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, 46 insertions, 0 deletions

diff --git a/include/dt-bindings/clock/berlin2.h b/include/dt-bindings/clock/berlin2.h
new file mode 100644
index 000000000..b07b8efab
--- /dev/null
+++ b/include/dt-bindings/clock/berlin2.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Berlin2 BG2/BG2CD clock tree IDs
+ */
+
+#define CLKID_SYS		0
+#define CLKID_CPU		1
+#define CLKID_DRMFIGO		2
+#define CLKID_CFG		3
+#define CLKID_GFX		4
+#define CLKID_ZSP		5
+#define CLKID_PERIF		6
+#define CLKID_PCUBE		7
+#define CLKID_VSCOPE		8
+#define CLKID_NFC_ECC		9
+#define CLKID_VPP		10
+#define CLKID_APP		11
+#define CLKID_AUDIO0		12
+#define CLKID_AUDIO2		13
+#define CLKID_AUDIO3		14
+#define CLKID_AUDIO1		15
+#define CLKID_GFX3D_CORE	16
+#define CLKID_GFX3D_SYS		17
+#define CLKID_ARC		18
+#define CLKID_VIP		19
+#define CLKID_SDIO0XIN		20
+#define CLKID_SDIO1XIN		21
+#define CLKID_GFX3D_EXTRA	22
+#define CLKID_GC360		23
+#define CLKID_SDIO_DLLMST	24
+#define CLKID_GETH0		25
+#define CLKID_GETH1		26
+#define CLKID_SATA		27
+#define CLKID_AHBAPB		28
+#define CLKID_USB0		29
+#define CLKID_USB1		30
+#define CLKID_PBRIDGE		31
+#define CLKID_SDIO0		32
+#define CLKID_SDIO1		33
+#define CLKID_NFC		34
+#define CLKID_SMEMC		35
+#define CLKID_AUDIOHD		36
+#define CLKID_VIDEO0		37
+#define CLKID_VIDEO1		38
+#define CLKID_VIDEO2		39
+#define CLKID_TWD		40