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, 119 insertions, 0 deletions

diff --git a/include/scsi/fcoe_sysfs.h b/include/scsi/fcoe_sysfs.h
new file mode 100644
index 000000000..2b28a05e4
--- /dev/null
+++ b/include/scsi/fcoe_sysfs.h
@@ -0,0 +1,119 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2011-2012 Intel Corporation.  All rights reserved.
+ *
+ * Maintained at www.Open-FCoE.org
+ */
+
+#ifndef FCOE_SYSFS
+#define FCOE_SYSFS
+
+#include <linux/if_ether.h>
+#include <linux/device.h>
+#include <scsi/fc/fc_fcoe.h>
+
+struct fcoe_ctlr_device;
+struct fcoe_fcf_device;
+
+struct fcoe_sysfs_function_template {
+	void (*get_fcoe_ctlr_link_fail)(struct fcoe_ctlr_device *);
+	void (*get_fcoe_ctlr_vlink_fail)(struct fcoe_ctlr_device *);
+	void (*get_fcoe_ctlr_miss_fka)(struct fcoe_ctlr_device *);
+	void (*get_fcoe_ctlr_symb_err)(struct fcoe_ctlr_device *);
+	void (*get_fcoe_ctlr_err_block)(struct fcoe_ctlr_device *);
+	void (*get_fcoe_ctlr_fcs_error)(struct fcoe_ctlr_device *);
+	void (*set_fcoe_ctlr_mode)(struct fcoe_ctlr_device *);
+	int  (*set_fcoe_ctlr_enabled)(struct fcoe_ctlr_device *);
+	void (*get_fcoe_fcf_selected)(struct fcoe_fcf_device *);
+	void (*get_fcoe_fcf_vlan_id)(struct fcoe_fcf_device *);
+};
+
+#define dev_to_ctlr(d)					\
+	container_of((d), struct fcoe_ctlr_device, dev)
+
+enum fip_conn_type {
+	FIP_CONN_TYPE_UNKNOWN,
+	FIP_CONN_TYPE_FABRIC,
+	FIP_CONN_TYPE_VN2VN,
+};
+
+enum ctlr_enabled_state {
+	FCOE_CTLR_ENABLED,
+	FCOE_CTLR_DISABLED,
+	FCOE_CTLR_UNUSED,
+};
+
+struct fcoe_ctlr_device {
+	u32				id;
+
+	struct device			dev;
+	struct fcoe_sysfs_function_template *f;
+
+	struct list_head		fcfs;
+	struct workqueue_struct		*work_q;
+	struct workqueue_struct		*devloss_work_q;
+	struct mutex			lock;
+
+	int                             fcf_dev_loss_tmo;
+	enum fip_conn_type              mode;
+
+	enum ctlr_enabled_state         enabled;
+
+	/* expected in host order for displaying */
+	struct fcoe_fc_els_lesb         lesb;
+};
+
+static inline void *fcoe_ctlr_device_priv(const struct fcoe_ctlr_device *ctlr)
+{
+	return (void *)(ctlr + 1);
+}
+
+/* fcf states */
+enum fcf_state {
+	FCOE_FCF_STATE_UNKNOWN,
+	FCOE_FCF_STATE_DISCONNECTED,
+	FCOE_FCF_STATE_CONNECTED,
+	FCOE_FCF_STATE_DELETED,
+};
+
+struct fcoe_fcf_device {
+	u32		    id;
+	struct device	    dev;
+	struct list_head    peers;
+	struct work_struct  delete_work;
+	struct delayed_work dev_loss_work;
+	u32		    dev_loss_tmo;
+	void                *priv;
+	enum fcf_state      state;
+
+	u64                 fabric_name;
+	u64                 switch_name;
+	u32                 fc_map;
+	u16                 vfid;
+	u8                  mac[ETH_ALEN];
+	u8                  priority;
+	u32                 fka_period;
+	u8                  selected;
+	u16                 vlan_id;
+};
+
+#define dev_to_fcf(d)					\
+	container_of((d), struct fcoe_fcf_device, dev)
+/* parentage should never be missing */
+#define fcoe_fcf_dev_to_ctlr_dev(x)		\
+	dev_to_ctlr((x)->dev.parent)
+#define fcoe_fcf_device_priv(x)			\
+	((x)->priv)
+
+struct fcoe_ctlr_device *fcoe_ctlr_device_add(struct device *parent,
+			    struct fcoe_sysfs_function_template *f,
+			    int priv_size);
+void fcoe_ctlr_device_delete(struct fcoe_ctlr_device *);
+struct fcoe_fcf_device *fcoe_fcf_device_add(struct fcoe_ctlr_device *,
+					    struct fcoe_fcf_device *);
+void fcoe_fcf_device_delete(struct fcoe_fcf_device *);
+
+int __init fcoe_sysfs_setup(void);
+void __exit fcoe_sysfs_teardown(void);
+
+#endif /* FCOE_SYSFS */