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| author | Jiong Wang <jiong.wang@netronome.com> | 2018-07-06 15:13:22 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-07-07 01:45:31 +0200 |
| commit | 2a952b03d1a011e2e7ddc9ca59cbb21df7dc3525 (patch) | |
| tree | 65fec3490f3538a15d1f35a89a806aec9cbe495b /drivers/net/ethernet/netronome/nfp/bpf/main.h | |
| parent | d3d23fdb4688de4421e94227c95b1d54b233f432 (diff) | |
| download | linux-2a952b03d1a011e2e7ddc9ca59cbb21df7dc3525.tar.bz2 | |
nfp: bpf: support u32 divide using reciprocal_div.h
NFP doesn't have integer divide instruction, this patch use reciprocal
algorithm (the basic one, reciprocal_div) to emulate it.
For each u32 divide, we would need 11 instructions to finish the operation.
7 (for multiplication) + 4 (various ALUs) = 11
Given NFP only supports multiplication no bigger than u32, we'd require
divisor and dividend no bigger than that as well.
Also eBPF doesn't support signed divide and has enforced this on C language
level by failing compilation. However LLVM assembler hasn't enforced this,
so it is possible for negative constant to leak in as a BPF_K operand
through assembly code, we reject such cases as well.
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'drivers/net/ethernet/netronome/nfp/bpf/main.h')
| -rw-r--r-- | drivers/net/ethernet/netronome/nfp/bpf/main.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h index c10079b1a312..9845c1a2d4c2 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/main.h +++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h @@ -399,6 +399,11 @@ static inline bool is_mbpf_mul(const struct nfp_insn_meta *meta) return is_mbpf_alu(meta) && mbpf_op(meta) == BPF_MUL; } +static inline bool is_mbpf_div(const struct nfp_insn_meta *meta) +{ + return is_mbpf_alu(meta) && mbpf_op(meta) == BPF_DIV; +} + /** * struct nfp_prog - nfp BPF program * @bpf: backpointer to the bpf app priv structure |