diff options
Diffstat (limited to 'drivers/net/ethernet/netronome/nfp/bpf/jit.c')
| -rw-r--r-- | drivers/net/ethernet/netronome/nfp/bpf/jit.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c index f272247d1708..d4bf0e694541 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c @@ -328,7 +328,18 @@ __emit_shf(struct nfp_prog *nfp_prog, u16 dst, enum alu_dst_ab dst_ab, return; } - if (sc == SHF_SC_L_SHF) + /* NFP shift instruction has something special. If shift direction is + * left then shift amount of 1 to 31 is specified as 32 minus the amount + * to shift. + * + * But no need to do this for indirect shift which has shift amount be + * 0. Even after we do this subtraction, shift amount 0 will be turned + * into 32 which will eventually be encoded the same as 0 because only + * low 5 bits are encoded, but shift amount be 32 will fail the + * FIELD_PREP check done later on shift mask (0x1f), due to 32 is out of + * mask range. + */ + if (sc == SHF_SC_L_SHF && shift) shift = 32 - shift; insn = OP_SHF_BASE | |