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[BOLT][AArch64] Do not crash on authenticated branch instructions (#129898)

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When an indirect branch instruction is decoded, analyzeIndirectBranch
method is asked if this is a well-known code pattern. On AArch64, the
only special pattern which is detected is Jump Table, emitted as a
branch to the sum of a constant base address and a variable offset.
Therefore, `Inst.getOpcode()` being one of `AArch64::BRA*` means Inst
cannot belong to such Jump Table pattern, thus returning early.
This commit is contained in:
Anatoly Trosinenko 2025-03-17 12:00:05 +03:00 committed by GitHub
parent 8cc6c2e80f
commit 4f2ee07454
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GPG Key ID: B5690EEEBB952194
2 changed files with 39 additions and 1 deletions
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17
bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
View File

@ -547,6 +547,18 @@ public:
return false;
}
bool isBRA(const MCInst &Inst) const {
switch (Inst.getOpcode()) {
case AArch64::BRAA:
case AArch64::BRAB:
case AArch64::BRAAZ:
case AArch64::BRABZ:
return true;
default:
return false;
}
}
bool mayLoad(const MCInst &Inst) const override {
return isLDRB(Inst) || isLDRH(Inst) || isLDRW(Inst) || isLDRX(Inst) ||
isLDRQ(Inst) || isLDRD(Inst) || isLDRS(Inst);
@ -941,6 +953,11 @@ public:
DenseMap<const MCInst *, SmallVector<MCInst *, 4>> &UDChain,
const MCExpr *&JumpTable, int64_t &Offset, int64_t &ScaleValue,
MCInst *&PCRelBase) const {
// The only kind of indirect branches we match is jump table, thus ignore
// authenticating branch instructions early.
if (isBRA(Inst))
return false;
// Expect AArch64 BR
assert(Inst.getOpcode() == AArch64::BR && "Unexpected opcode");

23
bolt/test/AArch64/test-indirect-branch.s
View File

@ -5,7 +5,7 @@
// REQUIRES: system-linux, asserts
// RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown %s -o %t.o
// RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown -mattr=+pauth %s -o %t.o
// RUN: %clang %cflags --target=aarch64-unknown-linux %t.o -o %t.exe -Wl,-q
// RUN: llvm-bolt %t.exe -o %t.bolt --print-cfg --strict --debug-only=mcplus \
// RUN: -v=1 2>&1 | FileCheck %s
@ -73,6 +73,27 @@ test2_0:
test2_1:
ret
// Make sure BOLT does not crash trying to disassemble BRA* instructions.
.globl test_braa
.type test_braa, %function
test_braa:
braa x0, x1
.globl test_brab
.type test_brab, %function
test_brab:
brab x0, x1
.globl test_braaz
.type test_braaz, %function
test_braaz:
braaz x0
.globl test_brabz
.type test_brabz, %function
test_brabz:
brabz x0
.section .rodata,"a",@progbits
datatable:
.word test1_0-datatable