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, 69 insertions, 0 deletions

diff --git a/include/scsi/sas_ata.h b/include/scsi/sas_ata.h
new file mode 100644
index 000000000..a161c0222
--- /dev/null
+++ b/include/scsi/sas_ata.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Support for SATA devices on Serial Attached SCSI (SAS) controllers
+ *
+ * Copyright (C) 2006 IBM Corporation
+ *
+ * Written by: Darrick J. Wong <djwong@us.ibm.com>, IBM Corporation
+ */
+
+#ifndef _SAS_ATA_H_
+#define _SAS_ATA_H_
+
+#include <linux/libata.h>
+#include <scsi/libsas.h>
+
+#ifdef CONFIG_SCSI_SAS_ATA
+
+static inline bool dev_is_sata(struct domain_device *dev)
+{
+	switch (dev->dev_type) {
+	case SAS_SATA_DEV:
+	case SAS_SATA_PENDING:
+	case SAS_SATA_PM:
+	case SAS_SATA_PM_PORT:
+		return true;
+	default:
+		return false;
+	}
+}
+
+void sas_ata_schedule_reset(struct domain_device *dev);
+void sas_ata_device_link_abort(struct domain_device *dev, bool force_reset);
+int sas_execute_ata_cmd(struct domain_device *device, u8 *fis, int force_phy_id);
+int smp_ata_check_ready_type(struct ata_link *link);
+
+extern const struct attribute_group sas_ata_sdev_attr_group;
+
+#else
+
+static inline bool dev_is_sata(struct domain_device *dev)
+{
+	return false;
+}
+
+static inline void sas_ata_schedule_reset(struct domain_device *dev)
+{
+}
+
+static inline void sas_ata_device_link_abort(struct domain_device *dev,
+					     bool force_reset)
+{
+}
+
+static inline int sas_execute_ata_cmd(struct domain_device *device, u8 *fis,
+				      int force_phy_id)
+{
+	return 0;
+}
+
+static inline int smp_ata_check_ready_type(struct ata_link *link)
+{
+	return 0;
+}
+
+#define sas_ata_sdev_attr_group ((struct attribute_group) {})
+
+#endif
+
+#endif /* _SAS_ATA_H_ */