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[Thumb,ELF] Fix access to dso_preemptable __stack_chk_guard with static relocation model #78950

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Merged
merged 2 commits into from
Jan 22, 2024
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[Thumb,ELF] Fix access to dso_preemptable __stack_chk_guard with static relocation model #78950

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2ce5748
[𝘀𝗽𝗿] initial version
MaskRay Jan 22, 2024
7bd52da
fix mingw. use 'auto'
MaskRay Jan 22, 2024
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4 changes: 2 additions & 2 deletions llvm/lib/Target/ARM/Thumb1InstrInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -135,14 +135,14 @@ void Thumb1InstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
void Thumb1InstrInfo::expandLoadStackGuard(
MachineBasicBlock::iterator MI) const {
MachineFunction &MF = *MI->getParent()->getParent();
const TargetMachine &TM = MF.getTarget();
const ARMSubtarget &ST = MF.getSubtarget<ARMSubtarget>();
const auto *GV = cast<GlobalValue>((*MI->memoperands_begin())->getValue());

assert(MF.getFunction().getParent()->getStackProtectorGuard() != "tls" &&
"TLS stack protector not supported for Thumb1 targets");

unsigned Instr;
if (TM.isPositionIndependent())
if (!GV->isDSOLocal())
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does Thumb1 need similar guards for whether the target is elf?

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@MaskRay MaskRay Jan 22, 2024 •
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I believe the answer is no.

Based on my archaeology to the Thumb1InstrInfo::expandLoadStackGuard function, the changes haven't been related to Thumb1-only microarchitectures (before v6T2/v7) for non-ELF object file formats.

https://reviews.llvm.org/D75453 says that Windows AArch32 requires at least v7.

Instr = ARM::tLDRLIT_ga_pcrel;
else if (ST.genExecuteOnly() && ST.hasV8MBaselineOps())
Instr = ARM::t2MOVi32imm;
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6 changes: 2 additions & 4 deletions llvm/lib/Target/ARM/Thumb2InstrInfo.cpp
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Expand Up @@ -261,10 +261,8 @@ void Thumb2InstrInfo::expandLoadStackGuard(
return;
}

const GlobalValue *GV =
cast<GlobalValue>((*MI->memoperands_begin())->getValue());

if (MF.getSubtarget<ARMSubtarget>().isGVInGOT(GV))
const auto *GV = cast<GlobalValue>((*MI->memoperands_begin())->getValue());
if (MF.getSubtarget<ARMSubtarget>().isTargetELF() && !GV->isDSOLocal())
expandLoadStackGuardBase(MI, ARM::t2LDRLIT_ga_pcrel, ARM::t2LDRi12);
else if (MF.getTarget().isPositionIndependent())
expandLoadStackGuardBase(MI, ARM::t2MOV_ga_pcrel, ARM::t2LDRi12);
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30 changes: 24 additions & 6 deletions llvm/test/CodeGen/ARM/stack-guard-elf.ll
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Expand Up @@ -59,6 +59,8 @@ define i32 @test1() #0 {
; THUMB1-NEXT: .pad #16
; THUMB1-NEXT: sub sp, #16
; THUMB1-NEXT: ldr r0, .LCPI0_0
; THUMB1-NEXT: .LPC0_0:
; THUMB1-NEXT: add r0, pc
; THUMB1-NEXT: ldr r0, [r0]
; THUMB1-NEXT: ldr r0, [r0]
; THUMB1-NEXT: add r1, sp, #904
Expand All @@ -67,7 +69,9 @@ define i32 @test1() #0 {
; THUMB1-NEXT: bl foo
; THUMB1-NEXT: add r0, sp, #904
; THUMB1-NEXT: ldr r0, [r0, #124]
; THUMB1-NEXT: ldr r1, .LCPI0_0
; THUMB1-NEXT: ldr r1, .LCPI0_1
; THUMB1-NEXT: .LPC0_1:
; THUMB1-NEXT: add r1, pc
; THUMB1-NEXT: ldr r1, [r1]
; THUMB1-NEXT: ldr r1, [r1]
; THUMB1-NEXT: cmp r1, r0
Expand All @@ -83,7 +87,11 @@ define i32 @test1() #0 {
; THUMB1-NEXT: .p2align 2
; THUMB1-NEXT: @ %bb.3:
; THUMB1-NEXT: .LCPI0_0:
; THUMB1-NEXT: .long __stack_chk_guard
; THUMB1-NEXT: .Ltmp0:
; THUMB1-NEXT: .long __stack_chk_guard(GOT_PREL)-((.LPC0_0+4)-.Ltmp0)
; THUMB1-NEXT: .LCPI0_1:
; THUMB1-NEXT: .Ltmp1:
; THUMB1-NEXT: .long __stack_chk_guard(GOT_PREL)-((.LPC0_1+4)-.Ltmp1)
;
; THUMB1-PIC-LABEL: test1:
; THUMB1-PIC: @ %bb.0:
Expand Down Expand Up @@ -136,16 +144,18 @@ define i32 @test1() #0 {
; THUMB2-NEXT: push {r7, lr}
; THUMB2-NEXT: .pad #1032
; THUMB2-NEXT: sub.w sp, sp, #1032
; THUMB2-NEXT: movw r0, :lower16:__stack_chk_guard
; THUMB2-NEXT: movt r0, :upper16:__stack_chk_guard
; THUMB2-NEXT: ldr r0, .LCPI0_0
; THUMB2-NEXT: .LPC0_0:
; THUMB2-NEXT: add r0, pc
; THUMB2-NEXT: ldr r0, [r0]
; THUMB2-NEXT: ldr r0, [r0]
; THUMB2-NEXT: str.w r0, [sp, #1028]
; THUMB2-NEXT: add r0, sp, #4
; THUMB2-NEXT: bl foo
; THUMB2-NEXT: movw r1, :lower16:__stack_chk_guard
; THUMB2-NEXT: ldr.w r0, [sp, #1028]
; THUMB2-NEXT: movt r1, :upper16:__stack_chk_guard
; THUMB2-NEXT: ldr r1, .LCPI0_1
; THUMB2-NEXT: .LPC0_1:
; THUMB2-NEXT: add r1, pc
; THUMB2-NEXT: ldr r1, [r1]
; THUMB2-NEXT: ldr r1, [r1]
; THUMB2-NEXT: cmp r1, r0
Expand All @@ -155,6 +165,14 @@ define i32 @test1() #0 {
; THUMB2-NEXT: popeq {r7, pc}
; THUMB2-NEXT: .LBB0_1:
; THUMB2-NEXT: bl __stack_chk_fail
; THUMB2-NEXT: .p2align 2
; THUMB2-NEXT: @ %bb.2:
; THUMB2-NEXT: .LCPI0_0:
; THUMB2-NEXT: .Ltmp0:
; THUMB2-NEXT: .long __stack_chk_guard(GOT_PREL)-((.LPC0_0+4)-.Ltmp0)
; THUMB2-NEXT: .LCPI0_1:
; THUMB2-NEXT: .Ltmp1:
; THUMB2-NEXT: .long __stack_chk_guard(GOT_PREL)-((.LPC0_1+4)-.Ltmp1)
;
; THUMB2-PIC-LABEL: test1:
; THUMB2-PIC: @ %bb.0:
Expand Down