Messages in this thread | | | Date | Tue, 8 Nov 2022 15:12:30 -0800 | Subject | Re: [PATCH bpf v2 1/5] bpf: Adapt 32-bit return value kfunc for 32-bit ARM when zext extension | From | Martin KaFai Lau <> |
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On 11/7/22 1:20 AM, Yang Jihong wrote: > For ARM32 architecture, if data width of kfunc return value is 32 bits, > need to do explicit zero extension for high 32-bit, insn_def_regno should > return dst_reg for BPF_JMP type of BPF_PSEUDO_KFUNC_CALL. Otherwise, > opt_subreg_zext_lo32_rnd_hi32 returns -EFAULT, resulting in BPF failure. > > Signed-off-by: Yang Jihong <yangjihong1@huawei.com> > --- > kernel/bpf/verifier.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 7f0a9f6cb889..bac37757ffca 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -2404,6 +2404,9 @@ static int insn_def_regno(const struct bpf_insn *insn) > { > switch (BPF_CLASS(insn->code)) { > case BPF_JMP: > + if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) > + return insn->dst_reg;
This does not look right. A kfunc can return void. The btf type of the kfunc's return value needs to be checked against "void" first? Also, this will affect insn_has_def32(), does is_reg64 (called from insn_has_def32) need to be adjusted also?
For patch 2, as replied earlier in v1, I would separate out the prog that does __sk_buff->sk and use the uapi's bpf.h instead of vmlinux.h since it does not need CO-RE.
This set should target for bpf-next instead of bpf.
> + fallthrough; > case BPF_JMP32: > case BPF_ST: > return -1;
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