1 files changed, 389 insertions, 0 deletions
diff --git a/src/Ryujinx.Cpu/ManagedPageFlags.cs b/src/Ryujinx.Cpu/ManagedPageFlags.cs
new file mode 100644
index 00000000..a839dae6
--- /dev/null
+++ b/src/Ryujinx.Cpu/ManagedPageFlags.cs
@@ -0,0 +1,389 @@
+using Ryujinx.Memory;
+using Ryujinx.Memory.Tracking;
+using System;
+using System.Runtime.CompilerServices;
+using System.Threading;
+
+namespace Ryujinx.Cpu
+{
+    /// <summary>
+    /// A page bitmap that keeps track of mapped state and tracking protection
+    /// for managed memory accesses (not using host page protection).
+    /// </summary>
+    internal readonly struct ManagedPageFlags
+    {
+        public const int PageBits = 12;
+        public const int PageSize = 1 << PageBits;
+        public const int PageMask = PageSize - 1;
+
+        private readonly ulong[] _pageBitmap;
+
+        public const int PageToPteShift = 5; // 32 pages (2 bits each) in one ulong page table entry.
+        public const ulong BlockMappedMask = 0x5555555555555555; // First bit of each table entry set.
+
+        private enum ManagedPtBits : ulong
+        {
+            Unmapped = 0,
+            Mapped,
+            WriteTracked,
+            ReadWriteTracked,
+
+            MappedReplicated = 0x5555555555555555,
+            WriteTrackedReplicated = 0xaaaaaaaaaaaaaaaa,
+            ReadWriteTrackedReplicated = ulong.MaxValue,
+        }
+
+        public ManagedPageFlags(int addressSpaceBits)
+        {
+            int bits = Math.Max(0, addressSpaceBits - (PageBits + PageToPteShift));
+            _pageBitmap = new ulong[1 << bits];
+        }
+
+        /// <summary>
+        /// Computes the number of pages in a virtual address range.
+        /// </summary>
+        /// <param name="va">Virtual address of the range</param>
+        /// <param name="size">Size of the range</param>
+        /// <param name="startVa">The virtual address of the beginning of the first page</param>
+        /// <remarks>This function does not differentiate between allocated and unallocated pages.</remarks>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static int GetPagesCount(ulong va, ulong size, out ulong startVa)
+        {
+            // WARNING: Always check if ulong does not overflow during the operations.
+            startVa = va & ~(ulong)PageMask;
+            ulong vaSpan = (va - startVa + size + PageMask) & ~(ulong)PageMask;
+
+            return (int)(vaSpan / PageSize);
+        }
+
+        /// <summary>
+        /// Checks if the page at a given CPU virtual address is mapped.
+        /// </summary>
+        /// <param name="va">Virtual address to check</param>
+        /// <returns>True if the address is mapped, false otherwise</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public readonly bool IsMapped(ulong va)
+        {
+            ulong page = va >> PageBits;
+
+            int bit = (int)((page & 31) << 1);
+
+            int pageIndex = (int)(page >> PageToPteShift);
+            ref ulong pageRef = ref _pageBitmap[pageIndex];
+
+            ulong pte = Volatile.Read(ref pageRef);
+
+            return ((pte >> bit) & 3) != 0;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void GetPageBlockRange(ulong pageStart, ulong pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex)
+        {
+            startMask = ulong.MaxValue << ((int)(pageStart & 31) << 1);
+            endMask = ulong.MaxValue >> (64 - ((int)(pageEnd & 31) << 1));
+
+            pageIndex = (int)(pageStart >> PageToPteShift);
+            pageEndIndex = (int)((pageEnd - 1) >> PageToPteShift);
+        }
+
+        /// <summary>
+        /// Checks if a memory range is mapped.
+        /// </summary>
+        /// <param name="va">Virtual address of the range</param>
+        /// <param name="size">Size of the range in bytes</param>
+        /// <returns>True if the entire range is mapped, false otherwise</returns>
+        public readonly bool IsRangeMapped(ulong va, ulong size)
+        {
+            int pages = GetPagesCount(va, size, out _);
+
+            if (pages == 1)
+            {
+                return IsMapped(va);
+            }
+
+            ulong pageStart = va >> PageBits;
+            ulong pageEnd = pageStart + (ulong)pages;
+
+            GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+            // Check if either bit in each 2 bit page entry is set.
+            // OR the block with itself shifted down by 1, and check the first bit of each entry.
+
+            ulong mask = BlockMappedMask & startMask;
+
+            while (pageIndex <= pageEndIndex)
+            {
+                if (pageIndex == pageEndIndex)
+                {
+                    mask &= endMask;
+                }
+
+                ref ulong pageRef = ref _pageBitmap[pageIndex++];
+                ulong pte = Volatile.Read(ref pageRef);
+
+                pte |= pte >> 1;
+                if ((pte & mask) != mask)
+                {
+                    return false;
+                }
+
+                mask = BlockMappedMask;
+            }
+
+            return true;
+        }
+
+        /// <summary>
+        /// Reprotect a region of virtual memory for tracking.
+        /// </summary>
+        /// <param name="va">Virtual address base</param>
+        /// <param name="size">Size of the region to protect</param>
+        /// <param name="protection">Memory protection to set</param>
+        public readonly void TrackingReprotect(ulong va, ulong size, MemoryPermission protection)
+        {
+            // Protection is inverted on software pages, since the default value is 0.
+            protection = (~protection) & MemoryPermission.ReadAndWrite;
+
+            int pages = GetPagesCount(va, size, out va);
+            ulong pageStart = va >> PageBits;
+
+            if (pages == 1)
+            {
+                ulong protTag = protection switch
+                {
+                    MemoryPermission.None => (ulong)ManagedPtBits.Mapped,
+                    MemoryPermission.Write => (ulong)ManagedPtBits.WriteTracked,
+                    _ => (ulong)ManagedPtBits.ReadWriteTracked,
+                };
+
+                int bit = (int)((pageStart & 31) << 1);
+
+                ulong tagMask = 3UL << bit;
+                ulong invTagMask = ~tagMask;
+
+                ulong tag = protTag << bit;
+
+                int pageIndex = (int)(pageStart >> PageToPteShift);
+                ref ulong pageRef = ref _pageBitmap[pageIndex];
+
+                ulong pte;
+
+                do
+                {
+                    pte = Volatile.Read(ref pageRef);
+                }
+                while ((pte & tagMask) != 0 && Interlocked.CompareExchange(ref pageRef, (pte & invTagMask) | tag, pte) != pte);
+            }
+            else
+            {
+                ulong pageEnd = pageStart + (ulong)pages;
+
+                GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+                ulong mask = startMask;
+
+                ulong protTag = protection switch
+                {
+                    MemoryPermission.None => (ulong)ManagedPtBits.MappedReplicated,
+                    MemoryPermission.Write => (ulong)ManagedPtBits.WriteTrackedReplicated,
+                    _ => (ulong)ManagedPtBits.ReadWriteTrackedReplicated,
+                };
+
+                while (pageIndex <= pageEndIndex)
+                {
+                    if (pageIndex == pageEndIndex)
+                    {
+                        mask &= endMask;
+                    }
+
+                    ref ulong pageRef = ref _pageBitmap[pageIndex++];
+
+                    ulong pte;
+                    ulong mappedMask;
+
+                    // Change the protection of all 2 bit entries that are mapped.
+                    do
+                    {
+                        pte = Volatile.Read(ref pageRef);
+
+                        mappedMask = pte | (pte >> 1);
+                        mappedMask |= (mappedMask & BlockMappedMask) << 1;
+                        mappedMask &= mask; // Only update mapped pages within the given range.
+                    }
+                    while (Interlocked.CompareExchange(ref pageRef, (pte & (~mappedMask)) | (protTag & mappedMask), pte) != pte);
+
+                    mask = ulong.MaxValue;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Alerts the memory tracking that a given region has been read from or written to.
+        /// This should be called before read/write is performed.
+        /// </summary>
+        /// <param name="tracking">Memory tracking structure to call when pages are protected</param>
+        /// <param name="va">Virtual address of the region</param>
+        /// <param name="size">Size of the region</param>
+        /// <param name="write">True if the region was written, false if read</param>
+        /// <param name="exemptId">Optional ID of the handles that should not be signalled</param>
+        /// <remarks>
+        /// This function also validates that the given range is both valid and mapped, and will throw if it is not.
+        /// </remarks>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public readonly void SignalMemoryTracking(MemoryTracking tracking, ulong va, ulong size, bool write, int? exemptId = null)
+        {
+            // Software table, used for managed memory tracking.
+
+            int pages = GetPagesCount(va, size, out _);
+            ulong pageStart = va >> PageBits;
+
+            if (pages == 1)
+            {
+                ulong tag = (ulong)(write ? ManagedPtBits.WriteTracked : ManagedPtBits.ReadWriteTracked);
+
+                int bit = (int)((pageStart & 31) << 1);
+
+                int pageIndex = (int)(pageStart >> PageToPteShift);
+                ref ulong pageRef = ref _pageBitmap[pageIndex];
+
+                ulong pte = Volatile.Read(ref pageRef);
+                ulong state = ((pte >> bit) & 3);
+
+                if (state >= tag)
+                {
+                    tracking.VirtualMemoryEvent(va, size, write, precise: false, exemptId);
+                    return;
+                }
+                else if (state == 0)
+                {
+                    ThrowInvalidMemoryRegionException($"Not mapped: va=0x{va:X16}, size=0x{size:X16}");
+                }
+            }
+            else
+            {
+                ulong pageEnd = pageStart + (ulong)pages;
+
+                GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+                ulong mask = startMask;
+
+                ulong anyTrackingTag = (ulong)ManagedPtBits.WriteTrackedReplicated;
+
+                while (pageIndex <= pageEndIndex)
+                {
+                    if (pageIndex == pageEndIndex)
+                    {
+                        mask &= endMask;
+                    }
+
+                    ref ulong pageRef = ref _pageBitmap[pageIndex++];
+
+                    ulong pte = Volatile.Read(ref pageRef);
+                    ulong mappedMask = mask & BlockMappedMask;
+
+                    ulong mappedPte = pte | (pte >> 1);
+                    if ((mappedPte & mappedMask) != mappedMask)
+                    {
+                        ThrowInvalidMemoryRegionException($"Not mapped: va=0x{va:X16}, size=0x{size:X16}");
+                    }
+
+                    pte &= mask;
+                    if ((pte & anyTrackingTag) != 0) // Search for any tracking.
+                    {
+                        // Writes trigger any tracking.
+                        // Only trigger tracking from reads if both bits are set on any page.
+                        if (write || (pte & (pte >> 1) & BlockMappedMask) != 0)
+                        {
+                            tracking.VirtualMemoryEvent(va, size, write, precise: false, exemptId);
+                            break;
+                        }
+                    }
+
+                    mask = ulong.MaxValue;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Adds the given address mapping to the page table.
+        /// </summary>
+        /// <param name="va">Virtual memory address</param>
+        /// <param name="size">Size to be mapped</param>
+        public readonly void AddMapping(ulong va, ulong size)
+        {
+            int pages = GetPagesCount(va, size, out _);
+            ulong pageStart = va >> PageBits;
+            ulong pageEnd = pageStart + (ulong)pages;
+
+            GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+            ulong mask = startMask;
+
+            while (pageIndex <= pageEndIndex)
+            {
+                if (pageIndex == pageEndIndex)
+                {
+                    mask &= endMask;
+                }
+
+                ref ulong pageRef = ref _pageBitmap[pageIndex++];
+
+                ulong pte;
+                ulong mappedMask;
+
+                // Map all 2-bit entries that are unmapped.
+                do
+                {
+                    pte = Volatile.Read(ref pageRef);
+
+                    mappedMask = pte | (pte >> 1);
+                    mappedMask |= (mappedMask & BlockMappedMask) << 1;
+                    mappedMask |= ~mask; // Treat everything outside the range as mapped, thus unchanged.
+                }
+                while (Interlocked.CompareExchange(ref pageRef, (pte & mappedMask) | (BlockMappedMask & (~mappedMask)), pte) != pte);
+
+                mask = ulong.MaxValue;
+            }
+        }
+
+        /// <summary>
+        /// Removes the given address mapping from the page table.
+        /// </summary>
+        /// <param name="va">Virtual memory address</param>
+        /// <param name="size">Size to be unmapped</param>
+        public readonly void RemoveMapping(ulong va, ulong size)
+        {
+            int pages = GetPagesCount(va, size, out _);
+            ulong pageStart = va >> PageBits;
+            ulong pageEnd = pageStart + (ulong)pages;
+
+            GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+            startMask = ~startMask;
+            endMask = ~endMask;
+
+            ulong mask = startMask;
+
+            while (pageIndex <= pageEndIndex)
+            {
+                if (pageIndex == pageEndIndex)
+                {
+                    mask |= endMask;
+                }
+
+                ref ulong pageRef = ref _pageBitmap[pageIndex++];
+                ulong pte;
+
+                do
+                {
+                    pte = Volatile.Read(ref pageRef);
+                }
+                while (Interlocked.CompareExchange(ref pageRef, pte & mask, pte) != pte);
+
+                mask = 0;
+            }
+        }
+
+        private static void ThrowInvalidMemoryRegionException(string message) => throw new InvalidMemoryRegionException(message);
+    }
+}