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 62fa708ceb with fixed
tests.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D148385
67 lines
2.0 KiB
LLVM
67 lines
2.0 KiB
LLVM
; RUN: llc -mtriple=riscv32 -verify-machineinstrs -riscv-no-aliases < %s \
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; RUN: | FileCheck %s --check-prefixes=CHECK,RV32
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; RUN: llc -mtriple=riscv64 -verify-machineinstrs -riscv-no-aliases < %s \
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; RUN: | FileCheck %s --check-prefixes=CHECK,RV64
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; CHECK: .word 12345678
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define void @f1(ptr noundef %x) !kcfi_type !1 {
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; CHECK-LABEL: f1:
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; CHECK: # %bb.0:
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; CHECK: lw t1, -4(a0)
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; CHECK-NEXT: lui t2, 3014
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; RV32-NEXT: addi t2, t2, 334
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; RV64-NEXT: addiw t2, t2, 334
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; CHECK-NEXT: beq t1, t2, .Ltmp0
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; CHECK-NEXT: .Ltmp1:
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; CHECK-NEXT: ebreak
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; CHECK-NEXT: .section .kcfi_traps,"ao",@progbits,.text
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; CHECK-NEXT: .Ltmp2:
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; CHECK-NEXT: .word .Ltmp1-.Ltmp2
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; CHECK-NEXT: .text
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; CHECK-NEXT: .Ltmp0:
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; CHECK-NEXT: jalr ra, 0(a0)
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call void %x() [ "kcfi"(i32 12345678) ]
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; CHECK: lw t1, -4(s0)
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; CHECK-NEXT: addi t2, t2, 1234
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; CHECK-NEXT: beq t1, t2, .Ltmp3
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; CHECK-NEXT: .Ltmp4:
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; CHECK-NEXT: ebreak
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; CHECK-NEXT: .section .kcfi_traps,"ao",@progbits,.text
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; CHECK-NEXT: .Ltmp5:
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; CHECK-NEXT: .word .Ltmp4-.Ltmp5
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; CHECK-NEXT: .text
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; CHECK-NEXT: .Ltmp3:
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; CHECK-NEXT: jalr ra, 0(s0)
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call void %x() [ "kcfi"(i32 1234) ]
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ret void
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}
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; CHECK-NOT: .word:
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define void @f2(ptr noundef %x) #0 {
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; CHECK-LABEL: f2:
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; CHECK: # %bb.0:
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; CHECK-NEXT: addi zero, zero, 0
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; CHECK-NEXT: addi zero, zero, 0
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; CHECK-NEXT: lw t1, -4(a0)
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; CHECK-NEXT: lui t2, 3014
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; RV32-NEXT: addi t2, t2, 334
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; RV64-NEXT: addiw t2, t2, 334
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; CHECK-NEXT: beq t1, t2, .Ltmp6
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; CHECK-NEXT: .Ltmp7:
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; CHECK-NEXT: ebreak
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; CHECK-NEXT: .section .kcfi_traps,"ao",@progbits,.text
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; CHECK-NEXT: .Ltmp8:
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; CHECK-NEXT: .word .Ltmp7-.Ltmp8
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; CHECK-NEXT: .text
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; CHECK-NEXT: .Ltmp6:
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; CHECK-NEXT: jalr zero, 0(a0)
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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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