rust: make mutually exclusive with CFI_CLANG

On RISC-V and arm64, and presumably x86, if CFI_CLANG is enabled,
loading a rust module will trigger a kernel panic. Support for
sanitisers, including kcfi (CFI_CLANG), is in the works, but for now
they're nightly-only options in rustc. Make RUST depend on !CFI_CLANG
to prevent configuring a kernel without symmetrical support for kfi.

[ Matthew Maurer writes [1]:

    This patch is fine by me - the last patch needed for KCFI to be
    functional in Rust just landed upstream last night, so we should
    revisit this (in the form of enabling it) once we move to
    `rustc-1.79.0` or later.

  Ramon de C Valle also gave feedback [2] on the status of KCFI for
  Rust and created a tracking issue [3] in upstream Rust.   - Miguel ]

Fixes: 2f7ab1267dc9 ("Kbuild: add Rust support")
Cc: stable@vger.kernel.org
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/CAGSQo024u1gHJgzsO38Xg3c4or+JupoPABQx_+0BLEpPg0cOEA@mail.gmail.com/
Link: https://lore.kernel.org/rust-for-linux/CAOcBZOS2kPyH0Dm7Fuh4GC3=v7nZhyzBj_-dKu3PfAnrHZvaxg@mail.gmail.com/
Link: https://github.com/rust-lang/rust/issues/123479
Link: https://lore.kernel.org/r/20240404-providing-emporium-e652e359c711@spud
[ Added feedback from the list, links, and used Cc for the tag. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/init/Kconfig b/init/Kconfig
index b9a336a3d7d8fde3ad0b5a0390827cb919bb9178..664bedb9a71fbe97c9726c1397d5c8b2043d1da4 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1899,6 +1899,7 @@ config RUST
        bool "Rust support"
        depends on HAVE_RUST
        depends on RUST_IS_AVAILABLE
+       depends on !CFI_CLANG
        depends on !MODVERSIONS
        depends on !GCC_PLUGINS
        depends on !RANDSTRUCT