linux/scripts/is_rust_module.sh
Andrea Righi ccc4505454 rust: fix regexp in scripts/is_rust_module.sh
nm can use "R" or "r" to show read-only data sections, but
scripts/is_rust_module.sh can only recognize "r", so with some versions
of binutils it can fail to detect if a module is a Rust module or not.

Right now we're using this script only to determine if we need to skip
BTF generation (that is disabled globally if CONFIG_RUST is enabled),
but it's still nice to fix this script to do the proper job.

Moreover, with this patch applied I can also relax the constraint of
"RUST depends on !DEBUG_INFO_BTF" and build a kernel with Rust and BTF
enabled at the same time (of course BTF generation is still skipped for
Rust modules).

[ Miguel: The actual reason is likely to be a change on the Rust
  compiler between 1.61.0 and 1.62.0:

    echo '#[used] static S: () = ();' |
        rustup run 1.61.0 rustc --emit=obj --crate-type=lib - &&
        nm rust_out.o

    echo '#[used] static S: () = ();' |
        rustup run 1.62.0 rustc --emit=obj --crate-type=lib - &&
        nm rust_out.o

  Gives:

    0000000000000000 r _ZN8rust_out1S17h48027ce0da975467E
    0000000000000000 R _ZN8rust_out1S17h58e1f3d9c0e97cefE

  See https://godbolt.org/z/KE6jneoo4. ]

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-04-19 19:28:49 +02:00

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#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
#
# is_rust_module.sh module.ko
#
# Returns `0` if `module.ko` is a Rust module, `1` otherwise.
set -e
# Using the `16_` prefix ensures other symbols with the same substring
# are not picked up (even if it would be unlikely). The last part is
# used just in case LLVM decides to use the `.` suffix.
#
# In the future, checking for the `.comment` section may be another
# option, see https://github.com/rust-lang/rust/pull/97550.
${NM} "$*" | grep -qE '^[0-9a-fA-F]+ [Rr] _R[^[:space:]]+16___IS_RUST_MODULE[^[:space:]]*$'