[PATCH] D158425: [BPF] Check jump and memory offsets to avoid truncation

[Eduard Zingerman via Phabricator via llvm-commits]

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The following assembly code should issue two errors specifying that
both jump and load offsets are out of range:

  if r1 > r2 goto +100500
  r1 = *(u64 *)(r1 - 100500)

This commit updates BPFAsmParser to check that:

- offset specified for jump is either identifier (label) or a 16-bit signed constant;
- offset specified for memory operations is a signed 16-bit constant.

(Which matches expectations in the BPFELFObjectWriter and
 BPFMCCodeEmitter).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D158425

Files:
  llvm/lib/Target/BPF/AsmParser/BPFAsmParser.cpp
  llvm/lib/Target/BPF/BPFInstrInfo.td
  llvm/test/MC/BPF/bad-offsets.s
  llvm/test/MC/BPF/expr-offset.s

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