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, 212 insertions, 0 deletions

diff --git a/include/sound/hda-mlink.h b/include/sound/hda-mlink.h
new file mode 100644
index 000000000..fed69998c
--- /dev/null
+++ b/include/sound/hda-mlink.h
@@ -0,0 +1,212 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
+/*
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * Copyright(c) 2022-2023 Intel Corporation
+ */
+
+struct hdac_bus;
+struct hdac_ext_link;
+
+#if IS_ENABLED(CONFIG_SND_SOC_SOF_HDA_MLINK)
+
+int hda_bus_ml_init(struct hdac_bus *bus);
+void hda_bus_ml_free(struct hdac_bus *bus);
+
+int hdac_bus_eml_get_count(struct hdac_bus *bus, bool alt, int elid);
+void hdac_bus_eml_enable_interrupt_unlocked(struct hdac_bus *bus, bool alt, int elid, bool enable);
+void hdac_bus_eml_enable_interrupt(struct hdac_bus *bus, bool alt, int elid, bool enable);
+bool hdac_bus_eml_check_interrupt(struct hdac_bus *bus, bool alt, int elid);
+
+int hdac_bus_eml_set_syncprd_unlocked(struct hdac_bus *bus, bool alt, int elid, u32 syncprd);
+int hdac_bus_eml_sdw_set_syncprd_unlocked(struct hdac_bus *bus, u32 syncprd);
+
+int hdac_bus_eml_wait_syncpu_unlocked(struct hdac_bus *bus, bool alt, int elid);
+int hdac_bus_eml_sdw_wait_syncpu_unlocked(struct hdac_bus *bus);
+
+void hdac_bus_eml_sync_arm_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink);
+void hdac_bus_eml_sdw_sync_arm_unlocked(struct hdac_bus *bus, int sublink);
+
+int hdac_bus_eml_sync_go_unlocked(struct hdac_bus *bus, bool alt, int elid);
+int hdac_bus_eml_sdw_sync_go_unlocked(struct hdac_bus *bus);
+
+bool hdac_bus_eml_check_cmdsync_unlocked(struct hdac_bus *bus, bool alt, int elid);
+bool hdac_bus_eml_sdw_check_cmdsync_unlocked(struct hdac_bus *bus);
+
+int hdac_bus_eml_power_up(struct hdac_bus *bus, bool alt, int elid, int sublink);
+int hdac_bus_eml_power_up_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink);
+
+int hdac_bus_eml_power_down(struct hdac_bus *bus, bool alt, int elid, int sublink);
+int hdac_bus_eml_power_down_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink);
+
+int hdac_bus_eml_sdw_power_up_unlocked(struct hdac_bus *bus, int sublink);
+int hdac_bus_eml_sdw_power_down_unlocked(struct hdac_bus *bus, int sublink);
+
+int hdac_bus_eml_sdw_get_lsdiid_unlocked(struct hdac_bus *bus, int sublink, u16 *lsdiid);
+int hdac_bus_eml_sdw_set_lsdiid(struct hdac_bus *bus, int sublink, int dev_num);
+
+int hdac_bus_eml_sdw_map_stream_ch(struct hdac_bus *bus, int sublink, int y,
+				   int channel_mask, int stream_id, int dir);
+
+void hda_bus_ml_put_all(struct hdac_bus *bus);
+void hda_bus_ml_reset_losidv(struct hdac_bus *bus);
+int hda_bus_ml_resume(struct hdac_bus *bus);
+int hda_bus_ml_suspend(struct hdac_bus *bus);
+
+struct hdac_ext_link *hdac_bus_eml_ssp_get_hlink(struct hdac_bus *bus);
+struct hdac_ext_link *hdac_bus_eml_dmic_get_hlink(struct hdac_bus *bus);
+struct hdac_ext_link *hdac_bus_eml_sdw_get_hlink(struct hdac_bus *bus);
+
+struct mutex *hdac_bus_eml_get_mutex(struct hdac_bus *bus, bool alt, int elid);
+
+void hdac_bus_eml_enable_offload(struct hdac_bus *bus, bool alt, int elid, bool enable);
+
+/* microphone privacy specific function supported by ACE3+ architecture */
+void hdac_bus_eml_set_mic_privacy_mask(struct hdac_bus *bus, bool alt, int elid,
+				       unsigned long mask);
+bool hdac_bus_eml_is_mic_privacy_changed(struct hdac_bus *bus, bool alt, int elid);
+bool hdac_bus_eml_get_mic_privacy_state(struct hdac_bus *bus, bool alt, int elid);
+
+#else
+
+static inline int
+hda_bus_ml_init(struct hdac_bus *bus) { return 0; }
+
+static inline void hda_bus_ml_free(struct hdac_bus *bus) { }
+
+static inline int
+hdac_bus_eml_get_count(struct hdac_bus *bus, bool alt, int elid) { return 0; }
+
+static inline void
+hdac_bus_eml_enable_interrupt_unlocked(struct hdac_bus *bus, bool alt, int elid, bool enable) { }
+
+static inline void
+hdac_bus_eml_enable_interrupt(struct hdac_bus *bus, bool alt, int elid, bool enable) { }
+
+static inline bool
+hdac_bus_eml_check_interrupt(struct hdac_bus *bus, bool alt, int elid) { return false; }
+
+static inline int
+hdac_bus_eml_set_syncprd_unlocked(struct hdac_bus *bus, bool alt, int elid, u32 syncprd)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_sdw_set_syncprd_unlocked(struct hdac_bus *bus, u32 syncprd)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_wait_syncpu_unlocked(struct hdac_bus *bus, bool alt, int elid)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_sdw_wait_syncpu_unlocked(struct hdac_bus *bus) { return 0; }
+
+static inline void
+hdac_bus_eml_sync_arm_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink) { }
+
+static inline void
+hdac_bus_eml_sdw_sync_arm_unlocked(struct hdac_bus *bus, int sublink) { }
+
+static inline int
+hdac_bus_eml_sync_go_unlocked(struct hdac_bus *bus, bool alt, int elid) { return 0; }
+
+static inline int
+hdac_bus_eml_sdw_sync_go_unlocked(struct hdac_bus *bus) { return 0; }
+
+static inline bool
+hdac_bus_eml_check_cmdsync_unlocked(struct hdac_bus *bus, bool alt, int elid) { return false; }
+
+static inline bool
+hdac_bus_eml_sdw_check_cmdsync_unlocked(struct hdac_bus *bus) { return false; }
+
+static inline int
+hdac_bus_eml_power_up(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_power_up_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_power_down(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_power_down_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_sdw_power_up_unlocked(struct hdac_bus *bus, int sublink) { return 0; }
+
+static inline int
+hdac_bus_eml_sdw_power_down_unlocked(struct hdac_bus *bus, int sublink) { return 0; }
+
+static inline int
+hdac_bus_eml_sdw_get_lsdiid_unlocked(struct hdac_bus *bus, int sublink, u16 *lsdiid) { return 0; }
+
+static inline int
+hdac_bus_eml_sdw_set_lsdiid(struct hdac_bus *bus, int sublink, int dev_num) { return 0; }
+
+static inline int
+hdac_bus_eml_sdw_map_stream_ch(struct hdac_bus *bus, int sublink, int y,
+			       int channel_mask, int stream_id, int dir)
+{
+	return 0;
+}
+
+static inline void hda_bus_ml_put_all(struct hdac_bus *bus) { }
+static inline void hda_bus_ml_reset_losidv(struct hdac_bus *bus) { }
+static inline int hda_bus_ml_resume(struct hdac_bus *bus) { return 0; }
+static inline int hda_bus_ml_suspend(struct hdac_bus *bus) { return 0; }
+
+static inline struct hdac_ext_link *
+hdac_bus_eml_ssp_get_hlink(struct hdac_bus *bus) { return NULL; }
+
+static inline struct hdac_ext_link *
+hdac_bus_eml_dmic_get_hlink(struct hdac_bus *bus) { return NULL; }
+
+static inline struct hdac_ext_link *
+hdac_bus_eml_sdw_get_hlink(struct hdac_bus *bus) { return NULL; }
+
+static inline struct mutex *
+hdac_bus_eml_get_mutex(struct hdac_bus *bus, bool alt, int elid) { return NULL; }
+
+static inline void
+hdac_bus_eml_enable_offload(struct hdac_bus *bus, bool alt, int elid, bool enable)
+{
+}
+
+static inline void
+hdac_bus_eml_set_mic_privacy_mask(struct hdac_bus *bus, bool alt, int elid,
+				  unsigned long mask)
+{
+}
+
+static inline bool
+hdac_bus_eml_is_mic_privacy_changed(struct hdac_bus *bus, bool alt, int elid)
+{
+	return false;
+}
+
+static inline bool
+hdac_bus_eml_get_mic_privacy_state(struct hdac_bus *bus, bool alt, int elid)
+{
+	return false;
+}
+
+#endif /* CONFIG_SND_SOC_SOF_HDA_MLINK */