On Thu, Aug 21, 2025 at 8:49 AM Jinyang He <hejinyang@xxxxxxxxxxx> wrote:
>
> On 2025-08-20 18:39, Hengqi Chen wrote:
>
> > The ns_bpf_qdisc selftest triggers a kernel panic:
> >
> [...]
> >
> > +/*
> > + * Sign-extend the register if necessary
> > + */
> > +static int sign_extend(struct jit_ctx *ctx, int r, u8 size)
> > +{
> > + switch (size) {
> > + case 1:
> > + emit_insn(ctx, sllid, r, r, 56);
> > + emit_insn(ctx, sraid, r, r, 56);
> > + return 0;
> > + case 2:
> > + emit_insn(ctx, sllid, r, r, 48);
> > + emit_insn(ctx, sraid, r, r, 48);
> > + return 0;
> Hi, Hengqi,
>
> For sign-extend char or short, we can use `ext.w.b` or `ext.w.h`.
>
Great. Will do.
>
> > + case 4:
> > + emit_insn(ctx, addiw, r, r, 0);
> > + return 0;
> > + case 8:
> > + return 0;
> > + default:
> > + return -1;
> > + }
> > +}
> > +
> > static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_image *im,
> > const struct btf_func_model *m, struct bpf_tramp_links *tlinks,
> > void *func_addr, u32 flags)
> > @@ -1602,8 +1628,8 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
> > }
> >
> > for (i = 0; i < fentry->nr_links; i++) {
> > - ret = invoke_bpf_prog(ctx, fentry->links[i], args_off, retval_off,
> > - run_ctx_off, flags & BPF_TRAMP_F_RET_FENTRY_RET);
> > + ret = invoke_bpf_prog(ctx, fentry->links[i], m, args_off, retval_off,
> > + run_ctx_off, flags & BPF_TRAMP_F_RET_FENTRY_RET);
> > if (ret)
> > return ret;
> > }
> > @@ -1612,7 +1638,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
> > if (!branches)
> > return -ENOMEM;
> >
> > - invoke_bpf_mod_ret(ctx, fmod_ret, args_off, retval_off, run_ctx_off, branches);
> > + invoke_bpf_mod_ret(ctx, fmod_ret, m, args_off, retval_off, run_ctx_off, branches);
> > }
> >
> > if (flags & BPF_TRAMP_F_CALL_ORIG) {
> > @@ -1638,7 +1664,8 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
> > }
> >
> > for (i = 0; i < fexit->nr_links; i++) {
> > - ret = invoke_bpf_prog(ctx, fexit->links[i], args_off, retval_off, run_ctx_off, false);
> > + ret = invoke_bpf_prog(ctx, fexit->links[i], m, args_off,
> > + retval_off, run_ctx_off, false);
> > if (ret)
> > goto out;
> > }
> > @@ -1657,6 +1684,12 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
> > if (save_ret) {
> > emit_insn(ctx, ldd, LOONGARCH_GPR_A0, LOONGARCH_GPR_FP, -retval_off);
> > emit_insn(ctx, ldd, regmap[BPF_REG_0], LOONGARCH_GPR_FP, -(retval_off - 8));
> > + if (is_struct_ops) {
> > + move_reg(ctx, LOONGARCH_GPR_A0, regmap[BPF_REG_0]);
> > + ret = sign_extend(ctx, LOONGARCH_GPR_A0, m->ret_size);
> > + if (ret)
> > + goto out;
> > + }
> > }
> >
> > emit_insn(ctx, ldd, LOONGARCH_GPR_S1, LOONGARCH_GPR_FP, -sreg_off);
>
