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-rw-r--r--lib/crypto/utils.c88
1 files changed, 88 insertions, 0 deletions
diff --git a/lib/crypto/utils.c b/lib/crypto/utils.c
new file mode 100644
index 000000000000..53230ab1b195
--- /dev/null
+++ b/lib/crypto/utils.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Crypto library utility functions
+ *
+ * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <asm/unaligned.h>
+#include <crypto/algapi.h>
+#include <linux/module.h>
+
+/*
+ * XOR @len bytes from @src1 and @src2 together, writing the result to @dst
+ * (which may alias one of the sources). Don't call this directly; call
+ * crypto_xor() or crypto_xor_cpy() instead.
+ */
+void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len)
+{
+ int relalign = 0;
+
+ if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
+ int size = sizeof(unsigned long);
+ int d = (((unsigned long)dst ^ (unsigned long)src1) |
+ ((unsigned long)dst ^ (unsigned long)src2)) &
+ (size - 1);
+
+ relalign = d ? 1 << __ffs(d) : size;
+
+ /*
+ * If we care about alignment, process as many bytes as
+ * needed to advance dst and src to values whose alignments
+ * equal their relative alignment. This will allow us to
+ * process the remainder of the input using optimal strides.
+ */
+ while (((unsigned long)dst & (relalign - 1)) && len > 0) {
+ *dst++ = *src1++ ^ *src2++;
+ len--;
+ }
+ }
+
+ while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) {
+ if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
+ u64 l = get_unaligned((u64 *)src1) ^
+ get_unaligned((u64 *)src2);
+ put_unaligned(l, (u64 *)dst);
+ } else {
+ *(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2;
+ }
+ dst += 8;
+ src1 += 8;
+ src2 += 8;
+ len -= 8;
+ }
+
+ while (len >= 4 && !(relalign & 3)) {
+ if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
+ u32 l = get_unaligned((u32 *)src1) ^
+ get_unaligned((u32 *)src2);
+ put_unaligned(l, (u32 *)dst);
+ } else {
+ *(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2;
+ }
+ dst += 4;
+ src1 += 4;
+ src2 += 4;
+ len -= 4;
+ }
+
+ while (len >= 2 && !(relalign & 1)) {
+ if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
+ u16 l = get_unaligned((u16 *)src1) ^
+ get_unaligned((u16 *)src2);
+ put_unaligned(l, (u16 *)dst);
+ } else {
+ *(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2;
+ }
+ dst += 2;
+ src1 += 2;
+ src2 += 2;
+ len -= 2;
+ }
+
+ while (len--)
+ *dst++ = *src1++ ^ *src2++;
+}
+EXPORT_SYMBOL_GPL(__crypto_xor);
+
+MODULE_LICENSE("GPL");