Squashed commit upgrading to mbedtls-2.28.1

Squash merging branch import/mbedtls-2.28.1

 ebf1f6a58089 ("libmbedtls: compile new files added with 2.28.1")
 3ffb51b58a54 ("libmbedtls: add SM2 curve")
 c425755720b4 ("libmbedtls: mbedtls_mpi_exp_mod(): optimize mempool usage")
 23493c822a82 ("libmbedtls: mbedtls_mpi_exp_mod(): reduce stack usage")
 dcdca2348dff ("libmbedtls: mbedtls_mpi_exp_mod() initialize W")
 dc2994976958 ("libmbedtls: fix no CRT issue")
 c6628873b281 ("libmbedtls: add interfaces in mbedtls for context memory operation")
 8acd202d3e55 ("libmedtls: mpi_miller_rabin: increase count limit")
 37284e28d5d9 ("libmbedtls: add mbedtls_mpi_init_mempool()")
 b499a75f29f3 ("libmbedtls: make mbedtls_mpi_mont*() available")
 2080a8c96a5d ("mbedtls: configure mbedtls to reach for config")
 e0858334327a ("mbedtls: remove default include/mbedtls/config.h")
 dd9688e6b8ce ("Import mbedtls-2.28.1")

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/chacha20.c b/lib/libmbedtls/mbedtls/library/chacha20.c
index 78467d3..658f046 100644
--- a/lib/libmbedtls/mbedtls/library/chacha20.c
+++ b/lib/libmbedtls/mbedtls/library/chacha20.c
@@ -54,13 +54,6 @@
 #define CHACHA20_VALIDATE( cond )                                           \
     MBEDTLS_INTERNAL_VALIDATE( cond )
 
-#define BYTES_TO_U32_LE( data, offset )                           \
-    ( (uint32_t) (data)[offset]                                   \
-      | (uint32_t) ( (uint32_t) (data)[( offset ) + 1] << 8 )     \
-      | (uint32_t) ( (uint32_t) (data)[( offset ) + 2] << 16 )    \
-      | (uint32_t) ( (uint32_t) (data)[( offset ) + 3] << 24 )    \
-    )
-
 #define ROTL32( value, amount ) \
     ( (uint32_t) ( (value) << (amount) ) | ( (value) >> ( 32 - (amount) ) ) )
 
@@ -171,10 +164,7 @@
     {
         size_t offset = i * 4U;
 
-        keystream[offset     ] = (unsigned char)( working_state[i]       );
-        keystream[offset + 1U] = (unsigned char)( working_state[i] >>  8 );
-        keystream[offset + 2U] = (unsigned char)( working_state[i] >> 16 );
-        keystream[offset + 3U] = (unsigned char)( working_state[i] >> 24 );
+        MBEDTLS_PUT_UINT32_LE(working_state[i], keystream, offset);
     }
 
     mbedtls_platform_zeroize( working_state, sizeof( working_state ) );
@@ -212,14 +202,14 @@
     ctx->state[3] = 0x6b206574;
 
     /* Set key */
-    ctx->state[4]  = BYTES_TO_U32_LE( key, 0 );
-    ctx->state[5]  = BYTES_TO_U32_LE( key, 4 );
-    ctx->state[6]  = BYTES_TO_U32_LE( key, 8 );
-    ctx->state[7]  = BYTES_TO_U32_LE( key, 12 );
-    ctx->state[8]  = BYTES_TO_U32_LE( key, 16 );
-    ctx->state[9]  = BYTES_TO_U32_LE( key, 20 );
-    ctx->state[10] = BYTES_TO_U32_LE( key, 24 );
-    ctx->state[11] = BYTES_TO_U32_LE( key, 28 );
+    ctx->state[4]  = MBEDTLS_GET_UINT32_LE( key, 0 );
+    ctx->state[5]  = MBEDTLS_GET_UINT32_LE( key, 4 );
+    ctx->state[6]  = MBEDTLS_GET_UINT32_LE( key, 8 );
+    ctx->state[7]  = MBEDTLS_GET_UINT32_LE( key, 12 );
+    ctx->state[8]  = MBEDTLS_GET_UINT32_LE( key, 16 );
+    ctx->state[9]  = MBEDTLS_GET_UINT32_LE( key, 20 );
+    ctx->state[10] = MBEDTLS_GET_UINT32_LE( key, 24 );
+    ctx->state[11] = MBEDTLS_GET_UINT32_LE( key, 28 );
 
     return( 0 );
 }
@@ -235,9 +225,9 @@
     ctx->state[12] = counter;
 
     /* Nonce */
-    ctx->state[13] = BYTES_TO_U32_LE( nonce, 0 );
-    ctx->state[14] = BYTES_TO_U32_LE( nonce, 4 );
-    ctx->state[15] = BYTES_TO_U32_LE( nonce, 8 );
+    ctx->state[13] = MBEDTLS_GET_UINT32_LE( nonce, 0 );
+    ctx->state[14] = MBEDTLS_GET_UINT32_LE( nonce, 4 );
+    ctx->state[15] = MBEDTLS_GET_UINT32_LE( nonce, 8 );
 
     mbedtls_platform_zeroize( ctx->keystream8, sizeof( ctx->keystream8 ) );