commit 9c682e724a35cda220ee26f91f62bd8bebc24654
author Gilles Peskine <Gilles.Peskine@arm.com> Thu Mar 16 17:21:33 2023 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Thu Mar 16 17:21:33 2023 +0100
tree 30c5d1396fcda75ccdc4b71eef4a8e3d065cce81
parent 0de8f853f04217ba982d08bb6393bb529eeb596a

AESNI: Overhaul implementation selection

Have clearly separated code to:
* determine whether the assembly-based implementation is available;
* determine whether the intrinsics-based implementation is available;
* select one of the available implementations if any.

Now MBEDTLS_AESNI_HAVE_CODE can be the single interface for aes.c and
aesni.c to determine which AESNI is built.

Change the implementation selection: now, if both implementations are
available, always prefer assembly. Before, the intrinsics were used if
available. This preference is to minimize disruption, and will likely
be revised in a later minor release.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

library/aesni.c

diff --git a/library/aesni.c b/library/aesni.c
index e24527c..a23c5b5 100644
--- a/library/aesni.c
+++ b/library/aesni.c
@@ -30,9 +30,9 @@
 
 #include <string.h>
 
-#if defined(MBEDTLS_HAVE_AESNI_INTRINSICS) || defined(MBEDTLS_HAVE_X86_64)
+#if defined(MBEDTLS_AESNI_HAVE_CODE)
 
-#if defined(MBEDTLS_HAVE_AESNI_INTRINSICS)
+#if MBEDTLS_AESNI_HAVE_CODE == 2
 #if !defined(_WIN32)
 #include <cpuid.h>
 #endif
@@ -48,7 +48,7 @@
     static unsigned int c = 0;
 
     if (!done) {
-#if defined(MBEDTLS_HAVE_AESNI_INTRINSICS)
+#if MBEDTLS_AESNI_HAVE_CODE == 2
         static unsigned info[4] = { 0, 0, 0, 0 };
 #if defined(_MSC_VER)
         __cpuid(info, 1);
@@ -56,20 +56,20 @@
         __cpuid(1, info[0], info[1], info[2], info[3]);
 #endif
         c = info[2];
-#else
+#else /* AESNI using asm */
         asm ("movl  $1, %%eax   \n\t"
              "cpuid             \n\t"
              : "=c" (c)
              :
              : "eax", "ebx", "edx");
-#endif
+#endif /* MBEDTLS_AESNI_HAVE_CODE */
         done = 1;
     }
 
     return (c & what) != 0;
 }
 
-#if defined(MBEDTLS_HAVE_AESNI_INTRINSICS)
+#if MBEDTLS_AESNI_HAVE_CODE == 2
 
 /*
  * AES-NI AES-ECB block en(de)cryption
@@ -388,7 +388,7 @@
     aesni_set_rk_256(rk[12], rk[13], _mm_aeskeygenassist_si128(rk[13], 0x40), &rk[14], &rk[15]);
 }
 
-#else  /* MBEDTLS_HAVE_AESNI_INTRINSICS */
+#else /* MBEDTLS_AESNI_HAVE_CODE == 1 */
 
 #if defined(__has_feature)
 #if __has_feature(memory_sanitizer)
@@ -776,7 +776,7 @@
          : "memory", "cc", "0");
 }
 
-#endif  /* MBEDTLS_HAVE_AESNI_INTRINSICS */
+#endif  /* MBEDTLS_AESNI_HAVE_CODE */
 
 /*
  * Key expansion, wrapper
@@ -795,6 +795,6 @@
     return 0;
 }
 
-#endif /* MBEDTLS_HAVE_X86_64 */
+#endif /* MBEDTLS_AESNI_HAVE_CODE */
 
 #endif /* MBEDTLS_AESNI_C */