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/net/xdp_sock.h | 212 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 212 insertions(+) create mode 100644 include/net/xdp_sock.h (limited to 'include/net/xdp_sock.h') diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h new file mode 100644 index 000000000..6e70b320b --- /dev/null +++ b/include/net/xdp_sock.h @@ -0,0 +1,212 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* AF_XDP internal functions + * Copyright(c) 2018 Intel Corporation. + */ + +#ifndef _LINUX_XDP_SOCK_H +#define _LINUX_XDP_SOCK_H + +#include +#include +#include +#include +#include +#include +#include + +#define XDP_UMEM_SG_FLAG BIT(3) + +struct net_device; +struct xsk_queue; +struct xdp_buff; + +struct xdp_umem { + void *addrs; + u64 size; + u32 headroom; + u32 chunk_size; + u32 chunks; + u32 npgs; + struct user_struct *user; + refcount_t users; + u8 flags; + u8 tx_metadata_len; + bool zc; + struct page **pgs; + int id; + struct list_head xsk_dma_list; + struct work_struct work; +}; + +struct xsk_map { + struct bpf_map map; + spinlock_t lock; /* Synchronize map updates */ + atomic_t count; + struct xdp_sock __rcu *xsk_map[]; +}; + +struct xdp_sock { + /* struct sock must be the first member of struct xdp_sock */ + struct sock sk; + struct xsk_queue *rx ____cacheline_aligned_in_smp; + struct net_device *dev; + struct xdp_umem *umem; + struct list_head flush_node; + struct xsk_buff_pool *pool; + u16 queue_id; + bool zc; + bool sg; + enum { + XSK_READY = 0, + XSK_BOUND, + XSK_UNBOUND, + } state; + + struct xsk_queue *tx ____cacheline_aligned_in_smp; + struct list_head tx_list; + /* record the number of tx descriptors sent by this xsk and + * when it exceeds MAX_PER_SOCKET_BUDGET, an opportunity needs + * to be given to other xsks for sending tx descriptors, thereby + * preventing other XSKs from being starved. + */ + u32 tx_budget_spent; + + /* Statistics */ + u64 rx_dropped; + u64 rx_queue_full; + + /* When __xsk_generic_xmit() must return before it sees the EOP descriptor for the current + * packet, the partially built skb is saved here so that packet building can resume in next + * call of __xsk_generic_xmit(). + */ + struct sk_buff *skb; + bool drain_cont; + + struct list_head map_list; + /* Protects map_list */ + spinlock_t map_list_lock; + u32 max_tx_budget; + /* Protects multiple processes in the control path */ + struct mutex mutex; + struct xsk_queue *fq_tmp; /* Only as tmp storage before bind */ + struct xsk_queue *cq_tmp; /* Only as tmp storage before bind */ +}; + +/* + * AF_XDP TX metadata hooks for network devices. + * The following hooks can be defined; unless noted otherwise, they are + * optional and can be filled with a null pointer. + * + * void (*tmo_request_timestamp)(void *priv) + * Called when AF_XDP frame requested egress timestamp. + * + * u64 (*tmo_fill_timestamp)(void *priv) + * Called when AF_XDP frame, that had requested egress timestamp, + * received a completion. The hook needs to return the actual HW timestamp. + * + * void (*tmo_request_checksum)(u16 csum_start, u16 csum_offset, void *priv) + * Called when AF_XDP frame requested HW checksum offload. csum_start + * indicates position where checksumming should start. + * csum_offset indicates position where checksum should be stored. + * + * void (*tmo_request_launch_time)(u64 launch_time, void *priv) + * Called when AF_XDP frame requested launch time HW offload support. + * launch_time indicates the PTP time at which the device can schedule the + * packet for transmission. + */ +struct xsk_tx_metadata_ops { + void (*tmo_request_timestamp)(void *priv); + u64 (*tmo_fill_timestamp)(void *priv); + void (*tmo_request_checksum)(u16 csum_start, u16 csum_offset, void *priv); + void (*tmo_request_launch_time)(u64 launch_time, void *priv); +}; + +#ifdef CONFIG_XDP_SOCKETS + +int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp); +int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp); +void __xsk_map_flush(struct list_head *flush_list); +INDIRECT_CALLABLE_DECLARE(void xsk_destruct_skb(struct sk_buff *)); + +/** + * xsk_tx_metadata_to_compl - Save enough relevant metadata information + * to perform tx completion in the future. + * @meta: pointer to AF_XDP metadata area + * @compl: pointer to output struct xsk_tx_metadata_to_compl + * + * This function should be called by the networking device when + * it prepares AF_XDP egress packet. The value of @compl should be stored + * and passed to xsk_tx_metadata_complete upon TX completion. + */ +static inline void xsk_tx_metadata_to_compl(struct xsk_tx_metadata *meta, + struct xsk_tx_metadata_compl *compl) +{ + compl->tx_timestamp = NULL; + + if (!meta) + return; + + /* we can only arrive here if the completion timestamp has been + * requested via XDP_TXMD_FLAGS_TIMESTAMP, see xsk_tx_metadata_request + */ + + compl->tx_timestamp = &meta->completion.tx_timestamp; +} + +/** + * xsk_tx_metadata_complete - Evaluate AF_XDP TX metadata at completion + * and call appropriate xsk_tx_metadata_ops operation. + * @compl: pointer to completion metadata produced from xsk_tx_metadata_to_compl + * @ops: pointer to struct xsk_tx_metadata_ops + * @priv: pointer to driver-private aread + * + * This function should be called by the networking device upon + * AF_XDP egress completion. + */ +static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_compl *compl, + const struct xsk_tx_metadata_ops *ops, + void *priv) +{ + if (!compl) + return; + if (!compl->tx_timestamp) + return; + + *compl->tx_timestamp = ops->tmo_fill_timestamp(priv); +} + +#else + +static inline int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp) +{ + return -ENOTSUPP; +} + +static inline int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp) +{ + return -EOPNOTSUPP; +} + +static inline void __xsk_map_flush(struct list_head *flush_list) +{ +} + +#ifdef CONFIG_MITIGATION_RETPOLINE +static inline void xsk_destruct_skb(struct sk_buff *skb) +{ +} +#endif + +static inline void xsk_tx_metadata_to_compl(struct xsk_tx_metadata *meta, + struct xsk_tx_metadata_compl *compl) +{ +} + +static inline void xsk_tx_metadata_complete(struct xsk_tx_metadata_compl *compl, + const struct xsk_tx_metadata_ops *ops, + void *priv) +{ +} + +#endif /* CONFIG_XDP_SOCKETS */ +#endif /* _LINUX_XDP_SOCK_H */ -- cgit v1.3.1