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/fq_impl.h | 393 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 393 insertions(+) create mode 100644 include/net/fq_impl.h (limited to 'include/net/fq_impl.h') diff --git a/include/net/fq_impl.h b/include/net/fq_impl.h new file mode 100644 index 000000000..8aca88193 --- /dev/null +++ b/include/net/fq_impl.h @@ -0,0 +1,393 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (c) 2016 Qualcomm Atheros, Inc + * + * Based on net/sched/sch_fq_codel.c + */ +#ifndef __NET_SCHED_FQ_IMPL_H +#define __NET_SCHED_FQ_IMPL_H + +#include + +/* functions that are embedded into includer */ + + +static void +__fq_adjust_removal(struct fq *fq, struct fq_flow *flow, unsigned int packets, + unsigned int bytes, unsigned int truesize) +{ + struct fq_tin *tin = flow->tin; + int idx; + + tin->backlog_bytes -= bytes; + tin->backlog_packets -= packets; + flow->backlog -= bytes; + fq->backlog -= packets; + fq->memory_usage -= truesize; + + if (flow->backlog) + return; + + if (flow == &tin->default_flow) { + list_del_init(&tin->tin_list); + return; + } + + idx = flow - fq->flows; + __clear_bit(idx, fq->flows_bitmap); +} + +static void fq_adjust_removal(struct fq *fq, + struct fq_flow *flow, + struct sk_buff *skb) +{ + __fq_adjust_removal(fq, flow, 1, skb->len, skb->truesize); +} + +static struct sk_buff *fq_flow_dequeue(struct fq *fq, + struct fq_flow *flow) +{ + struct sk_buff *skb; + + lockdep_assert_held(&fq->lock); + + skb = __skb_dequeue(&flow->queue); + if (!skb) + return NULL; + + fq_adjust_removal(fq, flow, skb); + + return skb; +} + +static int fq_flow_drop(struct fq *fq, struct fq_flow *flow, + fq_skb_free_t free_func) +{ + unsigned int packets = 0, bytes = 0, truesize = 0; + struct fq_tin *tin = flow->tin; + struct sk_buff *skb; + int pending; + + lockdep_assert_held(&fq->lock); + + pending = min_t(int, 32, skb_queue_len(&flow->queue) / 2); + do { + skb = __skb_dequeue(&flow->queue); + if (!skb) + break; + + packets++; + bytes += skb->len; + truesize += skb->truesize; + free_func(fq, tin, flow, skb); + } while (packets < pending); + + __fq_adjust_removal(fq, flow, packets, bytes, truesize); + + return packets; +} + +static struct sk_buff *fq_tin_dequeue(struct fq *fq, + struct fq_tin *tin, + fq_tin_dequeue_t dequeue_func) +{ + struct fq_flow *flow; + struct list_head *head; + struct sk_buff *skb; + + lockdep_assert_held(&fq->lock); + +begin: + head = &tin->new_flows; + if (list_empty(head)) { + head = &tin->old_flows; + if (list_empty(head)) + return NULL; + } + + flow = list_first_entry(head, struct fq_flow, flowchain); + + if (flow->deficit <= 0) { + flow->deficit += fq->quantum; + list_move_tail(&flow->flowchain, + &tin->old_flows); + goto begin; + } + + skb = dequeue_func(fq, tin, flow); + if (!skb) { + /* force a pass through old_flows to prevent starvation */ + if ((head == &tin->new_flows) && + !list_empty(&tin->old_flows)) { + list_move_tail(&flow->flowchain, &tin->old_flows); + } else { + list_del_init(&flow->flowchain); + flow->tin = NULL; + } + goto begin; + } + + flow->deficit -= skb->len; + tin->tx_bytes += skb->len; + tin->tx_packets++; + + return skb; +} + +static u32 fq_flow_idx(struct fq *fq, struct sk_buff *skb) +{ + u32 hash = skb_get_hash(skb); + + return reciprocal_scale(hash, fq->flows_cnt); +} + +static struct fq_flow *fq_flow_classify(struct fq *fq, + struct fq_tin *tin, u32 idx, + struct sk_buff *skb) +{ + struct fq_flow *flow; + + lockdep_assert_held(&fq->lock); + + flow = &fq->flows[idx]; + if (flow->tin && flow->tin != tin) { + flow = &tin->default_flow; + tin->collisions++; + fq->collisions++; + } + + if (!flow->tin) + tin->flows++; + + return flow; +} + +static struct fq_flow *fq_find_fattest_flow(struct fq *fq) +{ + struct fq_tin *tin; + struct fq_flow *flow = NULL; + u32 len = 0; + int i; + + for_each_set_bit(i, fq->flows_bitmap, fq->flows_cnt) { + struct fq_flow *cur = &fq->flows[i]; + unsigned int cur_len; + + cur_len = cur->backlog; + if (cur_len <= len) + continue; + + flow = cur; + len = cur_len; + } + + list_for_each_entry(tin, &fq->tin_backlog, tin_list) { + unsigned int cur_len = tin->default_flow.backlog; + + if (cur_len <= len) + continue; + + flow = &tin->default_flow; + len = cur_len; + } + + return flow; +} + +static void fq_tin_enqueue(struct fq *fq, + struct fq_tin *tin, u32 idx, + struct sk_buff *skb, + fq_skb_free_t free_func) +{ + struct fq_flow *flow; + struct sk_buff *next; + bool oom; + + lockdep_assert_held(&fq->lock); + + flow = fq_flow_classify(fq, tin, idx, skb); + + if (!flow->backlog) { + if (flow != &tin->default_flow) + __set_bit(idx, fq->flows_bitmap); + else if (list_empty(&tin->tin_list)) + list_add(&tin->tin_list, &fq->tin_backlog); + } + + flow->tin = tin; + skb_list_walk_safe(skb, skb, next) { + skb_mark_not_on_list(skb); + flow->backlog += skb->len; + tin->backlog_bytes += skb->len; + tin->backlog_packets++; + fq->memory_usage += skb->truesize; + fq->backlog++; + __skb_queue_tail(&flow->queue, skb); + } + + if (list_empty(&flow->flowchain)) { + flow->deficit = fq->quantum; + list_add_tail(&flow->flowchain, + &tin->new_flows); + } + + oom = (fq->memory_usage > fq->memory_limit); + while (fq->backlog > fq->limit || oom) { + flow = fq_find_fattest_flow(fq); + if (!flow) + return; + + if (!fq_flow_drop(fq, flow, free_func)) + return; + + flow->tin->overlimit++; + fq->overlimit++; + if (oom) { + fq->overmemory++; + oom = (fq->memory_usage > fq->memory_limit); + } + } +} + +static void fq_flow_filter(struct fq *fq, + struct fq_flow *flow, + fq_skb_filter_t filter_func, + void *filter_data, + fq_skb_free_t free_func) +{ + struct fq_tin *tin = flow->tin; + struct sk_buff *skb, *tmp; + + lockdep_assert_held(&fq->lock); + + skb_queue_walk_safe(&flow->queue, skb, tmp) { + if (!filter_func(fq, tin, flow, skb, filter_data)) + continue; + + __skb_unlink(skb, &flow->queue); + fq_adjust_removal(fq, flow, skb); + free_func(fq, tin, flow, skb); + } +} + +static void fq_tin_filter(struct fq *fq, + struct fq_tin *tin, + fq_skb_filter_t filter_func, + void *filter_data, + fq_skb_free_t free_func) +{ + struct fq_flow *flow; + + lockdep_assert_held(&fq->lock); + + list_for_each_entry(flow, &tin->new_flows, flowchain) + fq_flow_filter(fq, flow, filter_func, filter_data, free_func); + list_for_each_entry(flow, &tin->old_flows, flowchain) + fq_flow_filter(fq, flow, filter_func, filter_data, free_func); +} + +static void fq_flow_reset(struct fq *fq, + struct fq_flow *flow, + fq_skb_free_t free_func) +{ + struct fq_tin *tin = flow->tin; + struct sk_buff *skb; + + while ((skb = fq_flow_dequeue(fq, flow))) + free_func(fq, tin, flow, skb); + + if (!list_empty(&flow->flowchain)) { + list_del_init(&flow->flowchain); + if (list_empty(&tin->new_flows) && + list_empty(&tin->old_flows)) + list_del_init(&tin->tin_list); + } + + flow->tin = NULL; + + WARN_ON_ONCE(flow->backlog); +} + +static void fq_tin_reset(struct fq *fq, + struct fq_tin *tin, + fq_skb_free_t free_func) +{ + struct list_head *head; + struct fq_flow *flow; + + for (;;) { + head = &tin->new_flows; + if (list_empty(head)) { + head = &tin->old_flows; + if (list_empty(head)) + break; + } + + flow = list_first_entry(head, struct fq_flow, flowchain); + fq_flow_reset(fq, flow, free_func); + } + + WARN_ON_ONCE(!list_empty(&tin->tin_list)); + WARN_ON_ONCE(tin->backlog_bytes); + WARN_ON_ONCE(tin->backlog_packets); +} + +static void fq_flow_init(struct fq_flow *flow) +{ + INIT_LIST_HEAD(&flow->flowchain); + __skb_queue_head_init(&flow->queue); +} + +static void fq_tin_init(struct fq_tin *tin) +{ + INIT_LIST_HEAD(&tin->new_flows); + INIT_LIST_HEAD(&tin->old_flows); + INIT_LIST_HEAD(&tin->tin_list); + fq_flow_init(&tin->default_flow); +} + +static int fq_init(struct fq *fq, int flows_cnt) +{ + int i; + + memset(fq, 0, sizeof(fq[0])); + spin_lock_init(&fq->lock); + INIT_LIST_HEAD(&fq->tin_backlog); + fq->flows_cnt = max_t(u32, flows_cnt, 1); + fq->quantum = 300; + fq->limit = 8192; + fq->memory_limit = 16 << 20; /* 16 MBytes */ + + fq->flows = kvzalloc_objs(fq->flows[0], fq->flows_cnt); + if (!fq->flows) + return -ENOMEM; + + fq->flows_bitmap = bitmap_zalloc(fq->flows_cnt, GFP_KERNEL); + if (!fq->flows_bitmap) { + kvfree(fq->flows); + fq->flows = NULL; + return -ENOMEM; + } + + for (i = 0; i < fq->flows_cnt; i++) + fq_flow_init(&fq->flows[i]); + + return 0; +} + +static void fq_reset(struct fq *fq, + fq_skb_free_t free_func) +{ + int i; + + for (i = 0; i < fq->flows_cnt; i++) + fq_flow_reset(fq, &fq->flows[i], free_func); + + kvfree(fq->flows); + fq->flows = NULL; + + bitmap_free(fq->flows_bitmap); + fq->flows_bitmap = NULL; +} + +#endif -- cgit v1.3.1