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 --- net/rxrpc/txbuf.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) create mode 100644 net/rxrpc/txbuf.c (limited to 'net/rxrpc/txbuf.c') diff --git a/net/rxrpc/txbuf.c b/net/rxrpc/txbuf.c new file mode 100644 index 000000000..55ef7a048 --- /dev/null +++ b/net/rxrpc/txbuf.c @@ -0,0 +1,96 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* RxRPC Tx data buffering. + * + * Copyright (C) 2022 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include "ar-internal.h" + +static atomic_t rxrpc_txbuf_debug_ids; +atomic_t rxrpc_nr_txbuf; + +/* + * Allocate and partially initialise a data transmission buffer. + */ +struct rxrpc_txbuf *rxrpc_alloc_data_txbuf(struct rxrpc_call *call, size_t data_size, + size_t data_align, gfp_t gfp) +{ + struct rxrpc_txbuf *txb; + size_t total, doff, jsize = sizeof(struct rxrpc_jumbo_header); + void *buf; + + txb = kzalloc_obj(*txb, gfp); + if (!txb) + return NULL; + + /* We put a jumbo header in the buffer, but not a full wire header to + * avoid delayed-corruption problems with zerocopy. + */ + doff = round_up(jsize, data_align); + total = doff + data_size; + + data_align = umax(data_align, L1_CACHE_BYTES); + mutex_lock(&call->conn->tx_data_alloc_lock); + buf = page_frag_alloc_align(&call->conn->tx_data_alloc, total, gfp, + data_align); + mutex_unlock(&call->conn->tx_data_alloc_lock); + if (!buf) { + kfree(txb); + return NULL; + } + + refcount_set(&txb->ref, 1); + txb->call_debug_id = call->debug_id; + txb->debug_id = atomic_inc_return(&rxrpc_txbuf_debug_ids); + txb->alloc_size = data_size; + txb->space = data_size; + txb->offset = 0; + txb->flags = call->conn->out_clientflag; + txb->seq = call->send_top + 1; + txb->data = buf + doff; + + trace_rxrpc_txbuf(txb->debug_id, txb->call_debug_id, txb->seq, 1, + rxrpc_txbuf_alloc_data); + + atomic_inc(&rxrpc_nr_txbuf); + return txb; +} + +void rxrpc_see_txbuf(struct rxrpc_txbuf *txb, enum rxrpc_txbuf_trace what) +{ + int r = refcount_read(&txb->ref); + + trace_rxrpc_txbuf(txb->debug_id, txb->call_debug_id, txb->seq, r, what); +} + +static void rxrpc_free_txbuf(struct rxrpc_txbuf *txb) +{ + trace_rxrpc_txbuf(txb->debug_id, txb->call_debug_id, txb->seq, 0, + rxrpc_txbuf_free); + if (txb->data) + page_frag_free(txb->data); + kfree(txb); + atomic_dec(&rxrpc_nr_txbuf); +} + +void rxrpc_put_txbuf(struct rxrpc_txbuf *txb, enum rxrpc_txbuf_trace what) +{ + unsigned int debug_id, call_debug_id; + rxrpc_seq_t seq; + bool dead; + int r; + + if (txb) { + debug_id = txb->debug_id; + call_debug_id = txb->call_debug_id; + seq = txb->seq; + dead = __refcount_dec_and_test(&txb->ref, &r); + trace_rxrpc_txbuf(debug_id, call_debug_id, seq, r - 1, what); + if (dead) + rxrpc_free_txbuf(txb); + } +} -- cgit v1.3.1