On Thu, Sep 07, 2023 at 09:08:46AM +0000, Puranjay Mohan wrote: > On Thu, Sep 07 2023, Russell King (Oracle) wrote: > > > On Wed, Sep 06, 2023 at 06:33:16PM +0000, Puranjay Mohan wrote: > >> @@ -1633,8 +1633,10 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) > >> /* dst = htobe(dst) */ > >> case BPF_ALU | BPF_END | BPF_FROM_LE: > >> case BPF_ALU | BPF_END | BPF_FROM_BE: > >> + /* dst = bswap(dst) */ > >> + case BPF_ALU64 | BPF_END | BPF_TO_LE: > >> rd = arm_bpf_get_reg64(dst, tmp, ctx); > >> - if (BPF_SRC(code) == BPF_FROM_LE) > >> + if (BPF_SRC(code) == BPF_FROM_LE && BPF_CLASS(code) != BPF_ALU64) > > > > With the addition of the BPF_ALU64 case, I'm wondering why this if() is > > affected. If you were adding: > > > > case BPF_ALU64 | BPF_END | BPF_FROM_LE: > > > > then maybe there would be a reason, but the BPF_ALU64 | BPF_END | > > BPF_TO_LE case will never match even the original if() statement. > > The reason is that these mean the same thing. > from: include/uapi/linux/bpf.h > > #define BPF_TO_LE 0x00 /* convert to little-endian */ > #define BPF_TO_BE 0x08 /* convert to big-endian */ > #define BPF_FROM_LE BPF_TO_LE > #define BPF_FROM_BE BPF_TO_BE > > So, to not cause confusion and follow the earlier cases I can add: > > case BPF_ALU64 | BPF_END | BPF_FROM_LE: > > in the next version. It might be worth adding a comment after each stating one of: /* also BPF_TO_LE */ /* also BPF_TO_BE */ as appropriate to make this more readable. Thanks. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
