Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/lib/mpi/mpi-inv.c b/lib/mpi/mpi-inv.c
new file mode 100644
index 0000000..61e37d1
--- /dev/null
+++ b/lib/mpi/mpi-inv.c
@@ -0,0 +1,143 @@
+/* mpi-inv.c - MPI functions
+ * Copyright (C) 1998, 2001, 2002, 2003 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "mpi-internal.h"
+
+/****************
+ * Calculate the multiplicative inverse X of A mod N
+ * That is: Find the solution x for
+ * 1 = (a*x) mod n
+ */
+int mpi_invm(MPI x, MPI a, MPI n)
+{
+ /* Extended Euclid's algorithm (See TAOCP Vol II, 4.5.2, Alg X)
+ * modified according to Michael Penk's solution for Exercise 35
+ * with further enhancement
+ */
+ MPI u, v, u1, u2 = NULL, u3, v1, v2 = NULL, v3, t1, t2 = NULL, t3;
+ unsigned int k;
+ int sign;
+ int odd;
+
+ if (!mpi_cmp_ui(a, 0))
+ return 0; /* Inverse does not exists. */
+ if (!mpi_cmp_ui(n, 1))
+ return 0; /* Inverse does not exists. */
+
+ u = mpi_copy(a);
+ v = mpi_copy(n);
+
+ for (k = 0; !mpi_test_bit(u, 0) && !mpi_test_bit(v, 0); k++) {
+ mpi_rshift(u, u, 1);
+ mpi_rshift(v, v, 1);
+ }
+ odd = mpi_test_bit(v, 0);
+
+ u1 = mpi_alloc_set_ui(1);
+ if (!odd)
+ u2 = mpi_alloc_set_ui(0);
+ u3 = mpi_copy(u);
+ v1 = mpi_copy(v);
+ if (!odd) {
+ v2 = mpi_alloc(mpi_get_nlimbs(u));
+ mpi_sub(v2, u1, u); /* U is used as const 1 */
+ }
+ v3 = mpi_copy(v);
+ if (mpi_test_bit(u, 0)) { /* u is odd */
+ t1 = mpi_alloc_set_ui(0);
+ if (!odd) {
+ t2 = mpi_alloc_set_ui(1);
+ t2->sign = 1;
+ }
+ t3 = mpi_copy(v);
+ t3->sign = !t3->sign;
+ goto Y4;
+ } else {
+ t1 = mpi_alloc_set_ui(1);
+ if (!odd)
+ t2 = mpi_alloc_set_ui(0);
+ t3 = mpi_copy(u);
+ }
+
+ do {
+ do {
+ if (!odd) {
+ if (mpi_test_bit(t1, 0) || mpi_test_bit(t2, 0)) {
+ /* one is odd */
+ mpi_add(t1, t1, v);
+ mpi_sub(t2, t2, u);
+ }
+ mpi_rshift(t1, t1, 1);
+ mpi_rshift(t2, t2, 1);
+ mpi_rshift(t3, t3, 1);
+ } else {
+ if (mpi_test_bit(t1, 0))
+ mpi_add(t1, t1, v);
+ mpi_rshift(t1, t1, 1);
+ mpi_rshift(t3, t3, 1);
+ }
+Y4:
+ ;
+ } while (!mpi_test_bit(t3, 0)); /* while t3 is even */
+
+ if (!t3->sign) {
+ mpi_set(u1, t1);
+ if (!odd)
+ mpi_set(u2, t2);
+ mpi_set(u3, t3);
+ } else {
+ mpi_sub(v1, v, t1);
+ sign = u->sign; u->sign = !u->sign;
+ if (!odd)
+ mpi_sub(v2, u, t2);
+ u->sign = sign;
+ sign = t3->sign; t3->sign = !t3->sign;
+ mpi_set(v3, t3);
+ t3->sign = sign;
+ }
+ mpi_sub(t1, u1, v1);
+ if (!odd)
+ mpi_sub(t2, u2, v2);
+ mpi_sub(t3, u3, v3);
+ if (t1->sign) {
+ mpi_add(t1, t1, v);
+ if (!odd)
+ mpi_sub(t2, t2, u);
+ }
+ } while (mpi_cmp_ui(t3, 0)); /* while t3 != 0 */
+ /* mpi_lshift( u3, k ); */
+ mpi_set(x, u1);
+
+ mpi_free(u1);
+ mpi_free(v1);
+ mpi_free(t1);
+ if (!odd) {
+ mpi_free(u2);
+ mpi_free(v2);
+ mpi_free(t2);
+ }
+ mpi_free(u3);
+ mpi_free(v3);
+ mpi_free(t3);
+
+ mpi_free(u);
+ mpi_free(v);
+ return 1;
+}
+EXPORT_SYMBOL_GPL(mpi_invm);