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, 396 insertions, 0 deletions

diff --git a/sound/soc/codecs/hda.c b/sound/soc/codecs/hda.c
new file mode 100644
index 000000000..237b0b060
--- /dev/null
+++ b/sound/soc/codecs/hda.c
@@ -0,0 +1,396 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright(c) 2021-2022 Intel Corporation
+//
+// Author: Cezary Rojewski <cezary.rojewski@intel.com>
+//
+
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <sound/soc.h>
+#include <sound/hdaudio_ext.h>
+#include <sound/hda_i915.h>
+#include <sound/hda_codec.h>
+#include "hda.h"
+
+static int hda_codec_create_dais(struct hda_codec *codec, int pcm_count,
+				 struct snd_soc_dai_driver **drivers)
+{
+	struct device *dev = &codec->core.dev;
+	struct snd_soc_dai_driver *drvs;
+	struct hda_pcm *pcm;
+	int i;
+
+	drvs = devm_kcalloc(dev, pcm_count, sizeof(*drvs), GFP_KERNEL);
+	if (!drvs)
+		return -ENOMEM;
+
+	pcm = list_first_entry(&codec->pcm_list_head, struct hda_pcm, list);
+
+	for (i = 0; i < pcm_count; i++, pcm = list_next_entry(pcm, list)) {
+		struct snd_soc_pcm_stream *stream;
+		int dir;
+
+		dev_info(dev, "creating for %s %d\n", pcm->name, i);
+		drvs[i].id = i;
+		drvs[i].name = pcm->name;
+		drvs[i].ops = &snd_soc_hda_codec_dai_ops;
+
+		dir = SNDRV_PCM_STREAM_PLAYBACK;
+		stream = &drvs[i].playback;
+		if (!pcm->stream[dir].substreams) {
+			dev_info(dev, "skipping playback dai for %s\n", pcm->name);
+			goto capture_dais;
+		}
+
+		stream->stream_name =
+			devm_kasprintf(dev, GFP_KERNEL, "%s %s", pcm->name,
+				       snd_pcm_direction_name(dir));
+		if (!stream->stream_name)
+			return -ENOMEM;
+		stream->channels_min = pcm->stream[dir].channels_min;
+		stream->channels_max = pcm->stream[dir].channels_max;
+		stream->rates = pcm->stream[dir].rates;
+		stream->formats = pcm->stream[dir].formats;
+		stream->subformats = pcm->stream[dir].subformats;
+		stream->sig_bits = pcm->stream[dir].maxbps;
+
+capture_dais:
+		dir = SNDRV_PCM_STREAM_CAPTURE;
+		stream = &drvs[i].capture;
+		if (!pcm->stream[dir].substreams) {
+			dev_info(dev, "skipping capture dai for %s\n", pcm->name);
+			continue;
+		}
+
+		stream->stream_name =
+			devm_kasprintf(dev, GFP_KERNEL, "%s %s", pcm->name,
+				       snd_pcm_direction_name(dir));
+		if (!stream->stream_name)
+			return -ENOMEM;
+		stream->channels_min = pcm->stream[dir].channels_min;
+		stream->channels_max = pcm->stream[dir].channels_max;
+		stream->rates = pcm->stream[dir].rates;
+		stream->formats = pcm->stream[dir].formats;
+		stream->subformats = pcm->stream[dir].subformats;
+		stream->sig_bits = pcm->stream[dir].maxbps;
+	}
+
+	*drivers = drvs;
+	return 0;
+}
+
+static int hda_codec_register_dais(struct hda_codec *codec, struct snd_soc_component *component)
+{
+	struct snd_soc_dai_driver *drvs = NULL;
+	struct snd_soc_dapm_context *dapm;
+	struct hda_pcm *pcm;
+	int ret, pcm_count = 0;
+
+	if (list_empty(&codec->pcm_list_head))
+		return -EINVAL;
+	list_for_each_entry(pcm, &codec->pcm_list_head, list)
+		pcm_count++;
+
+	ret = hda_codec_create_dais(codec, pcm_count, &drvs);
+	if (ret < 0)
+		return ret;
+
+	dapm = snd_soc_component_to_dapm(component);
+
+	list_for_each_entry(pcm, &codec->pcm_list_head, list) {
+		struct snd_soc_dai *dai;
+
+		dai = snd_soc_register_dai(component, drvs, false);
+		if (!dai) {
+			dev_err(component->dev, "register dai for %s failed\n", pcm->name);
+			return -EINVAL;
+		}
+
+		ret = snd_soc_dapm_new_dai_widgets(dapm, dai);
+		if (ret < 0) {
+			dev_err(component->dev, "create widgets failed: %d\n", ret);
+			snd_soc_unregister_dai(dai);
+			return ret;
+		}
+
+		snd_soc_dai_init_dma_data(dai, &pcm->stream[0], &pcm->stream[1]);
+		drvs++;
+	}
+
+	return 0;
+}
+
+static void hda_codec_unregister_dais(struct hda_codec *codec,
+				      struct snd_soc_component *component)
+{
+	struct snd_soc_dai *dai, *save;
+	struct hda_pcm *pcm;
+
+	for_each_component_dais_safe(component, dai, save) {
+		int stream;
+
+		list_for_each_entry(pcm, &codec->pcm_list_head, list) {
+			if (strcmp(dai->driver->name, pcm->name))
+				continue;
+
+			for_each_pcm_streams(stream)
+				snd_soc_dapm_free_widget(snd_soc_dai_get_widget(dai, stream));
+
+			snd_soc_unregister_dai(dai);
+			break;
+		}
+	}
+}
+
+int hda_codec_probe_complete(struct hda_codec *codec)
+{
+	struct hdac_device *hdev = &codec->core;
+	struct hdac_bus *bus = hdev->bus;
+	int ret;
+
+	ret = snd_hda_codec_build_controls(codec);
+	if (ret < 0) {
+		dev_err(&hdev->dev, "unable to create controls %d\n", ret);
+		return ret;
+	}
+
+	/* Bus suspended codecs as it does not manage their pm */
+	pm_runtime_set_active(&hdev->dev);
+	/* rpm was forbidden in snd_hda_codec_device_new() */
+	snd_hda_codec_set_power_save(codec, 2000);
+	snd_hda_codec_register(codec);
+
+	/* Complement pm_runtime_get_sync(bus) in probe */
+	pm_runtime_put_autosuspend(bus->dev);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(hda_codec_probe_complete);
+
+/* Expects codec with usage_count=1 and status=suspended */
+static int hda_codec_probe(struct snd_soc_component *component)
+{
+	struct hda_codec *codec = dev_to_hda_codec(component->dev);
+	struct hda_codec_driver *driver = hda_codec_to_driver(codec);
+	struct hdac_device *hdev = &codec->core;
+	struct hdac_bus *bus = hdev->bus;
+	struct hdac_ext_link *hlink;
+	int ret;
+
+#ifdef CONFIG_PM
+	WARN_ON(atomic_read(&hdev->dev.power.usage_count) != 1 ||
+		!pm_runtime_status_suspended(&hdev->dev));
+#endif
+
+	hlink = snd_hdac_ext_bus_get_hlink_by_addr(bus, hdev->addr);
+	if (!hlink) {
+		dev_err(&hdev->dev, "hdac link not found\n");
+		return -EIO;
+	}
+
+	pm_runtime_get_sync(bus->dev);
+	if (hda_codec_is_display(codec))
+		snd_hdac_display_power(bus, hdev->addr, true);
+	snd_hdac_ext_bus_link_get(bus, hlink);
+
+	ret = snd_hda_codec_device_new(codec->bus, component->card->snd_card, hdev->addr, codec,
+				       false);
+	if (ret < 0) {
+		dev_err(&hdev->dev, "codec create failed: %d\n", ret);
+		goto device_new_err;
+	}
+
+	ret = snd_hda_codec_set_name(codec, codec->preset->name);
+	if (ret < 0) {
+		dev_err(&hdev->dev, "set name: %s failed: %d\n", codec->preset->name, ret);
+		goto err;
+	}
+
+	ret = snd_hdac_regmap_init(&codec->core);
+	if (ret < 0) {
+		dev_err(&hdev->dev, "regmap init failed: %d\n", ret);
+		goto err;
+	}
+
+	if (WARN_ON(!(driver->ops && driver->ops->probe))) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	ret = driver->ops->probe(codec, codec->preset);
+	if (ret < 0) {
+		dev_err(&hdev->dev, "codec init failed: %d\n", ret);
+		goto err;
+	}
+
+	ret = snd_hda_codec_parse_pcms(codec);
+	if (ret < 0) {
+		dev_err(&hdev->dev, "unable to map pcms to dai: %d\n", ret);
+		goto parse_pcms_err;
+	}
+
+	ret = hda_codec_register_dais(codec, component);
+	if (ret < 0) {
+		dev_err(&hdev->dev, "update dais failed: %d\n", ret);
+		goto parse_pcms_err;
+	}
+
+	if (!hda_codec_is_display(codec)) {
+		ret = hda_codec_probe_complete(codec);
+		if (ret < 0)
+			goto complete_err;
+	}
+
+	codec->core.lazy_cache = true;
+
+	return 0;
+
+complete_err:
+	hda_codec_unregister_dais(codec, component);
+parse_pcms_err:
+	if (driver->ops->remove)
+		driver->ops->remove(codec);
+err:
+	snd_hda_codec_cleanup_for_unbind(codec);
+device_new_err:
+	if (hda_codec_is_display(codec))
+		snd_hdac_display_power(bus, hdev->addr, false);
+
+	snd_hdac_ext_bus_link_put(bus, hlink);
+
+	pm_runtime_put_autosuspend(bus->dev);
+	return ret;
+}
+
+/* Leaves codec with usage_count=1 and status=suspended */
+static void hda_codec_remove(struct snd_soc_component *component)
+{
+	struct hda_codec *codec = dev_to_hda_codec(component->dev);
+	struct hda_codec_driver *driver = hda_codec_to_driver(codec);
+	struct hdac_device *hdev = &codec->core;
+	struct hdac_bus *bus = hdev->bus;
+	struct hdac_ext_link *hlink;
+	bool was_registered = codec->core.registered;
+
+	/* Don't allow any more runtime suspends */
+	pm_runtime_forbid(&hdev->dev);
+
+	hda_codec_unregister_dais(codec, component);
+
+	if (driver->ops->remove)
+		driver->ops->remove(codec);
+
+	snd_hda_codec_cleanup_for_unbind(codec);
+	pm_runtime_put_noidle(&hdev->dev);
+	/* snd_hdac_device_exit() is only called on bus remove */
+	pm_runtime_set_suspended(&hdev->dev);
+
+	if (hda_codec_is_display(codec))
+		snd_hdac_display_power(bus, hdev->addr, false);
+
+	hlink = snd_hdac_ext_bus_get_hlink_by_addr(bus, hdev->addr);
+	if (hlink)
+		snd_hdac_ext_bus_link_put(bus, hlink);
+	/*
+	 * HDMI card's hda_codec_probe_complete() (see late_probe()) may
+	 * not be called due to early error, leaving bus uc unbalanced
+	 */
+	if (!was_registered) {
+		pm_runtime_put_autosuspend(bus->dev);
+	}
+
+#ifdef CONFIG_PM
+	WARN_ON(atomic_read(&hdev->dev.power.usage_count) != 1 ||
+		!pm_runtime_status_suspended(&hdev->dev));
+#endif
+}
+
+static const struct snd_soc_dapm_route hda_dapm_routes[] = {
+	{"AIF1TX", NULL, "Codec Input Pin1"},
+	{"AIF2TX", NULL, "Codec Input Pin2"},
+	{"AIF3TX", NULL, "Codec Input Pin3"},
+
+	{"Codec Output Pin1", NULL, "AIF1RX"},
+	{"Codec Output Pin2", NULL, "AIF2RX"},
+	{"Codec Output Pin3", NULL, "AIF3RX"},
+};
+
+static const struct snd_soc_dapm_widget hda_dapm_widgets[] = {
+	/* Audio Interface */
+	SND_SOC_DAPM_AIF_IN("AIF1RX", "Analog Codec Playback", 0, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_AIF_IN("AIF2RX", "Digital Codec Playback", 0, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_AIF_IN("AIF3RX", "Alt Analog Codec Playback", 0, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_AIF_OUT("AIF1TX", "Analog Codec Capture", 0, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_AIF_OUT("AIF2TX", "Digital Codec Capture", 0, SND_SOC_NOPM, 0, 0),
+	SND_SOC_DAPM_AIF_OUT("AIF3TX", "Alt Analog Codec Capture", 0, SND_SOC_NOPM, 0, 0),
+
+	/* Input Pins */
+	SND_SOC_DAPM_INPUT("Codec Input Pin1"),
+	SND_SOC_DAPM_INPUT("Codec Input Pin2"),
+	SND_SOC_DAPM_INPUT("Codec Input Pin3"),
+
+	/* Output Pins */
+	SND_SOC_DAPM_OUTPUT("Codec Output Pin1"),
+	SND_SOC_DAPM_OUTPUT("Codec Output Pin2"),
+	SND_SOC_DAPM_OUTPUT("Codec Output Pin3"),
+};
+
+static struct snd_soc_dai_driver card_binder_dai = {
+	.id = -1,
+	.name = "codec-probing-DAI",
+};
+
+static int hda_hdev_attach(struct hdac_device *hdev)
+{
+	struct hda_codec *codec = dev_to_hda_codec(&hdev->dev);
+	struct snd_soc_component_driver *comp_drv;
+
+	if (hda_codec_is_display(codec) && !hdev->bus->audio_component) {
+		dev_dbg(&hdev->dev, "no i915, skip registration for 0x%08x\n", hdev->vendor_id);
+		return -ENODEV;
+	}
+
+	comp_drv = devm_kzalloc(&hdev->dev, sizeof(*comp_drv), GFP_KERNEL);
+	if (!comp_drv)
+		return -ENOMEM;
+
+	/*
+	 * It's save to rely on dev_name() rather than a copy as component
+	 * driver's lifetime is directly tied to hda codec one
+	 */
+	comp_drv->name = dev_name(&hdev->dev);
+	comp_drv->probe = hda_codec_probe;
+	comp_drv->remove = hda_codec_remove;
+	comp_drv->idle_bias_on = false;
+	if (!hda_codec_is_display(codec)) {
+		comp_drv->dapm_widgets = hda_dapm_widgets;
+		comp_drv->num_dapm_widgets = ARRAY_SIZE(hda_dapm_widgets);
+		comp_drv->dapm_routes = hda_dapm_routes;
+		comp_drv->num_dapm_routes = ARRAY_SIZE(hda_dapm_routes);
+	}
+
+	return snd_soc_register_component(&hdev->dev, comp_drv, &card_binder_dai, 1);
+}
+
+static int hda_hdev_detach(struct hdac_device *hdev)
+{
+	struct hda_codec *codec = dev_to_hda_codec(&hdev->dev);
+
+	if (codec->core.registered)
+		cancel_delayed_work_sync(&codec->jackpoll_work);
+
+	snd_soc_unregister_component(&hdev->dev);
+
+	return 0;
+}
+
+const struct hdac_ext_bus_ops soc_hda_ext_bus_ops = {
+	.hdev_attach = hda_hdev_attach,
+	.hdev_detach = hda_hdev_detach,
+};
+EXPORT_SYMBOL_GPL(soc_hda_ext_bus_ops);
+
+MODULE_DESCRIPTION("HD-Audio codec driver");
+MODULE_AUTHOR("Cezary Rojewski <cezary.rojewski@intel.com>");
+MODULE_LICENSE("GPL");