82 lines
1.9 KiB
C
82 lines
1.9 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* This provides an optimized implementation of memcpy, and a simplified
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* implementation of memset and memmove. These are used here because the
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* standard kernel runtime versions are not yet available and we don't
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* trust the gcc built-in implementations as they may do unexpected things
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* (e.g. FPU ops) in the minimal decompression stub execution environment.
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*/
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#include "error.h"
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#include "../string.c"
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#ifdef CONFIG_X86_32
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static void *____memcpy(void *dest, const void *src, size_t n)
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{
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int d0, d1, d2;
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asm volatile(
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"rep ; movsl\n\t"
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"movl %4,%%ecx\n\t"
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"rep ; movsb\n\t"
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: "=&c" (d0), "=&D" (d1), "=&S" (d2)
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: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
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: "memory");
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return dest;
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}
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#else
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static void *____memcpy(void *dest, const void *src, size_t n)
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{
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long d0, d1, d2;
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asm volatile(
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"rep ; movsq\n\t"
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"movq %4,%%rcx\n\t"
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"rep ; movsb\n\t"
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: "=&c" (d0), "=&D" (d1), "=&S" (d2)
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: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
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: "memory");
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return dest;
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}
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#endif
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void *memset(void *s, int c, size_t n)
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{
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int i;
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char *ss = s;
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for (i = 0; i < n; i++)
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ss[i] = c;
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return s;
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}
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void *memmove(void *dest, const void *src, size_t n)
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{
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unsigned char *d = dest;
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const unsigned char *s = src;
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if (d <= s || d - s >= n)
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return ____memcpy(dest, src, n);
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while (n-- > 0)
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d[n] = s[n];
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return dest;
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}
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/* Detect and warn about potential overlaps, but handle them with memmove. */
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void *memcpy(void *dest, const void *src, size_t n)
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{
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if (dest > src && dest - src < n) {
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warn("Avoiding potentially unsafe overlapping memcpy()!");
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return memmove(dest, src, n);
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}
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return ____memcpy(dest, src, n);
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}
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#ifdef CONFIG_KASAN
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extern void *__memset(void *s, int c, size_t n) __alias(memset);
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extern void *__memmove(void *dest, const void *src, size_t n) __alias(memmove);
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extern void *__memcpy(void *dest, const void *src, size_t n) __alias(memcpy);
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#endif
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