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From:   Andrea Righi <andrea.righi@canonical.com>
To:     Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>
Cc:     Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>, Tom Rix <trix@redhat.com>,
        linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org,
        linux-kbuild@vger.kernel.org, llvm@lists.linux.dev
Subject: [PATCH] btf, scripts: rust: drop is_rust_module.sh
Date:   Tue,  4 Jul 2023 07:21:36 +0200
Message-Id: <20230704052136.155445-1-andrea.righi@canonical.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

With commit c1177979af9c ("btf, scripts: Exclude Rust CUs with pahole")
we are now able to use pahole directly to identify Rust compilation
units (CUs) and exclude them from generating BTF debugging information
(when DEBUG_INFO_BTF is enabled).

And if pahole doesn't support the --lang-exclude flag, we can't enable
both RUST and DEBUG_INFO_BTF at the same time.

So, in any case, the script is_rust_module.sh is just redundant and we
can drop it.

NOTE: we may also be able to drop the "Rust loadable module" mark
inside Rust modules, but it seems safer to keep it for now to make sure
we are not breaking any external tool that may potentially rely on it.

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
---
 rust/macros/module.rs     |  2 +-
 scripts/Makefile.modfinal |  2 --
 scripts/is_rust_module.sh | 16 ----------------
 3 files changed, 1 insertion(+), 19 deletions(-)
 delete mode 100755 scripts/is_rust_module.sh

diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index fb1244f8c2e6..d62d8710d77a 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -199,7 +199,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
             /// Used by the printing macros, e.g. [`info!`].
             const __LOG_PREFIX: &[u8] = b\"{name}\\0\";
 
-            /// The \"Rust loadable module\" mark, for `scripts/is_rust_module.sh`.
+            /// The \"Rust loadable module\" mark.
             //
             // This may be best done another way later on, e.g. as a new modinfo
             // key or a new section. For the moment, keep it simple.
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index fc19f67039bd..b3a6aa8fbe8c 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -41,8 +41,6 @@ quiet_cmd_btf_ko = BTF [M] $@
       cmd_btf_ko = 							\
 	if [ ! -f vmlinux ]; then					\
 		printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \
-	elif [ -n "$(CONFIG_RUST)" ] && $(srctree)/scripts/is_rust_module.sh $@; then 		\
-		printf "Skipping BTF generation for %s because it's a Rust module\n" $@ 1>&2; \
 	else								\
 		LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) --btf_base vmlinux $@; \
 		$(RESOLVE_BTFIDS) -b vmlinux $@; 			\
diff --git a/scripts/is_rust_module.sh b/scripts/is_rust_module.sh
deleted file mode 100755
index 464761a7cf7f..000000000000
--- a/scripts/is_rust_module.sh
+++ /dev/null
@@ -1,16 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0
-#
-# is_rust_module.sh module.ko
-#
-# Returns `0` if `module.ko` is a Rust module, `1` otherwise.
-
-set -e
-
-# Using the `16_` prefix ensures other symbols with the same substring
-# are not picked up (even if it would be unlikely). The last part is
-# used just in case LLVM decides to use the `.` suffix.
-#
-# In the future, checking for the `.comment` section may be another
-# option, see https://github.com/rust-lang/rust/pull/97550.
-${NM} "$*" | grep -qE '^[0-9a-fA-F]+ [Rr] _R[^[:space:]]+16___IS_RUST_MODULE[^[:space:]]*$'
-- 
2.40.1