forked from OSchip/llvm-project
56db145164
If the offset cannot fit into the instruction, an addition to the
pointer is emitted before the actual access. However, BPF offsets are
16-bit but LLVM considers them to be, for the matter of this check,
to be 32-bit long.
This causes the following program:
int bpf_prog1(void *ign)
{
volatile unsigned long t = 0x8983984739ull;
return *(unsigned long *)((0xffffffff8fff0002ull) + t);
}
To generate the following (wrong) code:
0: 18 01 00 00 39 47 98 83 00 00 00 00 89 00 00 00
r1 = 590618314553ll
2: 7b 1a f8 ff 00 00 00 00 *(u64 *)(r10 - 8) = r1
3: 79 a1 f8 ff 00 00 00 00 r1 = *(u64 *)(r10 - 8)
4: 79 10 02 00 00 00 00 00 r0 = *(u64 *)(r1 + 2)
5: 95 00 00 00 00 00 00 00 exit
Fix it by changing the offset check to 16-bit.
Patch by Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Differential Revision: https://reviews.llvm.org/D32055
llvm-svn: 300269
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||
|---|---|---|
| .. | ||
| Disassembler | ||
| InstPrinter | ||
| MCTargetDesc | ||
| TargetInfo | ||
| BPF.h | ||
| BPF.td | ||
| BPFAsmPrinter.cpp | ||
| BPFCallingConv.td | ||
| BPFFrameLowering.cpp | ||
| BPFFrameLowering.h | ||
| BPFISelDAGToDAG.cpp | ||
| BPFISelLowering.cpp | ||
| BPFISelLowering.h | ||
| BPFInstrFormats.td | ||
| BPFInstrInfo.cpp | ||
| BPFInstrInfo.h | ||
| BPFInstrInfo.td | ||
| BPFMCInstLower.cpp | ||
| BPFMCInstLower.h | ||
| BPFRegisterInfo.cpp | ||
| BPFRegisterInfo.h | ||
| BPFRegisterInfo.td | ||
| BPFSubtarget.cpp | ||
| BPFSubtarget.h | ||
| BPFTargetMachine.cpp | ||
| BPFTargetMachine.h | ||
| CMakeLists.txt | ||
| LLVMBuild.txt | ||