kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 32 insertions, 0 deletions

diff --git a/tools/perf/ui/keysyms.h b/tools/perf/ui/keysyms.h
new file mode 100644
index 000000000..969060edc
--- /dev/null
+++ b/tools/perf/ui/keysyms.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PERF_KEYSYMS_H_
+#define _PERF_KEYSYMS_H_ 1
+
+#include "libslang.h"
+
+#define K_DOWN	SL_KEY_DOWN
+#define K_END	SL_KEY_END
+#define K_ENTER	'\r'
+#define K_ESC	033
+#define K_F1	SL_KEY_F(1)
+#define K_HOME	SL_KEY_HOME
+#define K_LEFT	SL_KEY_LEFT
+#define K_PGDN	SL_KEY_NPAGE
+#define K_PGUP	SL_KEY_PPAGE
+#define K_RIGHT	SL_KEY_RIGHT
+#define K_TAB	'\t'
+#define K_UNTAB	SL_KEY_UNTAB
+#define K_UP	SL_KEY_UP
+#define K_BKSPC 0x7f
+#define K_DEL	SL_KEY_DELETE
+
+/* Not really keys */
+#define K_TIMER	 -1
+#define K_ERROR	 -2
+#define K_RESIZE -3
+#define K_SWITCH_INPUT_DATA -4
+#define K_RELOAD -5
+
+const char *key_name(int key, char *bf, size_t size);
+
+#endif /* _PERF_KEYSYMS_H_ */