Relocations.c

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#include <Uefi.h>
 
#include <IndustryStandard/AppleMachoImage.h>
 
#include <Library/DebugLib.h>
#include <Library/OcMachoLib.h>
 
#include "OcMachoLibInternal.h"
 
BOOLEAN
MachoRelocationIsPairIntel32 (
  IN UINT8  Type
  )
{
  return (Type == MachGenericRelocSectDiff || Type == MachGenericRelocLocalSectDiff);
}
 
BOOLEAN
MachoRelocationIsPairIntel64 (
  IN UINT8  Type
  )
{
  return (Type == MachX8664RelocSubtractor);
}
 
BOOLEAN
MachoIsRelocationPairTypeIntel64 (
  IN UINT8  Type
  )
{
  return (Type == MachX8664RelocUnsigned);
}
 
BOOLEAN
MachoPreserveRelocationIntel64 (
  IN UINT8  Type
  )
{
  return (Type == MachX8664RelocUnsigned);
}
 
STATIC
MACH_RELOCATION_INFO *
InternalLookupRelocationByOffset (
  IN     UINT64                Address,
  IN     UINT32                NumRelocs,
  IN     MACH_RELOCATION_INFO  *Relocs
  )
{
  UINT32                Index;
  MACH_RELOCATION_INFO  *Relocation;
 
  for (Index = 0; Index < NumRelocs; ++Index) {
    Relocation = &Relocs[Index];
    //
    // A section-based relocation entry can be skipped for absolute symbols.
    //
    if (  (Relocation->Extern == 0)
       && (Relocation->SymbolNumber == MACH_RELOC_ABSOLUTE))
    {
      continue;
    }
 
    if ((UINT64)Relocation->Address == Address) {
      return Relocation;
    }
 
    //
    // Relocation Pairs can be skipped.
    // Assumption: Intel X64.  Currently verified by the Context
    //             initialization.
    //
    if (MachoRelocationIsPairIntel64 ((UINT8)Relocation->Type)) {
      if (Index == (MAX_UINT32 - 1)) {
        break;
      }
 
      ++Index;
    }
  }
 
  return NULL;
}
 
STATIC
MACH_RELOCATION_INFO *
InternalLookupSectionRelocationByOffset (
  IN OUT OC_MACHO_CONTEXT  *Context,
  IN     UINT64            Address,
  IN     BOOLEAN           External
  )
{
  MACH_SECTION_ANY  *Section;
  UINT32            SectionIndex;
  UINT32            Index;
 
  MACH_RELOCATION_INFO  *Relocations;
  MACH_RELOCATION_INFO  *Relocation;
  UINT32                RelocationCount;
 
  SectionIndex = 0;
  while (TRUE) {
    Section = MachoGetSectionByIndex (Context, SectionIndex);
    if (Section == NULL) {
      break;
    }
 
    //
    // Each section has its own relocations table.
    //
    RelocationCount = Context->Is32Bit ? Section->Section32.NumRelocations : Section->Section64.NumRelocations;
    if (RelocationCount > 0) {
      Relocations = (MACH_RELOCATION_INFO *)(((UINTN)(Context->FileData))
                                             + (Context->Is32Bit ? Section->Section32.RelocationsOffset : Section->Section64.RelocationsOffset));
 
      for (Index = 0; Index < RelocationCount; Index++) {
        Relocation = &Relocations[Index];
        //
        // A section-based relocation entry can be skipped for absolute symbols.
        //
        if (  (Relocation->Extern == 0)
           && (Relocation->SymbolNumber == MACH_RELOC_ABSOLUTE))
        {
          continue;
        }
 
        //
        // Filter out the other relocation type.
        //
        if (Relocation->Extern != (UINT32)(External ? 1 : 0)) {
          continue;
        }
 
        if (Context->Is32Bit) {
          if (((UINT32)Relocation->Address + Section->Section32.Address) == Address) {
            return Relocation;
          }
        } else {
          if (((UINT64)Relocation->Address + Section->Section64.Address) == Address) {
            return Relocation;
          }
        }
      }
    }
 
    SectionIndex++;
  }
 
  return NULL;
}
 
MACH_RELOCATION_INFO *
InternalGetExternRelocationByOffset (
  IN OUT OC_MACHO_CONTEXT  *Context,
  IN     UINT64            Address
  )
{
  //
  // MH_OBJECT does not have a DYSYMTAB.
  //
  if (Context->DySymtab == NULL) {
    return InternalLookupSectionRelocationByOffset (
             Context,
             Address,
             TRUE
             );
  }
 
  return InternalLookupRelocationByOffset (
           Address,
           Context->DySymtab->NumExternalRelocations,
           Context->ExternRelocations
           );
}
 
MACH_RELOCATION_INFO *
InternalGetLocalRelocationByOffset (
  IN OUT OC_MACHO_CONTEXT  *Context,
  IN     UINT64            Address
  )
{
  //
  // MH_OBJECT does not have a DYSYMTAB.
  //
  if (Context->DySymtab == NULL) {
    return InternalLookupSectionRelocationByOffset (
             Context,
             Address,
             FALSE
             );
  }
 
  return InternalLookupRelocationByOffset (
           Address,
           Context->DySymtab->NumOfLocalRelocations,
           Context->LocalRelocations
           );
}