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Remove memcpy unrolling in bn_lib.c

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Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Andy Polyakov <appro@openssl.org>
This commit is contained in:
Emilia Kasper 2017-02-28 18:12:25 +01:00
parent c26f655fdd
commit d5aa14dde5
1 changed files with 10 additions and 80 deletions
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90
crypto/bn/bn_lib.c
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@ -245,9 +245,7 @@ BIGNUM *BN_new(void)
/* The caller MUST check that words > b->dmax before calling this */
static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
{
BN_ULONG *A, *a = NULL;
const BN_ULONG *B;
int i;
BN_ULONG *a = NULL;
bn_check_top(b);
@ -260,56 +258,18 @@ static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
return (NULL);
}
if (BN_get_flags(b, BN_FLG_SECURE))
a = A = OPENSSL_secure_zalloc(words * sizeof(*a));
a = OPENSSL_secure_zalloc(words * sizeof(*a));
else
a = A = OPENSSL_zalloc(words * sizeof(*a));
if (A == NULL) {
a = OPENSSL_zalloc(words * sizeof(*a));
if (a == NULL) {
BNerr(BN_F_BN_EXPAND_INTERNAL, ERR_R_MALLOC_FAILURE);
return (NULL);
}
#if 1
B = b->d;
/* Check if the previous number needs to be copied */
if (B != NULL) {
for (i = b->top >> 2; i > 0; i--, A += 4, B += 4) {
/*
* The fact that the loop is unrolled
* 4-wise is a tribute to Intel. It's
* the one that doesn't have enough
* registers to accommodate more data.
* I'd unroll it 8-wise otherwise:-)
*
* <appro@fy.chalmers.se>
*/
BN_ULONG a0, a1, a2, a3;
a0 = B[0];
a1 = B[1];
a2 = B[2];
a3 = B[3];
A[0] = a0;
A[1] = a1;
A[2] = a2;
A[3] = a3;
}
switch (b->top & 3) {
case 3:
A[2] = B[2];
case 2:
A[1] = B[1];
case 1:
A[0] = B[0];
case 0:
/* Without the "case 0" some old optimizers got this wrong. */
;
}
}
#else
memset(A, 0, sizeof(*A) * words);
memcpy(A, b->d, sizeof(b->d[0]) * b->top);
#endif
assert(b->top <= words);
memcpy(a, b->d, sizeof(*a) * b->top);
return (a);
return a;
}
/*
@ -361,49 +321,19 @@ BIGNUM *BN_dup(const BIGNUM *a)
BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
{
int i;
BN_ULONG *A;
const BN_ULONG *B;
bn_check_top(b);
if (a == b)
return (a);
return a;
if (bn_wexpand(a, b->top) == NULL)
return (NULL);
return NULL;
#if 1
A = a->d;
B = b->d;
for (i = b->top >> 2; i > 0; i--, A += 4, B += 4) {
BN_ULONG a0, a1, a2, a3;
a0 = B[0];
a1 = B[1];
a2 = B[2];
a3 = B[3];
A[0] = a0;
A[1] = a1;
A[2] = a2;
A[3] = a3;
}
/* ultrix cc workaround, see comments in bn_expand_internal */
switch (b->top & 3) {
case 3:
A[2] = B[2];
case 2:
A[1] = B[1];
case 1:
A[0] = B[0];
case 0:;
}
#else
memcpy(a->d, b->d, sizeof(b->d[0]) * b->top);
#endif
a->top = b->top;
a->neg = b->neg;
bn_check_top(a);
return (a);
return a;
}
void BN_swap(BIGNUM *a, BIGNUM *b)