[llvm-commits] [llvm] r128161 - /llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
Jim Grosbach
grosbach at apple.com
Wed Mar 23 12:52:00 PDT 2011
Author: grosbach
Date: Wed Mar 23 14:52:00 2011
New Revision: 128161
URL: http://llvm.org/viewvc/llvm-project?rev=128161&view=rev
Log:
Start of relocation resolution for the runtime dyld library.
Modified:
llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp?rev=128161&r1=128160&r2=128161&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp Wed Mar 23 14:52:00 2011
@@ -11,15 +11,21 @@
//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "dyld"
#include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/ExecutionEngine/RuntimeDyld.h"
#include "llvm/Object/MachOObject.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Format.h"
#include "llvm/Support/Memory.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/system_error.h"
+#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace llvm::object;
@@ -43,6 +49,10 @@
return true;
}
+ bool resolveRelocation(uint32_t BaseSection, macho::RelocationEntry RE,
+ SmallVectorImpl<void *> &SectionBases,
+ SmallVectorImpl<StringRef> &SymbolNames);
+
bool loadSegment32(const MachOObject *Obj,
const MachOObject::LoadCommandInfo *SegmentLCI,
const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC);
@@ -73,7 +83,85 @@
StringRef getErrorString() { return ErrorStr; }
};
+// FIXME: Relocations for targets other than x86_64.
+bool RuntimeDyldImpl::
+resolveRelocation(uint32_t BaseSection, macho::RelocationEntry RE,
+ SmallVectorImpl<void *> &SectionBases,
+ SmallVectorImpl<StringRef> &SymbolNames) {
+ // struct relocation_info {
+ // int32_t r_address;
+ // uint32_t r_symbolnum:24,
+ // r_pcrel:1,
+ // r_length:2,
+ // r_extern:1,
+ // r_type:4;
+ // };
+ uint32_t SymbolNum = RE.Word1 & 0xffffff; // 24-bit value
+ bool isPCRel = (RE.Word1 >> 24) & 1;
+ unsigned Log2Size = (RE.Word1 >> 25) & 3;
+ bool isExtern = (RE.Word1 >> 27) & 1;
+ unsigned Type = (RE.Word1 >> 28) & 0xf;
+ if (RE.Word0 & macho::RF_Scattered)
+ return Error("NOT YET IMPLEMENTED: scattered relocations.");
+
+ // The address requiring a relocation.
+ intptr_t Address = (intptr_t)SectionBases[BaseSection] + RE.Word0;
+
+ // Figure out the target address of the relocation. If isExtern is true,
+ // this relocation references the symbol table, otherwise it references
+ // a section in the same object, numbered from 1 through NumSections
+ // (SectionBases is [0, NumSections-1]).
+ intptr_t Value;
+ if (isExtern) {
+ StringRef Name = SymbolNames[SymbolNum];
+ if (SymbolTable.lookup(Name)) {
+ // The symbol is in our symbol table, so we can resolve it directly.
+ Value = (intptr_t)SymbolTable[Name];
+ } else {
+ return Error("NOT YET IMPLEMENTED: relocations to pre-compiled code.");
+ }
+ DEBUG(dbgs() << "Resolve relocation(" << Type << ") from '" << Name
+ << "' to " << format("0x%x", Address) << ".\n");
+ } else {
+ // For non-external relocations, the SymbolNum is actual a section number
+ // as described above.
+ Value = (intptr_t)SectionBases[SymbolNum - 1];
+ }
+ // If the relocation is PC-relative, the value to be encoded is the
+ // pointer difference.
+ if (isPCRel)
+ // FIXME: It seems this value needs to be adjusted by 4 for an effective PC
+ // address. Is that expected? Only for branches, perhaps?
+ Value -= Address + 4;
+
+ switch(Type) {
+ default:
+ llvm_unreachable("Invalid relocation type!");
+ case macho::RIT_X86_64_Unsigned:
+ case macho::RIT_X86_64_Branch: {
+ // Mask in the target value a byte at a time (we don't have an alignment
+ // guarantee for the target address, so this is safest).
+ unsigned Len = 1 << Log2Size;
+ uint8_t *p = (uint8_t*)Address;
+ for (unsigned i = 0; i < Len; ++i) {
+ *p++ = (uint8_t)Value;
+ Value >>= 8;
+ }
+ return false;
+ }
+ case macho::RIT_X86_64_Signed:
+ case macho::RIT_X86_64_GOTLoad:
+ case macho::RIT_X86_64_GOT:
+ case macho::RIT_X86_64_Subtractor:
+ case macho::RIT_X86_64_Signed1:
+ case macho::RIT_X86_64_Signed2:
+ case macho::RIT_X86_64_Signed4:
+ case macho::RIT_X86_64_TLV:
+ return Error("Relocation type not implemented yet!");
+ }
+ return false;
+}
bool RuntimeDyldImpl::
loadSegment32(const MachOObject *Obj,
@@ -96,7 +184,7 @@
Segment32LC->VMSize - Segment32LC->FileSize);
// Bind the section indices to address.
- void **SectionBases = new void*[Segment32LC->NumSections];
+ SmallVector<void *, 16> SectionBases;
for (unsigned i = 0; i != Segment32LC->NumSections; ++i) {
InMemoryStruct<macho::Section> Sect;
Obj->ReadSection(*SegmentLCI, i, Sect);
@@ -111,7 +199,7 @@
if (Sect->Flags != 0x80000400)
return Error("unsupported section type!");
- SectionBases[i] = (char*) Data.base() + Sect->Address;
+ SectionBases.push_back((char*) Data.base() + Sect->Address);
}
// Bind all the symbols to address.
@@ -142,6 +230,8 @@
if (STE->Flags != 0x0)
return Error("unexpected symbol type!");
+ DEBUG(dbgs() << "Symbol: '" << Name << "' @ " << Address << "\n");
+
SymbolTable[Name] = Address;
}
@@ -149,7 +239,6 @@
// FIXME: We really should use the JITMemoryManager for this.
sys::Memory::setRangeExecutable(Data.base(), Data.size());
- delete SectionBases;
return false;
}
@@ -174,41 +263,54 @@
memset((char*)Data.base() + Segment64LC->FileSize, 0,
Segment64LC->VMSize - Segment64LC->FileSize);
- // Bind the section indices to address.
- void **SectionBases = new void*[Segment64LC->NumSections];
+ // Bind the section indices to addresses and record the relocations we
+ // need to resolve.
+ typedef std::pair<uint32_t, macho::RelocationEntry> RelocationMap;
+ SmallVector<RelocationMap, 64> Relocations;
+
+ SmallVector<void *, 16> SectionBases;
for (unsigned i = 0; i != Segment64LC->NumSections; ++i) {
InMemoryStruct<macho::Section64> Sect;
Obj->ReadSection64(*SegmentLCI, i, Sect);
if (!Sect)
return Error("unable to load section: '" + Twine(i) + "'");
- // FIXME: We don't support relocations yet.
- if (Sect->NumRelocationTableEntries != 0)
- return Error("not yet implemented: relocations!");
+ // Resolve any relocations the section has.
+ for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
+ InMemoryStruct<macho::RelocationEntry> RE;
+ Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
+ Relocations.push_back(RelocationMap(j, *RE));
+ }
// FIXME: Improve check.
if (Sect->Flags != 0x80000400)
return Error("unsupported section type!");
- SectionBases[i] = (char*) Data.base() + Sect->Address;
+ SectionBases.push_back((char*) Data.base() + Sect->Address);
}
- // Bind all the symbols to address.
+ // Bind all the symbols to address. Keep a record of the names for use
+ // by relocation resolution.
+ SmallVector<StringRef, 64> SymbolNames;
for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
InMemoryStruct<macho::Symbol64TableEntry> STE;
Obj->ReadSymbol64TableEntry(SymtabLC->SymbolTableOffset, i, STE);
if (!STE)
return Error("unable to read symbol: '" + Twine(i) + "'");
+ // Get the symbol name.
+ StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
+ SymbolNames.push_back(Name);
+
+ // Just skip undefined symbols. They'll be loaded from whatever
+ // module they come from (or system dylib) when we resolve relocations
+ // involving them.
if (STE->SectionIndex == 0)
- return Error("unexpected undefined symbol!");
+ continue;
unsigned Index = STE->SectionIndex - 1;
if (Index >= Segment64LC->NumSections)
return Error("invalid section index for symbol: '" + Twine() + "'");
- // Get the symbol name.
- StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
-
// Get the section base address.
void *SectionBase = SectionBases[Index];
@@ -221,14 +323,21 @@
if (STE->Flags != 0x0)
return Error("unexpected symbol type!");
+ DEBUG(dbgs() << "Symbol: '" << Name << "' @ " << Address << "\n");
SymbolTable[Name] = Address;
}
+ // Now resolve any relocations.
+ for (unsigned i = 0, e = Relocations.size(); i != e; ++i) {
+ if (resolveRelocation(Relocations[i].first, Relocations[i].second,
+ SectionBases, SymbolNames))
+ return true;
+ }
+
// We've loaded the section; now mark the functions in it as executable.
// FIXME: We really should use the JITMemoryManager for this.
sys::Memory::setRangeExecutable(Data.base(), Data.size());
- delete SectionBases;
return false;
}
@@ -291,12 +400,12 @@
return Error("unable to load dynamic link-exit load command");
// FIXME: We don't support anything interesting yet.
- if (DysymtabLC->LocalSymbolsIndex != 0)
- return Error("NOT YET IMPLEMENTED: local symbol entries");
- if (DysymtabLC->ExternalSymbolsIndex != 0)
- return Error("NOT YET IMPLEMENTED: non-external symbol entries");
- if (DysymtabLC->UndefinedSymbolsIndex != SymtabLC->NumSymbolTableEntries)
- return Error("NOT YET IMPLEMENTED: undefined symbol entries");
+// if (DysymtabLC->LocalSymbolsIndex != 0)
+// return Error("NOT YET IMPLEMENTED: local symbol entries");
+// if (DysymtabLC->ExternalSymbolsIndex != 0)
+// return Error("NOT YET IMPLEMENTED: non-external symbol entries");
+// if (DysymtabLC->UndefinedSymbolsIndex != SymtabLC->NumSymbolTableEntries)
+// return Error("NOT YET IMPLEMENTED: undefined symbol entries");
}
// Load the segment load command.
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