[llvm] [ARM] Fix __stack_chk_guard access when non-zero "PIC Level" is used with static relocation model (PR #70014)
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 24 01:25:28 PDT 2023
https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/70014
The ELF code from https://reviews.llvm.org/D112811 emits LDRLIT_ga_pcrel when `TM.isPositionIndependent()`
but uses a different condition `Subtarget.isGVIndirectSymbol(GV)` (aka dso_preemptable on ELF targets).
This is not correct when non-zero "PIC Level" is used with static relocation
model, which is the case using -fPIE/-fPIC LTO compiles with -no-pie linking.
To fix this, prefer `!TM.shouldAssumeDSOLocal` to decide whether
`__stack_chk_guard` accesses are GOT-indirect. Using GOT-indirection matches
other targets.
Due to using `TM.shouldAssumeDSOLocal`, this patch also changes Mach-O
-mdynamic-no-pic to be like -fpic instead of -fno-pic, which I think is fine.
Fix #64999
>From e147b7150408c340e0426140361677f834bb06cc Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Mon, 23 Oct 2023 23:43:48 -0700
Subject: [PATCH] [ARM] Fix __stack_chk_guard access when non-zero "PIC Level"
is used with static relocation model
The ELF code from https://reviews.llvm.org/D112811 emits LDRLIT_ga_pcrel when `TM.isPositionIndependent()`
but uses a different condition `Subtarget.isGVIndirectSymbol(GV)` (aka dso_preemptable on ELF targets).
This is not correct when non-zero "PIC Level" is used with static relocation
model, which is the case using -fPIE/-fPIC LTO compiles with -no-pie linking.
To fix this, prefer `!TM.shouldAssumeDSOLocal` to decide whether
`__stack_chk_guard` accesses are GOT-indirect. Using GOT-indirection matches
other targets.
Due to using `TM.shouldAssumeDSOLocal`, this patch also changes Mach-O
-mdynamic-no-pic to be like -fpic instead of -fno-pic, which I think is fine.
Fix #64999
---
llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp | 2 +-
llvm/lib/Target/ARM/ARMInstrInfo.cpp | 9 +++++----
llvm/test/CodeGen/ARM/stack_guard_remat.ll | 16 ++++++++++------
llvm/test/LTO/ARM/ssp-static-reloc.ll | 3 ++-
4 files changed, 18 insertions(+), 12 deletions(-)
diff --git a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 1ffdde0360cf623..4c78379ccf5c467 100644
--- a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -4978,7 +4978,7 @@ void ARMBaseInstrInfo::expandLoadStackGuardBase(MachineBasicBlock::iterator MI,
TargetFlags |= ARMII::MO_DLLIMPORT;
else if (IsIndirect)
TargetFlags |= ARMII::MO_COFFSTUB;
- } else if (Subtarget.isGVInGOT(GV)) {
+ } else if (IsIndirect) {
TargetFlags |= ARMII::MO_GOT;
}
diff --git a/llvm/lib/Target/ARM/ARMInstrInfo.cpp b/llvm/lib/Target/ARM/ARMInstrInfo.cpp
index 00db13f2eb520d7..1199e6f1981cca6 100644
--- a/llvm/lib/Target/ARM/ARMInstrInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMInstrInfo.cpp
@@ -104,11 +104,12 @@ void ARMInstrInfo::expandLoadStackGuard(MachineBasicBlock::iterator MI) const {
const GlobalValue *GV =
cast<GlobalValue>((*MI->memoperands_begin())->getValue());
- if (!Subtarget.useMovt() || Subtarget.isGVInGOT(GV)) {
- if (TM.isPositionIndependent())
- expandLoadStackGuardBase(MI, ARM::LDRLIT_ga_pcrel, ARM::LDRi12);
- else
+ if (!Subtarget.useMovt() ||
+ (Subtarget.isTargetELF() && !TM.shouldAssumeDSOLocal(M, GV))) {
+ if (TM.shouldAssumeDSOLocal(M, GV))
expandLoadStackGuardBase(MI, ARM::LDRLIT_ga_abs, ARM::LDRi12);
+ else
+ expandLoadStackGuardBase(MI, ARM::LDRLIT_ga_pcrel, ARM::LDRi12);
return;
}
diff --git a/llvm/test/CodeGen/ARM/stack_guard_remat.ll b/llvm/test/CodeGen/ARM/stack_guard_remat.ll
index ad40212c9b6f1d0..8904884e3d4f444 100644
--- a/llvm/test/CodeGen/ARM/stack_guard_remat.ll
+++ b/llvm/test/CodeGen/ARM/stack_guard_remat.ll
@@ -1,9 +1,11 @@
-; RUN: llc < %s -mtriple=arm-apple-ios -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=PIC
-; RUN: llc < %s -mtriple=arm-apple-ios -relocation-model=static -no-integrated-as | FileCheck %s -check-prefix=NO-PIC -check-prefix=STATIC
-; RUN: llc < %s -mtriple=arm-apple-ios -relocation-model=dynamic-no-pic -no-integrated-as | FileCheck %s -check-prefix=NO-PIC -check-prefix=DYNAMIC-NO-PIC
-; RUN: llc < %s -mtriple=armv7-apple-ios -mcpu=cortex-a8 -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=PIC-V7
-; RUN: llc < %s -mtriple=armv7-apple-ios -mcpu=cortex-a8 -relocation-model=static -no-integrated-as | FileCheck %s -check-prefix=STATIC-V7
-; RUN: llc < %s -mtriple=armv7-apple-ios -mcpu=cortex-a8 -relocation-model=dynamic-no-pic -no-integrated-as | FileCheck %s -check-prefix=DYNAMIC-NO-PIC-V7
+; RUN: rm -rf %t && split-file %s %t && cd %t
+; RUN: cat main.ll pic-flag.ll > pic.ll
+; RUN: llc < pic.ll -mtriple=arm-apple-ios -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=PIC
+; RUN: llc < main.ll -mtriple=arm-apple-ios -relocation-model=static -no-integrated-as | FileCheck %s -check-prefix=NO-PIC -check-prefix=STATIC
+; RUN: llc < main.ll -mtriple=arm-apple-ios -relocation-model=dynamic-no-pic -no-integrated-as | FileCheck %s -check-prefix=PIC
+; RUN: llc < pic.ll -mtriple=armv7-apple-ios -mcpu=cortex-a8 -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=PIC-V7
+; RUN: llc < main.ll -mtriple=armv7-apple-ios -mcpu=cortex-a8 -relocation-model=static -no-integrated-as | FileCheck %s -check-prefix=STATIC-V7
+; RUN: llc < main.ll -mtriple=armv7-apple-ios -mcpu=cortex-a8 -relocation-model=dynamic-no-pic -no-integrated-as | FileCheck %s -check-prefix=DYNAMIC-NO-PIC-V7
;PIC: foo2
;PIC: ldr [[R0:r[0-9]+]], [[LABEL0:LCPI[0-9_]+]]
@@ -47,6 +49,7 @@
;DYNAMIC-NO-PIC-V7: L___stack_chk_guard$non_lazy_ptr:
;DYNAMIC-NO-PIC-V7: .indirect_symbol ___stack_chk_guard
+;--- main.ll
; Function Attrs: nounwind ssp
define i32 @test_stack_guard_remat() #0 {
%a1 = alloca [256 x i32], align 4
@@ -67,5 +70,6 @@ declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
attributes #0 = { nounwind ssp "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+;--- pic-flag.ll
!llvm.module.flags = !{!0}
!0 = !{i32 7, !"PIC Level", i32 2}
diff --git a/llvm/test/LTO/ARM/ssp-static-reloc.ll b/llvm/test/LTO/ARM/ssp-static-reloc.ll
index c8825c2aae0fbb6..2ea6977ef78e752 100644
--- a/llvm/test/LTO/ARM/ssp-static-reloc.ll
+++ b/llvm/test/LTO/ARM/ssp-static-reloc.ll
@@ -19,11 +19,12 @@ entry:
; CHECK: <foo>:
; CHECK: [[#%x,CURPC:]]:{{.*}} ldr r[[REG1:[0-9]+]], [pc, #0x[[#%x,OFFSET:]]]
+; CHECK-NEXT: add r0, pc, r0
; CHECK-NEXT: ldr r[[REG2:[0-9]+]], [r[[REG1]]]
; CHECK-NEXT: ldr r[[REG3:[0-9]+]], [r[[REG2]]]
; CHECK-NEXT: str r[[REG3]],
; CHECK: [[#CURPC + OFFSET + 8]]:{{.*}}.word
-; CHECK-NEXT: R_ARM_ABS32 __stack_chk_guard
+; CHECK-NEXT: R_ARM_GOT_PREL __stack_chk_guard
declare void @llvm.memset.p0.i32(ptr nocapture writeonly, i8, i32, i1 immarg)
More information about the llvm-commits
mailing list