rust: Disallow BTF generation with Rust + LTO

The kernel cannot currently self-parse BTF containing Rust debug
information. pahole uses the language of the CU to determine whether to
filter out debug information when generating the BTF. When LTO is
enabled, Rust code can cross CU boundaries, resulting in Rust debug
information in CUs labeled as C. This results in a system which cannot
parse its own BTF.

Signed-off-by: Matthew Maurer <mmaurer@google.com>
Cc: stable@vger.kernel.org
Fixes: c1177979af9c ("btf, scripts: Exclude Rust CUs with pahole")
Link: https://lore.kernel.org/r/20250108-rust-btf-lto-incompat-v1-1-60243ff6d820@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/init/Kconfig b/init/Kconfig
index d0d021b3fa3b3da5576421b4e1c63baf6c8afc09..324c2886b2ea31e84d6ff221338a1effa06298f2 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1973,7 +1973,7 @@ config RUST
        depends on !MODVERSIONS || GENDWARFKSYMS
        depends on !GCC_PLUGIN_RANDSTRUCT
        depends on !RANDSTRUCT
-       depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
+       depends on !DEBUG_INFO_BTF || (PAHOLE_HAS_LANG_EXCLUDE && !LTO)
        depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
        select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG
        depends on !CALL_PADDING || RUSTC_VERSION >= 108100