Index: llvm/include/llvm/BinaryFormat/ELF.h
===================================================================
--- llvm/include/llvm/BinaryFormat/ELF.h
+++ llvm/include/llvm/BinaryFormat/ELF.h
@@ -1308,6 +1308,13 @@
enum {
GNU_PROPERTY_STACK_SIZE = 1,
GNU_PROPERTY_NO_COPY_ON_PROTECTED = 2,
+ GNU_PROPERTY_X86_FEATURE_1_AND = 0xc0000002
+};
+
+// CET properties
+enum {
+ GNU_PROPERTY_X86_FEATURE_1_IBT = 1 << 0,
+ GNU_PROPERTY_X86_FEATURE_1_SHSTK = 1 << 1
};
// AMDGPU specific notes.
Index: llvm/lib/Target/X86/X86AsmPrinter.cpp
===================================================================
--- llvm/lib/Target/X86/X86AsmPrinter.cpp
+++ llvm/lib/Target/X86/X86AsmPrinter.cpp
@@ -19,6 +19,7 @@
#include "X86InstrInfo.h"
#include "X86MachineFunctionInfo.h"
#include "llvm/BinaryFormat/COFF.h"
+#include "llvm/BinaryFormat/ELF.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineModuleInfoImpls.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
@@ -539,6 +540,43 @@
void X86AsmPrinter::EmitStartOfAsmFile(Module &M) {
const Triple &TT = TM.getTargetTriple();
+ if (TT.isOSBinFormatELF()) {
+ // Assemble feature flags that may require creation of a note section.
+ char FeatureFlagsAnd = 0;
+ if (M.getModuleFlag("cf-protection-branch"))
+ FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_IBT;
+ if (M.getModuleFlag("cf-protection-return"))
+ FeatureFlagsAnd |= ELF::GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+
+ if (FeatureFlagsAnd) {
+ // Emit a .note.gnu.property section with the flags.
+ MCSection *Cur = OutStreamer->getCurrentSectionOnly();
+ MCSection *Nt = (MCSection *)MMI->getContext().getELFSection(
+ ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
+ int WordSize = TT.isArch64Bit() ? 8 : 4;
+ assert((TT.isArch32Bit() || WordSize == 8) &&
+ "CFProtection used on invalid architecture");
+ OutStreamer->SwitchSection(Nt);
+
+ // Emitting section header.
+ OutStreamer->EmitIntValue(4, 4 /*size*/); // data size for "GNU\0"
+ OutStreamer->EmitIntValue(8 + WordSize, 4 /*size*/); // Elf_Prop size
+ OutStreamer->EmitIntValue(ELF::NT_GNU_PROPERTY_TYPE_0, 4 /*size*/);
+ OutStreamer->EmitIntValue('G', 1 /*size*/); // note name "GNU"
+ OutStreamer->EmitIntValue('N', 1 /*size*/);
+ OutStreamer->EmitIntValue('U', 1 /*size*/);
+ OutStreamer->EmitIntValue(0, 1 /*size*/);
+
+ // Emitting an Elf_Prop for the CET properties.
+ OutStreamer->EmitIntValue(ELF::GNU_PROPERTY_X86_FEATURE_1_AND, 4);
+ OutStreamer->EmitIntValue(WordSize, 4); // data size
+ OutStreamer->EmitIntValue(FeatureFlagsAnd, WordSize); // data
+
+ OutStreamer->endSection(Nt);
+ OutStreamer->SwitchSection(Cur);
+ }
+ }
+
if (TT.isOSBinFormatMachO())
OutStreamer->SwitchSection(getObjFileLowering().getTextSection());
Index: llvm/test/CodeGen/X86/note-cet-property.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/note-cet-property.ll
@@ -0,0 +1,20 @@
+; RUN: llc -mtriple x86_64-pc-linux < %s | FileCheck %s
+
+; This test checks that the compiler emits a .note.gnu.property section for
+; modules with "cf-protection" module flags.
+
+; CHECK: .section .note.gnu.property,"a",@note
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 16
+; CHECK-NEXT: .long 5
+; CHECK-NEXT: .byte 71
+; CHECK-NEXT: .byte 78
+; CHECK-NEXT: .byte 85
+; CHECK-NEXT: .byte 0
+; CHECK-NEXT: .long 3221225474
+; CHECK-NEXT: .long 8
+; CHECK-NEXT: .quad 2
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 4, !"cf-protection-return", i32 1}
Index: llvm/test/tools/llvm-readobj/note-gnu-property.s
===================================================================
--- llvm/test/tools/llvm-readobj/note-gnu-property.s
+++ llvm/test/tools/llvm-readobj/note-gnu-property.s
@@ -2,16 +2,21 @@
// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o %t
// RUN: llvm-readobj -elf-output-style GNU --notes %t | FileCheck %s
-// CHECK: Displaying notes found at file offset 0x00000040 with length 0x00000070:
+// CHECK: Displaying notes found at file offset 0x00000040 with length 0x000000b8:
// CHECK-NEXT: Owner Data size Description
-// CHECK-NEXT: GNU 0x00000060 NT_GNU_PROPERTY_TYPE_0 (property note)
+// CHECK-NEXT: GNU 0x000000a8 NT_GNU_PROPERTY_TYPE_0 (property note)
// CHECK-NEXT: Properties: stack size: 0x100
// CHECK-NEXT: stack size: 0x100
// CHECK-NEXT: no copy on protected
+// CHECK-NEXT: X86 features: SHSTK
+// CHECK-NEXT: X86 features: IBT, SHSTK
+// CHECK-NEXT: X86 features: none
// CHECK-NEXT: <application-specific type 0xfefefefe>
// CHECK-NEXT: stack size: <corrupt length: 0x0>
// CHECK-NEXT: stack size: <corrupt length: 0x4>
// CHECK-NEXT: no copy on protected <corrupt length: 0x1>
+// CHECK-NEXT: X86 features: <corrupt length: 0x0>
+// CHECK-NEXT: X86 features: IBT, <unknown flags: 0x80>
// CHECK-NEXT: <corrupt type (0x2) datasz: 0x1>
.section ".note.gnu.property", "a"
@@ -26,7 +31,7 @@
.long 8 /* Data size */
.quad 0x100 /* Data (stack size) */
.p2align 3 /* Align to 8 byte for 64 bit */
-
+
/* Test we handle alignment properly */
.long 1 /* Type: GNU_PROPERTY_STACK_SIZE */
.long 8 /* Data size */
@@ -36,6 +41,22 @@
.long 2 /* Type: GNU_PROPERTY_NO_COPY_ON_PROTECTED */
.long 0 /* Data size */
.p2align 3 /* Align to 8 byte for 64 bit */
+
+ /* CET property note */
+ .long 0xc0000002 /* Type: GNU_PROPERTY_X86_FEATURE_1_AND */
+ .long 8 /* Data size */
+ .quad 2 /* GNU_PROPERTY_X86_FEATURE_1_SHSTK */
+ .p2align 3 /* Align to 8 byte for 64 bit */
+
+ .long 0xc0000002 /* Type: GNU_PROPERTY_X86_FEATURE_1_AND */
+ .long 8 /* Data size */
+ .quad 3 /* Full CET support */
+ .p2align 3 /* Align to 8 byte for 64 bit */
+
+ .long 0xc0000002 /* Type: GNU_PROPERTY_X86_FEATURE_1_AND */
+ .long 8 /* Data size */
+ .quad 0 /* Empty flags, not an error */
+ .p2align 3 /* Align to 8 byte for 64 bit */
/* All notes below are broken. Test we are able to report them. */
@@ -60,6 +81,17 @@
.long 1 /* Data size (corrupted) */
.byte 1 /* Data */
.p2align 3 /* Align to 8 byte for 64 bit */
+
+ /* CET note with size zero */
+ .long 0xc0000002 /* Type: GNU_PROPERTY_X86_FEATURE_1_AND */
+ .long 0 /* Data size */
+ .p2align 3 /* Align to 8 byte for 64 bit */
+
+ /* CET note with bad flags */
+ .long 0xc0000002 /* Type: GNU_PROPERTY_X86_FEATURE_1_AND */
+ .long 8 /* Data size */
+ .quad 0x81 /* GNU_PROPERTY_X86_FEATURE_1_IBT and a bad bit */
+ .p2align 3 /* Align to 8 byte for 64 bit */
/* GNU_PROPERTY_NO_COPY_ON_PROTECTED with pr_datasz and without data */
.long 2 /* Type: GNU_PROPERTY_NO_COPY_ON_PROTECTED */
Index: llvm/tools/llvm-readobj/ELFDumper.cpp
===================================================================
--- llvm/tools/llvm-readobj/ELFDumper.cpp
+++ llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -3469,6 +3469,41 @@
OS << format(" <corrupt length: 0x%x>", DataSize);
OS << "\n";
break;
+ case GNU_PROPERTY_X86_FEATURE_1_AND:
+ OS << " X86 features: ";
+ if (DataSize == sizeof(typename ELFT::uint)) {
+ uint64_t CFProtection =
+ (uint64_t)(*(const typename ELFT::Addr *)Data.data());
+ bool First = true;
+ if (CFProtection == 0) {
+ OS << "none\n";
+ break;
+ }
+ if (CFProtection & GNU_PROPERTY_X86_FEATURE_1_IBT) {
+ if (First)
+ First = false;
+ else
+ OS << ", ";
+ OS << "IBT";
+ CFProtection &= ~GNU_PROPERTY_X86_FEATURE_1_IBT;
+ }
+ if (CFProtection & GNU_PROPERTY_X86_FEATURE_1_SHSTK) {
+ if (First)
+ First = false;
+ else
+ OS << ", ";
+ OS << "SHSTK";
+ CFProtection &= ~GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+ }
+ if (CFProtection) {
+ if (!First)
+ OS << ", ";
+ OS << format("<unknown flags: 0x%x>", CFProtection);
+ }
+ } else
+ OS << format("<corrupt length: 0x%x>", DataSize);
+ OS << "\n";
+ break;
}
}