[PATCH v2 0/6] Rust: support `CPU_MITIGATIONS` and enable `objtool`

[Miguel Ojeda <ojeda@kernel.org>]

Hi,

This is an updated series to the CPU mitigations support for Rust. It
also has the patch to enable `objtool`, so that we can start running it
for Rust.

It would be nice to get this applied soon, so that we start being
warning-free (since we already get warnings under IBT builds via
`vmlinux.o`). I am happy to take it through the Rust tree if the x86 and
objtool maintainers give an Acked-by, or through any of the other trees,
as you prefer. Otherwise, I think at this point we would need to make
Rust exclusive to the mitigations, which isn't great.

With this series, again, x86_64 is warning-free with `objtool` enabled. I
tested `-O2`/`-Os` and the Rust versions we support under `-O2` (mainly
for the `noreturn` patch, which uses heuristics), as well as IBT vs. no
IBT (i.e.  running on individual object files vs. in `vmlinux`). I also
did an arm64 build.

Testing is very welcome for this one!

Cheers,
Miguel

v2:
  - Add patch to enable `objtool` for Rust.

  - Add patch to list `noreturn` Rust functions (via heuristics) to avoid
    warnings related to that.

  - Make the `RETHUNK` patch not an RFC since the Rust compiler has
  support for
    it now.

  - Update the names of the migitation config symbols, given the changes
  at e.g.
    commit 7b75782ffd82 ("x86/bugs: Rename CONFIG_MITIGATION_SLS =>
    CONFIG_MITIGATION_SLS").

Miguel Ojeda (6):
  rust: module: add static pointer to `{init,cleanup}_module()`
  x86/rust: support MITIGATION_RETPOLINE
  x86/rust: support MITIGATION_RETHUNK
  x86/rust: support MITIGATION_SLS
  objtool: list `noreturn` Rust functions
  objtool/kbuild/rust: enable objtool for Rust

 arch/x86/Makefile               |  7 ++++++-
 rust/Makefile                   | 22 ++++++++++++--------
 rust/macros/module.rs           | 12 +++++++++++
 scripts/Makefile.build          |  9 +++++++--
 scripts/generate_rust_target.rs | 15 ++++++++++++++
 tools/objtool/check.c           | 36 ++++++++++++++++++++++++++++++++-
 tools/objtool/noreturns.h       |  2 ++
 7 files changed, 91 insertions(+), 12 deletions(-)


base-commit: b1263411112305acf2af728728591465becb45b0
--
2.45.2