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[AArch64] Return address signing B key support 

- Add support to generate AUTIBSP, PACIBSP, RETAB instructions for return
  address signing
- The key used to sign the function is controlled by the function attribute
  "sign-return-address-key"

Differential Revision: https://reviews.llvm.org/D51427

llvm-svn: 345511
This commit is contained in:
Luke Cheeseman 2018-10-29 16:26:58 +00:00
parent e2806f857b
commit 71c989ae1f
2 changed files with 43 additions and 3 deletions
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23
llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
View File

@ -597,6 +597,17 @@ static void adaptForLdStOpt(MachineBasicBlock &MBB,
//
}
static bool ShouldSignWithAKey(MachineFunction &MF) {
const Function &F = MF.getFunction();
if (!F.hasFnAttribute("sign-return-address-key"))
return true;
const StringRef Key =
F.getFnAttribute("sign-return-address-key").getValueAsString();
assert(Key.equals_lower("a_key") || Key.equals_lower("b_key"));
return Key.equals_lower("a_key");
}
void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.begin();
@ -620,7 +631,9 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
DebugLoc DL;
if (ShouldSignReturnAddress(MF)) {
BuildMI(MBB, MBBI, DL, TII->get(AArch64::PACIASP))
BuildMI(
MBB, MBBI, DL,
TII->get(ShouldSignWithAKey(MF) ? AArch64::PACIASP : AArch64::PACIBSP))
.setMIFlag(MachineInstr::FrameSetup);
}
@ -907,10 +920,14 @@ static void InsertReturnAddressAuth(MachineFunction &MF,
// instructions, namely RETA{A,B}, that can be used instead.
if (Subtarget.hasV8_3aOps() && MBBI != MBB.end() &&
MBBI->getOpcode() == AArch64::RET_ReallyLR) {
BuildMI(MBB, MBBI, DL, TII->get(AArch64::RETAA)).copyImplicitOps(*MBBI);
BuildMI(MBB, MBBI, DL,
TII->get(ShouldSignWithAKey(MF) ? AArch64::RETAA : AArch64::RETAB))
.copyImplicitOps(*MBBI);
MBB.erase(MBBI);
} else {
BuildMI(MBB, MBBI, DL, TII->get(AArch64::AUTIASP))
BuildMI(
MBB, MBBI, DL,
TII->get(ShouldSignWithAKey(MF) ? AArch64::AUTIASP : AArch64::AUTIBSP))
.setMIFlag(MachineInstr::FrameDestroy);
}
}

23
llvm/test/CodeGen/AArch64/sign-return-address.ll
View File

@ -84,3 +84,26 @@ define fastcc void @spill_lr_and_tail_call(i64 %x) "sign-return-address"="all" {
tail call fastcc i64 @bar(i64 %x)
ret void
}
; CHECK-LABEL: @leaf_sign_all_a_key
; CHECK: paciasp
; CHECK: autiasp
define i32 @leaf_sign_all_a_key(i32 %x) "sign-return-address"="all" "sign-return-address-key"="a_key" {
ret i32 %x
}
; CHECK-LABEL: @leaf_sign_all_b_key
; CHECK: pacibsp
; CHECK: autibsp
define i32 @leaf_sign_all_b_key(i32 %x) "sign-return-address"="all" "sign-return-address-key"="b_key" {
ret i32 %x
}
; CHECK-LABEL: @leaf_sign_all_v83_b_key
; CHECK: pacibsp
; CHECK-NOT: ret
; CHECK: retab
; CHECK-NOT: ret
define i32 @leaf_sign_all_v83_b_key(i32 %x) "sign-return-address"="all" "target-features"="+v8.3a" "sign-return-address-key"="b_key" {
ret i32 %x
}