exo2: implement GenerateRandomBytes

exosphere2/program/source/smc/secmon_random_cache.cpp

@@ -21,8 +21,6 @@ namespace ams::secmon::smc {
 
     namespace {
 
-        constexpr inline size_t MaxRandomBytes  = sizeof(SmcArguments) - sizeof(SmcArguments{}.r[0]);
-
         constinit int g_random_offset_low  = 0;
         constinit int g_random_offset_high = 0;
 

exosphere2/program/source/smc/secmon_random_cache.hpp

@@ -19,6 +19,8 @@
 
 namespace ams::secmon::smc {
 
+    constexpr inline size_t MaxRandomBytes  = sizeof(SmcArguments) - sizeof(SmcArguments{}.r[0]);
+
     void FillRandomCache();
     void RefillRandomCache();
     void GetRandomFromCache(void *dst, size_t size);

exosphere2/program/source/smc/secmon_smc_common.hpp

@@ -22,7 +22,7 @@ namespace ams::secmon::smc {
         Success               = 0,
         NotImplemented        = 1,
         InvalidArgument       = 2,
-        InProgress            = 3,
+        Busy                  = 3,
         NoAsyncOperation      = 4,
         InvalidAsyncOperation = 5,
         NotPermitted          = 6,

exosphere2/program/source/smc/secmon_smc_random.cpp

@@ -16,17 +16,69 @@
 #include <exosphere.hpp>
 #include "../secmon_error.hpp"
 #include "secmon_smc_random.hpp"
+#include "secmon_random_cache.hpp"
+#include "secmon_smc_se_lock.hpp"
 
 namespace ams::secmon::smc {
 
+    namespace {
+
+        SmcResult GenerateRandomBytesImpl(SmcArguments &args) {
+            /* Validate the input size. */
+            const size_t size = args.r[1];
+
+            if (size > MaxRandomBytes) {
+                return SmcResult::InvalidArgument;
+            }
+
+            /* Create a buffer that the se can generate bytes into. */
+            util::AlignedBuffer<hw::DataCacheLineSize, MaxRandomBytes> buffer;
+            hw::FlushDataCache(buffer, size);
+            hw::DataSynchronizationBarrierInnerShareable();
+
+            /* Generate random bytes into the buffer. */
+            se::GenerateRandomBytes(buffer, size);
+
+            /* Ensure that the cpu sees consistent data. */
+            hw::DataSynchronizationBarrierInnerShareable();
+            hw::FlushDataCache(buffer, size);
+            hw::DataSynchronizationBarrierInnerShareable();
+
+            /* Copy the bytes to output. */
+            std::memcpy(std::addressof(args.r[1]), buffer, size);
+            return SmcResult::Success;
+        }
+
+    }
+
     SmcResult SmcGenerateRandomBytes(SmcArguments &args) {
-        /* TODO */
-        return SmcResult::NotImplemented;
+        return LockSecurityEngineAndInvoke(args, GenerateRandomBytesImpl);
     }
 
     SmcResult SmcGenerateRandomBytesNonBlocking(SmcArguments &args) {
-        /* TODO */
-        return SmcResult::NotImplemented;
+        /* Try to lock the security engine, so that we can call the standard impl. */
+        if (TryLockSecurityEngine()) {
+            /* Ensure we unlock the security engine when done. */
+            ON_SCOPE_EXIT { UnlockSecurityEngine(); };
+
+            /* Take advantage of our lock to refill lthe random cache. */
+            ON_SCOPE_EXIT { RefillRandomCache(); };
+
+            /* If we lock it successfully, we can just call the blocking impl. */
+            return GenerateRandomBytesImpl(args);
+        } else {
+            /* Otherwise, we'll retrieve some bytes from the cache. */
+            const size_t size = args.r[1];
+
+            /* Validate the input size. */
+            if (size > MaxRandomBytes) {
+                return SmcResult::InvalidArgument;
+            }
+
+            /* Get random bytes from the cache. */
+            GetRandomFromCache(std::addressof(args.r[1]), size);
+            return SmcResult::Success;
+        }
     }
 
 }

exosphere2/program/source/smc/secmon_smc_se_lock.cpp

@@ -38,4 +38,41 @@ namespace ams::secmon::smc {
         return g_is_locked;
     }
 
+    SmcResult LockSecurityEngineAndInvoke(SmcArguments &args, SmcHandler impl) {
+        /* Try to lock the SE. */
+        if (!TryLockSecurityEngine()) {
+            return SmcResult::Busy;
+        }
+        ON_SCOPE_EXIT { UnlockSecurityEngine(); };
+
+        return impl(args);
+    }
+
+    SmcResult LockSecurityEngineAndInvokeAsync(SmcArguments &args, SmcHandler impl, GetResultHandler result_handler) {
+        SmcResult result = SmcResult::Busy;
+
+        /* Try to lock the security engine. */
+        if (TryLockSecurityEngine()) {
+            /* Try to start an async operation. */
+            if (const u64 async_key = BeginAsyncOperation(result_handler); async_key != InvalidAsyncKey) {
+                /* Invoke the operation. */
+                result = impl(args);
+
+                /* If the operation was successful, return the key. */
+                if (result == SmcResult::Success) {
+                    args.r[1] = async_key;
+                    return SmcResult::Success;
+                }
+
+                /* Otherwise, cancel the async operation. */
+                CancelAsyncOperation(async_key);
+            }
+
+            /* We failed to invoke the async op, so unlock the security engine. */
+            UnlockSecurityEngine();
+        }
+
+        return result;
+    }
+
 }

exosphere2/program/source/smc/secmon_smc_se_lock.hpp

@@ -16,6 +16,8 @@
 #pragma once
 #include <exosphere.hpp>
 #include "secmon_smc_common.hpp"
+#include "secmon_smc_handler.hpp"
+#include "secmon_smc_result.hpp"
 
 namespace ams::secmon::smc {
 
@@ -23,4 +25,7 @@ namespace ams::secmon::smc {
     void UnlockSecurityEngine();
     bool IsSecurityEngineLocked();
 
+    SmcResult LockSecurityEngineAndInvoke(SmcArguments &args, SmcHandler impl);
+    SmcResult LockSecurityEngineAndInvokeAsync(SmcArguments &args, SmcHandler impl, GetResultHandler result_handler);
+
 }