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7968749f42
Daniel reported a llvm-objdump segfault like below:
$ llvm-objdump -D bpf_xdp.o
...
0000000000000000 <.strtab>:
0: 00 63 69 6c 69 75 6d 5f <unknown>
1: 6c 62 36 5f 61 66 66 69 w2 <<= w6
...
(llvm-objdump: lib/Target/BPF/BPFGenAsmWriter.inc:1087: static const char*
llvm::BPFInstPrinter::getRegisterName(unsigned int): Assertion
`RegNo && RegNo < 25 && "Invalid register number!"' failed.
Stack dump:
0. Program arguments: llvm-objdump -D bpf_xdp.o
...
abort
...
llvm::BPFInstPrinter::getRegisterName(unsigned int)
llvm::BPFInstPrinter::printMemOperand(llvm::MCInst const*,
int, llvm::raw_ostream&, char const*)
llvm::BPFInstPrinter::printInstruction(llvm::MCInst const*,
unsigned long, llvm::raw_ostream&)
llvm::BPFInstPrinter::printInst(llvm::MCInst const*,
unsigned long, llvm::StringRef, llvm::MCSubtargetInfo const&,
llvm::raw_ostream&)
...
Basically, since -D enables disassembly for all sections, .strtab is also disassembled,
but some strings are decoded as legal instructions but with illegal register numbers.
When llvm-objdump tries to print register name for these illegal register numbers,
assertion and segfault happens.
The patch fixed the issue by returning fail for a disassembled insn if
that insn contains a reg operand with illegal reg number.
The insn will be printed as "<unknown>" instead of causing an assertion.
27 lines
739 B
LLVM
27 lines
739 B
LLVM
; RUN: llc -march=bpfel -filetype=obj -o - %s | llvm-objdump -D - | FileCheck %s
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;
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; Source:
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; /* *(u64 *)(r10 - 16) = r1 */
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; unsigned long long g = 0x00000000fff01a7bULL;
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; /* *(u64 *)(r15 - 16) = r1 */
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; unsigned long long h = 0x00000000fff01f7bULL;
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; int test() {
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; return 0;
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; }
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; Compilation flag:
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; clang -target bpf -O2 -S -emit-llvm t.c
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@g = dso_local local_unnamed_addr global i64 4293925499, align 8
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@h = dso_local local_unnamed_addr global i64 4293926779, align 8
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; Function Attrs: norecurse nounwind readnone
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define dso_local i32 @test() local_unnamed_addr {
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entry:
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ret i32 0
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}
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; CHECK-LABEL: section .data
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; CHECK-LABEL: g
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; CHECK: *(u64 *)(r10 - 16) = r1
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; CHECK-LABEL: h
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; CHECK: <unknown>
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