[llvm] r228939 - On ELF, put PIC jump tables in a non executable section.
Rafael Espindola
rafael.espindola at gmail.com
Thu Feb 12 09:46:49 PST 2015
Author: rafael
Date: Thu Feb 12 11:46:49 2015
New Revision: 228939
URL: http://llvm.org/viewvc/llvm-project?rev=228939&view=rev
Log:
On ELF, put PIC jump tables in a non executable section.
Fixes PR22558.
Modified:
llvm/trunk/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
llvm/trunk/include/llvm/Target/TargetLoweringObjectFile.h
llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
llvm/trunk/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
llvm/trunk/lib/Target/TargetLoweringObjectFile.cpp
llvm/trunk/test/CodeGen/X86/global-sections.ll
Modified: llvm/trunk/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h?rev=228939&r1=228938&r2=228939&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h (original)
+++ llvm/trunk/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h Thu Feb 12 11:46:49 2015
@@ -60,6 +60,9 @@ public:
getSectionForJumpTable(const Function &F, Mangler &Mang,
const TargetMachine &TM) const override;
+ bool shouldPutJumpTableInFunctionSection(bool UsesLabelDifference,
+ const Function &F) const override;
+
/// Return an MCExpr to use for a reference to the specified type info global
/// variable from exception handling information.
const MCExpr *
Modified: llvm/trunk/include/llvm/Target/TargetLoweringObjectFile.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetLoweringObjectFile.h?rev=228939&r1=228938&r2=228939&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetLoweringObjectFile.h (original)
+++ llvm/trunk/include/llvm/Target/TargetLoweringObjectFile.h Thu Feb 12 11:46:49 2015
@@ -98,6 +98,9 @@ public:
getSectionForJumpTable(const Function &F, Mangler &Mang,
const TargetMachine &TM) const;
+ virtual bool shouldPutJumpTableInFunctionSection(bool UsesLabelDifference,
+ const Function &F) const;
+
/// Targets should implement this method to assign a section to globals with
/// an explicit section specfied. The implementation of this method can
/// assume that GV->hasSection() is true.
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp?rev=228939&r1=228938&r2=228939&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/AsmPrinter.cpp Thu Feb 12 11:46:49 2015
@@ -1178,23 +1178,14 @@ void AsmPrinter::EmitJumpTableInfo() {
// the appropriate section.
const Function *F = MF->getFunction();
const TargetLoweringObjectFile &TLOF = getObjFileLowering();
- bool JTInDiffSection = false;
- if (// In PIC mode, we need to emit the jump table to the same section as the
- // function body itself, otherwise the label differences won't make sense.
- // FIXME: Need a better predicate for this: what about custom entries?
- MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 ||
- // We should also do if the section name is NULL or function is declared
- // in discardable section
- // FIXME: this isn't the right predicate, should be based on the MCSection
- // for the function.
- F->isWeakForLinker()) {
- OutStreamer.SwitchSection(TLOF.SectionForGlobal(F, *Mang, TM));
- } else {
+ bool JTInDiffSection = !TLOF.shouldPutJumpTableInFunctionSection(
+ MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32,
+ *F);
+ if (JTInDiffSection) {
// Otherwise, drop it in the readonly section.
const MCSection *ReadOnlySection =
TLOF.getSectionForJumpTable(*F, *Mang, TM);
OutStreamer.SwitchSection(ReadOnlySection);
- JTInDiffSection = true;
}
EmitAlignment(Log2_32(
Modified: llvm/trunk/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TargetLoweringObjectFileImpl.cpp?rev=228939&r1=228938&r2=228939&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TargetLoweringObjectFileImpl.cpp (original)
+++ llvm/trunk/lib/CodeGen/TargetLoweringObjectFileImpl.cpp Thu Feb 12 11:46:49 2015
@@ -356,6 +356,13 @@ const MCSection *TargetLoweringObjectFil
return getContext().getELFSection(Name, ELF::SHT_PROGBITS, Flags, 0, Group);
}
+bool TargetLoweringObjectFileELF::shouldPutJumpTableInFunctionSection(
+ bool UsesLabelDifference, const Function &F) const {
+ // We can always create relative relocations, so use another section
+ // that can be marked non-executable.
+ return false;
+}
+
/// getSectionForConstant - Given a mergeable constant with the
/// specified size and relocation information, return a section that it
/// should be placed in.
Modified: llvm/trunk/lib/Target/TargetLoweringObjectFile.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/TargetLoweringObjectFile.cpp?rev=228939&r1=228938&r2=228939&view=diff
==============================================================================
--- llvm/trunk/lib/Target/TargetLoweringObjectFile.cpp (original)
+++ llvm/trunk/lib/Target/TargetLoweringObjectFile.cpp Thu Feb 12 11:46:49 2015
@@ -275,6 +275,24 @@ const MCSection *TargetLoweringObjectFil
return getSectionForConstant(SectionKind::getReadOnly(), /*C=*/nullptr);
}
+bool TargetLoweringObjectFile::shouldPutJumpTableInFunctionSection(
+ bool UsesLabelDifference, const Function &F) const {
+ // In PIC mode, we need to emit the jump table to the same section as the
+ // function body itself, otherwise the label differences won't make sense.
+ // FIXME: Need a better predicate for this: what about custom entries?
+ if (UsesLabelDifference)
+ return true;
+
+ // We should also do if the section name is NULL or function is declared
+ // in discardable section
+ // FIXME: this isn't the right predicate, should be based on the MCSection
+ // for the function.
+ if (F.isWeakForLinker())
+ return true;
+
+ return false;
+}
+
/// getSectionForConstant - Given a mergable constant with the
/// specified size and relocation information, return a section that it
/// should be placed in.
Modified: llvm/trunk/test/CodeGen/X86/global-sections.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/global-sections.ll?rev=228939&r1=228938&r2=228939&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/global-sections.ll (original)
+++ llvm/trunk/test/CodeGen/X86/global-sections.ll Thu Feb 12 11:46:49 2015
@@ -3,6 +3,7 @@
; RUN: llc < %s -mtriple=i386-apple-darwin10 -relocation-model=static | FileCheck %s -check-prefix=DARWIN-STATIC
; RUN: llc < %s -mtriple=x86_64-apple-darwin10 | FileCheck %s -check-prefix=DARWIN64
; RUN: llc < %s -mtriple=i386-unknown-linux-gnu -data-sections -function-sections | FileCheck %s -check-prefix=LINUX-SECTIONS
+; RUN: llc < %s -mtriple=x86_64-pc-linux -data-sections -function-sections -relocation-model=pic | FileCheck %s -check-prefix=LINUX-SECTIONS-PIC
; RUN: llc < %s -mtriple=i686-pc-win32 -data-sections -function-sections | FileCheck %s -check-prefix=WIN32-SECTIONS
define void @F1() {
@@ -41,6 +42,11 @@ bb5:
; LINUX-SECTIONS-NEXT: .cfi_endproc
; LINUX-SECTIONS-NEXT: .section .rodata.F2,"a", at progbits
+; LINUX-SECTIONS-PIC: .section .text.F2,"ax", at progbits
+; LINUX-SECTIONS-PIC: .size F2,
+; LINUX-SECTIONS-PIC-NEXT: .cfi_endproc
+; LINUX-SECTIONS-PIC-NEXT: .section .rodata.F2,"a", at progbits
+
; int G1;
@G1 = common global i32 0
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