utils: Auto-inlining memxor()

Similar to memwipe(), inlined memxor() can improve performance significantly
for some algorithms making use of it. In AES-GCM, this can be up to ~20%.

diff --git a/src/libstrongswan/utils/utils.c b/src/libstrongswan/utils/utils.c
index 3d5e3dfc90bb20e824c152ed154ed1d6ac3be3f6..b01a1b16f8e80c57206e683c16b1046dbe549c6d 100644 (file)
--- a/src/libstrongswan/utils/utils.c
+++ b/src/libstrongswan/utils/utils.c
@@ -61,44 +61,9 @@ ENUM(status_names, SUCCESS, NEED_MORE,
 /**
  * Described in header.
  */
-void memxor(u_int8_t dst[], u_int8_t src[], size_t n)
+void memxor_noinline(u_int8_t dst[], u_int8_t src[], size_t n)
 {
-       int m, i;
-
-       /* byte wise XOR until dst aligned */
-       for (i = 0; (uintptr_t)&dst[i] % sizeof(long) && i < n; i++)
-       {
-               dst[i] ^= src[i];
-       }
-       /* try to use words if src shares an aligment with dst */
-       switch (((uintptr_t)&src[i] % sizeof(long)))
-       {
-               case 0:
-                       for (m = n - sizeof(long); i <= m; i += sizeof(long))
-                       {
-                               *(long*)&dst[i] ^= *(long*)&src[i];
-                       }
-                       break;
-               case sizeof(int):
-                       for (m = n - sizeof(int); i <= m; i += sizeof(int))
-                       {
-                               *(int*)&dst[i] ^= *(int*)&src[i];
-                       }
-                       break;
-               case sizeof(short):
-                       for (m = n - sizeof(short); i <= m; i += sizeof(short))
-                       {
-                               *(short*)&dst[i] ^= *(short*)&src[i];
-                       }
-                       break;
-               default:
-                       break;
-       }
-       /* byte wise XOR of the rest */
-       for (; i < n; i++)
-       {
-               dst[i] ^= src[i];
-       }
+       memxor_inline(dst, src, n);
 }
 
 /**

diff --git a/src/libstrongswan/utils/utils.h b/src/libstrongswan/utils/utils.h
index 029a3751826f4dc69731487277f8510df5174cc9..8ee94ab091bb50f2b9d770789577aabf038ef277 100644 (file)
--- a/src/libstrongswan/utils/utils.h
+++ b/src/libstrongswan/utils/utils.h
@@ -551,10 +551,68 @@ typedef struct timespec timespec_t;
  */
 typedef struct sockaddr sockaddr_t;
 
+ /**
+  * Same as memcpy, but XORs src into dst instead of copy, non-inlining.
+  */
+void memxor_noinline(u_int8_t dst[], u_int8_t src[], size_t n);
+
+/**
+ * Same as memcpy, but XORs src into dst instead of copy, inlining.
+ */
+static inline void memxor_inline(u_int8_t dst[], u_int8_t src[], size_t n)
+{
+       int m, i;
+
+       /* byte wise XOR until dst aligned */
+       for (i = 0; (uintptr_t)&dst[i] % sizeof(long) && i < n; i++)
+       {
+               dst[i] ^= src[i];
+       }
+       /* try to use words if src shares an aligment with dst */
+       switch (((uintptr_t)&src[i] % sizeof(long)))
+       {
+               case 0:
+                       for (m = n - sizeof(long); i <= m; i += sizeof(long))
+                       {
+                               *(long*)&dst[i] ^= *(long*)&src[i];
+                       }
+                       break;
+               case sizeof(int):
+                       for (m = n - sizeof(int); i <= m; i += sizeof(int))
+                       {
+                               *(int*)&dst[i] ^= *(int*)&src[i];
+                       }
+                       break;
+               case sizeof(short):
+                       for (m = n - sizeof(short); i <= m; i += sizeof(short))
+                       {
+                               *(short*)&dst[i] ^= *(short*)&src[i];
+                       }
+                       break;
+               default:
+                       break;
+       }
+       /* byte wise XOR of the rest */
+       for (; i < n; i++)
+       {
+               dst[i] ^= src[i];
+       }
+}
+
 /**
- * Same as memcpy, but XORs src into dst instead of copy
+ * Same as memcpy, but XORs src into dst instead of copy, auto-inlining.
  */
-void memxor(u_int8_t dest[], u_int8_t src[], size_t n);
+static inline void memxor(u_int8_t dest[], u_int8_t src[], size_t n)
+{
+       if (__builtin_constant_p(n))
+       {
+               memxor_inline(dest, src, n);
+       }
+       else
+       {
+               memxor_noinline(dest, src, n);
+       }
+}
 
 /**
  * Safely overwrite n bytes of memory at ptr with zero, non-inlining variant.