linux-kernel - Re: [PATCH bpf-next v3 3/6] bpf: fix the usage of BPF_TRAMP_F_SKIP

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Message-ID: <878qeyedaw.fsf@igel.home>
Date: Fri, 19 Dec 2025 15:50:15 +0100
From: Andreas Schwab <schwab@...ux-m68k.org>
To: Menglong Dong <menglong8.dong@...il.com>
Cc: Menglong Dong <menglong.dong@...ux.dev>,  ast@...nel.org,
  rostedt@...dmis.org,  daniel@...earbox.net,  john.fastabend@...il.com,
  andrii@...nel.org,  martin.lau@...ux.dev,  eddyz87@...il.com,
  song@...nel.org,  yonghong.song@...ux.dev,  kpsingh@...nel.org,
  sdf@...ichev.me,  haoluo@...gle.com,  jolsa@...nel.org,
  mhiramat@...nel.org,  mark.rutland@....com,
  mathieu.desnoyers@...icios.com,  jiang.biao@...ux.dev,
  bpf@...r.kernel.org,  linux-kernel@...r.kernel.org,
  linux-trace-kernel@...r.kernel.org,  linux-riscv@...ts.infradead.org
Subject: Re: [PATCH bpf-next v3 3/6] bpf: fix the usage of
 BPF_TRAMP_F_SKIP_FRAME

On Dez 19 2025, Menglong Dong wrote:

> @@ -1171,6 +1167,8 @@ static int __arch_prepare_bpf_trampoline(struct
> bpf_tramp_image *im,
>         }
>
>         if (flags & BPF_TRAMP_F_CALL_ORIG) {
> +               /* skip to actual body of traced function */
> +               orig_call += RV_FENTRY_NINSNS * 4;

Before this line, orig_call still contains the same value as func_addr,
with the latter being dead, so there is not much point in using a copy.

-- 
Andreas Schwab, schwab@...ux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."