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

2 files changed, 82 insertions, 11 deletions

diff --git a/lld/COFF/Writer.cpp b/lld/COFF/Writer.cpp
index 6acfaf9..56b7974 100644
--- a/lld/COFF/Writer.cpp
+++ b/lld/COFF/Writer.cpp
@@ -1351,19 +1351,47 @@ 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.
-  Chunk *RefChunk = D->getChunk();
-  OutputSection *OS = RefChunk ? RefChunk->getOutputSection() : nullptr;
-  if (OS && OS->Header.Characteristics & IMAGE_SCN_MEM_EXECUTE)
-    addSymbolToRVASet(AddressTakenSyms, D);
+  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
diff --git a/lld/test/COFF/guardcf-thunk.s b/lld/test/COFF/guardcf-thunk.s
new file mode 100644
index 0000000..0969c58
--- /dev/null
+++ b/lld/test/COFF/guardcf-thunk.s
@@ -0,0 +1,43 @@
+# 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
+