mbedtls_ssl_handshake_params: reorder fields to save code size
Reorder fields mbedtls_ssl_handshake_params in order to save code on Arm
Thumb builds. The general idea is to put often-used fields in the direct
access window of 128 elements from the beginning of the structure.
The reordering is a human selection based on a report of field offset and
use counts, and informed by measuring the code size with various
arrangements. Some notes:
* This is the same reordering as the corresponding commit in #5189 for 2.2x.
* I moved most byte-sized fields at the beginning where they're sure to be
in the direct access window.
* I moved buffering earlier because it can be around the threshold depending
on the configuration, and it's accessed in a lot of places.
* I moved several fields, including update_checksum and friends, early so
that they're guaranteed to be in the early access window.
Results (arm-none-eabi-gcc 7.3.1, build_arm_none_eabi_gcc_m0plus build):
library/ssl_cli.o: 19763 -> 19687 (diff: 76)
library/ssl_msg.o: 24874 -> 24834 (diff: 40)
library/ssl_srv.o: 20754 -> 20562 (diff: 192)
library/ssl_tls.o: 21003 -> 20907 (diff: 96)
library/ssl_tls13_client.o: 7284 -> 7272 (diff: 12)
library/ssl_tls13_generic.o: 4749 -> 4721 (diff: 28)
library/ssl_tls13_keys.o: 5133 -> 5077 (diff: 56)
Results (same architecture, config-suite-b.h + MBEDTLS_ECDH_LEGACY_CONTEXT +
MBEDTLS_ECP_RESTARTABLE):
library/ssl_cli.o: 3000 -> 2936 (diff: 64)
library/ssl_msg.o: 3084 -> 3080 (diff: 4)
library/ssl_srv.o: 3428 -> 3400 (diff: 28)
library/ssl_tls.o: 6754 -> 6730 (diff: 24)
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index e4d7d72..6af125f 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -525,6 +525,56 @@
*/
struct mbedtls_ssl_handshake_params
{
+ /* Frequently-used boolean or byte fields (placed early to take
+ * advantage of smaller code size for indirect access on Arm Thumb) */
+ uint8_t max_major_ver; /*!< max. major version client*/
+ uint8_t max_minor_ver; /*!< max. minor version client*/
+ uint8_t resume; /*!< session resume indicator*/
+ uint8_t cli_exts; /*!< client extension presence*/
+
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+ uint8_t sni_authmode; /*!< authmode from SNI callback */
+#endif
+
+#if defined(MBEDTLS_SSL_SESSION_TICKETS)
+ uint8_t new_session_ticket; /*!< use NewSessionTicket? */
+#endif /* MBEDTLS_SSL_SESSION_TICKETS */
+
+#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
+ uint8_t extended_ms; /*!< use Extended Master Secret? */
+#endif
+
+#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
+ uint8_t async_in_progress; /*!< an asynchronous operation is in progress */
+#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+ unsigned char retransmit_state; /*!< Retransmission state */
+#endif
+
+#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
+ uint8_t ecrs_enabled; /*!< Handshake supports EC restart? */
+ mbedtls_x509_crt_restart_ctx ecrs_ctx; /*!< restart context */
+ enum { /* this complements ssl->state with info on intra-state operations */
+ ssl_ecrs_none = 0, /*!< nothing going on (yet) */
+ ssl_ecrs_crt_verify, /*!< Certificate: crt_verify() */
+ ssl_ecrs_ske_start_processing, /*!< ServerKeyExchange: pk_verify() */
+ ssl_ecrs_cke_ecdh_calc_secret, /*!< ClientKeyExchange: ECDH step 2 */
+ ssl_ecrs_crt_vrfy_sign, /*!< CertificateVerify: pk_sign() */
+ } ecrs_state; /*!< current (or last) operation */
+ mbedtls_x509_crt *ecrs_peer_cert; /*!< The peer's CRT chain. */
+ size_t ecrs_n; /*!< place for saving a length */
+#endif
+
+ size_t pmslen; /*!< premaster length */
+
+ mbedtls_ssl_ciphersuite_t const *ciphersuite_info;
+
+ void (*update_checksum)(mbedtls_ssl_context *, const unsigned char *, size_t);
+ void (*calc_verify)(const mbedtls_ssl_context *, unsigned char *, size_t *);
+ void (*calc_finished)(mbedtls_ssl_context *, unsigned char *, int);
+ mbedtls_ssl_tls_prf_cb *tls_prf;
+
/*
* Handshake specific crypto variables
*/
@@ -532,11 +582,6 @@
int tls1_3_kex_modes; /*!< key exchange modes for TLS 1.3 */
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
-#if !defined(MBEDTLS_DEPRECATED_REMOVED)
- const uint16_t *group_list;
- unsigned char group_list_heap_allocated;
-#endif
-
#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
mbedtls_ssl_sig_hash_set_t hash_algs; /*!< Set of suitable sig-hash pairs */
@@ -587,65 +632,17 @@
#if defined(MBEDTLS_X509_CRT_PARSE_C)
mbedtls_ssl_key_cert *key_cert; /*!< chosen key/cert pair (server) */
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
- uint8_t sni_authmode; /*!< authmode from SNI callback */
mbedtls_ssl_key_cert *sni_key_cert; /*!< key/cert list from SNI */
mbedtls_x509_crt *sni_ca_chain; /*!< trusted CAs from SNI callback */
mbedtls_x509_crl *sni_ca_crl; /*!< trusted CAs CRLs from SNI */
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
#endif /* MBEDTLS_X509_CRT_PARSE_C */
-#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
- uint8_t ecrs_enabled; /*!< Handshake supports EC restart? */
- mbedtls_x509_crt_restart_ctx ecrs_ctx; /*!< restart context */
- enum { /* this complements ssl->state with info on intra-state operations */
- ssl_ecrs_none = 0, /*!< nothing going on (yet) */
- ssl_ecrs_crt_verify, /*!< Certificate: crt_verify() */
- ssl_ecrs_ske_start_processing, /*!< ServerKeyExchange: pk_verify() */
- ssl_ecrs_cke_ecdh_calc_secret, /*!< ClientKeyExchange: ECDH step 2 */
- ssl_ecrs_crt_vrfy_sign, /*!< CertificateVerify: pk_sign() */
- } ecrs_state; /*!< current (or last) operation */
- mbedtls_x509_crt *ecrs_peer_cert; /*!< The peer's CRT chain. */
- size_t ecrs_n; /*!< place for saving a length */
-#endif
-
#if defined(MBEDTLS_X509_CRT_PARSE_C) && \
!defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
mbedtls_pk_context peer_pubkey; /*!< The public key from the peer. */
#endif /* MBEDTLS_X509_CRT_PARSE_C && !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
-#if defined(MBEDTLS_SSL_PROTO_DTLS)
- unsigned int out_msg_seq; /*!< Outgoing handshake sequence number */
- unsigned int in_msg_seq; /*!< Incoming handshake sequence number */
-
- unsigned char *verify_cookie; /*!< Cli: HelloVerifyRequest cookie
- Srv: unused */
- unsigned char verify_cookie_len; /*!< Cli: cookie length
- Srv: flag for sending a cookie */
-
- uint32_t retransmit_timeout; /*!< Current value of timeout */
- unsigned char retransmit_state; /*!< Retransmission state */
- mbedtls_ssl_flight_item *flight; /*!< Current outgoing flight */
- mbedtls_ssl_flight_item *cur_msg; /*!< Current message in flight */
- unsigned char *cur_msg_p; /*!< Position in current message */
- unsigned int in_flight_start_seq; /*!< Minimum message sequence in the
- flight being received */
- mbedtls_ssl_transform *alt_transform_out; /*!< Alternative transform for
- resending messages */
- unsigned char alt_out_ctr[MBEDTLS_SSL_SEQUENCE_NUMBER_LEN]; /*!< Alternative record epoch/counter
- for resending messages */
-
-#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
- /* The state of CID configuration in this handshake. */
-
- uint8_t cid_in_use; /*!< This indicates whether the use of the CID extension
- * has been negotiated. Possible values are
- * #MBEDTLS_SSL_CID_ENABLED and
- * #MBEDTLS_SSL_CID_DISABLED. */
- unsigned char peer_cid[ MBEDTLS_SSL_CID_OUT_LEN_MAX ]; /*! The peer's CID */
- uint8_t peer_cid_len; /*!< The length of
- * \c peer_cid. */
-#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
-
struct
{
size_t total_bytes_buffered; /*!< Cumulative size of heap allocated
@@ -672,6 +669,38 @@
} buffering;
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+ unsigned int out_msg_seq; /*!< Outgoing handshake sequence number */
+ unsigned int in_msg_seq; /*!< Incoming handshake sequence number */
+
+ unsigned char *verify_cookie; /*!< Cli: HelloVerifyRequest cookie
+ Srv: unused */
+ unsigned char verify_cookie_len; /*!< Cli: cookie length
+ Srv: flag for sending a cookie */
+
+ uint32_t retransmit_timeout; /*!< Current value of timeout */
+ mbedtls_ssl_flight_item *flight; /*!< Current outgoing flight */
+ mbedtls_ssl_flight_item *cur_msg; /*!< Current message in flight */
+ unsigned char *cur_msg_p; /*!< Position in current message */
+ unsigned int in_flight_start_seq; /*!< Minimum message sequence in the
+ flight being received */
+ mbedtls_ssl_transform *alt_transform_out; /*!< Alternative transform for
+ resending messages */
+ unsigned char alt_out_ctr[MBEDTLS_SSL_SEQUENCE_NUMBER_LEN]; /*!< Alternative record epoch/counter
+ for resending messages */
+
+#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
+ /* The state of CID configuration in this handshake. */
+
+ uint8_t cid_in_use; /*!< This indicates whether the use of the CID extension
+ * has been negotiated. Possible values are
+ * #MBEDTLS_SSL_CID_ENABLED and
+ * #MBEDTLS_SSL_CID_DISABLED. */
+ unsigned char peer_cid[ MBEDTLS_SSL_CID_OUT_LEN_MAX ]; /*! The peer's CID */
+ uint8_t peer_cid_len; /*!< The length of
+ * \c peer_cid. */
+#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
+
uint16_t mtu; /*!< Handshake mtu, used to fragment outgoing messages */
#endif /* MBEDTLS_SSL_PROTO_DTLS */
@@ -702,11 +731,6 @@
#endif
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
- void (*update_checksum)(mbedtls_ssl_context *, const unsigned char *, size_t);
- void (*calc_verify)(const mbedtls_ssl_context *, unsigned char *, size_t *);
- void (*calc_finished)(mbedtls_ssl_context *, unsigned char *, int);
- mbedtls_ssl_tls_prf_cb *tls_prf;
-
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
uint16_t offered_group_id; /* The NamedGroup value for the group
* that is being used for ephemeral
@@ -749,20 +773,12 @@
/* End of state-local variables. */
- mbedtls_ssl_ciphersuite_t const *ciphersuite_info;
-
- size_t pmslen; /*!< premaster length */
-
unsigned char randbytes[MBEDTLS_CLIENT_HELLO_RANDOM_LEN +
MBEDTLS_SERVER_HELLO_RANDOM_LEN];
/*!< random bytes */
unsigned char premaster[MBEDTLS_PREMASTER_SIZE];
/*!< premaster secret */
- uint8_t max_major_ver; /*!< max. major version client*/
- uint8_t max_minor_ver; /*!< max. minor version client*/
- uint8_t resume; /*!< session resume indicator*/
- uint8_t cli_exts; /*!< client extension presence*/
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
int extensions_present; /*!< extension presence; Each bitfield
represents an extension and defined
@@ -778,18 +794,6 @@
mbedtls_ssl_tls1_3_handshake_secrets tls13_hs_secrets;
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
-#if defined(MBEDTLS_SSL_SESSION_TICKETS)
- uint8_t new_session_ticket; /*!< use NewSessionTicket? */
-#endif /* MBEDTLS_SSL_SESSION_TICKETS */
-
-#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
- uint8_t extended_ms; /*!< use Extended Master Secret? */
-#endif
-
-#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
- uint8_t async_in_progress; /*!< an asynchronous operation is in progress */
-#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
-
#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
/** Asynchronous operation context. This field is meant for use by the
* asynchronous operation callbacks (mbedtls_ssl_config::f_async_sign_start,
@@ -798,6 +802,11 @@
* The library does not use it internally. */
void *user_async_ctx;
#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
+
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+ const uint16_t *group_list;
+ unsigned char group_list_heap_allocated;
+#endif
};
typedef struct mbedtls_ssl_hs_buffer mbedtls_ssl_hs_buffer;