commit 6dec541e6871973fb21a186bad899bed43c6c1f1
author Gilles Peskine <Gilles.Peskine@arm.com> Thu Mar 16 17:21:33 2023 +0100
committer Tom Cosgrove <tom.cosgrove@arm.com> Fri Mar 17 16:31:59 2023 +0000
tree 6afff90fd5f573d91ef2ec9d53e6e6c57dc0db63
parent b71d40228d5373964e5e0a7107d529feb553e3ec

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/aes.c

diff --git a/library/aes.c b/library/aes.c
index 4eaa76d..d7e4a7c 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -518,7 +518,7 @@
  * i.e. an offset of 1 means 4 bytes and so on.
  */
 #if (defined(MBEDTLS_PADLOCK_C) && defined(MBEDTLS_HAVE_X86)) ||        \
-    defined(MBEDTLS_HAVE_AESNI_INTRINSICS)
+    (defined(MBEDTLS_AESNI_C) && MBEDTLS_AESNI_HAVE_CODE == 2)
 #define MAY_NEED_TO_ALIGN
 #endif
 static unsigned mbedtls_aes_rk_offset(uint32_t *buf)
@@ -535,7 +535,7 @@
     }
 #endif
 
-#if defined(MBEDTLS_AESNI_C) && defined(MBEDTLS_HAVE_AESNI_INTRINSICS)
+#if defined(MBEDTLS_AESNI_C) && MBEDTLS_AESNI_HAVE_CODE == 2
     if (mbedtls_aesni_has_support(MBEDTLS_AESNI_AES)) {
         align_16_bytes = 1;
     }

library/aesni.c

diff --git a/library/aesni.c b/library/aesni.c
index 75543df..c909f65 100644
--- a/library/aesni.c
+++ b/library/aesni.c
@@ -36,9 +36,9 @@
 #endif
 /* *INDENT-ON* */
 
-#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
@@ -54,7 +54,7 @@
     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);
@@ -62,20 +62,20 @@
         __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
@@ -394,7 +394,7 @@
     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)
@@ -782,7 +782,7 @@
          : "memory", "cc", "0");
 }
 
-#endif  /* MBEDTLS_HAVE_AESNI_INTRINSICS */
+#endif  /* MBEDTLS_AESNI_HAVE_CODE */
 
 /*
  * Key expansion, wrapper
@@ -801,6 +801,6 @@
     return 0;
 }
 
-#endif /* MBEDTLS_HAVE_X86_64 */
+#endif /* MBEDTLS_AESNI_HAVE_CODE */
 
 #endif /* MBEDTLS_AESNI_C */