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[LLD][COFF] Set __guard_flags to CF_INSTRUMENTED if any object is instrumented #115374

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Merged
merged 1 commit into from
Nov 8, 2024
Merged

[LLD][COFF] Set __guard_flags to CF_INSTRUMENTED if any object is instrumented #115374

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17 changes: 15 additions & 2 deletions lld/COFF/Writer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1217,8 +1217,7 @@ void Writer::createMiscChunks() {
createSEHTable();

// Create /guard:cf tables if requested.
if (config->guardCF != GuardCFLevel::Off)
createGuardCFTables();
createGuardCFTables();

if (isArm64EC(config->machine))
createECChunks();
Expand Down Expand Up @@ -1979,6 +1978,20 @@ void Writer::markSymbolsWithRelocations(ObjFile *file,
void Writer::createGuardCFTables() {
Configuration *config = &ctx.config;

if (config->guardCF == GuardCFLevel::Off) {
// MSVC marks the entire image as instrumented if any input object was built
// with /guard:cf.
for (ObjFile *file : ctx.objFileInstances) {
if (file->hasGuardCF()) {
Symbol *flagSym = ctx.symtab.findUnderscore("__guard_flags");
cast<DefinedAbsolute>(flagSym)->setVA(
uint32_t(GuardFlags::CF_INSTRUMENTED));
break;
}
}
return;
}

SymbolRVASet addressTakenSyms;
SymbolRVASet giatsRVASet;
std::vector<Symbol *> giatsSymbols;
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22 changes: 22 additions & 0 deletions lld/test/COFF/cfguard-off-instrumented.s
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@@ -0,0 +1,22 @@
// Verify that __guard_flags is set to CF_INSTRUMENTED if CF guard is disabled,
// but the input object was built with CF guard.

// REQUIRES: x86

// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t.obj
// RUN: lld-link -out:%t1.dll %t.obj -dll -noentry
// RUN: lld-link -out:%t2.dll %t.obj -dll -noentry -guard:no

// RUN: llvm-readobj --hex-dump=.test %t1.dll | FileCheck %s
// RUN: llvm-readobj --hex-dump=.test %t2.dll | FileCheck %s
// CHECK: 0x180001000 00010000

.def @feat.00;
.scl 3;
.type 0;
.endef
.globl @feat.00
@feat.00 = 0x800

.section .test, "r"
.long __guard_flags
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