sim: Initialize PSA Crypto subsystem based on psa-crypto-api feature

If the psa-crypto-api feature is defined, the simulator will
initialize the PSA Crypto API exactly once. It needs also to
enable the test external RNG as the assumption is that the
PSA subsystem is configured to use MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG

Signed-off-by: David Brown <david.brown@linaro.org>
Signed-off-by: Antonio de Angelis <Antonio.deAngelis@arm.com>
Signed-off-by: Matthew Dalzell <Matthew.Dalzell@arm.com>
Change-Id: Id02727b8673867ecf1e4fbbdfa3c4b6d6f98f8df

sim/Cargo.toml

@@ -31,6 +31,7 @@ direct-xip = ["mcuboot-sys/direct-xip"]
 downgrade-prevention = ["mcuboot-sys/downgrade-prevention"]
 max-align-32 = ["mcuboot-sys/max-align-32"]
 hw-rollback-protection = ["mcuboot-sys/hw-rollback-protection"]
+psa-crypto-api = ["mcuboot-sys/psa-crypto-api"]
 
 [dependencies]
 byteorder = "1.4"

sim/mcuboot-sys/Cargo.toml

@@ -86,6 +86,9 @@ max-align-32 = []
 # Enable hardware rollback protection
 hw-rollback-protection = []
 
+# Enable the PSA Crypto APIs where supported for cryptography related operations.
+psa-crypto-api = []
+
 [build-dependencies]
 cc = "1.0.25"
 

sim/mcuboot-sys/src/c.rs

@@ -10,6 +10,9 @@ use crate::area::AreaDesc;
 use simflash::SimMultiFlash;
 use crate::api;
 
+#[allow(unused)]
+use std::sync::Once;
+
 /// The result of an invocation of `boot_go`.  This is intentionally opaque so that we can provide
 /// accessors for everything we need from this.
 #[derive(Debug)]
@@ -66,6 +69,8 @@ impl BootGoResult {
 pub fn boot_go(multiflash: &mut SimMultiFlash, areadesc: &AreaDesc,
                counter: Option<&mut i32>, image_index: Option<i32>,
                catch_asserts: bool) -> BootGoResult {
+    init_crypto();
+
     for (&dev_id, flash) in multiflash.iter_mut() {
         api::set_flash(dev_id, flash);
     }
@@ -183,5 +188,38 @@ mod raw {
 
         pub fn kw_encrypt_(kek: *const u8, seckey: *const u8,
                            encbuf: *mut u8) -> libc::c_int;
+
+        #[allow(unused)]
+        pub fn psa_crypto_init() -> u32;
+
+        #[allow(unused)]
+        pub fn mbedtls_test_enable_insecure_external_rng();
     }
 }
+
+#[allow(unused)]
+static PSA_INIT_SYNC: Once = Once::new();
+
+#[allow(unused)]
+static MBEDTLS_EXTERNAL_RNG_ENABLE_SYNC: Once = Once::new();
+
+#[cfg(feature = "psa-crypto-api")]
+fn init_crypto() {
+    PSA_INIT_SYNC.call_once(|| {
+        assert_eq!(unsafe { raw::psa_crypto_init() }, 0);
+    });
+
+    /* The PSA APIs require properly initialisation of the entropy subsystem
+     * The configuration adds the option MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG when the
+     * psa-crypto-api feature is enabled. As a result the tests use the implementation
+     * of the test external rng that needs to be initialised before being able to use it
+     */
+    MBEDTLS_EXTERNAL_RNG_ENABLE_SYNC.call_once(|| {
+        unsafe { raw::mbedtls_test_enable_insecure_external_rng() }
+    });
+}
+
+#[cfg(not(feature = "psa-crypto-api"))]
+fn init_crypto() {
+   // When the feature is not enabled, the init is just empty
+}