On Thu, Sep 21, 2017 at 04:09:34PM +0100, Edward Cree wrote:
> print_bpf_insn() was treating all BPF_ALU[64] the same, but BPF_END has a
> different structure: it has a size in insn->imm (even if it's BPF_X) and
> uses the BPF_SRC (X or K) to indicate which endianness to use. So it
> needs different code to print it.
>
> Signed-off-by: Edward Cree <ec...@solarflare.com>
> ---
> It's not the same format as the new LLVM asm uses, does that matter?
> AFAIK the LLVM format doesn't comprehend BPF_TO_LE, just assumes that all
> endian ops are necessarily swaps (rather than sometimes nops).
that is being fixed and we will fix asm format too.
Let's pick good format first.
> kernel/bpf/verifier.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 799b245..e7657a4 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -331,20 +331,29 @@ static void print_bpf_insn(const struct
> bpf_verifier_env *env,
> u8 class = BPF_CLASS(insn->code);
>
> if (class == BPF_ALU || class == BPF_ALU64) {
> - if (BPF_SRC(insn->code) == BPF_X)
> + if (BPF_OP(insn->code) == BPF_END) {
> + if (class == BPF_ALU64)
> + verbose("BUG_alu64_%02x\n", insn->code);
> + else
> + verbose("(%02x) (u%d) r%d %s %s\n",
> + insn->code, insn->imm, insn->dst_reg,
> + bpf_alu_string[BPF_END >> 4],
> + BPF_SRC(insn->code) == BPF_X ? "be" :
> "le");
yes the bit the same, but please use BPF_SRC(insn->code) == BPF_TO_BE.
imo
(u16) r4 endian be
isn't intuitive.
Can we come up with some better syntax?
Like
bswap16be r4
bswap32le r4
or
to_be16 r4
to_le32 r4
It will be more obvious what's happening.
