GP-2223: Better strategy for computing module base with GDB.

Ghidra/Debug/Debugger-agent-gdb/src/main/java/agent/gdb/manager/GdbInferior.java

@@ -16,8 +16,7 @@
 package agent.gdb.manager;
 
 import java.math.BigInteger;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 import java.util.concurrent.CompletableFuture;
 
 import agent.gdb.manager.GdbManager.StepCmd;
@@ -133,14 +132,14 @@ public interface GdbInferior extends GdbConsoleOperations, GdbMemoryOperations {
 	 * 
 	 * @return a map of start addresses to mapped memory regions
 	 */
-	Map<BigInteger, GdbMemoryMapping> getKnownMappings();
+	NavigableMap<BigInteger, GdbMemoryMapping> getKnownMappings();
 
 	/**
 	 * List the memory mappings of this inferior's process
 	 * 
 	 * @return a future that completes with a map of start addresses to mapped memory regions
 	 */
-	CompletableFuture<Map<BigInteger, GdbMemoryMapping>> listMappings();
+	CompletableFuture<NavigableMap<BigInteger, GdbMemoryMapping>> listMappings();
 
 	/**
 	 * Change CLI focus to this inferior

Ghidra/Debug/Debugger-agent-gdb/src/main/java/agent/gdb/manager/impl/GdbInferiorImpl.java

@@ -252,9 +252,12 @@ public class GdbInferiorImpl implements GdbInferior {
 	}
 
 	protected CompletableFuture<Map<String, GdbModule>> doListModules() {
-		return manager.execMaintInfoSectionsAllObjects(this).thenApply(lines -> {
-			parseAndUpdateAllModuleSections(lines);
-			return unmodifiableModules;
+		return manager.execMaintInfoSectionsAllObjects(this).thenCompose(lines -> {
+			return listMappings().thenApply(mappings -> {
+				GdbMemoryMapping.Index index = new GdbMemoryMapping.Index(mappings);
+				parseAndUpdateAllModuleSections(lines, index);
+				return unmodifiableModules;
+			});
 		});
 	}
 
@@ -297,7 +300,7 @@ public class GdbInferiorImpl implements GdbInferior {
 		return name;
 	}
 
-	protected void parseAndUpdateAllModuleSections(String[] lines) {
+	protected void parseAndUpdateAllModuleSections(String[] lines, GdbMemoryMapping.Index index) {
 		Set<String> modNamesSeen = new HashSet<>();
 		Set<String> secNamesSeen = new HashSet<>();
 		GdbModuleImpl curModule = null;
@@ -312,7 +315,7 @@ public class GdbInferiorImpl implements GdbInferior {
 				curModule = modules.computeIfAbsent(name, this::resyncCreateModule);
 			}
 			else if (curModule != null) {
-				curModule.processSectionLine(line, secNamesSeen);
+				curModule.processSectionLine(line, secNamesSeen, index);
 			}
 		}
 		if (curModule != null) {
@@ -323,12 +326,12 @@ public class GdbInferiorImpl implements GdbInferior {
 	}
 
 	@Override
-	public Map<BigInteger, GdbMemoryMapping> getKnownMappings() {
+	public NavigableMap<BigInteger, GdbMemoryMapping> getKnownMappings() {
 		return unmodifiableMappings;
 	}
 
 	@Override
-	public CompletableFuture<Map<BigInteger, GdbMemoryMapping>> listMappings() {
+	public CompletableFuture<NavigableMap<BigInteger, GdbMemoryMapping>> listMappings() {
 		return consoleCapture("info proc mappings", CompletesWithRunning.CANNOT)
 				.thenApply(this::parseMappings);
 	}
@@ -361,7 +364,7 @@ public class GdbInferiorImpl implements GdbInferior {
 		return new GdbMemoryMapping(start, end, size, offset, "rwx", objfile);
 	}
 
-	protected Map<BigInteger, GdbMemoryMapping> parseMappings(String out) {
+	protected NavigableMap<BigInteger, GdbMemoryMapping> parseMappings(String out) {
 		Set<BigInteger> startsSeen = new TreeSet<>();
 		for (String line : out.split("\n")) {
 			try {

Ghidra/Debug/Debugger-agent-gdb/src/main/java/agent/gdb/manager/impl/GdbMemoryMapping.java

@@ -16,12 +16,51 @@
 package agent.gdb.manager.impl;
 
 import java.math.BigInteger;
-import java.util.Objects;
+import java.util.*;
+import java.util.Map.Entry;
 
 /**
  * The abstraction for a line of output from {@code info proc mappings}
  */
 public class GdbMemoryMapping {
+
+	static class Index {
+		final NavigableMap<BigInteger, GdbMemoryMapping> mappings;
+		final Map<String, BigInteger> bases;
+
+		public Index(NavigableMap<BigInteger, GdbMemoryMapping> mappings) {
+			this.mappings = mappings;
+			this.bases = new HashMap<>();
+			for (GdbMemoryMapping mapping : mappings.values()) {
+				if (mapping.objfile == null || mapping.objfile.isBlank()) {
+					continue;
+				}
+				// Values should be ordered ascending by address
+				if (bases.containsKey(mapping.objfile)) {
+					continue;
+				}
+				bases.put(mapping.objfile, mapping.start);
+			}
+		}
+
+		public BigInteger computeBase(BigInteger vma) {
+			Entry<BigInteger, GdbMemoryMapping> floor = mappings.floorEntry(vma);
+			if (floor == null) {
+				return vma;
+			}
+			GdbMemoryMapping mapping = floor.getValue();
+			// NB. Ends given by GDB are exclusive
+			if (mapping.objfile.isBlank() || mapping.end.compareTo(vma) <= 0) {
+				return vma;
+			}
+			return Objects.requireNonNull(bases.get(mapping.objfile));
+		}
+
+		public long computeBase(long vma) {
+			return computeBase(BigInteger.valueOf(vma)).longValueExact();
+		}
+	}
+
 	private final BigInteger start;
 	private final BigInteger end;
 	private final BigInteger size;

Ghidra/Debug/Debugger-agent-gdb/src/main/java/agent/gdb/manager/impl/GdbModuleImpl.java

@@ -150,7 +150,8 @@ public class GdbModuleImpl implements GdbModule {
 		return minimalSymbols.request();
 	}
 
-	protected void processSectionLine(String line, Set<String> namesSeen) {
+	protected void processSectionLine(String line, Set<String> namesSeen,
+			GdbMemoryMapping.Index index) {
 		Matcher matcher = inferior.manager.matchSectionLine(line);
 		if (matcher != null) {
 			try {
@@ -167,7 +168,7 @@ public class GdbModuleImpl implements GdbModule {
 					}
 				}
 				if (attrs.contains("ALLOC")) {
-					long b = vmaStart - offset;
+					long b = index.computeBase(vmaStart);
 					base = base == null ? b : MathUtilities.unsignedMin(base, b);
 					max = max == null ? b : MathUtilities.unsignedMax(max, vmaEnd);
 				}

Ghidra/Debug/Debugger-agent-gdb/src/main/java/agent/gdb/model/impl/GdbModelTargetProcessMemory.java

@@ -131,7 +131,8 @@ public class GdbModelTargetProcessMemory
 		}
 		return inferior.listMappings().exceptionally(ex -> {
 			Msg.error(this, "Could not list regions. Using default.");
-			return Map.of(); // empty map will be replaced with default
+			// empty map will be replaced with default
+			return new TreeMap<>();
 		}).thenAccept(this::updateUsingMappings);
 	}