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, 88 insertions, 0 deletions

diff --git a/include/drm/drm_ras.h b/include/drm/drm_ras.h
new file mode 100644
index 000000000..0beede3dd
--- /dev/null
+++ b/include/drm/drm_ras.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2026 Intel Corporation
+ */
+
+#ifndef __DRM_RAS_H__
+#define __DRM_RAS_H__
+
+#include <linux/types.h>
+
+#include <uapi/drm/drm_ras.h>
+
+/**
+ * struct drm_ras_node - A DRM RAS Node
+ */
+struct drm_ras_node {
+	/** @id: Unique identifier for the node. Dynamically assigned. */
+	u32 id;
+	/**
+	 * @device_name: Human-readable name of the device. Given by the driver.
+	 */
+	const char *device_name;
+	/** @node_name: Human-readable name of the node. Given by the driver. */
+	const char *node_name;
+	/** @type: Type of the node (enum drm_ras_node_type). */
+	enum drm_ras_node_type type;
+
+	/* Error-Counter Related Callback and Variables */
+
+	/** @error_counter_range: Range of valid Error IDs for this node. */
+	struct {
+		/** @first: First valid Error ID. */
+		u32 first;
+		/** @last: Last valid Error ID. Mandatory entry. */
+		u32 last;
+	} error_counter_range;
+
+	/**
+	 * @query_error_counter:
+	 *
+	 * This callback is used by drm-ras to query a specific error counter.
+	 * Used for input check and to iterate all error counters in a node.
+	 *
+	 * Driver should expect query_error_counter() to be called with
+	 * error_id from `error_counter_range.first` to
+	 * `error_counter_range.last`.
+	 *
+	 * The @query_error_counter is a mandatory callback for
+	 * error_counter_node.
+	 *
+	 * Returns: 0 on success,
+	 *          -ENOENT when error_id is not supported as an indication that
+	 *                  drm_ras should silently skip this entry. Used for
+	 *                  supporting non-contiguous error ranges.
+	 *                  Driver is responsible for maintaining the list of
+	 *                  supported error IDs in the range of first to last.
+	 *          Other negative values on errors that should terminate the
+	 *          netlink query.
+	 */
+	int (*query_error_counter)(struct drm_ras_node *node, u32 error_id,
+				   const char **name, u32 *val);
+
+	/**
+	 * @clear_error_counter:
+	 *
+	 * This callback is used by drm_ras to clear a specific error counter.
+	 * Driver should implement this callback to support clearing error counters
+	 * of a node.
+	 *
+	 * Returns: 0 on success, negative error code on failure.
+	 */
+	int (*clear_error_counter)(struct drm_ras_node *node, u32 error_id);
+
+	/** @priv: Driver private data */
+	void *priv;
+};
+
+struct drm_device;
+
+#if IS_ENABLED(CONFIG_DRM_RAS)
+int drm_ras_node_register(struct drm_ras_node *node);
+void drm_ras_node_unregister(struct drm_ras_node *node);
+#else
+static inline int drm_ras_node_register(struct drm_ras_node *node) { return 0; }
+static inline void drm_ras_node_unregister(struct drm_ras_node *node) { }
+#endif
+
+#endif