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 --- io_uring/splice.c | 149 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 149 insertions(+) create mode 100644 io_uring/splice.c (limited to 'io_uring/splice.c') diff --git a/io_uring/splice.c b/io_uring/splice.c new file mode 100644 index 000000000..e81ebbb91 --- /dev/null +++ b/io_uring/splice.c @@ -0,0 +1,149 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "filetable.h" +#include "io_uring.h" +#include "splice.h" + +struct io_splice { + struct file *file_out; + loff_t off_out; + loff_t off_in; + u64 len; + int splice_fd_in; + unsigned int flags; + struct io_rsrc_node *rsrc_node; +}; + +static int __io_splice_prep(struct io_kiocb *req, + const struct io_uring_sqe *sqe) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + unsigned int valid_flags = SPLICE_F_FD_IN_FIXED | SPLICE_F_ALL; + + sp->len = READ_ONCE(sqe->len); + sp->flags = READ_ONCE(sqe->splice_flags); + if (unlikely(sp->flags & ~valid_flags)) + return -EINVAL; + sp->splice_fd_in = READ_ONCE(sqe->splice_fd_in); + sp->rsrc_node = NULL; + req->flags |= REQ_F_FORCE_ASYNC; + return 0; +} + +int io_tee_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + if (READ_ONCE(sqe->splice_off_in) || READ_ONCE(sqe->off)) + return -EINVAL; + return __io_splice_prep(req, sqe); +} + +void io_splice_cleanup(struct io_kiocb *req) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + + if (sp->rsrc_node) + io_put_rsrc_node(req->ctx, sp->rsrc_node); +} + +static struct file *io_splice_get_file(struct io_kiocb *req, + unsigned int issue_flags) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + struct io_ring_ctx *ctx = req->ctx; + struct io_rsrc_node *node; + struct file *file = NULL; + + if (!(sp->flags & SPLICE_F_FD_IN_FIXED)) + return io_file_get_normal(req, sp->splice_fd_in); + + io_ring_submit_lock(ctx, issue_flags); + node = io_rsrc_node_lookup(&ctx->file_table.data, sp->splice_fd_in); + if (node) { + node->refs++; + sp->rsrc_node = node; + file = io_slot_file(node); + req->flags |= REQ_F_NEED_CLEANUP; + } + io_ring_submit_unlock(ctx, issue_flags); + return file; +} + +int io_tee(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + struct file *out = sp->file_out; + unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED; + struct file *in; + ssize_t ret = 0; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + in = io_splice_get_file(req, issue_flags); + if (!in) { + ret = -EBADF; + goto done; + } + + if (sp->len) + ret = do_tee(in, out, sp->len, flags); + + if (!(sp->flags & SPLICE_F_FD_IN_FIXED)) + fput(in); +done: + if (ret != sp->len) + req_set_fail(req); + io_req_set_res(req, ret, 0); + return IOU_COMPLETE; +} + +int io_splice_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + + sp->off_in = READ_ONCE(sqe->splice_off_in); + sp->off_out = READ_ONCE(sqe->off); + return __io_splice_prep(req, sqe); +} + +int io_splice(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_splice *sp = io_kiocb_to_cmd(req, struct io_splice); + struct file *out = sp->file_out; + unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED; + loff_t *poff_in, *poff_out; + struct file *in; + ssize_t ret = 0; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + in = io_splice_get_file(req, issue_flags); + if (!in) { + ret = -EBADF; + goto done; + } + + poff_in = (sp->off_in == -1) ? NULL : &sp->off_in; + poff_out = (sp->off_out == -1) ? NULL : &sp->off_out; + + if (sp->len) + ret = do_splice(in, poff_in, out, poff_out, sp->len, flags); + + if (!(sp->flags & SPLICE_F_FD_IN_FIXED)) + fput(in); +done: + if (ret != sp->len) + req_set_fail(req); + io_req_set_res(req, ret, 0); + return IOU_COMPLETE; +} -- cgit v1.3.1