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AESNI: Overhaul implementation selection

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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>
This commit is contained in:
Gilles Peskine
2023-03-16 17:21:33 +01:00
parent 0de8f853f0
commit 9c682e724a
3 changed files with 37 additions and 20 deletions
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35
library/aesni.h
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@@ -32,6 +32,9 @@
#define MBEDTLS_AESNI_AES 0x02000000u
#define MBEDTLS_AESNI_CLMUL 0x00000002u
/* Can we do AESNI with inline assembly?
* (Only implemented with gas syntax, only for 64-bit.)
*/
#if defined(MBEDTLS_HAVE_ASM) && defined(__GNUC__) && \
(defined(__amd64__) || defined(__x86_64__)) && \
!defined(MBEDTLS_HAVE_X86_64)
@@ -40,19 +43,33 @@
#if defined(MBEDTLS_AESNI_C)
#if defined(MBEDTLS_HAVE_X86_64)
#define MBEDTLS_AESNI_HAVE_CODE // via assembly
#endif
/* Can we do AESNI with intrinsics?
* (Only implemented with certain compilers, .)
*/
#undef MBEDTLS_AESNI_HAVE_INTRINSICS
#if defined(_MSC_VER)
#define MBEDTLS_HAVE_AESNI_INTRINSICS
/* Visual Studio supports AESNI intrinsics since VS 2008 SP1. We only support
* VS 2013 and up for other reasons anyway, so no need to check the version. */
#define MBEDTLS_AESNI_HAVE_INTRINSICS
#endif
#if defined(__GNUC__) && defined(__AES__)
#define MBEDTLS_HAVE_AESNI_INTRINSICS
/* GCC-like compilers: currently, we only support intrinsics if the requisite
* target flag is enabled when building the library (e.g. `gcc -mpclmul -msse2`
* or `clang -maes -mpclmul`). */
#if defined(__GNUC__) && defined(__AES__) && defined(__PCLMUL__)
#define MBEDTLS_AESNI_HAVE_INTRINSICS
#endif
#if defined(MBEDTLS_HAVE_AESNI_INTRINSICS)
#define MBEDTLS_AESNI_HAVE_CODE // via intrinsics
/* Choose the implementation of AESNI, if one is available. */
#undef MBEDTLS_AESNI_HAVE_CODE
/* To minimize disruption when releasing the intrinsics-based implementation,
* favor the assembly-based implementation if it's available. We intend to
* revise this in a later release of Mbed TLS 3.x. In the long run, we will
* likely remove the assembly implementation. */
#if defined(MBEDTLS_HAVE_X86_64)
#define MBEDTLS_AESNI_HAVE_CODE 1 // via assembly
#endif
#if defined(MBEDTLS_AESNI_HAVE_INTRINSICS)
#define MBEDTLS_AESNI_HAVE_CODE 2 // via intrinsics
#endif
#if defined(MBEDTLS_AESNI_HAVE_CODE)