From 9f2b290addfc4d9f514790b47773b141682b0db5 Mon Sep 17 00:00:00 2001 From: Francis Visoiu Mistrih Date: Wed, 17 Jul 2019 20:46:19 +0000 Subject: [PATCH] [PEI] Don't re-allocate a pre-allocated stack protector slot The LocalStackSlotPass pre-allocates a stack protector and makes sure that it comes before the local variables on the stack. We need to make sure that later during PEI we don't re-allocate a new stack protector slot. If that happens, the new stack protector slot will end up being **after** the local variables that it should be protecting. Therefore, we would have two slots assigned for two different stack protectors, one at the top of the stack, and one at the bottom. Since PEI will overwrite the assigned slot for the stack protector, the load that is used to compare the value of the stack protector will use the slot assigned by PEI, which is wrong. For this, we need to check if the object is pre-allocated, and re-use that pre-allocated slot. Differential Revision: https://reviews.llvm.org/D64757 llvm-svn: 366371 --- llvm/lib/CodeGen/LocalStackSlotAllocation.cpp | 8 ++++++++ llvm/lib/CodeGen/PrologEpilogInserter.cpp | 21 +++++++++++++++++++-- llvm/test/CodeGen/AArch64/stack-guard-reassign.ll | 2 +- llvm/test/CodeGen/AArch64/stack-guard-reassign.mir | 4 ++-- llvm/test/CodeGen/AArch64/stack-guard-vaarg.ll | 2 +- llvm/test/CodeGen/ARM/stack-guard-reassign.ll | 6 +++--- llvm/test/CodeGen/PowerPC/stack-guard-reassign.ll | 4 +++- 7 files changed, 37 insertions(+), 10 deletions(-) diff --git a/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp b/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp index aa8f824..b14d76a 100644 --- a/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp +++ b/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp @@ -201,6 +201,14 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) { SmallSet ProtectedObjs; if (MFI.hasStackProtectorIndex()) { int StackProtectorFI = MFI.getStackProtectorIndex(); + + // We need to make sure we didn't pre-allocate the stack protector when + // doing this. + // If we already have a stack protector, this will re-assign it to a slot + // that is **not** covering the protected objects. + assert(!MFI.isObjectPreAllocated(StackProtectorFI) && + "Stack protector pre-allocated in LocalStackSlotAllocation"); + StackObjSet LargeArrayObjs; StackObjSet SmallArrayObjs; StackObjSet AddrOfObjs; diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp index dfbf665..d463bee 100644 --- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp +++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp @@ -933,8 +933,16 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &MF) { StackObjSet SmallArrayObjs; StackObjSet AddrOfObjs; - AdjustStackOffset(MFI, StackProtectorFI, StackGrowsDown, Offset, MaxAlign, - Skew); + // If we need a stack protector, we need to make sure that + // LocalStackSlotPass didn't already allocate a slot for it. + // If we are told to use the LocalStackAllocationBlock, the stack protector + // is expected to be already pre-allocated. + if (!MFI.getUseLocalStackAllocationBlock()) + AdjustStackOffset(MFI, StackProtectorFI, StackGrowsDown, Offset, MaxAlign, + Skew); + else if (!MFI.isObjectPreAllocated(MFI.getStackProtectorIndex())) + llvm_unreachable( + "Stack protector not pre-allocated by LocalStackSlotPass."); // Assign large stack objects first. for (unsigned i = 0, e = MFI.getObjectIndexEnd(); i != e; ++i) { @@ -968,6 +976,15 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &MF) { llvm_unreachable("Unexpected SSPLayoutKind."); } + // We expect **all** the protected stack objects to be pre-allocated by + // LocalStackSlotPass. If it turns out that PEI still has to allocate some + // of them, we may end up messing up the expected order of the objects. + if (MFI.getUseLocalStackAllocationBlock() && + !(LargeArrayObjs.empty() && SmallArrayObjs.empty() && + AddrOfObjs.empty())) + llvm_unreachable("Found protected stack objects not pre-allocated by " + "LocalStackSlotPass."); + AssignProtectedObjSet(LargeArrayObjs, ProtectedObjs, MFI, StackGrowsDown, Offset, MaxAlign, Skew); AssignProtectedObjSet(SmallArrayObjs, ProtectedObjs, MFI, StackGrowsDown, diff --git a/llvm/test/CodeGen/AArch64/stack-guard-reassign.ll b/llvm/test/CodeGen/AArch64/stack-guard-reassign.ll index a3b00fd..632774c 100644 --- a/llvm/test/CodeGen/AArch64/stack-guard-reassign.ll +++ b/llvm/test/CodeGen/AArch64/stack-guard-reassign.ll @@ -3,7 +3,7 @@ ; Verify that the offset assigned to the stack protector is at the top of the ; frame, covering the locals. ; CHECK-LABEL: fn: -; CHECK: add x8, sp, #24 +; CHECK: sub x8, x29, #24 ; CHECK-NEXT: adrp x9, __stack_chk_guard ; CHECK-NEXT: ldr x9, [x9, :lo12:__stack_chk_guard] ; CHECK-NEXT: str x9, [x8] diff --git a/llvm/test/CodeGen/AArch64/stack-guard-reassign.mir b/llvm/test/CodeGen/AArch64/stack-guard-reassign.mir index 296290e..c0dfcbc 100644 --- a/llvm/test/CodeGen/AArch64/stack-guard-reassign.mir +++ b/llvm/test/CodeGen/AArch64/stack-guard-reassign.mir @@ -11,13 +11,13 @@ name: main tracksRegLiveness: true frameInfo: -# CHECK: stackSize: 560 +# CHECK: stackSize: 544 stackProtector: '%stack.0.StackGuardSlot' stack: - { id: 0, name: StackGuardSlot, size: 8, alignment: 8, stack-id: default } # Verify that the offset assigned to the stack protector is at the top of the # frame, covering the locals. -# CHECK: - { id: 0, name: StackGuardSlot, type: default, offset: -552, size: 8, +# CHECK: - { id: 0, name: StackGuardSlot, type: default, offset: -24, size: 8, # CHECK-NEXT: alignment: 8, stack-id: default, callee-saved-register: '', callee-saved-restored: true, # CHECK-NEXT: local-offset: -8, debug-info-variable: '', debug-info-expression: '', # CHECK-NEXT: debug-info-location: '' } diff --git a/llvm/test/CodeGen/AArch64/stack-guard-vaarg.ll b/llvm/test/CodeGen/AArch64/stack-guard-vaarg.ll index e083aa1..29e66d9 100644 --- a/llvm/test/CodeGen/AArch64/stack-guard-vaarg.ll +++ b/llvm/test/CodeGen/AArch64/stack-guard-vaarg.ll @@ -9,7 +9,7 @@ ; CHECK: ldr [[GUARD:x[0-9]+]]{{.*}}:lo12:__stack_chk_guard] ; Make sure the canary is placed relative to the frame pointer, not ; the stack pointer. -; CHECK: str [[GUARD]], [sp, #8] +; CHECK: stur [[GUARD]], [x29, #-24] define void @test(i8* %i, ...) #0 { entry: %buf = alloca [10 x i8], align 1 diff --git a/llvm/test/CodeGen/ARM/stack-guard-reassign.ll b/llvm/test/CodeGen/ARM/stack-guard-reassign.ll index ae3d913..2ce1d15 100644 --- a/llvm/test/CodeGen/ARM/stack-guard-reassign.ll +++ b/llvm/test/CodeGen/ARM/stack-guard-reassign.ll @@ -3,12 +3,12 @@ ; Verify that the offset assigned to the stack protector is at the top of the ; frame, covering the locals. ; CHECK-LABEL: fn: -; CHECK: sub sp, sp, #40 +; CHECK: sub sp, sp, #32 ; CHECK-NEXT: sub sp, sp, #65536 -; CHECK-NEXT: add r1, sp, #28 +; CHECK-NEXT: add lr, sp, #65536 +; CHECK-NEXT: add r1, lr, #28 ; CHECK-NEXT: ldr r2, .LCPI0_0 ; CHECK-NEXT: ldr r3, [r2] ; CHECK-NEXT: str r3, [r1] -; CHECK-NEXT: str r0, [sp, #32] ; CHECK: .LCPI0_0: ; CHECK-NEXT: .long __stack_chk_guard diff --git a/llvm/test/CodeGen/PowerPC/stack-guard-reassign.ll b/llvm/test/CodeGen/PowerPC/stack-guard-reassign.ll index 3a8cac5..8128b63 100644 --- a/llvm/test/CodeGen/PowerPC/stack-guard-reassign.ll +++ b/llvm/test/CodeGen/PowerPC/stack-guard-reassign.ll @@ -9,7 +9,9 @@ ; CHECK-NEXT: ori 0, 0, 65488 ; CHECK-NEXT: stwux 1, 1, 0 ; CHECK-NEXT: subf 0, 0, 1 -; CHECK-NEXT: addi 4, 1, 36 +; CHECK-NEXT: lis 4, 1 +; CHECK-NEXT: ori 4, 4, 44 +; CHECK-NEXT: add 4, 1, 4 ; CHECK-NEXT: lis 5, __stack_chk_guard@ha ; CHECK-NEXT: lwz 6, __stack_chk_guard@l(5) ; CHECK-NEXT: stw 6, 0(4) -- 2.7.4