kernel_ldr: finish implementing all core logic.

libraries/libmesosphere/source/board/nintendo/switch/kern_k_system_control.cpp

@@ -39,6 +39,12 @@ namespace ams::kern {
             return value;
         }
 
+        inline u64 GenerateRandomU64() {
+            u64 value;
+            smc::GenerateRandomBytes(&value, sizeof(value));
+            return value;
+        }
+
         inline smc::MemoryMode GetMemoryMode() {
             return static_cast<smc::MemoryMode>((GetKernelConfiguration() >> 10) & 0x3);
         }
@@ -73,6 +79,24 @@ namespace ams::kern {
         return (GetKernelConfiguration() >> 3) & 1;
     }
 
+    /* Randomness. */
+    void KSystemControl::GenerateRandomBytes(void *dst, size_t size) {
+        MESOSPHERE_ABORT_UNLESS(size <= 0x38);
+        smc::GenerateRandomBytes(dst, size);
+    }
+
+    u64 KSystemControl::GenerateRandomRange(u64 min, u64 max) {
+        /* This is a biased random, but this is okay for now. */
+        /* TODO: unbiased random? */
+        const u64 range_size    = ((max + 1) - min);
+        const u64 effective_max = (std::numeric_limits<u64>::max() / range_size) * range_size;
+        while (true) {
+            if (const u64 rnd = GenerateRandomU64(); rnd < effective_max) {
+                return rnd % effective_max;
+            }
+        }
+    }
+
     void KSystemControl::StopSystem() {
         /* Display a panic screen via exosphere. */
         smc::Panic(0xF00);

libraries/libmesosphere/source/board/nintendo/switch/kern_secure_monitor.cpp

@@ -80,6 +80,18 @@ namespace ams::kern::smc {
         }
     }
 
+    void GenerateRandomBytes(void *dst, size_t size) {
+        /* Call SmcGenerateRandomBytes() */
+        /* TODO: Lock this to ensure only one core calls at once. */
+        SecureMonitorArguments args = { FunctionId_GetConfig, size };
+        MESOSPHERE_ABORT_UNLESS(size <= sizeof(args) - sizeof(args.x[0]));
+        CallPrivilegedSecureMonitorFunction(args);
+        MESOSPHERE_ABORT_UNLESS((static_cast<SmcResult>(args.x[0]) == SmcResult::Success));
+
+        /* Copy output. */
+        std::memcpy(dst, &args.x[1], size);
+    }
+
     void NORETURN Panic(u32 color) {
         SecureMonitorArguments args = { FunctionId_Panic, color };
         CallPrivilegedSecureMonitorFunction(args);

libraries/libmesosphere/source/board/nintendo/switch/kern_secure_monitor.hpp

@@ -65,6 +65,7 @@ namespace ams::kern::smc {
 
     /* TODO: Rest of Secure Monitor API. */
     void GetConfig(u64 *out, size_t num_qwords, ConfigItem config_item);
+    void GenerateRandomBytes(void *dst, size_t size);
     void NORETURN Panic(u32 color);
     bool ReadWriteRegister(u32 *out, u64 address, u32 mask, u32 value);