From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers 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 Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- include/drm/drm_syncobj.h | 136 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 136 insertions(+) create mode 100644 include/drm/drm_syncobj.h (limited to 'include/drm/drm_syncobj.h') diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h new file mode 100644 index 000000000..b40052132 --- /dev/null +++ b/include/drm/drm_syncobj.h @@ -0,0 +1,136 @@ +/* + * Copyright © 2017 Red Hat + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + * + * Authors: + * + */ +#ifndef __DRM_SYNCOBJ_H__ +#define __DRM_SYNCOBJ_H__ + +#include +#include + +struct drm_file; + +/** + * struct drm_syncobj - sync object. + * + * This structure defines a generic sync object which wraps a &dma_fence. + */ +struct drm_syncobj { + /** + * @refcount: Reference count of this object. + */ + struct kref refcount; + /** + * @fence: + * NULL or a pointer to the fence bound to this object. + * + * This field should not be used directly. Use drm_syncobj_fence_get() + * and drm_syncobj_replace_fence() instead. + */ + struct dma_fence __rcu *fence; + /** + * @cb_list: List of callbacks to call when the &fence gets replaced. + */ + struct list_head cb_list; + /** + * @ev_fd_list: List of registered eventfd. + */ + struct list_head ev_fd_list; + /** + * @lock: Protects &cb_list and &ev_fd_list, and write-locks &fence. + */ + spinlock_t lock; + /** + * @file: A file backing for this syncobj. + */ + struct file *file; +}; + +void drm_syncobj_free(struct kref *kref); + +/** + * drm_syncobj_get - acquire a syncobj reference + * @obj: sync object + * + * This acquires an additional reference to @obj. It is illegal to call this + * without already holding a reference. No locks required. + */ +static inline void +drm_syncobj_get(struct drm_syncobj *obj) +{ + kref_get(&obj->refcount); +} + +/** + * drm_syncobj_put - release a reference to a sync object. + * @obj: sync object. + */ +static inline void +drm_syncobj_put(struct drm_syncobj *obj) +{ + kref_put(&obj->refcount, drm_syncobj_free); +} + +/** + * drm_syncobj_fence_get - get a reference to a fence in a sync object + * @syncobj: sync object. + * + * This acquires additional reference to &drm_syncobj.fence contained in @obj, + * if not NULL. It is illegal to call this without already holding a reference. + * No locks required. + * + * Returns: + * Either the fence of @obj or NULL if there's none. + */ +static inline struct dma_fence * +drm_syncobj_fence_get(struct drm_syncobj *syncobj) +{ + struct dma_fence *fence; + + rcu_read_lock(); + fence = dma_fence_get_rcu_safe(&syncobj->fence); + rcu_read_unlock(); + + return fence; +} + +struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private, + u32 handle); +void drm_syncobj_add_point(struct drm_syncobj *syncobj, + struct dma_fence_chain *chain, + struct dma_fence *fence, + uint64_t point); +void drm_syncobj_replace_fence(struct drm_syncobj *syncobj, + struct dma_fence *fence); +int drm_syncobj_find_fence(struct drm_file *file_private, + u32 handle, u64 point, u64 flags, + struct dma_fence **fence); +void drm_syncobj_free(struct kref *kref); +int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags, + struct dma_fence *fence); +int drm_syncobj_get_handle(struct drm_file *file_private, + struct drm_syncobj *syncobj, u32 *handle); +int drm_syncobj_get_fd(struct drm_syncobj *syncobj, int *p_fd); + +#endif -- cgit v1.3.1