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, 130 insertions, 0 deletions

diff --git a/include/sound/soc-jack.h b/include/sound/soc-jack.h
new file mode 100644
index 000000000..3a81d4b8c
--- /dev/null
+++ b/include/sound/soc-jack.h
@@ -0,0 +1,130 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * soc-jack.h
+ *
+ * Copyright (C) 2019 Renesas Electronics Corp.
+ * Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
+ */
+#ifndef __SOC_JACK_H
+#define __SOC_JACK_H
+
+/**
+ * struct snd_soc_jack_pin - Describes a pin to update based on jack detection
+ *
+ * @pin:    name of the pin to update
+ * @mask:   bits to check for in reported jack status
+ * @invert: if non-zero then pin is enabled when status is not reported
+ * @list:   internal list entry
+ */
+struct snd_soc_jack_pin {
+	struct list_head list;
+	const char *pin;
+	int mask;
+	bool invert;
+};
+
+/**
+ * struct snd_soc_jack_zone - Describes voltage zones of jack detection
+ *
+ * @min_mv: start voltage in mv
+ * @max_mv: end voltage in mv
+ * @jack_type: type of jack that is expected for this voltage
+ * @debounce_time: debounce_time for jack, codec driver should wait for this
+ *		duration before reading the adc for voltages
+ * @list:   internal list entry
+ */
+struct snd_soc_jack_zone {
+	unsigned int min_mv;
+	unsigned int max_mv;
+	unsigned int jack_type;
+	unsigned int debounce_time;
+	struct list_head list;
+};
+
+/**
+ * struct snd_soc_jack_gpio - Describes a gpio pin for jack detection
+ *
+ * @idx:          gpio descriptor index within the function of the GPIO
+ *                consumer device
+ * @gpiod_dev:    GPIO consumer device
+ * @name:         gpio name. Also as connection ID for the GPIO consumer
+ *                device function name lookup
+ * @report:       value to report when jack detected
+ * @invert:       report presence in low state
+ * @debounce_time: debounce time in ms
+ * @wake:	  enable as wake source
+ * @jack_status_check: callback function which overrides the detection
+ *		       to provide more complex checks (eg, reading an
+ *		       ADC).
+ */
+struct snd_soc_jack_gpio {
+	unsigned int idx;
+	struct device *gpiod_dev;
+	const char *name;
+	int report;
+	int invert;
+	int debounce_time;
+	bool wake;
+
+	/* private: */
+	struct snd_soc_jack *jack;
+	struct delayed_work work;
+	struct notifier_block pm_notifier;
+	struct gpio_desc *desc;
+
+	void *data;
+	/* public: */
+	int (*jack_status_check)(void *data);
+};
+
+struct snd_soc_jack {
+	struct mutex mutex;
+	struct snd_jack *jack;
+	struct snd_soc_card *card;
+	struct list_head pins;
+	int status;
+	struct blocking_notifier_head notifier;
+	struct list_head jack_zones;
+};
+
+/* Jack reporting */
+void snd_soc_jack_report(struct snd_soc_jack *jack, int status, int mask);
+int snd_soc_jack_add_pins(struct snd_soc_jack *jack, int count,
+			  struct snd_soc_jack_pin *pins);
+void snd_soc_jack_notifier_register(struct snd_soc_jack *jack,
+				    struct notifier_block *nb);
+void snd_soc_jack_notifier_unregister(struct snd_soc_jack *jack,
+				      struct notifier_block *nb);
+int snd_soc_jack_add_zones(struct snd_soc_jack *jack, int count,
+			   struct snd_soc_jack_zone *zones);
+int snd_soc_jack_get_type(struct snd_soc_jack *jack, int micbias_voltage);
+#ifdef CONFIG_GPIOLIB
+int snd_soc_jack_add_gpios(struct snd_soc_jack *jack, int count,
+			   struct snd_soc_jack_gpio *gpios);
+int snd_soc_jack_add_gpiods(struct device *gpiod_dev,
+			    struct snd_soc_jack *jack,
+			    int count, struct snd_soc_jack_gpio *gpios);
+void snd_soc_jack_free_gpios(struct snd_soc_jack *jack, int count,
+			     struct snd_soc_jack_gpio *gpios);
+#else
+static inline int snd_soc_jack_add_gpios(struct snd_soc_jack *jack, int count,
+					 struct snd_soc_jack_gpio *gpios)
+{
+	return 0;
+}
+
+static inline int snd_soc_jack_add_gpiods(struct device *gpiod_dev,
+					  struct snd_soc_jack *jack,
+					  int count,
+					  struct snd_soc_jack_gpio *gpios)
+{
+	return 0;
+}
+
+static inline void snd_soc_jack_free_gpios(struct snd_soc_jack *jack, int count,
+					   struct snd_soc_jack_gpio *gpios)
+{
+}
+#endif
+
+#endif /* __SOC_JACK_H */