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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
105 lines
2.5 KiB
C
105 lines
2.5 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright 1996-1998 John D. Polstra.
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* 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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "rtld.h"
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#include "rtld_printf.h"
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#include "rtld_malloc.h"
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#include "rtld_libc.h"
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void *
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xcalloc(size_t number, size_t size)
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{
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void *p;
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p = __crt_calloc(number, size);
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if (p == NULL) {
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rtld_fdputstr(STDERR_FILENO, "Out of memory\n");
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_exit(1);
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}
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return (p);
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}
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void *
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xmalloc(size_t size)
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{
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void *p;
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p = __crt_malloc(size);
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if (p == NULL) {
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rtld_fdputstr(STDERR_FILENO, "Out of memory\n");
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_exit(1);
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}
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return (p);
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}
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char *
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xstrdup(const char *str)
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{
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char *copy;
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size_t len;
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len = strlen(str) + 1;
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copy = xmalloc(len);
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memcpy(copy, str, len);
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return (copy);
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}
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void *
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malloc_aligned(size_t size, size_t align)
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{
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void *mem, *res;
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if (align < sizeof(void *))
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align = sizeof(void *);
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mem = xmalloc(size + sizeof(void *) + align - 1);
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res = (void *)round((uintptr_t)mem + sizeof(void *), align);
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*(void **)((uintptr_t)res - sizeof(void *)) = mem;
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return (res);
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}
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void
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free_aligned(void *ptr)
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{
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void *mem;
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uintptr_t x;
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if (ptr == NULL)
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return;
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x = (uintptr_t)ptr;
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x -= sizeof(void *);
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mem = *(void **)x;
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free(mem);
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}
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