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relocation: Piggyback on Ghidra's native MIPS relocation handler
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Ghidra's built-in MIPS relocation handler has support for all of the
non-proprietary relocations we care about. Instead of rolling our
own version or not supporting them, fall back to `super.relocate()`
if the relocation type isn't custom.
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@abelbriggs1
abelbriggs1 committed Nov 4, 2023
1 parent 030e4fb commit 303d0d2
Showing 1 changed file with 11 additions and 37 deletions.
48 changes: 11 additions & 37 deletions src/main/java/ghidra/emotionengine/relocation/EmotionEngine_ElfRelocationHandler.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,19 +17,14 @@

import ghidra.app.util.bin.format.elf.*;
import ghidra.app.util.bin.format.elf.relocation.ElfRelocationContext;
import ghidra.app.util.bin.format.elf.relocation.MIPS_ElfRelocationConstants;
import ghidra.app.util.bin.format.elf.relocation.MIPS_ElfRelocationHandler;
import ghidra.app.util.importer.MessageLog;
import ghidra.program.model.address.*;
import ghidra.program.model.listing.BookmarkManager;
import ghidra.program.model.listing.BookmarkType;
import ghidra.program.model.listing.Program;
import ghidra.program.model.mem.*;
import ghidra.program.model.reloc.Relocation.Status;
import ghidra.program.model.reloc.RelocationResult;
import ghidra.util.classfinder.ExtensionPointProperties;
import ghidra.util.exception.NotFoundException;

@ExtensionPointProperties(priority = 2)
public class EmotionEngine_ElfRelocationHandler extends MIPS_ElfRelocationHandler {

Expand Down Expand Up @@ -63,7 +58,6 @@ public RelocationResult relocate(ElfRelocationContext elfRelocationContext, ElfR
Program program = elfRelocationContext.getProgram();
Memory memory = program.getMemory();
MessageLog log = elfRelocationContext.getLog();
BookmarkManager bMan = program.getBookmarkManager();
ElfSymbol elfSymbol = elfRelocationContext.getSymbol(relocation.getSymbolIndex());

String symbolName = elfSymbol.getNameAsString();
Expand All @@ -73,22 +67,6 @@ public RelocationResult relocate(ElfRelocationContext elfRelocationContext, ElfR
int newValue = 0;
int oldValue = memory.getInt(relocationAddress);
switch(relocation.getType()) {
case MIPS_ElfRelocationConstants.R_MIPS_16:
value = (oldValue << 16) >> 16;
value += base;
newValue = oldValue & HIGH_MASK;
newValue |= value & LOW_MASK;
break;
case MIPS_ElfRelocationConstants.R_MIPS_32:
newValue = oldValue+base;
break;
case MIPS_ElfRelocationConstants.R_MIPS_26:
value = (oldValue & MIPS_ElfRelocationConstants.MIPS_LOW26) << 2;
value |= (oldValue & 0xf0000000);
value += base;
newValue = oldValue & 0xfc000000;
newValue |= (value << 4) >> 6;
break;
case R_MIPS_MHI16:
if (elfRelocationContext.getElfHeader().e_type() == ET_IRX2) {
markAsError(program, relocationAddress, relocation.getType(),
Expand Down Expand Up @@ -137,7 +115,8 @@ public RelocationResult relocate(ElfRelocationContext elfRelocationContext, ElfR
value += base;
newValue = oldValue & ~DVP_MASK;
newValue |= value & DVP_MASK;
break;
memory.setInt(relocationAddress, newValue);
return new RelocationResult(Status.APPLIED, 4);
case R_MIPS_ADDEND:
// already accounted for
return RelocationResult.SKIPPED;
Expand All @@ -159,7 +138,8 @@ public RelocationResult relocate(ElfRelocationContext elfRelocationContext, ElfR
*/
value = (oldValue + base) & 0x001fffc0;
newValue = (oldValue & ~0x001fffc0) | (value >> 3);
break;
memory.setInt(relocationAddress, newValue);
return new RelocationResult(Status.APPLIED, 4);
case R_MIPS_DVP_11_PCREL:
/*
HOWTO (R_MIPS_DVP_11_PCREL, /* type
Expand All @@ -178,7 +158,8 @@ public RelocationResult relocate(ElfRelocationContext elfRelocationContext, ElfR
*/
value = (oldValue + base) & 0x7ff;
newValue = (oldValue & ~0x7ff) | (value >> 3);
break;
memory.setInt(relocationAddress, newValue);
return new RelocationResult(Status.APPLIED, 4);
case R_MIPS_DVP_11_S4:
/*
HOWTO (R_MIPS_DVP_11_S4, /* type
Expand All @@ -197,7 +178,8 @@ public RelocationResult relocate(ElfRelocationContext elfRelocationContext, ElfR
*/
value = (oldValue + base) & 0x03ff;
newValue = (oldValue & ~0x03ff) | (value >> 4);
break;
memory.setInt(relocationAddress, newValue);
return new RelocationResult(Status.APPLIED, 4);
case R_MIPS_DVP_U15_S3:
/*
HOWTO (R_MIPS_DVP_U15_S3, /* type
Expand All @@ -216,20 +198,12 @@ public RelocationResult relocate(ElfRelocationContext elfRelocationContext, ElfR
*/
value = ((oldValue + base) >> 3) & 0xf03ff;
newValue = (oldValue & ~0xf03ff) | value;
break;
memory.setInt(relocationAddress, newValue);
return new RelocationResult(Status.APPLIED, 4);
default:
String msg = String.format("Unexpected relocation type %d", relocation.getType());
bMan.setBookmark(relocationAddress, BookmarkType.ERROR, BookmarkType.ERROR, msg);
case MIPS_ElfRelocationConstants.R_MIPS_NONE:
case MIPS_ElfRelocationConstants.R_MIPS_HI16:
case MIPS_ElfRelocationConstants.R_MIPS_LO16:
case MIPS_ElfRelocationConstants.R_MIPS_GPREL16:
return RelocationResult.UNSUPPORTED;
return super.relocate(elfRelocationContext, relocation, relocationAddress);
}

memory.setInt(relocationAddress, newValue);

return new RelocationResult(Status.APPLIED, 4);
}

private ElfRelocation getNextRelocation(ElfRelocationContext context,
Expand Down

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