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Avoid compiler optimization removing memmove.

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Thanks to Szczepan Zalega.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka
2020-09-08 09:22:40 +09:00
parent ffbb754fc0
commit dd47cf4312
3 changed files with 17 additions and 37 deletions
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12
ChangeLog
View File

@@ -1,11 +1,17 @@
2020-09-08 NIIBE Yutaka <gniibe@fsij.org>
* src/modp256k1.c (modp256k1_add, modp256k1_reduce): Avoid
optimization to remove call of memmove.
* src/modp256r1.c (modp256r1_add, modp256r1_sub)
(modp256r1_reduce): Likewise.
2020-09-07 NIIBE Yutaka <gniibe@fsij.org>
* src/openpgp.c (gpg_get_firmware_update_key): Use an array.
* src/modp256k1.c (modp256k1_add, modp256k1_sub): Use memmove.
* src/modp256r1.c (modp256r1_add, modp256r1_sub)
(modp256r1_reduce): Use memmove.
* (modp256k1_add, modp256k1_sub): Use memmove.
(modp256r1_reduce): Likewise.
2020-09-04 NIIBE Yutaka <gniibe@fsij.org>

11
src/modp256k1.c
View File

@@ -74,11 +74,7 @@ modp256k1_add (bn256 *X, const bn256 *A, const bn256 *B)
cond = (bn256_add (X, A, B) == 0);
cond &= bn256_sub (tmp, X, P256K1);
if (cond)
/* No-carry AND borrow */
memmove (tmp, tmp, sizeof (bn256));
else
memcpy (X, tmp, sizeof (bn256));
memmove (cond?tmp:X, tmp, sizeof (bn256));
}
/**
@@ -92,10 +88,7 @@ modp256k1_sub (bn256 *X, const bn256 *A, const bn256 *B)
borrow = bn256_sub (X, A, B);
bn256_add (tmp, X, P256K1);
if (borrow)
memcpy (X, tmp, sizeof (bn256));
else
memmove (tmp, tmp, sizeof (bn256));
memmove (borrow?X:tmp, tmp, sizeof (bn256));
}
/**

31
src/modp256r1.c
View File

@@ -69,11 +69,7 @@ modp256r1_add (bn256 *X, const bn256 *A, const bn256 *B)
cond = (bn256_add (X, A, B) == 0);
cond &= bn256_sub (tmp, X, P256R1);
if (cond)
/* No-carry AND borrow */
memmove (tmp, tmp, sizeof (bn256));
else
memcpy (X, tmp, sizeof (bn256));
memmove (cond?tmp:X, tmp, sizeof (bn256));
}
/**
@@ -87,10 +83,7 @@ modp256r1_sub (bn256 *X, const bn256 *A, const bn256 *B)
borrow = bn256_sub (X, A, B);
bn256_add (tmp, X, P256R1);
if (borrow)
memcpy (X, tmp, sizeof (bn256));
else
memmove (tmp, tmp, sizeof (bn256));
memmove (borrow?X:tmp, tmp, sizeof (bn256));
}
/**
@@ -121,10 +114,7 @@ modp256r1_reduce (bn256 *X, const bn512 *A)
S1->word[1] = A->word[1];
S1->word[0] = A->word[0];
borrow = bn256_sub (tmp0, S1, P256R1);
if (borrow)
memmove (tmp0, tmp0, sizeof (bn256));
else
memcpy (S1, tmp0, sizeof (bn256));
memmove (borrow?tmp0:S1, tmp0, sizeof (bn256));
/* X = S1 */
S2->word[7] = A->word[15];
@@ -165,10 +155,7 @@ modp256r1_reduce (bn256 *X, const bn512 *A)
S5->word[1] = A->word[10];
S5->word[0] = A->word[9];
borrow = bn256_sub (tmp0, S5, P256R1);
if (borrow)
memmove (tmp0, tmp0, sizeof (bn256));
else
memcpy (S5, tmp0, sizeof (bn256));
memmove (borrow?tmp0:S5, tmp0, sizeof (bn256));
/* X += S5 */
modp256r1_add (X, X, S5);
@@ -179,10 +166,7 @@ modp256r1_reduce (bn256 *X, const bn512 *A)
S6->word[1] = A->word[12];
S6->word[0] = A->word[11];
borrow = bn256_sub (tmp0, S6, P256R1);
if (borrow)
memmove (tmp0, tmp0, sizeof (bn256));
else
memcpy (S6, tmp0, sizeof (bn256));
memmove (borrow?tmp0:S6, tmp0, sizeof (bn256));
/* X -= S6 */
modp256r1_sub (X, X, S6);
@@ -194,10 +178,7 @@ modp256r1_reduce (bn256 *X, const bn512 *A)
S7->word[1] = A->word[13];
S7->word[0] = A->word[12];
borrow = bn256_sub (tmp0, S7, P256R1);
if (borrow)
memmove (tmp0, tmp0, sizeof (bn256));
else
memcpy (S7, tmp0, sizeof (bn256));
memmove (borrow?tmp0:S7, tmp0, sizeof (bn256));
/* X -= S7 */
modp256r1_sub (X, X, S7);