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/romfs/storage.c | 287 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 287 insertions(+) create mode 100644 fs/romfs/storage.c (limited to 'fs/romfs/storage.c') diff --git a/fs/romfs/storage.c b/fs/romfs/storage.c new file mode 100644 index 000000000..b57b3ffcb --- /dev/null +++ b/fs/romfs/storage.c @@ -0,0 +1,287 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* RomFS storage access routines + * + * Copyright © 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include "internal.h" + +#if !defined(CONFIG_ROMFS_ON_MTD) && !defined(CONFIG_ROMFS_ON_BLOCK) +#error no ROMFS backing store interface configured +#endif + +#ifdef CONFIG_ROMFS_ON_MTD +#define ROMFS_MTD_READ(sb, ...) mtd_read((sb)->s_mtd, ##__VA_ARGS__) + +/* + * read data from an romfs image on an MTD device + */ +static int romfs_mtd_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen) +{ + size_t rlen; + int ret; + + ret = ROMFS_MTD_READ(sb, pos, buflen, &rlen, buf); + return (ret < 0 || rlen != buflen) ? -EIO : 0; +} + +/* + * determine the length of a string in a romfs image on an MTD device + */ +static ssize_t romfs_mtd_strnlen(struct super_block *sb, + unsigned long pos, size_t maxlen) +{ + ssize_t n = 0; + size_t segment; + u_char buf[16], *p; + size_t len; + int ret; + + /* scan the string up to 16 bytes at a time */ + while (maxlen > 0) { + segment = min_t(size_t, maxlen, 16); + ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf); + if (ret < 0) + return ret; + p = memchr(buf, 0, len); + if (p) + return n + (p - buf); + maxlen -= len; + pos += len; + n += len; + } + + return n; +} + +/* + * compare a string to one in a romfs image on MTD + * - return 1 if matched, 0 if differ, -ve if error + */ +static int romfs_mtd_strcmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size) +{ + u_char buf[17]; + size_t len, segment; + int ret; + + /* scan the string up to 16 bytes at a time, and attempt to grab the + * trailing NUL whilst we're at it */ + buf[0] = 0xff; + + while (size > 0) { + segment = min_t(size_t, size + 1, 17); + ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf); + if (ret < 0) + return ret; + len--; + if (memcmp(buf, str, len) != 0) + return 0; + buf[0] = buf[len]; + size -= len; + pos += len; + str += len; + } + + /* check the trailing NUL was */ + if (buf[0]) + return 0; + + return 1; +} +#endif /* CONFIG_ROMFS_ON_MTD */ + +#ifdef CONFIG_ROMFS_ON_BLOCK +/* + * read data from an romfs image on a block device + */ +static int romfs_blk_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen) +{ + struct buffer_head *bh; + unsigned long offset; + size_t segment; + + /* copy the string up to blocksize bytes at a time */ + while (buflen > 0) { + offset = pos & (ROMBSIZE - 1); + segment = min_t(size_t, buflen, ROMBSIZE - offset); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + memcpy(buf, bh->b_data + offset, segment); + brelse(bh); + buf += segment; + buflen -= segment; + pos += segment; + } + + return 0; +} + +/* + * determine the length of a string in romfs on a block device + */ +static ssize_t romfs_blk_strnlen(struct super_block *sb, + unsigned long pos, size_t limit) +{ + struct buffer_head *bh; + unsigned long offset; + ssize_t n = 0; + size_t segment; + u_char *buf, *p; + + /* scan the string up to blocksize bytes at a time */ + while (limit > 0) { + offset = pos & (ROMBSIZE - 1); + segment = min_t(size_t, limit, ROMBSIZE - offset); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + buf = bh->b_data + offset; + p = memchr(buf, 0, segment); + brelse(bh); + if (p) + return n + (p - buf); + limit -= segment; + pos += segment; + n += segment; + } + + return n; +} + +/* + * compare a string to one in a romfs image on a block device + * - return 1 if matched, 0 if differ, -ve if error + */ +static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size) +{ + struct buffer_head *bh; + unsigned long offset; + size_t segment; + bool matched, terminated = false; + + /* compare string up to a block at a time */ + while (size > 0) { + offset = pos & (ROMBSIZE - 1); + segment = min_t(size_t, size, ROMBSIZE - offset); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + matched = (memcmp(bh->b_data + offset, str, segment) == 0); + + size -= segment; + pos += segment; + str += segment; + if (matched && size == 0 && offset + segment < ROMBSIZE) { + if (!bh->b_data[offset + segment]) + terminated = true; + else + matched = false; + } + brelse(bh); + if (!matched) + return 0; + } + + if (!terminated) { + /* the terminating NUL must be on the first byte of the next + * block */ + BUG_ON((pos & (ROMBSIZE - 1)) != 0); + bh = sb_bread(sb, pos >> ROMBSBITS); + if (!bh) + return -EIO; + matched = !bh->b_data[0]; + brelse(bh); + if (!matched) + return 0; + } + + return 1; +} +#endif /* CONFIG_ROMFS_ON_BLOCK */ + +/* + * read data from the romfs image + */ +int romfs_dev_read(struct super_block *sb, unsigned long pos, + void *buf, size_t buflen) +{ + size_t limit; + + limit = romfs_maxsize(sb); + if (pos >= limit || buflen > limit - pos) + return -EIO; + +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) + return romfs_mtd_read(sb, pos, buf, buflen); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) + return romfs_blk_read(sb, pos, buf, buflen); +#endif + return -EIO; +} + +/* + * determine the length of a string in romfs + */ +ssize_t romfs_dev_strnlen(struct super_block *sb, + unsigned long pos, size_t maxlen) +{ + size_t limit; + + limit = romfs_maxsize(sb); + if (pos >= limit) + return -EIO; + if (maxlen > limit - pos) + maxlen = limit - pos; + +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) + return romfs_mtd_strnlen(sb, pos, maxlen); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) + return romfs_blk_strnlen(sb, pos, maxlen); +#endif + return -EIO; +} + +/* + * compare a string to one in romfs + * - the string to be compared to, str, may not be NUL-terminated; instead the + * string is of the specified size + * - return 1 if matched, 0 if differ, -ve if error + */ +int romfs_dev_strcmp(struct super_block *sb, unsigned long pos, + const char *str, size_t size) +{ + size_t limit; + + limit = romfs_maxsize(sb); + if (pos >= limit) + return -EIO; + if (size > ROMFS_MAXFN) + return -ENAMETOOLONG; + if (size + 1 > limit - pos) + return -EIO; + +#ifdef CONFIG_ROMFS_ON_MTD + if (sb->s_mtd) + return romfs_mtd_strcmp(sb, pos, str, size); +#endif +#ifdef CONFIG_ROMFS_ON_BLOCK + if (sb->s_bdev) + return romfs_blk_strcmp(sb, pos, str, size); +#endif + return -EIO; +} -- cgit v1.3.1