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, 390 insertions, 0 deletions

diff --git a/drivers/dpll/zl3073x/devlink.c b/drivers/dpll/zl3073x/devlink.c
new file mode 100644
index 000000000..218b08fd8
--- /dev/null
+++ b/drivers/dpll/zl3073x/devlink.c
@@ -0,0 +1,390 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/device/devres.h>
+#include <linux/netlink.h>
+#include <linux/sprintf.h>
+#include <linux/types.h>
+#include <net/devlink.h>
+
+#include "core.h"
+#include "devlink.h"
+#include "dpll.h"
+#include "flash.h"
+#include "fw.h"
+#include "regs.h"
+
+/**
+ * zl3073x_devlink_info_get - Devlink device info callback
+ * @devlink: devlink structure pointer
+ * @req: devlink request pointer to store information
+ * @extack: netlink extack pointer to report errors
+ *
+ * Return: 0 on success, <0 on error
+ */
+static int
+zl3073x_devlink_info_get(struct devlink *devlink, struct devlink_info_req *req,
+			 struct netlink_ext_ack *extack)
+{
+	struct zl3073x_dev *zldev = devlink_priv(devlink);
+	u16 id, revision, fw_ver;
+	char buf[16];
+	u32 cfg_ver;
+	int rc;
+
+	rc = zl3073x_read_u16(zldev, ZL_REG_ID, &id);
+	if (rc)
+		return rc;
+
+	snprintf(buf, sizeof(buf), "%X", id);
+	rc = devlink_info_version_fixed_put(req,
+					    DEVLINK_INFO_VERSION_GENERIC_ASIC_ID,
+					    buf);
+	if (rc)
+		return rc;
+
+	rc = zl3073x_read_u16(zldev, ZL_REG_REVISION, &revision);
+	if (rc)
+		return rc;
+
+	snprintf(buf, sizeof(buf), "%X", revision);
+	rc = devlink_info_version_fixed_put(req,
+					    DEVLINK_INFO_VERSION_GENERIC_ASIC_REV,
+					    buf);
+	if (rc)
+		return rc;
+
+	rc = zl3073x_read_u16(zldev, ZL_REG_FW_VER, &fw_ver);
+	if (rc)
+		return rc;
+
+	snprintf(buf, sizeof(buf), "%u", fw_ver);
+	rc = devlink_info_version_running_put(req,
+					      DEVLINK_INFO_VERSION_GENERIC_FW,
+					      buf);
+	if (rc)
+		return rc;
+
+	rc = zl3073x_read_u32(zldev, ZL_REG_CUSTOM_CONFIG_VER, &cfg_ver);
+	if (rc)
+		return rc;
+
+	/* No custom config version */
+	if (cfg_ver == U32_MAX)
+		return 0;
+
+	snprintf(buf, sizeof(buf), "%lu.%lu.%lu.%lu",
+		 FIELD_GET(GENMASK(31, 24), cfg_ver),
+		 FIELD_GET(GENMASK(23, 16), cfg_ver),
+		 FIELD_GET(GENMASK(15, 8), cfg_ver),
+		 FIELD_GET(GENMASK(7, 0), cfg_ver));
+
+	return devlink_info_version_running_put(req, "custom_cfg", buf);
+}
+
+static int
+zl3073x_devlink_reload_down(struct devlink *devlink, bool netns_change,
+			    enum devlink_reload_action action,
+			    enum devlink_reload_limit limit,
+			    struct netlink_ext_ack *extack)
+{
+	struct zl3073x_dev *zldev = devlink_priv(devlink);
+
+	if (action != DEVLINK_RELOAD_ACTION_DRIVER_REINIT)
+		return -EOPNOTSUPP;
+
+	/* Stop normal operation */
+	zl3073x_dev_stop(zldev);
+
+	return 0;
+}
+
+static int
+zl3073x_devlink_reload_up(struct devlink *devlink,
+			  enum devlink_reload_action action,
+			  enum devlink_reload_limit limit,
+			  u32 *actions_performed,
+			  struct netlink_ext_ack *extack)
+{
+	struct zl3073x_dev *zldev = devlink_priv(devlink);
+	union devlink_param_value val;
+	int rc;
+
+	if (action != DEVLINK_RELOAD_ACTION_DRIVER_REINIT)
+		return -EOPNOTSUPP;
+
+	rc = devl_param_driverinit_value_get(devlink,
+					     DEVLINK_PARAM_GENERIC_ID_CLOCK_ID,
+					     &val);
+	if (rc)
+		return rc;
+
+	if (zldev->clock_id != val.vu64) {
+		dev_dbg(zldev->dev,
+			"'clock_id' changed to %016llx\n", val.vu64);
+		zldev->clock_id = val.vu64;
+	}
+
+	/* Restart normal operation */
+	rc = zl3073x_dev_start(zldev, false);
+	if (rc)
+		dev_warn(zldev->dev, "Failed to re-start normal operation\n");
+
+	*actions_performed = BIT(DEVLINK_RELOAD_ACTION_DRIVER_REINIT);
+
+	return 0;
+}
+
+void zl3073x_devlink_flash_notify(struct zl3073x_dev *zldev, const char *msg,
+				  const char *component, u32 done, u32 total)
+{
+	struct devlink *devlink = priv_to_devlink(zldev);
+
+	devlink_flash_update_status_notify(devlink, msg, component, done,
+					   total);
+}
+
+/**
+ * zl3073x_devlink_flash_prepare - Prepare and enter flash mode
+ * @zldev: zl3073x device pointer
+ * @zlfw: pointer to loaded firmware
+ * @extack: netlink extack pointer to report errors
+ *
+ * The function stops normal operation and switches the device to flash mode.
+ * If an error occurs the normal operation is resumed.
+ *
+ * Return: 0 on success, <0 on error
+ */
+static int
+zl3073x_devlink_flash_prepare(struct zl3073x_dev *zldev,
+			      struct zl3073x_fw *zlfw,
+			      struct netlink_ext_ack *extack)
+{
+	struct zl3073x_fw_component *util;
+	int rc;
+
+	util = zlfw->component[ZL_FW_COMPONENT_UTIL];
+	if (!util) {
+		zl3073x_devlink_flash_notify(zldev,
+					     "Utility is missing in firmware",
+					     NULL, 0, 0);
+		return -ENOEXEC;
+	}
+
+	/* Stop normal operation prior entering flash mode */
+	zl3073x_dev_stop(zldev);
+
+	rc = zl3073x_flash_mode_enter(zldev, util->data, util->size, extack);
+	if (rc) {
+		zl3073x_devlink_flash_notify(zldev,
+					     "Failed to enter flash mode",
+					     NULL, 0, 0);
+
+		/* Resume normal operation */
+		zl3073x_dev_start(zldev, true);
+
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * zl3073x_devlink_flash_finish - Leave flash mode and resume normal operation
+ * @zldev: zl3073x device pointer
+ * @extack: netlink extack pointer to report errors
+ *
+ * The function switches the device back to standard mode and resumes normal
+ * operation.
+ *
+ * Return: 0 on success, <0 on error
+ */
+static int
+zl3073x_devlink_flash_finish(struct zl3073x_dev *zldev,
+			     struct netlink_ext_ack *extack)
+{
+	int rc;
+
+	/* Reset device CPU to normal mode */
+	zl3073x_flash_mode_leave(zldev, extack);
+
+	/* Resume normal operation */
+	rc = zl3073x_dev_start(zldev, true);
+	if (rc)
+		zl3073x_devlink_flash_notify(zldev,
+					     "Failed to start normal operation",
+					     NULL, 0, 0);
+
+	return rc;
+}
+
+/**
+ * zl3073x_devlink_flash_update - Devlink flash update callback
+ * @devlink: devlink structure pointer
+ * @params: flashing parameters pointer
+ * @extack: netlink extack pointer to report errors
+ *
+ * Return: 0 on success, <0 on error
+ */
+static int
+zl3073x_devlink_flash_update(struct devlink *devlink,
+			     struct devlink_flash_update_params *params,
+			     struct netlink_ext_ack *extack)
+{
+	struct zl3073x_dev *zldev = devlink_priv(devlink);
+	struct zl3073x_fw *zlfw;
+	int rc = 0;
+
+	zlfw = zl3073x_fw_load(zldev, params->fw->data, params->fw->size,
+			       extack);
+	if (IS_ERR(zlfw)) {
+		zl3073x_devlink_flash_notify(zldev, "Failed to load firmware",
+					     NULL, 0, 0);
+		rc = PTR_ERR(zlfw);
+		goto finish;
+	}
+
+	/* Stop normal operation and enter flash mode */
+	rc = zl3073x_devlink_flash_prepare(zldev, zlfw, extack);
+	if (rc)
+		goto finish;
+
+	rc = zl3073x_fw_flash(zldev, zlfw, extack);
+	if (rc) {
+		zl3073x_devlink_flash_finish(zldev, extack);
+		goto finish;
+	}
+
+	/* Resume normal mode */
+	rc = zl3073x_devlink_flash_finish(zldev, extack);
+
+finish:
+	if (!IS_ERR(zlfw))
+		zl3073x_fw_free(zlfw);
+
+	zl3073x_devlink_flash_notify(zldev,
+				     rc ? "Flashing failed" : "Flashing done",
+				     NULL, 0, 0);
+
+	return rc;
+}
+
+static const struct devlink_ops zl3073x_devlink_ops = {
+	.info_get = zl3073x_devlink_info_get,
+	.reload_actions = BIT(DEVLINK_RELOAD_ACTION_DRIVER_REINIT),
+	.reload_down = zl3073x_devlink_reload_down,
+	.reload_up = zl3073x_devlink_reload_up,
+	.flash_update = zl3073x_devlink_flash_update,
+};
+
+static void
+zl3073x_devlink_free(void *ptr)
+{
+	devlink_free(ptr);
+}
+
+/**
+ * zl3073x_devm_alloc - allocates zl3073x device structure
+ * @dev: pointer to device structure
+ *
+ * Allocates zl3073x device structure as device resource.
+ *
+ * Return: pointer to zl3073x device on success, error pointer on error
+ */
+struct zl3073x_dev *zl3073x_devm_alloc(struct device *dev)
+{
+	struct zl3073x_dev *zldev;
+	struct devlink *devlink;
+	int rc;
+
+	devlink = devlink_alloc(&zl3073x_devlink_ops, sizeof(*zldev), dev);
+	if (!devlink)
+		return ERR_PTR(-ENOMEM);
+
+	/* Add devres action to free devlink device */
+	rc = devm_add_action_or_reset(dev, zl3073x_devlink_free, devlink);
+	if (rc)
+		return ERR_PTR(rc);
+
+	zldev = devlink_priv(devlink);
+	zldev->dev = dev;
+	dev_set_drvdata(zldev->dev, zldev);
+
+	return zldev;
+}
+EXPORT_SYMBOL_NS_GPL(zl3073x_devm_alloc, "ZL3073X");
+
+static int
+zl3073x_devlink_param_clock_id_validate(struct devlink *devlink, u32 id,
+					union devlink_param_value *val,
+					struct netlink_ext_ack *extack)
+{
+	if (!val->vu64) {
+		NL_SET_ERR_MSG_MOD(extack, "'clock_id' must be non-zero");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct devlink_param zl3073x_devlink_params[] = {
+	DEVLINK_PARAM_GENERIC(CLOCK_ID, BIT(DEVLINK_PARAM_CMODE_DRIVERINIT),
+			      NULL, NULL,
+			      zl3073x_devlink_param_clock_id_validate),
+};
+
+static void
+zl3073x_devlink_unregister(void *ptr)
+{
+	struct devlink *devlink = priv_to_devlink(ptr);
+
+	devl_lock(devlink);
+
+	/* Unregister devlink params */
+	devl_params_unregister(devlink, zl3073x_devlink_params,
+			       ARRAY_SIZE(zl3073x_devlink_params));
+
+	/* Unregister devlink instance */
+	devl_unregister(devlink);
+
+	devl_unlock(devlink);
+}
+
+/**
+ * zl3073x_devlink_register - register devlink instance and params
+ * @zldev: zl3073x device to register the devlink for
+ *
+ * Register the devlink instance and parameters associated with the device.
+ *
+ * Return: 0 on success, <0 on error
+ */
+int zl3073x_devlink_register(struct zl3073x_dev *zldev)
+{
+	struct devlink *devlink = priv_to_devlink(zldev);
+	union devlink_param_value value;
+	int rc;
+
+	devl_lock(devlink);
+
+	/* Register devlink params */
+	rc = devl_params_register(devlink, zl3073x_devlink_params,
+				  ARRAY_SIZE(zl3073x_devlink_params));
+	if (rc) {
+		devl_unlock(devlink);
+
+		return rc;
+	}
+
+	value.vu64 = zldev->clock_id;
+	devl_param_driverinit_value_set(devlink,
+					DEVLINK_PARAM_GENERIC_ID_CLOCK_ID,
+					&value);
+
+	/* Register devlink instance */
+	devl_register(devlink);
+
+	devl_unlock(devlink);
+
+	/* Add devres action to unregister devlink device */
+	return devm_add_action_or_reset(zldev->dev, zl3073x_devlink_unregister,
+					zldev);
+}