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Better boot.S and link script #10

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merged 2 commits into from Nov 21, 2021
Merged

Better boot.S and link script #10

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3eb0bbd
Better boot.S and link script
dinosaure Nov 20, 2021
9a02679
Much much much more simpler memcpy/memmove impl. and delete useless i…
dinosaure Nov 21, 2021
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122 changes: 5 additions & 117 deletions caml/nolibc/memcpy.c
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Expand Up @@ -2,123 +2,11 @@
#include <stdint.h>
#include <endian.h>

void *memcpy(void *restrict dest, const void *restrict src, size_t n)
void *memcpy(void *v_dst, const void *v_src, size_t len)
{
unsigned char *d = dest;
const unsigned char *s = src;
char *dst = v_dst;
const char *src = v_src;

#ifdef __GNUC__

#if __BYTE_ORDER == __LITTLE_ENDIAN
#define LS >>
#define RS <<
#else
#define LS <<
#define RS >>
#endif

typedef uint32_t __attribute__((__may_alias__)) u32;
uint32_t w, x;

for (; (uintptr_t)s % 4 && n; n--) *d++ = *s++;

if ((uintptr_t)d % 4 == 0) {
for (; n>=16; s+=16, d+=16, n-=16) {
*(u32 *)(d+0) = *(u32 *)(s+0);
*(u32 *)(d+4) = *(u32 *)(s+4);
*(u32 *)(d+8) = *(u32 *)(s+8);
*(u32 *)(d+12) = *(u32 *)(s+12);
}
if (n&8) {
*(u32 *)(d+0) = *(u32 *)(s+0);
*(u32 *)(d+4) = *(u32 *)(s+4);
d += 8; s += 8;
}
if (n&4) {
*(u32 *)(d+0) = *(u32 *)(s+0);
d += 4; s += 4;
}
if (n&2) {
*d++ = *s++; *d++ = *s++;
}
if (n&1) {
*d = *s;
}
return dest;
}

if (n >= 32) switch ((uintptr_t)d % 4) {
case 1:
w = *(u32 *)s;
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
n -= 3;
for (; n>=17; s+=16, d+=16, n-=16) {
x = *(u32 *)(s+1);
*(u32 *)(d+0) = (w LS 24) | (x RS 8);
w = *(u32 *)(s+5);
*(u32 *)(d+4) = (x LS 24) | (w RS 8);
x = *(u32 *)(s+9);
*(u32 *)(d+8) = (w LS 24) | (x RS 8);
w = *(u32 *)(s+13);
*(u32 *)(d+12) = (x LS 24) | (w RS 8);
}
break;
case 2:
w = *(u32 *)s;
*d++ = *s++;
*d++ = *s++;
n -= 2;
for (; n>=18; s+=16, d+=16, n-=16) {
x = *(u32 *)(s+2);
*(u32 *)(d+0) = (w LS 16) | (x RS 16);
w = *(u32 *)(s+6);
*(u32 *)(d+4) = (x LS 16) | (w RS 16);
x = *(u32 *)(s+10);
*(u32 *)(d+8) = (w LS 16) | (x RS 16);
w = *(u32 *)(s+14);
*(u32 *)(d+12) = (x LS 16) | (w RS 16);
}
break;
case 3:
w = *(u32 *)s;
*d++ = *s++;
n -= 1;
for (; n>=19; s+=16, d+=16, n-=16) {
x = *(u32 *)(s+3);
*(u32 *)(d+0) = (w LS 8) | (x RS 24);
w = *(u32 *)(s+7);
*(u32 *)(d+4) = (x LS 8) | (w RS 24);
x = *(u32 *)(s+11);
*(u32 *)(d+8) = (w LS 8) | (x RS 24);
w = *(u32 *)(s+15);
*(u32 *)(d+12) = (x LS 8) | (w RS 24);
}
break;
}
if (n&16) {
*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
}
if (n&8) {
*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
}
if (n&4) {
*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
}
if (n&2) {
*d++ = *s++; *d++ = *s++;
}
if (n&1) {
*d = *s;
}
return dest;
#endif

for (; n; n--) *d++ = *s++;
return dest;
for (; len; len--) *dst++ = *src++;
return dst;
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According to the man page, the memcpy function should return a pointer to the dest address (return v_dst;). The returned value does not appear to be used here but at least mirage/mirage-crypto@f351442 uses it to ensure aligned memory usage and it may fail there. This is the same for memmove below.

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Ok, I will propose a PR to fix that, thanks for this looking.

}
39 changes: 11 additions & 28 deletions caml/nolibc/memmove.c
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@@ -1,36 +1,19 @@
#include <string.h>
#include <stdint.h>
#include <stdio.h>

#define WT size_t
#define WS (sizeof(WT))

void *memmove(void *dest, const void *src, size_t n)
void *memmove(void *v_dst, const void *v_src, size_t len)
{
char *d = dest;
const char *s = src;
char *dst = v_dst;
const char *src = v_src;

if (d==s) return d;
if (s+n <= d || d+n <= s) return memcpy(d, s, n);
if (dst == src) return dst;
if (src + len <= dst || dst + len <= src) return memcpy(dst, src, len) ;

if (d<s) {
if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
while ((uintptr_t)d % WS) {
if (!n--) return dest;
*d++ = *s++;
}
for (; n>=WS; n-=WS, d+=WS, s+=WS) *(WT *)d = *(WT *)s;
}
for (; n; n--) *d++ = *s++;
} else {
if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
while ((uintptr_t)(d+n) % WS) {
if (!n--) return dest;
d[n] = s[n];
}
while (n>=WS) n-=WS, *(WT *)(d+n) = *(WT *)(s+n);
}
while (n) n--, d[n] = s[n];
}
if (dst < src)
for (; len; len--) *dst++ = *src++;
else
while (len) len--, dst[len] = src[len];

return dest;
return dst;
}
8 changes: 0 additions & 8 deletions kernel/lib/lib.h
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@@ -1,11 +1,3 @@
#include <stddef.h>

void *memset(void *dest, int c, size_t n);
void *memcpy(void *restrict dest, const void *restrict src, size_t n);
void *memmove(void *dest, const void *src, size_t n);
int memcmp(const void *vl, const void *vr, size_t n);
int strcmp(const char *l, const char *r);
int strncmp(const char *l, const char *r, size_t n);
char *strcpy(char *restrict dest, const char *restrict src);
size_t strlen(const char *s);
int isspace(int c);