:
    • No need for the target JSON file in the SDK root.
    • Stay up-to-date without pinning toolchain version.
    • Download Rust src via rustup add components rust-src.
    • (Optional) Use cargo -Zbuild-std instead of Xargo.
  • Other considerations:
    • Even after upstreaming to a tier-3 target, we cannot install our target via rustup, so build-std is still needed.
    • For Rustls and Ring (which use optee-utee-rs APIs such as random and time), we still need to port, or open PR to add our target.

TODOs:

• ARM32 TAs bug fix:
  • Rustc bug when linking: Rust compiler generates symbols.o for ARM32 Object files with EABI version 0, causing error source object xxx.rlib has EABI version 5, but target ta-xxx has EABI version 0. This can be fixed by applying a patch to the Rust compiler. A PR to the Rust repository will be made.
  • tls_client-rs TA ldelf error:
    • User mode data-abort at address xxx (write permission fault) before loading TA into an address.

This PR is a work in progress. Any comments would be appreciated. Thank you!

Updates:

• I'm preparing the Release v.0.3.0 and temporarily drop the ARM32 support for this Release. After the Rustc PR is finished we can enable the ARM32 in the further Release version.