crypto: algapi - use separate dst and src operands for __crypto_xor()

In preparation of introducing crypto_xor_cpy(), which will use separate
operands for input and output, modify the __crypto_xor() implementation,
which it will share with the existing crypto_xor(), which provides the
actual functionality when not using the inline version.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 15 insertions, 10 deletions

diff --git a/crypto/algapi.c b/crypto/algapi.c
index e4cc7615a139..aa699ff6c876 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -975,13 +975,15 @@ void crypto_inc(u8 *a, unsigned int size)
 }
 EXPORT_SYMBOL_GPL(crypto_inc);
 
-void __crypto_xor(u8 *dst, const u8 *src, unsigned int len)
+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)src) & (size - 1);
+                int d = (((unsigned long)dst ^ (unsigned long)src1) |
+                         ((unsigned long)dst ^ (unsigned long)src2)) &
+                        (size - 1);
 
                 relalign = d ? 1 << __ffs(d) : size;
 
@@ -992,34 +994,37 @@ void __crypto_xor(u8 *dst, const u8 *src, unsigned int len)
                  * process the remainder of the input using optimal strides.
                  */
                 while (((unsigned long)dst & (relalign - 1)) && len > 0) {
-                        *dst++ ^= *src++;
+                        *dst++ = *src1++ ^ *src2++;
                         len--;
                 }
         }
 
         while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) {
-                *(u64 *)dst ^= *(u64 *)src;
+                *(u64 *)dst = *(u64 *)src1 ^  *(u64 *)src2;
                 dst += 8;
-                src += 8;
+                src1 += 8;
+                src2 += 8;
                 len -= 8;
         }
 
         while (len >= 4 && !(relalign & 3)) {
-                *(u32 *)dst ^= *(u32 *)src;
+                *(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2;
                 dst += 4;
-                src += 4;
+                src1 += 4;
+                src2 += 4;
                 len -= 4;
         }
 
         while (len >= 2 && !(relalign & 1)) {
-                *(u16 *)dst ^= *(u16 *)src;
+                *(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2;
                 dst += 2;
-                src += 2;
+                src1 += 2;
+                src2 += 2;
                 len -= 2;
         }
 
         while (len--)
-                *dst++ ^= *src++;
+                *dst++ = *src1++ ^ *src2++;
 }
 EXPORT_SYMBOL_GPL(__crypto_xor);