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.