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, 229 insertions, 0 deletions

diff --git a/sound/soc/sof/control.c b/sound/soc/sof/control.c
new file mode 100644
index 000000000..74d997a4f
--- /dev/null
+++ b/sound/soc/sof/control.c
@@ -0,0 +1,229 @@
+// 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) 2018 Intel Corporation
+//
+// Author: Liam Girdwood <liam.r.girdwood@linux.intel.com>
+//
+
+/* Mixer Controls */
+
+#include <linux/pm_runtime.h>
+#include <linux/leds.h>
+#include "sof-priv.h"
+#include "sof-audio.h"
+
+int snd_sof_volume_get(struct snd_kcontrol *kcontrol,
+		       struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_mixer_control *sm = (struct soc_mixer_control *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = sm->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->volume_get)
+		return tplg_ops->control->volume_get(scontrol, ucontrol);
+
+	return 0;
+}
+
+int snd_sof_volume_put(struct snd_kcontrol *kcontrol,
+		       struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_mixer_control *sm = (struct soc_mixer_control *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = sm->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->volume_put)
+		return tplg_ops->control->volume_put(scontrol, ucontrol);
+
+	return false;
+}
+
+int snd_sof_volume_info(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_info *uinfo)
+{
+	struct soc_mixer_control *sm = (struct soc_mixer_control *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = sm->dobj.private;
+	unsigned int channels = scontrol->num_channels;
+	int platform_max;
+
+	if (!sm->platform_max)
+		sm->platform_max = sm->max;
+	platform_max = sm->platform_max;
+
+	if (platform_max == 1 && !strstr(kcontrol->id.name, " Volume"))
+		uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
+	else
+		uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+
+	uinfo->count = channels;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = platform_max - sm->min;
+	return 0;
+}
+
+int snd_sof_switch_get(struct snd_kcontrol *kcontrol,
+		       struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_mixer_control *sm = (struct soc_mixer_control *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = sm->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->switch_get)
+		return tplg_ops->control->switch_get(scontrol, ucontrol);
+
+	return 0;
+}
+
+int snd_sof_switch_put(struct snd_kcontrol *kcontrol,
+		       struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_mixer_control *sm = (struct soc_mixer_control *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = sm->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->switch_put)
+		return tplg_ops->control->switch_put(scontrol, ucontrol);
+
+	return false;
+}
+
+int snd_sof_enum_get(struct snd_kcontrol *kcontrol,
+		     struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_enum *se = (struct soc_enum *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = se->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->enum_get)
+		return tplg_ops->control->enum_get(scontrol, ucontrol);
+
+	return 0;
+}
+
+int snd_sof_enum_put(struct snd_kcontrol *kcontrol,
+		     struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_enum *se = (struct soc_enum *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = se->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->enum_put)
+		return tplg_ops->control->enum_put(scontrol, ucontrol);
+
+	return false;
+}
+
+int snd_sof_bytes_get(struct snd_kcontrol *kcontrol,
+		      struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_bytes_ext *be = (struct soc_bytes_ext *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = be->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->bytes_get)
+		return tplg_ops->control->bytes_get(scontrol, ucontrol);
+
+	return 0;
+}
+
+int snd_sof_bytes_put(struct snd_kcontrol *kcontrol,
+		      struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_bytes_ext *be = (struct soc_bytes_ext *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = be->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->bytes_put)
+		return tplg_ops->control->bytes_put(scontrol, ucontrol);
+
+	return 0;
+}
+
+int snd_sof_bytes_ext_put(struct snd_kcontrol *kcontrol,
+			  const unsigned int __user *binary_data,
+			  unsigned int size)
+{
+	struct soc_bytes_ext *be = (struct soc_bytes_ext *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = be->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	/* make sure we have at least a header */
+	if (size < sizeof(struct snd_ctl_tlv))
+		return -EINVAL;
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->bytes_ext_put)
+		return tplg_ops->control->bytes_ext_put(scontrol, binary_data, size);
+
+	return 0;
+}
+
+int snd_sof_bytes_ext_volatile_get(struct snd_kcontrol *kcontrol, unsigned int __user *binary_data,
+				   unsigned int size)
+{
+	struct soc_bytes_ext *be = (struct soc_bytes_ext *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = be->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+	int ret, err;
+
+	/* ignore the ext_volatile_get call if the callbacks are not provided */
+	if (!tplg_ops || !tplg_ops->control ||
+	    !tplg_ops->control->bytes_ext_volatile_get)
+		return 0;
+
+	ret = pm_runtime_resume_and_get(scomp->dev);
+	if (ret < 0 && ret != -EACCES) {
+		dev_err_ratelimited(scomp->dev, "%s: failed to resume %d\n", __func__, ret);
+		return ret;
+	}
+
+	/* Make sure the DSP/firmware is booted up */
+	ret = snd_sof_boot_dsp_firmware(sdev);
+	if (!ret)
+		ret = tplg_ops->control->bytes_ext_volatile_get(scontrol,
+								binary_data,
+								size);
+
+	err = pm_runtime_put_autosuspend(scomp->dev);
+	if (err < 0)
+		dev_err_ratelimited(scomp->dev, "%s: failed to idle %d\n", __func__, err);
+
+	return ret;
+}
+
+int snd_sof_bytes_ext_get(struct snd_kcontrol *kcontrol,
+			  unsigned int __user *binary_data,
+			  unsigned int size)
+{
+	struct soc_bytes_ext *be = (struct soc_bytes_ext *)kcontrol->private_value;
+	struct snd_sof_control *scontrol = be->dobj.private;
+	struct snd_soc_component *scomp = scontrol->scomp;
+	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(scomp);
+	const struct sof_ipc_tplg_ops *tplg_ops = sof_ipc_get_ops(sdev, tplg);
+
+	if (tplg_ops && tplg_ops->control && tplg_ops->control->bytes_ext_get)
+		return tplg_ops->control->bytes_ext_get(scontrol, binary_data, size);
+
+	return 0;
+}