b54a59f3ba
Currently RTLD is linked against libc_nossp_pic which means that any libc symbol used in rtld can pull in a lot of depedencies. This was causing symbol such as __libc_interposing and all the pthread stubs to be included in RTLD even though they are not required. It turns out most of these dependencies can easily be avoided by providing overrides inside of rtld. This change is motivated by CHERI, where we have an experimental ABI that requires additional relocation processing to allow the use of function pointers inside of rtld. Instead of adding this self-relocation code to RTLD I attempted to remove most function pointers from RTLD and discovered that most of them came from the libc dependencies instead of being actually used inside rtld. A nice side-effect of this change is that rtld is now 22% smaller on amd64. text data bss dec hex filename 0x21eb6 0xce0 0xe60 145910 239f6 /home/alr48/ld-elf-x86.before.so.1 0x1a6ed 0x728 0xdd8 113645 1bbed /home/alr48/ld-elf-x86.after.so.1 The number of R_X86_64_RELATIVE relocations that need to be processed on startup has also gone down from 368 to 187 (almost 50% less). Reviewed By: kib Differential Revision: https://reviews.freebsd.org/D20663
69 lines
2.6 KiB
C
69 lines
2.6 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _GEN_PRIVATE_H_
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#define _GEN_PRIVATE_H_
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struct _telldir; /* see telldir.h */
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struct pthread_mutex;
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/*
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* Structure describing an open directory.
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*
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* NOTE. Change structure layout with care, at least dd_fd field has to
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* remain unchanged to guarantee backward compatibility.
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*/
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struct _dirdesc {
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int dd_fd; /* file descriptor associated with directory */
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long dd_loc; /* offset in current buffer */
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long dd_size; /* amount of data returned by getdirentries */
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char *dd_buf; /* data buffer */
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int dd_len; /* size of data buffer */
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off_t dd_seek; /* magic cookie returned by getdirentries */
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int dd_flags; /* flags for readdir */
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#ifndef IN_RTLD
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struct pthread_mutex *dd_lock; /* lock */
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#else
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struct _donotuse *dd_lock; /* unused in rtld, keep same layout */
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#endif
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struct _telldir *dd_td; /* telldir position recording */
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void *dd_compat_de; /* compat dirent */
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};
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#define _dirfd(dirp) ((dirp)->dd_fd)
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struct dirent;
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int __readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result);
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#endif /* !_GEN_PRIVATE_H_ */
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