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Brooks Davis
17602eb3ea
- Use intptr_t in place of long as the word type in the core copying loop where aligned words a copied. This preserved the provenance of any copied pointers. - When working with the address of src or dst use ptraddr_t rather than uintptr_t. This avoid ambigious provenance in expressions involving multiple addresses. As a minor tweak, rename the function to memmove since that is the interface it implements (overlapping src and dst are permitted) and make memcpy the alias rather than the other way around. Reviewed by: kib, markj Effort: CHERI upstreaming Sponsored by: Innovate UK Differential Revision: https://reviews.freebsd.org/D57965
140 lines
3.8 KiB
C
140 lines
3.8 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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* Copyright (c) 1990 The Regents of the University of California.
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*
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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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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#include <sys/param.h>
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#ifdef _KERNEL
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#include <sys/systm.h>
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#include <sys/stddef.h>
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#else
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#include <stddef.h>
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#include <string.h>
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#endif
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#undef memcpy
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#undef memmove
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/*
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* sizeof(word) MUST BE A POWER OF TWO
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* SO THAT wmask BELOW IS ALL ONES
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*/
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typedef intptr_t word; /* "word" used for optimal copy speed */
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#define wsize sizeof(word)
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#define wmask (wsize - 1)
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/*
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* Copy a block of memory, handling overlap.
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* This is the routine that actually implements
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* (the portable versions of) bcopy, memcpy, and memmove.
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*/
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void *
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memmove(void *dst0, const void *src0, size_t length)
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{
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char *dst;
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const char *src;
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size_t t;
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dst = dst0;
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src = src0;
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if (length == 0 || dst == src) { /* nothing to do */
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goto done;
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}
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/*
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* Macros: loop-t-times; and loop-t-times, t>0
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*/
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#define TLOOP(s) if (t) TLOOP1(s)
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#define TLOOP1(s) do { s; } while (--t)
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if ((ptraddr_t)dst < (ptraddr_t)src) {
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/*
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* Copy forward.
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*/
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t = (size_t)src; /* only need low bits */
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if ((t | (ptraddr_t)dst) & wmask) {
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/*
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* Try to align operands. This cannot be done
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* unless the low bits match.
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*/
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if ((t ^ (ptraddr_t)dst) & wmask || length < wsize) {
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t = length;
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} else {
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t = wsize - (t & wmask);
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}
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length -= t;
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TLOOP1(*dst++ = *src++);
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}
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/*
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* Copy whole words, then mop up any trailing bytes.
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*/
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t = length / wsize;
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TLOOP(*(word *)dst = *(const word *)src; src += wsize;
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dst += wsize);
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t = length & wmask;
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TLOOP(*dst++ = *src++);
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} else {
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/*
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* Copy backwards. Otherwise essentially the same.
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* Alignment works as before, except that it takes
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* (t&wmask) bytes to align, not wsize-(t&wmask).
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*/
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src += length;
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dst += length;
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t = (size_t)src;
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if ((t | (ptraddr_t)dst) & wmask) {
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if ((t ^ (ptraddr_t)dst) & wmask || length <= wsize) {
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t = length;
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} else {
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t &= wmask;
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}
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length -= t;
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TLOOP1(*--dst = *--src);
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}
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t = length / wsize;
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TLOOP(src -= wsize; dst -= wsize;
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*(word *)dst = *(const word *)src);
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t = length & wmask;
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TLOOP(*--dst = *--src);
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}
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done:
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return (dst0);
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}
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__strong_reference(memmove, memcpy);
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