X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=crypto%2Fbn%2Fbn_exp.c;h=c5e579c77cf457b2557fc0caa0ea25684b65779b;hp=07f9288bb52b8a6258d05403f5cda26fb0abd37d;hb=8fc8f486f7fa098c9fbb6a6ae399e3c6856e0d87;hpb=d6d422e1ec48fac1c6194ab672e320281a214a32;ds=sidebyside

diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index 07f9288bb5..c5e579c77c 100644
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -787,8 +787,8 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
     if (window >= 5) {
         window = 5;             /* ~5% improvement for RSA2048 sign, and even
                                  * for RSA4096 */
-        if ((top & 7) == 0)
-            powerbufLen += 2 * top * sizeof(m->d[0]);
+        /* reserve space for mont->N.d[] copy */
+        powerbufLen += top * sizeof(mont->N.d[0]);
     }
 #endif
     (void)0;
@@ -1008,7 +1008,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
                                const BN_ULONG *not_used, const BN_ULONG *np,
                                const BN_ULONG *n0, int num);
 
-        BN_ULONG *np = mont->N.d, *n0 = mont->n0, *np2;
+        BN_ULONG *n0 = mont->n0, *np;
 
         /*
          * BN_to_montgomery can contaminate words above .top [in
@@ -1019,11 +1019,11 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
         for (i = tmp.top; i < top; i++)
             tmp.d[i] = 0;
 
-        if (top & 7)
-            np2 = np;
-        else
-            for (np2 = am.d + top, i = 0; i < top; i++)
-                np2[2 * i] = np[i];
+        /*
+         * copy mont->N.d[] to improve cache locality
+         */
+        for (np = am.d + top, i = 0; i < top; i++)
+            np[i] = mont->N.d[i];
 
         bn_scatter5(tmp.d, top, powerbuf, 0);
         bn_scatter5(am.d, am.top, powerbuf, 1);
@@ -1033,7 +1033,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 # if 0
         for (i = 3; i < 32; i++) {
             /* Calculate a^i = a^(i-1) * a */
-            bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np2, n0, top, i - 1);
+            bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
             bn_scatter5(tmp.d, top, powerbuf, i);
         }
 # else
@@ -1044,7 +1044,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
         }
         for (i = 3; i < 8; i += 2) {
             int j;
-            bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np2, n0, top, i - 1);
+            bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
             bn_scatter5(tmp.d, top, powerbuf, i);
             for (j = 2 * i; j < 32; j *= 2) {
                 bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
@@ -1052,13 +1052,13 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
             }
         }
         for (; i < 16; i += 2) {
-            bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np2, n0, top, i - 1);
+            bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
             bn_scatter5(tmp.d, top, powerbuf, i);
             bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
             bn_scatter5(tmp.d, top, powerbuf, 2 * i);
         }
         for (; i < 32; i += 2) {
-            bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np2, n0, top, i - 1);
+            bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
             bn_scatter5(tmp.d, top, powerbuf, i);
         }
 # endif
@@ -1087,11 +1087,11 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
             while (bits >= 0) {
                 wvalue = bn_get_bits5(p->d, bits - 4);
                 bits -= 5;
-                bn_power5(tmp.d, tmp.d, powerbuf, np2, n0, top, wvalue);
+                bn_power5(tmp.d, tmp.d, powerbuf, np, n0, top, wvalue);
             }
         }
 
-        ret = bn_from_montgomery(tmp.d, tmp.d, NULL, np2, n0, top);
+        ret = bn_from_montgomery(tmp.d, tmp.d, NULL, np, n0, top);
         tmp.top = top;
         bn_correct_top(&tmp);
         if (ret) {