bypass -data-read-memory-bytes when using lldb

Author: swermin

src/MIDebugEngine/Engine.Impl/Disassembly.cs

@@ -1,15 +1,14 @@
-// Copyright (c) Microsoft. All rights reserved.
+// Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using MICore;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
+using System.Globalization;
 using System.Linq;
-using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
-using System.Diagnostics;
-using MICore;
-using System.Globalization;
 
 namespace Microsoft.MIDebugEngine
 {
@@ -181,9 +180,22 @@ public async Task<ulong> SeekBack(ulong address, int nInstructions)
             }
             ulong endAddress;
             ulong startAddress;
-            var range = await _process.FindValidMemoryRange(address, (uint)(_process.MaxInstructionSize * (nInstructions+1)), (int)(_process.MaxInstructionSize * -nInstructions));
-            startAddress = range.Item1;
-            endAddress = range.Item2;
+
+            // LLDB does not work well with '-data-read-memory-bytes' as it cannot resolve the data.
+            // Querying the data returns following error: "LLDB unable to read entire memory block of n bytes at address 0x0...."
+            // Since lldb doesn't need to query the memory we can use the address and its offset as start and end addresses.
+            if (_process.LaunchOptions.DebuggerMIMode == MIMode.Lldb)
+            {
+                startAddress = (ulong)((long)address + (_process.MaxInstructionSize * -nInstructions));
+                endAddress = startAddress + (ulong)(_process.MaxInstructionSize * (nInstructions + 1));
+            }
+            else
+            {
+                var range = await _process.FindValidMemoryRange(address, (uint)(_process.MaxInstructionSize * (nInstructions + 1)), (int)(_process.MaxInstructionSize * -nInstructions));
+                startAddress = range.Item1;
+                endAddress = range.Item2;
+            }
+
             if (endAddress - startAddress == 0 || address < startAddress) // bad address range, no instructions
             {
                 return defaultAddr;
@@ -244,9 +256,22 @@ public async Task<ICollection<DisasmInstruction>> FetchInstructions(ulong addres
 
             ulong endAddress;
             ulong startAddress;
-            var range = await _process.FindValidMemoryRange(address, (uint)(_process.MaxInstructionSize * nInstructions), 0);
-            startAddress = range.Item1;
-            endAddress = range.Item2;
+
+            // LLDB does not work well with '-data-read-memory-bytes' as it cannot resolve the data.
+            // Querying the data returns following error: "LLDB unable to read entire memory block of n bytes at address 0x0...."
+            // Since lldb doesn't need to query the memory we can use the address and its offset as start and end addresses.
+            if (_process.LaunchOptions.DebuggerMIMode == MIMode.Lldb)
+            {
+                startAddress = address;
+                endAddress = address + (ulong)(_process.MaxInstructionSize * nInstructions);
+            }
+            else
+            {
+                var range = await _process.FindValidMemoryRange(address, (uint)(_process.MaxInstructionSize * nInstructions), 0);
+                startAddress = range.Item1;
+                endAddress = range.Item2;
+            }
+
             int gap = (int)(startAddress - address);   // num of bytes before instructions begin
             if (endAddress > startAddress && nInstructions > gap)
             {