83835e22c7
With `-fsanitize=kcfi` (Kernel Control-Flow Integrity), Clang emits "kcfi" operand bundles to indirect call instructions. Similarly to the target-specific lowering added in D119296, implement KCFI operand bundle lowering for RISC-V. This patch disables the generic KCFI pass for RISC-V in Clang, and adds the KCFI machine function pass in `RISCVPassConfig::addPreSched` to emit target-specific `KCFI_CHECK` pseudo instructions before calls that have KCFI operand bundles. The machine function pass also bundles the instructions to ensure we emit the checks immediately before the calls, which is not possible with the generic pass. `KCFI_CHECK` instructions are lowered in `RISCVAsmPrinter` to a contiguous code sequence that traps if the expected hash in the operand bundle doesn't match the hash before the target function address. This patch emits an `ebreak` instruction for error handling to match the Linux kernel's `BUG()` implementation. Just like for X86, we also emit trap locations to a `.kcfi_traps` section to support error handling, as we cannot embed additional information to the trap instruction itself. Relands commit 62fa708ceb027713b386c7e0efda994f8bdc27e2 with fixed tests. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D148385
34 lines
1.2 KiB
LLVM
34 lines
1.2 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 2
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; RUN: llc -mtriple=riscv64 -stop-after=finalize-isel -verify-machineinstrs -o - %s | FileCheck %s
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define void @f1(ptr noundef %x) !kcfi_type !1 {
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; CHECK-LABEL: name: f1
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; CHECK: bb.0 (%ir-block.0):
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; CHECK-NEXT: liveins: $x10
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; CHECK-NEXT: {{ $}}
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; CHECK-NEXT: [[COPY:%[0-9]+]]:gprjalr = COPY $x10
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; CHECK-NEXT: ADJCALLSTACKDOWN 0, 0, implicit-def dead $x2, implicit $x2
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; CHECK-NEXT: PseudoCALLIndirect [[COPY]], csr_ilp32_lp64, implicit-def dead $x1, implicit-def $x2, cfi-type 12345678
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; CHECK-NEXT: ADJCALLSTACKUP 0, 0, implicit-def dead $x2, implicit $x2
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; CHECK-NEXT: PseudoRET
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call void %x() [ "kcfi"(i32 12345678) ]
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ret void
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}
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define void @f2(ptr noundef %x) #0 {
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; CHECK-LABEL: name: f2
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; CHECK: bb.0 (%ir-block.0):
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; CHECK-NEXT: liveins: $x10
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; CHECK-NEXT: {{ $}}
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; CHECK-NEXT: [[COPY:%[0-9]+]]:gprtc = COPY $x10
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; CHECK-NEXT: PseudoTAILIndirect [[COPY]], implicit $x2, cfi-type 12345678
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tail call void %x() [ "kcfi"(i32 12345678) ]
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ret void
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}
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attributes #0 = { "patchable-function-entry"="2" }
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!llvm.module.flags = !{!0}
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!0 = !{i32 4, !"kcfi", i32 1}
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!1 = !{i32 12345678}
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