Import mbedtls-3.6.0

Imports Mbed TLS 3.6.0 from https://github.com/Mbed-TLS/mbedtls.git
tags mbedtls-3.6.0, v3.6.0

Files that are not needed are removed:

cd lib/libmbedtls
rm -rf mbedtls
cp -R path/to/mbedtls-3.6.0/mbedtls .
cd mbedtls
rm CMakeLists.txt DartConfiguration.tcl Makefile
rm .gitignore .travis.yml .pylintrc .globalrc .mypy.ini BRANCHES.md
rm include/.gitignore include/CMakeLists.txt library/.gitignore
rm library/CMakeLists.txt library/Makefile
rm -r cmake
rm -rf .git .github doxygen configs programs scripts tests visualc
rm -rf 3rdparty ChangeLog.d docs pkgconfig .gitmodules .readthedocs.yaml
rm library/mps_*
cd ..
git add mbedtls

This time we leave library/psa_* present to enable TLS 1.3 features.

This is a complete overwrite of previous code so earlier changes in the
previous branch import/mbedtls-3.4.0 will be added on top of this commit.

Signed-off-by: Tom Van Eyck <tom.vaneyck@kuleuven.be>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/threading.c b/lib/libmbedtls/mbedtls/library/threading.c
index 130c696..85db243 100644
--- a/lib/libmbedtls/mbedtls/library/threading.c
+++ b/lib/libmbedtls/mbedtls/library/threading.c
@@ -2,19 +2,7 @@
  *  Threading abstraction layer
  *
  *  Copyright The Mbed TLS Contributors
- *  SPDX-License-Identifier: Apache-2.0
- *
- *  Licensed under the Apache License, Version 2.0 (the "License"); you may
- *  not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *  http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  */
 
 /*
@@ -68,28 +56,27 @@
         return;
     }
 
-    /* A nonzero value of is_valid indicates a successfully initialized
-     * mutex. This is a workaround for not being able to return an error
-     * code for this function. The lock/unlock functions return an error
-     * if is_valid is nonzero. The Mbed TLS unit test code uses this field
-     * to distinguish more states of the mutex; see
-     * tests/src/threading_helpers for details. */
-    mutex->is_valid = pthread_mutex_init(&mutex->mutex, NULL) == 0;
+    /* One problem here is that calling lock on a pthread mutex without first
+     * having initialised it is undefined behaviour. Obviously we cannot check
+     * this here in a thread safe manner without a significant performance
+     * hit, so state transitions are checked in tests only via the state
+     * variable. Please make sure any new mutex that gets added is exercised in
+     * tests; see tests/src/threading_helpers.c for more details. */
+    (void) pthread_mutex_init(&mutex->mutex, NULL);
 }
 
 static void threading_mutex_free_pthread(mbedtls_threading_mutex_t *mutex)
 {
-    if (mutex == NULL || !mutex->is_valid) {
+    if (mutex == NULL) {
         return;
     }
 
     (void) pthread_mutex_destroy(&mutex->mutex);
-    mutex->is_valid = 0;
 }
 
 static int threading_mutex_lock_pthread(mbedtls_threading_mutex_t *mutex)
 {
-    if (mutex == NULL || !mutex->is_valid) {
+    if (mutex == NULL) {
         return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA;
     }
 
@@ -102,7 +89,7 @@
 
 static int threading_mutex_unlock_pthread(mbedtls_threading_mutex_t *mutex)
 {
-    if (mutex == NULL || !mutex->is_valid) {
+    if (mutex == NULL) {
         return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA;
     }
 
@@ -161,6 +148,11 @@
 #if defined(THREADING_USE_GMTIME)
     mbedtls_mutex_init(&mbedtls_threading_gmtime_mutex);
 #endif
+#if defined(MBEDTLS_PSA_CRYPTO_C)
+    mbedtls_mutex_init(&mbedtls_threading_key_slot_mutex);
+    mbedtls_mutex_init(&mbedtls_threading_psa_globaldata_mutex);
+    mbedtls_mutex_init(&mbedtls_threading_psa_rngdata_mutex);
+#endif
 }
 
 /*
@@ -174,6 +166,11 @@
 #if defined(THREADING_USE_GMTIME)
     mbedtls_mutex_free(&mbedtls_threading_gmtime_mutex);
 #endif
+#if defined(MBEDTLS_PSA_CRYPTO_C)
+    mbedtls_mutex_free(&mbedtls_threading_key_slot_mutex);
+    mbedtls_mutex_free(&mbedtls_threading_psa_globaldata_mutex);
+    mbedtls_mutex_free(&mbedtls_threading_psa_rngdata_mutex);
+#endif
 }
 #endif /* MBEDTLS_THREADING_ALT */
 
@@ -189,5 +186,10 @@
 #if defined(THREADING_USE_GMTIME)
 mbedtls_threading_mutex_t mbedtls_threading_gmtime_mutex MUTEX_INIT;
 #endif
+#if defined(MBEDTLS_PSA_CRYPTO_C)
+mbedtls_threading_mutex_t mbedtls_threading_key_slot_mutex MUTEX_INIT;
+mbedtls_threading_mutex_t mbedtls_threading_psa_globaldata_mutex MUTEX_INIT;
+mbedtls_threading_mutex_t mbedtls_threading_psa_rngdata_mutex MUTEX_INIT;
+#endif
 
 #endif /* MBEDTLS_THREADING_C */