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>

4 files changed, 484 insertions, 0 deletions

diff --git a/drivers/acpi/dptf/Kconfig b/drivers/acpi/dptf/Kconfig
new file mode 100644
index 000000000..4b3fdc03e
--- /dev/null
+++ b/drivers/acpi/dptf/Kconfig
@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menuconfig ACPI_DPTF
+	bool "Intel DPTF (Dynamic Platform and Thermal Framework) Support"
+	depends on X86
+	help
+	  Intel Dynamic Platform and Thermal Framework (DPTF) is a platform
+	  level hardware/software solution for power and thermal management.
+
+	  As a container for multiple power/thermal technologies, DPTF provides
+	  a coordinated approach for different policies to effect the hardware
+	  state of a system.
+
+if ACPI_DPTF
+
+config DPTF_POWER
+	tristate "Platform Power DPTF Participant"
+	default m
+	help
+	  This driver adds support for Dynamic Platform and Thermal Framework
+	  (DPTF) Platform Power Participant device (INT3407) support.
+	  This participant is responsible for exposing platform telemetry:
+		max_platform_power
+		platform_power_source
+		adapter_rating
+		battery_steady_power
+		charger_type
+
+	  To compile this driver as a module, choose M here:
+	  the module will be called dptf_power.
+
+config DPTF_PCH_FIVR
+	tristate "PCH FIVR DPTF Participant"
+	default m
+	help
+	  This driver adds support for Dynamic Platform and Thermal Framework
+	  (DPTF) PCH FIVR Participant device support. This driver allows to
+	  switch the PCH FIVR (Fully Integrated Voltage Regulator) frequency.
+	  This participant is responsible for exposing:
+		freq_mhz_low_clock
+		freq_mhz_high_clock
+
+	  To compile this driver as a module, choose M here:
+	  the module will be called dptf_pch_fivr.
+
+endif
diff --git a/drivers/acpi/dptf/Makefile b/drivers/acpi/dptf/Makefile
new file mode 100644
index 000000000..e912a3be1
--- /dev/null
+++ b/drivers/acpi/dptf/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_DPTF_POWER)	+= dptf_power.o
+obj-$(CONFIG_DPTF_PCH_FIVR)	+= dptf_pch_fivr.o
diff --git a/drivers/acpi/dptf/dptf_pch_fivr.c b/drivers/acpi/dptf/dptf_pch_fivr.c
new file mode 100644
index 000000000..8d7e55592
--- /dev/null
+++ b/drivers/acpi/dptf/dptf_pch_fivr.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * dptf_pch_fivr:  DPTF PCH FIVR Participant driver
+ * Copyright (c) 2020, Intel Corporation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+struct pch_fivr_resp {
+	u64 status;
+	u64 result;
+};
+
+static int pch_fivr_read(acpi_handle handle, char *method, struct pch_fivr_resp *fivr_resp)
+{
+	struct acpi_buffer resp = { sizeof(struct pch_fivr_resp), fivr_resp};
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct acpi_buffer format = { sizeof("NN"), "NN" };
+	union acpi_object *obj;
+	acpi_status status;
+	int ret = -EFAULT;
+
+	status = acpi_evaluate_object(handle, method, NULL, &buffer);
+	if (ACPI_FAILURE(status))
+		return ret;
+
+	obj = buffer.pointer;
+	if (!obj || obj->type != ACPI_TYPE_PACKAGE)
+		goto release_buffer;
+
+	status = acpi_extract_package(obj, &format, &resp);
+	if (ACPI_FAILURE(status))
+		goto release_buffer;
+
+	if (fivr_resp->status)
+		goto release_buffer;
+
+	ret = 0;
+
+release_buffer:
+	ACPI_FREE(buffer.pointer);
+	return ret;
+}
+
+/*
+ * Presentation of attributes which are defined for INTC10xx
+ * They are:
+ * freq_mhz_low_clock : Set PCH FIVR switching freq for
+ *			FIVR clock 19.2MHz and 24MHz
+ * freq_mhz_high_clock : Set PCH FIVR switching freq for
+ *			FIVR clock 38.4MHz
+ */
+#define PCH_FIVR_SHOW(name, method) \
+static ssize_t name##_show(struct device *dev,\
+			   struct device_attribute *attr,\
+			   char *buf)\
+{\
+	struct acpi_device *acpi_dev = dev_get_drvdata(dev);\
+	struct pch_fivr_resp fivr_resp;\
+	int status;\
+\
+	status = pch_fivr_read(acpi_dev->handle, #method, &fivr_resp);\
+	if (status)\
+		return status;\
+\
+	return sprintf(buf, "%llu\n", fivr_resp.result);\
+}
+
+#define PCH_FIVR_STORE(name, method) \
+static ssize_t name##_store(struct device *dev,\
+			    struct device_attribute *attr,\
+			    const char *buf, size_t count)\
+{\
+	struct acpi_device *acpi_dev = dev_get_drvdata(dev);\
+	acpi_status status;\
+	u32 val;\
+\
+	if (kstrtouint(buf, 0, &val) < 0)\
+		return -EINVAL;\
+\
+	status = acpi_execute_simple_method(acpi_dev->handle, #method, val);\
+	if (ACPI_SUCCESS(status))\
+		return count;\
+\
+	return -EINVAL;\
+}
+
+PCH_FIVR_SHOW(freq_mhz_low_clock, GFC0)
+PCH_FIVR_SHOW(freq_mhz_high_clock, GFC1)
+PCH_FIVR_SHOW(ssc_clock_info, GEMI)
+PCH_FIVR_SHOW(fivr_switching_freq_mhz, GFCS)
+PCH_FIVR_SHOW(fivr_switching_fault_status, GFFS)
+PCH_FIVR_STORE(freq_mhz_low_clock, RFC0)
+PCH_FIVR_STORE(freq_mhz_high_clock, RFC1)
+
+static DEVICE_ATTR_RW(freq_mhz_low_clock);
+static DEVICE_ATTR_RW(freq_mhz_high_clock);
+static DEVICE_ATTR_RO(ssc_clock_info);
+static DEVICE_ATTR_RO(fivr_switching_freq_mhz);
+static DEVICE_ATTR_RO(fivr_switching_fault_status);
+
+static struct attribute *fivr_attrs[] = {
+	&dev_attr_freq_mhz_low_clock.attr,
+	&dev_attr_freq_mhz_high_clock.attr,
+	&dev_attr_ssc_clock_info.attr,
+	&dev_attr_fivr_switching_freq_mhz.attr,
+	&dev_attr_fivr_switching_fault_status.attr,
+	NULL
+};
+
+static const struct attribute_group pch_fivr_attribute_group = {
+	.attrs = fivr_attrs,
+	.name = "pch_fivr_switch_frequency"
+};
+
+static int pch_fivr_add(struct platform_device *pdev)
+{
+	struct acpi_device *acpi_dev;
+	unsigned long long ptype;
+	acpi_status status;
+	int result;
+
+	acpi_dev = ACPI_COMPANION(&(pdev->dev));
+	if (!acpi_dev)
+		return -ENODEV;
+
+	status = acpi_evaluate_integer(acpi_dev->handle, "PTYP", NULL, &ptype);
+	if (ACPI_FAILURE(status) || ptype != 0x05)
+		return -ENODEV;
+
+	result = sysfs_create_group(&pdev->dev.kobj,
+				    &pch_fivr_attribute_group);
+	if (result)
+		return result;
+
+	platform_set_drvdata(pdev, acpi_dev);
+
+	return 0;
+}
+
+static void pch_fivr_remove(struct platform_device *pdev)
+{
+	sysfs_remove_group(&pdev->dev.kobj, &pch_fivr_attribute_group);
+}
+
+static const struct acpi_device_id pch_fivr_device_ids[] = {
+	{"INTC1045", 0},
+	{"INTC1049", 0},
+	{"INTC1064", 0},
+	{"INTC106B", 0},
+	{"INTC10A3", 0},
+	{"INTC10D7", 0},
+	{"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, pch_fivr_device_ids);
+
+static struct platform_driver pch_fivr_driver = {
+	.probe = pch_fivr_add,
+	.remove = pch_fivr_remove,
+	.driver = {
+		.name = "dptf_pch_fivr",
+		.acpi_match_table = pch_fivr_device_ids,
+	},
+};
+
+module_platform_driver(pch_fivr_driver);
+
+MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("ACPI DPTF PCH FIVR driver");
diff --git a/drivers/acpi/dptf/dptf_power.c b/drivers/acpi/dptf/dptf_power.c
new file mode 100644
index 000000000..55ccbb8dd
--- /dev/null
+++ b/drivers/acpi/dptf/dptf_power.c
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * dptf_power:  DPTF platform power driver
+ * Copyright (c) 2016, Intel Corporation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/acpi.h>
+#include <linux/platform_device.h>
+
+/*
+ * Presentation of attributes which are defined for INT3407 and INT3532.
+ * They are:
+ * PMAX : Maximum platform power
+ * PSRC : Platform power source
+ * ARTG : Adapter rating
+ * CTYP : Charger type
+ * PROP : Rest of worst case platform Power
+ * PBSS : Power Battery Steady State
+ * RBHF : High Frequency Impedance
+ * VBNL : Instantaneous No-Load Voltage
+ * CMPP : Current Discharge Capability
+ */
+#define DPTF_POWER_SHOW(name, object) \
+static ssize_t name##_show(struct device *dev,\
+			   struct device_attribute *attr,\
+			   char *buf)\
+{\
+	struct acpi_device *acpi_dev = dev_get_drvdata(dev);\
+	unsigned long long val;\
+	acpi_status status;\
+\
+	status = acpi_evaluate_integer(acpi_dev->handle, #object,\
+				       NULL, &val);\
+	if (ACPI_SUCCESS(status))\
+		return sprintf(buf, "%d\n", (int)val);\
+	else \
+		return -EINVAL;\
+}
+
+DPTF_POWER_SHOW(max_platform_power_mw, PMAX)
+DPTF_POWER_SHOW(platform_power_source, PSRC)
+DPTF_POWER_SHOW(adapter_rating_mw, ARTG)
+DPTF_POWER_SHOW(battery_steady_power_mw, PBSS)
+DPTF_POWER_SHOW(charger_type, CTYP)
+DPTF_POWER_SHOW(rest_of_platform_power_mw, PROP)
+DPTF_POWER_SHOW(max_steady_state_power_mw, PBSS)
+DPTF_POWER_SHOW(high_freq_impedance_mohm, RBHF)
+DPTF_POWER_SHOW(no_load_voltage_mv, VBNL)
+DPTF_POWER_SHOW(current_discharge_capbility_ma, CMPP);
+
+static DEVICE_ATTR_RO(max_platform_power_mw);
+static DEVICE_ATTR_RO(platform_power_source);
+static DEVICE_ATTR_RO(adapter_rating_mw);
+static DEVICE_ATTR_RO(battery_steady_power_mw);
+static DEVICE_ATTR_RO(charger_type);
+static DEVICE_ATTR_RO(rest_of_platform_power_mw);
+static DEVICE_ATTR_RO(max_steady_state_power_mw);
+static DEVICE_ATTR_RO(high_freq_impedance_mohm);
+static DEVICE_ATTR_RO(no_load_voltage_mv);
+static DEVICE_ATTR_RO(current_discharge_capbility_ma);
+
+static ssize_t prochot_confirm_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct acpi_device *acpi_dev = dev_get_drvdata(dev);
+	acpi_status status;
+	int seq_no;
+
+	if (kstrtouint(buf, 0, &seq_no) < 0)
+		return -EINVAL;
+
+	status = acpi_execute_simple_method(acpi_dev->handle, "PBOK", seq_no);
+	if (ACPI_SUCCESS(status))
+		return count;
+
+	return -EINVAL;
+}
+
+static DEVICE_ATTR_WO(prochot_confirm);
+
+static struct attribute *dptf_power_attrs[] = {
+	&dev_attr_max_platform_power_mw.attr,
+	&dev_attr_platform_power_source.attr,
+	&dev_attr_adapter_rating_mw.attr,
+	&dev_attr_battery_steady_power_mw.attr,
+	&dev_attr_charger_type.attr,
+	&dev_attr_rest_of_platform_power_mw.attr,
+	&dev_attr_prochot_confirm.attr,
+	NULL
+};
+
+static const struct attribute_group dptf_power_attribute_group = {
+	.attrs = dptf_power_attrs,
+	.name = "dptf_power"
+};
+
+static struct attribute *dptf_battery_attrs[] = {
+	&dev_attr_max_platform_power_mw.attr,
+	&dev_attr_max_steady_state_power_mw.attr,
+	&dev_attr_high_freq_impedance_mohm.attr,
+	&dev_attr_no_load_voltage_mv.attr,
+	&dev_attr_current_discharge_capbility_ma.attr,
+	NULL
+};
+
+static const struct attribute_group dptf_battery_attribute_group = {
+	.attrs = dptf_battery_attrs,
+	.name = "dptf_battery"
+};
+
+#define MAX_POWER_CHANGED		0x80
+#define POWER_STATE_CHANGED		0x81
+#define STEADY_STATE_POWER_CHANGED	0x83
+#define POWER_PROP_CHANGE_EVENT	0x84
+#define IMPEDANCE_CHANGED		0x85
+#define VOLTAGE_CURRENT_CHANGED	0x86
+
+static long long dptf_participant_type(acpi_handle handle)
+{
+	unsigned long long ptype;
+	acpi_status status;
+
+	status = acpi_evaluate_integer(handle, "PTYP", NULL, &ptype);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	return ptype;
+}
+
+static void dptf_power_notify(acpi_handle handle, u32 event, void *data)
+{
+	struct platform_device *pdev = data;
+	char *attr;
+
+	switch (event) {
+	case POWER_STATE_CHANGED:
+		attr = "platform_power_source";
+		break;
+	case POWER_PROP_CHANGE_EVENT:
+		attr = "rest_of_platform_power_mw";
+		break;
+	case MAX_POWER_CHANGED:
+		attr = "max_platform_power_mw";
+		break;
+	case STEADY_STATE_POWER_CHANGED:
+		attr = "max_steady_state_power_mw";
+		break;
+	case IMPEDANCE_CHANGED:
+		attr = "high_freq_impedance_mohm";
+		break;
+	case VOLTAGE_CURRENT_CHANGED:
+		attr = "no_load_voltage_mv";
+		break;
+	default:
+		dev_err(&pdev->dev, "Unsupported event [0x%x]\n", event);
+		return;
+	}
+
+	/*
+	 * Notify that an attribute is changed, so that user space can read
+	 * again.
+	 */
+	if (dptf_participant_type(handle) == 0x0CULL)
+		sysfs_notify(&pdev->dev.kobj, "dptf_battery", attr);
+	else
+		sysfs_notify(&pdev->dev.kobj, "dptf_power", attr);
+}
+
+static int dptf_power_add(struct platform_device *pdev)
+{
+	const struct attribute_group *attr_group;
+	struct acpi_device *acpi_dev;
+	unsigned long long ptype;
+	int result;
+
+	acpi_dev = ACPI_COMPANION(&(pdev->dev));
+	if (!acpi_dev)
+		return -ENODEV;
+
+	ptype = dptf_participant_type(acpi_dev->handle);
+	if (ptype == 0x11)
+		attr_group = &dptf_power_attribute_group;
+	else if (ptype == 0x0C)
+		attr_group = &dptf_battery_attribute_group;
+	else
+		return -ENODEV;
+
+	result = acpi_install_notify_handler(acpi_dev->handle,
+					     ACPI_DEVICE_NOTIFY,
+					     dptf_power_notify,
+					     (void *)pdev);
+	if (result)
+		return result;
+
+	result = sysfs_create_group(&pdev->dev.kobj,
+				    attr_group);
+	if (result) {
+		acpi_remove_notify_handler(acpi_dev->handle,
+					   ACPI_DEVICE_NOTIFY,
+					   dptf_power_notify);
+		return result;
+	}
+
+	platform_set_drvdata(pdev, acpi_dev);
+
+	return 0;
+}
+
+static void dptf_power_remove(struct platform_device *pdev)
+{
+	struct acpi_device *acpi_dev = platform_get_drvdata(pdev);
+
+	acpi_remove_notify_handler(acpi_dev->handle,
+				   ACPI_DEVICE_NOTIFY,
+				   dptf_power_notify);
+
+	if (dptf_participant_type(acpi_dev->handle) == 0x0CULL)
+		sysfs_remove_group(&pdev->dev.kobj, &dptf_battery_attribute_group);
+	else
+		sysfs_remove_group(&pdev->dev.kobj, &dptf_power_attribute_group);
+}
+
+static const struct acpi_device_id int3407_device_ids[] = {
+	{"INT3407", 0},
+	{"INT3532", 0},
+	{"INTC1047", 0},
+	{"INTC1050", 0},
+	{"INTC1060", 0},
+	{"INTC1061", 0},
+	{"INTC1065", 0},
+	{"INTC1066", 0},
+	{"INTC106C", 0},
+	{"INTC106D", 0},
+	{"INTC10A4", 0},
+	{"INTC10A5", 0},
+	{"INTC10D8", 0},
+	{"INTC10D9", 0},
+	{"INTC1100", 0},
+	{"INTC1101", 0},
+	{"INTC10F7", 0},
+	{"INTC10F8", 0},
+	{"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, int3407_device_ids);
+
+static struct platform_driver dptf_power_driver = {
+	.probe = dptf_power_add,
+	.remove = dptf_power_remove,
+	.driver = {
+		.name = "dptf_power",
+		.acpi_match_table = int3407_device_ids,
+	},
+};
+
+module_platform_driver(dptf_power_driver);
+
+MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("ACPI DPTF platform power driver");