Discovered this while exploring packet filtering. The arm64 BPF JIT did not implement BPF_LD | BPF_ABS or BPF_LD | BPF_IND, so cBPF filters converted by rte_bpf_convert() could not be JIT compiled and silently fell back to the interpreter on arm64.
The first patch fixes a latent bug in emit_return_zero_if_src_zero(): the offset of the branch to the epilogue was held in an unsigned. A backward branch wrapped around. Existing JIT tests were never being run on ARM. The next two patches make the bpf tests assert that, on an architecture with a JITbackend, code is actually generated, so a missing or failed JIT is reported rather than skipped. The final patch adds the ABS/IND opcodes, mirroring the x86 JIT with a fast path for data in the first mbuf segment and a __rte_pktmbuf_read() slow path for the rest. Stephen Hemminger (4): bpf/arm64: fix zero-return branch in multi-exit programs test: bpf check that JIT was generated test: bpf check that bpf_convert can be JIT'd bpf/arm64: add BPF_ABS/BPF_IND packet load support app/test/test_bpf.c | 23 ++++++- lib/bpf/bpf_jit_arm64.c | 149 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 169 insertions(+), 3 deletions(-) -- 2.53.0
