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 --- fs/fuse/req.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 fs/fuse/req.c (limited to 'fs/fuse/req.c') diff --git a/fs/fuse/req.c b/fs/fuse/req.c new file mode 100644 index 000000000..a01ee743d --- /dev/null +++ b/fs/fuse/req.c @@ -0,0 +1,99 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include "dev.h" +#include "fuse_i.h" + +static int fuse_fill_creds(struct fuse_mount *fm, struct fuse_args *args, struct mnt_idmap *idmap) +{ + struct fuse_conn *fc = fm->fc; + bool no_idmap = !fm->sb || (fm->sb->s_iflags & SB_I_NOIDMAP); + kuid_t fsuid = mapped_fsuid(idmap, fc->user_ns); + kgid_t fsgid = mapped_fsgid(idmap, fc->user_ns); + + args->pid = pid_nr_ns(task_pid(current), fc->pid_ns); + + if (args->force) { + if (args->nocreds) + return 0; + + if (no_idmap) { + args->uid = from_kuid_munged(fc->user_ns, current_fsuid()); + args->gid = from_kgid_munged(fc->user_ns, current_fsgid()); + } else { + args->uid = FUSE_INVALID_UIDGID; + args->gid = FUSE_INVALID_UIDGID; + } + return 0; + } + + WARN_ON(args->nocreds); + /* + * Keep the old behavior when idmappings support was not + * declared by a FUSE server. + * + * For those FUSE servers who support idmapped mounts, we send UID/GID + * only along with "inode creation" fuse requests, otherwise idmap == + * &invalid_mnt_idmap and req->in.h.{u,g}id will be equal to + * FUSE_INVALID_UIDGID. + */ + if (no_idmap) { + fsuid = current_fsuid(); + fsgid = current_fsgid(); + } + args->uid = from_kuid(fc->user_ns, fsuid); + args->gid = from_kgid(fc->user_ns, fsgid); + + if (no_idmap && unlikely(args->uid == ((uid_t)-1) || args->gid == ((gid_t)-1))) + return -EOVERFLOW; + + return 0; +} + +static int fuse_req_prep(struct fuse_mount *fm, struct fuse_args *args, struct mnt_idmap *idmap) +{ + if (!args->force && fm->fc->conn_error) + return -ECONNREFUSED; + + return fuse_fill_creds(fm, args, idmap); +} + +ssize_t __fuse_simple_request(struct mnt_idmap *idmap, struct fuse_mount *fm, + struct fuse_args *args) +{ + struct fuse_conn *fc = fm->fc; + int err = fuse_req_prep(fm, args, idmap); + + if (err) + return err; + + return fuse_chan_send(fc->chan, args); +} + +int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args, gfp_t gfp_flags) +{ + struct fuse_conn *fc = fm->fc; + int err; + + WARN_ON(args->force && !args->nocreds); + + err = fuse_req_prep(fm, args, &invalid_mnt_idmap); + if (err) + return err; + + return fuse_chan_send_bg(fc->chan, args, gfp_flags); +} +EXPORT_SYMBOL_GPL(fuse_simple_background); + +int fuse_simple_notify_reply(struct fuse_mount *fm, struct fuse_args *args, u64 unique) +{ + struct fuse_conn *fc = fm->fc; + int err; + + WARN_ON(args->force && !args->nocreds); + + err = fuse_req_prep(fm, args, &invalid_mnt_idmap); + if (err) + return err; + + return fuse_chan_send_notify_reply(fc->chan, args, unique); +} -- cgit v1.3.1