On Sun, Mar 16, 2025 at 6:58 PM Hengqi Chen <hengqi.chen@xxxxxxxxx> wrote:
>
> Vincent reported that running XDP synproxy program on LoongArch
> results in the following error:
> JIT doesn't support bpf-to-bpf calls
> With dmesg:
> multi-func JIT bug 1391 != 1390
>
> The root cause is that verifier will refill the imm with the
> correct addresses of bpf_calls for BPF_PSEUDO_FUNC instructions
> and then run the last pass of JIT. So we generate different JIT
> code for the same instruction in two passes (one for placeholder
> and one for real address). Let's use move_addr() instead.
>
> See commit 64f50f657572 ("LoongArch, bpf: Use 4 instructions for
> function address in JIT") for a similar fix.
>
> Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper")
> Fixes: bb035ef0cc91 ("LoongArch: BPF: Support mixing bpf2bpf and tailcalls")
> Reported-by: Vincent Li <vincent.mc.li@xxxxxxxxx>
> Closes: https://lore.kernel.org/loongarch/CAK3+h2yfM9FTNiXvEQBkvtuoJrvzmN4c_NZsFXqEk4Cj1tsBNA@xxxxxxxxxxxxxx/T/#u
> Signed-off-by: Hengqi Chen <hengqi.chen@xxxxxxxxx>
> ---
> arch/loongarch/net/bpf_jit.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c
> index ea357a3edc09..b25b0bb43428 100644
> --- a/arch/loongarch/net/bpf_jit.c
> +++ b/arch/loongarch/net/bpf_jit.c
> @@ -930,7 +930,10 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext
> {
> const u64 imm64 = (u64)(insn + 1)->imm << 32 | (u32)insn->imm;
>
> - move_imm(ctx, dst, imm64, is32);
> + if (bpf_pseudo_func(insn))
> + move_addr(ctx, dst, imm64);
> + else
> + move_imm(ctx, dst, imm64, is32);
> return 1;
> }
>
> --
> 2.43.5
>
Thanks Hengqi for the quick fix! tested and verified working now.
[root@fedora xdp-tools]# uname -a
Linux fedora 6.14.0-rc5 #2 SMP PREEMPT_DYNAMIC Sun Mar 16 17:16:21 PDT
2025 loongarch64 GNU/Linux
[root@fedora xdp-tools]# ./xdp-loader/xdp-loader load -vvv lo -m skb
-P 80 -p /sys/fs/bpf/xdp-synproxy-tailcall -n synproxy_tailcall
./xdp-synproxy-tailcall/xdp_synproxy_tailcall.bpf.o
Current rlimit 8388608 already >= minimum 1048576
Loading 1 files on interface 'lo'.
libbpf: loading object from
./xdp-synproxy-tailcall/xdp_synproxy_tailcall.bpf.o
...
libbpf: map 'tail_call_tbl': created successfully, fd=4
libbpf: pinned map '/sys/fs/bpf/xdp-synproxy-tailcall/tail_call_tbl'
libbpf: found no pinned map to reuse at
'/sys/fs/bpf/xdp-synproxy-tailcall/values'
libbpf: map 'values': created successfully, fd=5
libbpf: pinned map '/sys/fs/bpf/xdp-synproxy-tailcall/values'
libbpf: found no pinned map to reuse at
'/sys/fs/bpf/xdp-synproxy-tailcall/allowed_ports'
libbpf: map 'allowed_ports': created successfully, fd=6
libbpf: pinned map '/sys/fs/bpf/xdp-synproxy-tailcall/allowed_ports'
libbpf: map 'xdp_synp.rodata': created successfully, fd=7
libbpf: map 'tail_call_tbl': slot [0] set to prog 'syncookie_xdp' fd=65
libxdp: Loaded XDP program synproxy_tailcall, got fd 66
libxdp: Duplicated fd 66 to 3 for prog synproxy_tailcall
libxdp: Replacing XDP fd -1 with 3 on ifindex 1
[root@fedora xdp-tools]# bpftool prog
...
55: xdp name syncookie_xdp tag 1426f5e6593da050 gpl
loaded_at 2025-03-16T19:38:49-0700 uid 0
xlated 8392B jited 6412B memlock 16384B map_ids 11,10,12
btf_id 75
56: xdp name synproxy_tailcall tag 0433e599459b925f gpl
loaded_at 2025-03-16T19:38:49-0700 uid 0
xlated 192B jited 328B memlock 16384B map_ids 9,12
btf_id 75
