Add mesosphere (VERY VERY WIP)

mesosphere/include/mesosphere/arch/arm64/KSpinLock.hpp

@@ -0,0 +1,103 @@
+#pragma once
+
+#include <mutex>
+
+namespace mesosphere
+{
+inline namespace arch
+{
+inline namespace arm64
+{
+
+// This largely uses the Linux kernel spinlock code, which is more efficient than Nintendo's (serializing two u16s into an u32).
+class KSpinLock final {
+
+    private:
+
+    struct alignas(4) Ticket {
+        u16 owner, next;
+    };
+
+    Ticket ticket;
+
+    public:
+
+    bool try_lock()
+    {
+        u32 tmp;
+        Ticket lockval;
+
+        asm volatile(
+            "   prfm    pstl1strm, %2\n"
+            "1: ldaxr   %w0, %2\n"
+            "   eor     %w1, %w0, %w0, ror #16\n"
+            "   cbnz    %w1, 2f\n"
+            "   add     %w0, %w0, %3\n"
+            "   stxr    %w1, %w0, %2\n"
+            "   cbnz    %w1, 1b\n"
+            "2:"
+            : "=&r" (lockval), "=&r" (tmp), "+Q" (ticket)
+            : "I" (1 << 16)
+            : "memory"
+        );
+
+        return !tmp;
+    }
+
+    void lock()
+    {
+        u32 tmp;
+        Ticket lockval, newval;
+
+        asm volatile(
+            // Atomically increment the next ticket.
+        "   prfm    pstl1strm, %3\n"
+        "1: ldaxr   %w0, %3\n"
+        "   add     %w1, %w0, %w5\n"
+        "   stxr    %w2, %w1, %3\n"
+        "   cbnz    %w2, 1b\n"
+
+
+            // Did we get the lock?
+        "   eor %w1, %w0, %w0, ror #16\n"
+        "   cbz %w1, 3f\n"
+            /*
+                No: spin on the owner. Send a local event to avoid missing an
+                unlock before the exclusive load.
+            */
+        "   sevl\n"
+        "2: wfe\n"
+        "   ldaxrh  %w2, %4\n"
+        "   eor     %w1, %w2, %w0, lsr #16\n"
+        "   cbnz    %w1, 2b\n"
+            // We got the lock. Critical section starts here.
+        "3:"
+            : "=&r" (lockval), "=&r" (newval), "=&r" (tmp), "+Q" (*&ticket)
+            : "Q" (ticket.owner), "I" (1 << 16)
+            : "memory"
+        );
+    }
+
+    void unlock()
+    {
+        u64 tmp;
+        asm volatile(
+            "   ldrh    %w1, %0\n"
+            "   add     %w1, %w1, #1\n"
+            "   stlrh   %w1, %0"
+            : "=Q" (ticket.owner), "=&r" (tmp)
+            :
+            : "memory"
+        );
+
+    }
+    KSpinLock() = default;
+    KSpinLock(const KSpinLock &) = delete;
+    KSpinLock(KSpinLock &&) = delete;
+    KSpinLock &operator=(const KSpinLock &) = delete;
+    KSpinLock &operator=(KSpinLock &&) = delete;
+};
+
+}
+}
+}