[Kernel] Return largest available direct-memory span (#334)

2026-07-22 19:06:15 +08:00 · 2026-07-18 02:38:39 +03:00
parent ff3ac0bba1
commit cc290f860b
2 changed files with 132 additions and 7 deletions
@@ -9,8 +9,20 @@ using Xunit;

 namespace SharpEmu.Libs.Tests.Kernel;

+[CollectionDefinition(KernelMemoryCompatStateCollection.Name, DisableParallelization = true)]
+public sealed class KernelMemoryCompatStateCollection
+{
+    public const string Name = "KernelMemoryCompatState";
+}
+
+[Collection(KernelMemoryCompatStateCollection.Name)]
 public sealed class KernelMemoryCompatExportsTests
 {
+    private const ulong GuestMemoryBase = 0x1_0000_0000;
+    private const ulong AllocationOutAddress = GuestMemoryBase + 0x100;
+    private const ulong SpanStartOutAddress = GuestMemoryBase + 0x108;
+    private const ulong SpanSizeOutAddress = GuestMemoryBase + 0x110;
+
    [Fact]
    public void PosixStat_MissingFileReturnsMinusOne()
    {
@@ -63,4 +75,93 @@ public sealed class KernelMemoryCompatExportsTests
            CultureInfo.CurrentCulture = previousCulture;
        }
    }
+
+    [Fact]
+    public void AvailableDirectMemorySize_FragmentedRangeReturnsLargestAlignedSpan()
+    {
+        const ulong firstAllocationStart = 0x0020_0000;
+        const ulong firstAllocationLength = 0x0020_0000;
+        const ulong secondAllocationStart = 0x00C0_0000;
+        const ulong secondAllocationLength = 0x0040_0000;
+        var context = new CpuContext(new FakeCpuMemory(GuestMemoryBase, 0x1000), Generation.Gen5);
+
+        try
+        {
+            AllocateDirectMemory(context, firstAllocationStart, firstAllocationLength);
+            AllocateDirectMemory(context, secondAllocationStart, secondAllocationLength);
+
+            QueryAvailableDirectMemory(context, 0, 0x0100_0000, 0x4000);
+
+            Assert.True(context.TryReadUInt64(SpanStartOutAddress, out var spanStart));
+            Assert.True(context.TryReadUInt64(SpanSizeOutAddress, out var spanSize));
+            Assert.Equal(0x0040_0000UL, spanStart);
+            Assert.Equal(0x0080_0000UL, spanSize);
+        }
+        finally
+        {
+            ReleaseDirectMemory(context, firstAllocationStart, firstAllocationLength);
+            ReleaseDirectMemory(context, secondAllocationStart, secondAllocationLength);
+        }
+    }
+
+    [Fact]
+    public void AvailableDirectMemorySize_AppliesAlignmentBeforeComparingSpans()
+    {
+        const ulong allocationStart = 0x0070_0000;
+        const ulong allocationLength = 0x0010_0000;
+        var context = new CpuContext(new FakeCpuMemory(GuestMemoryBase, 0x1000), Generation.Gen5);
+
+        try
+        {
+            AllocateDirectMemory(context, allocationStart, allocationLength);
+
+            QueryAvailableDirectMemory(context, 0x0010_0000, 0x00C0_0000, 0x0040_0000);
+
+            Assert.True(context.TryReadUInt64(SpanStartOutAddress, out var spanStart));
+            Assert.True(context.TryReadUInt64(SpanSizeOutAddress, out var spanSize));
+            Assert.Equal(0x0080_0000UL, spanStart);
+            Assert.Equal(0x0040_0000UL, spanSize);
+        }
+        finally
+        {
+            ReleaseDirectMemory(context, allocationStart, allocationLength);
+        }
+    }
+
+    private static void AllocateDirectMemory(CpuContext context, ulong start, ulong length)
+    {
+        context[CpuRegister.Rdi] = start;
+        context[CpuRegister.Rsi] = start + length;
+        context[CpuRegister.Rdx] = length;
+        context[CpuRegister.Rcx] = 0x4000;
+        context[CpuRegister.R8] = 0;
+        context[CpuRegister.R9] = AllocationOutAddress;
+
+        Assert.Equal(0, KernelMemoryCompatExports.KernelAllocateDirectMemory(context));
+        Assert.True(context.TryReadUInt64(AllocationOutAddress, out var allocatedAddress));
+        Assert.Equal(start, allocatedAddress);
+    }
+
+    private static void QueryAvailableDirectMemory(
+        CpuContext context,
+        ulong searchStart,
+        ulong searchEnd,
+        ulong alignment)
+    {
+        context[CpuRegister.Rdi] = searchStart;
+        context[CpuRegister.Rsi] = searchEnd;
+        context[CpuRegister.Rdx] = alignment;
+        context[CpuRegister.Rcx] = SpanStartOutAddress;
+        context[CpuRegister.R8] = SpanSizeOutAddress;
+
+        Assert.Equal(0, KernelMemoryCompatExports.KernelAvailableDirectMemorySize(context));
+    }
+
+    private static void ReleaseDirectMemory(CpuContext context, ulong start, ulong length)
+    {
+        context[CpuRegister.Rdi] = start;
+        context[CpuRegister.Rsi] = length;
+
+        Assert.Equal(0, KernelMemoryCompatExports.KernelReleaseDirectMemory(context));
+    }
 }