linux-kernel - Re: [PATCH bpf-next v3 2/3] bpf, riscv: add fsession support for trampolines

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJ+HfNj5JZJ-k5bJibSgLPD5xnTzf7kfvma4kJOBKoNTnSLLDg@mail.gmail.com>
Date: Fri, 6 Feb 2026 14:42:22 +0100
From: Björn Töpel <bjorn@...nel.org>
To: menglong8.dong@...il.com
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	martin.lau@...ux.dev, eddyz87@...il.com, song@...nel.org, 
	yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org, 
	sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org, pulehui@...wei.com, 
	puranjay@...nel.org, pjw@...nel.org, palmer@...belt.com, 
	aou@...s.berkeley.edu, alex@...ti.fr, bpf@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	jiang.biao@...ux.dev, martin.lau@...nel.org, clm@...a.com, 
	ihor.solodrai@...ux.dev
Subject: Re: [PATCH bpf-next v3 2/3] bpf, riscv: add fsession support for trampolines

Menglong!

On Fri, 6 Feb 2026 at 13:51, <bot+bpf-ci@...nel.org> wrote:
>
> > diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
> > --- a/arch/riscv/net/bpf_jit_comp64.c
> > +++ b/arch/riscv/net/bpf_jit_comp64.c
>
> [ ... ]
>
> > +static int invoke_bpf(struct bpf_tramp_links *tl, int args_off, int retval_off,
> > +                   int run_ctx_off, int func_meta_off, bool save_ret, u64 func_meta,
> > +                   int cookie_off, struct rv_jit_context *ctx)
> > +{
> > +     int i, cur_cookie = (cookie_off - args_off) / 8;
> > +
> > +     for (i = 0; i < tl->nr_links; i++) {
> > +             int err;
> > +
> > +             if (bpf_prog_calls_session_cookie(&tl->links[i])) {
>                                                 ^^^^^^^^^^^^^^
>
> Should this be tl->links[i] instead of &tl->links[i]?
>
> The function bpf_prog_calls_session_cookie() expects a struct bpf_tramp_link
> pointer, but tl->links is an array of pointers, so tl->links[i] is already
> a struct bpf_tramp_link pointer. The extra & passes a pointer-to-pointer.
>
> For comparison, arm64 uses:
>
>     if (bpf_prog_calls_session_cookie(fentry->links[i]))
>
> And include/linux/bpf.h uses:
>
>     if (bpf_prog_calls_session_cookie(fentries.links[i]))
>
> Both without the &.
>
> > +                     u64 meta = func_meta | ((u64)cur_cookie << BPF_TRAMP_COOKIE_INDEX_SHIFT);
> > +
> > +                     emit_store_stack_imm64(RV_REG_T1, -func_meta_off, meta, ctx);
> > +                     cur_cookie--;
> > +             }
> > +             err = invoke_bpf_prog(tl->links[i], args_off, retval_off, run_ctx_off,
> > +                                   save_ret, ctx);
>
> Note that invoke_bpf_prog() correctly uses tl->links[i] without the &.

Menglong, the v3 doesn't build. Please refrain from just stressing
versions out. For v4, make sure you properly build/test. On that note;
on what hardware/simulator did you perform the tests on?