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, 249 insertions, 0 deletions

diff --git a/drivers/input/mouse/psmouse.h b/drivers/input/mouse/psmouse.h
new file mode 100644
index 000000000..90ed8cd15
--- /dev/null
+++ b/drivers/input/mouse/psmouse.h
@@ -0,0 +1,249 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PSMOUSE_H
+#define _PSMOUSE_H
+
+#define PSMOUSE_OOB_NONE	0x00
+#define PSMOUSE_OOB_EXTRA_BTNS	0x01
+
+#define PSMOUSE_CMD_SETSCALE11	0x00e6
+#define PSMOUSE_CMD_SETSCALE21	0x00e7
+#define PSMOUSE_CMD_SETRES	0x10e8
+#define PSMOUSE_CMD_GETINFO	0x03e9
+#define PSMOUSE_CMD_SETSTREAM	0x00ea
+#define PSMOUSE_CMD_SETPOLL	0x00f0
+#define PSMOUSE_CMD_POLL	0x00eb	/* caller sets number of bytes to receive */
+#define PSMOUSE_CMD_RESET_WRAP	0x00ec
+#define PSMOUSE_CMD_GETID	0x02f2
+#define PSMOUSE_CMD_SETRATE	0x10f3
+#define PSMOUSE_CMD_ENABLE	0x00f4
+#define PSMOUSE_CMD_DISABLE	0x00f5
+#define PSMOUSE_CMD_RESET_DIS	0x00f6
+#define PSMOUSE_CMD_RESET_BAT	0x02ff
+
+#define PSMOUSE_RET_BAT		0xaa
+#define PSMOUSE_RET_ID		0x00
+#define PSMOUSE_RET_ACK		0xfa
+#define PSMOUSE_RET_NAK		0xfe
+
+enum psmouse_state {
+	PSMOUSE_IGNORE,
+	PSMOUSE_INITIALIZING,
+	PSMOUSE_RESYNCING,
+	PSMOUSE_CMD_MODE,
+	PSMOUSE_ACTIVATED,
+};
+
+/* psmouse protocol handler return codes */
+typedef enum {
+	PSMOUSE_BAD_DATA,
+	PSMOUSE_GOOD_DATA,
+	PSMOUSE_FULL_PACKET
+} psmouse_ret_t;
+
+enum psmouse_scale {
+	PSMOUSE_SCALE11,
+	PSMOUSE_SCALE21
+};
+
+enum psmouse_type {
+	PSMOUSE_NONE,
+	PSMOUSE_PS2,
+	PSMOUSE_PS2PP,
+	PSMOUSE_THINKPS,
+	PSMOUSE_GENPS,
+	PSMOUSE_IMPS,
+	PSMOUSE_IMEX,
+	PSMOUSE_SYNAPTICS,
+	PSMOUSE_ALPS,
+	PSMOUSE_LIFEBOOK,
+	PSMOUSE_TRACKPOINT,
+	PSMOUSE_TOUCHKIT_PS2,
+	PSMOUSE_CORTRON,
+	PSMOUSE_HGPK,		/* No longer used */
+	PSMOUSE_ELANTECH,
+	PSMOUSE_FSP,
+	PSMOUSE_SYNAPTICS_RELATIVE,
+	PSMOUSE_CYPRESS,
+	PSMOUSE_FOCALTECH,
+	PSMOUSE_VMMOUSE,
+	PSMOUSE_BYD,
+	PSMOUSE_SYNAPTICS_SMBUS,
+	PSMOUSE_ELANTECH_SMBUS,
+	PSMOUSE_AUTO		/* This one should always be last */
+};
+
+struct psmouse;
+
+struct psmouse_protocol {
+	enum psmouse_type type;
+	bool maxproto;
+	bool ignore_parity; /* Protocol should ignore parity errors from KBC */
+	bool try_passthru; /* Try protocol also on passthrough ports */
+	bool smbus_companion; /* "Protocol" is a stub, device is on SMBus */
+	const char *name;
+	const char *alias;
+	int (*detect)(struct psmouse *, bool);
+	int (*init)(struct psmouse *);
+};
+
+struct psmouse {
+	void *private;
+	struct input_dev *dev;
+	struct ps2dev ps2dev;
+	struct work_struct resync_work;
+	const char *vendor;
+	const char *name;
+	const struct psmouse_protocol *protocol;
+	unsigned char packet[8];
+	unsigned char badbyte;
+	unsigned char pktcnt;
+	unsigned char pktsize;
+	unsigned char oob_data_type;
+	unsigned char extra_buttons;
+	bool acks_disable_command;
+	unsigned int model;
+	unsigned long last;
+	unsigned long out_of_sync_cnt;
+	unsigned long num_resyncs;
+	enum psmouse_state state;
+	char devname[64];
+	char phys[32];
+
+	unsigned int rate;
+	unsigned int resolution;
+	unsigned int resetafter;
+	unsigned int resync_time;
+	bool smartscroll;	/* Logitech only */
+
+	psmouse_ret_t (*protocol_handler)(struct psmouse *psmouse);
+	void (*set_rate)(struct psmouse *psmouse, unsigned int rate);
+	void (*set_resolution)(struct psmouse *psmouse, unsigned int resolution);
+	void (*set_scale)(struct psmouse *psmouse, enum psmouse_scale scale);
+
+	int (*reconnect)(struct psmouse *psmouse);
+	int (*fast_reconnect)(struct psmouse *psmouse);
+	void (*disconnect)(struct psmouse *psmouse);
+	void (*cleanup)(struct psmouse *psmouse);
+	int (*poll)(struct psmouse *psmouse);
+
+	void (*pt_activate)(struct psmouse *psmouse);
+	void (*pt_deactivate)(struct psmouse *psmouse);
+};
+
+struct psmouse *psmouse_from_serio(struct serio *serio);
+
+int psmouse_reset(struct psmouse *psmouse);
+void psmouse_set_state(struct psmouse *psmouse, enum psmouse_state new_state);
+void psmouse_set_resolution(struct psmouse *psmouse, unsigned int resolution);
+psmouse_ret_t psmouse_process_byte(struct psmouse *psmouse);
+int psmouse_activate(struct psmouse *psmouse);
+int psmouse_deactivate(struct psmouse *psmouse);
+bool psmouse_matches_pnp_id(struct psmouse *psmouse, const char * const ids[]);
+
+void psmouse_report_standard_buttons(struct input_dev *, u8 buttons);
+void psmouse_report_standard_motion(struct input_dev *, u8 *packet);
+void psmouse_report_standard_packet(struct input_dev *, u8 *packet);
+
+struct psmouse_attribute {
+	struct device_attribute dattr;
+	void *data;
+	ssize_t (*show)(struct psmouse *psmouse, void *data, char *buf);
+	ssize_t (*set)(struct psmouse *psmouse, void *data,
+			const char *buf, size_t count);
+	bool protect;
+};
+#define to_psmouse_attr(a)	container_of((a), struct psmouse_attribute, dattr)
+
+ssize_t psmouse_attr_show_helper(struct device *dev, struct device_attribute *attr,
+				 char *buf);
+ssize_t psmouse_attr_set_helper(struct device *dev, struct device_attribute *attr,
+				const char *buf, size_t count);
+
+#define __PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, _show, _set, _protect)	\
+static struct psmouse_attribute psmouse_attr_##_name = {			\
+	.dattr	= {								\
+		.attr	= {							\
+			.name	= __stringify(_name),				\
+			.mode	= _mode,					\
+		},								\
+		.show	= psmouse_attr_show_helper,				\
+		.store	= psmouse_attr_set_helper,				\
+	},									\
+	.data	= _data,							\
+	.show	= _show,							\
+	.set	= _set,								\
+	.protect = _protect,							\
+}
+
+#define __PSMOUSE_DEFINE_ATTR(_name, _mode, _data, _show, _set, _protect)	\
+	static ssize_t _show(struct psmouse *, void *, char *);			\
+	static ssize_t _set(struct psmouse *, void *, const char *, size_t);	\
+	__PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, _show, _set, _protect)
+
+#define PSMOUSE_DEFINE_ATTR(_name, _mode, _data, _show, _set)			\
+	__PSMOUSE_DEFINE_ATTR(_name, _mode, _data, _show, _set, true)
+
+#define PSMOUSE_DEFINE_RO_ATTR(_name, _mode, _data, _show)			\
+	static ssize_t _show(struct psmouse *, void *, char *);			\
+	__PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, _show, NULL, true)
+
+#define PSMOUSE_DEFINE_WO_ATTR(_name, _mode, _data, _set)			\
+	static ssize_t _set(struct psmouse *, void *, const char *, size_t);	\
+	__PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, NULL, _set, true)
+
+#ifndef psmouse_fmt
+#define psmouse_fmt(fmt)	KBUILD_BASENAME ": " fmt
+#endif
+
+#define psmouse_dbg(psmouse, format, ...)		\
+	dev_dbg(&(psmouse)->ps2dev.serio->dev,		\
+		psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_info(psmouse, format, ...)		\
+	dev_info(&(psmouse)->ps2dev.serio->dev,		\
+		 psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_warn(psmouse, format, ...)		\
+	dev_warn(&(psmouse)->ps2dev.serio->dev,		\
+		 psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_err(psmouse, format, ...)		\
+	dev_err(&(psmouse)->ps2dev.serio->dev,		\
+		psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_notice(psmouse, format, ...)		\
+	dev_notice(&(psmouse)->ps2dev.serio->dev,	\
+		   psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_printk(level, psmouse, format, ...)	\
+	dev_printk(level,				\
+		   &(psmouse)->ps2dev.serio->dev,	\
+		   psmouse_fmt(format), ##__VA_ARGS__)
+
+#ifdef CONFIG_MOUSE_PS2_SMBUS
+
+int psmouse_smbus_module_init(void);
+void psmouse_smbus_module_exit(void);
+
+struct i2c_board_info;
+
+int psmouse_smbus_init(struct psmouse *psmouse,
+		       const struct i2c_board_info *board,
+		       const void *pdata, size_t pdata_size,
+		       bool need_deactivate,
+		       bool leave_breadcrumbs);
+void psmouse_smbus_cleanup(struct psmouse *psmouse);
+
+#else /* !CONFIG_MOUSE_PS2_SMBUS */
+
+static inline int psmouse_smbus_module_init(void)
+{
+	return 0;
+}
+
+static inline void psmouse_smbus_module_exit(void)
+{
+}
+
+static inline void psmouse_smbus_cleanup(struct psmouse *psmouse)
+{
+}
+
+#endif /* CONFIG_MOUSE_PS2_SMBUS */
+
+#endif /* _PSMOUSE_H */