Commit 9916d8de authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r355141: 

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r355141 | rnk | 2019-02-28 13:05:41 -0800 (Thu, 28 Feb 2019) | 11 lines

[COFF] Add address-taken import thunks to the fid table

Summary: Fixes PR39799

Reviewers: dmajor, hans

Subscribers: jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58739
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llvm-svn: 360803
parent 35349ba7

lld/COFF/Writer.cpp

+39 −11
Original line number Diff line number Diff line
@@ -1351,20 +1351,48 @@ static void addSymbolToRVASet(SymbolRVASet &RVASet, Defined *S) { 
// symbol in an executable section.

static void maybeAddAddressTakenFunction(SymbolRVASet &AddressTakenSyms,

                                         Symbol *S) {

  auto *D = dyn_cast_or_null<DefinedCOFF>(S);



  // Ignore undefined symbols and references to non-functions (e.g. globals and

  // labels).

  if (!D ||

      D->getCOFFSymbol().getComplexType() != COFF::IMAGE_SYM_DTYPE_FUNCTION)

  if (!S)

    return;



  // Mark the symbol as address taken if it's in an executable section.

  switch (S->kind()) {

  case Symbol::DefinedLocalImportKind:

  case Symbol::DefinedImportDataKind:

    // Defines an __imp_ pointer, so it is data, so it is ignored.

    break;

  case Symbol::DefinedCommonKind:

    // Common is always data, so it is ignored.

    break;

  case Symbol::DefinedAbsoluteKind:

  case Symbol::DefinedSyntheticKind:

    // Absolute is never code, synthetic generally isn't and usually isn't

    // determinable.

    break;

  case Symbol::LazyKind:

  case Symbol::UndefinedKind:

    // Undefined symbols resolve to zero, so they don't have an RVA. Lazy

    // symbols shouldn't have relocations.

    break;



  case Symbol::DefinedImportThunkKind:

    // Thunks are always code, include them.

    addSymbolToRVASet(AddressTakenSyms, cast<Defined>(S));

    break;



  case Symbol::DefinedRegularKind: {

    // This is a regular, defined, symbol from a COFF file. Mark the symbol as

    // address taken if the symbol type is function and it's in an executable

    // section.

    auto *D = cast<DefinedRegular>(S);

    if (D->getCOFFSymbol().getComplexType() == COFF::IMAGE_SYM_DTYPE_FUNCTION) {

      Chunk *RefChunk = D->getChunk();

      OutputSection *OS = RefChunk ? RefChunk->getOutputSection() : nullptr;

      if (OS && OS->Header.Characteristics & IMAGE_SCN_MEM_EXECUTE)

        addSymbolToRVASet(AddressTakenSyms, D);

    }

    break;

  }

  }

}



// Visit all relocations from all section contributions of this object file and

// mark the relocation target as address-taken.

lld/test/COFF/guardcf-thunk.s

0 → 100644
+43 −0
Original line number Diff line number Diff line 
# REQUIRES: x86



# Make a DLL that exports exportfn1.

# RUN: yaml2obj < %p/Inputs/export.yaml > %t.obj

# RUN: lld-link /out:%t.dll /dll %t.obj /export:exportfn1 /implib:%t.lib



# Make an obj that takes the address of that exported function.

# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t2.obj

# RUN: lld-link -entry:main -guard:cf %t2.obj %t.lib -nodefaultlib -out:%t.exe

# RUN: llvm-readobj -coff-load-config %t.exe | FileCheck %s



# Check that the gfids table contains *exactly* two entries, one for exportfn1

# and one for main.

# CHECK: GuardFidTable [

# CHECK-NEXT: 0x{{[0-9A-Fa-f]+0$}}

# CHECK-NEXT: 0x{{[0-9A-Fa-f]+0$}}

# CHECK-NEXT: ]





        .def     @feat.00;

        .scl    3;

        .type   0;

        .endef

        .globl  @feat.00

@feat.00 = 0x001



        .section .text,"rx"

        .def     main; .scl    2; .type   32; .endef

        .global main

main:

        leaq exportfn1(%rip), %rax

        retq



        .section .rdata,"dr"

.globl _load_config_used

_load_config_used:

        .long 256

        .fill 124, 1, 0

        .quad __guard_fids_table

        .quad __guard_fids_count

        .long __guard_flags

        .fill 128, 1, 0