From: Menglong Dong <menglong.dong@linux.dev>
To: Menglong Dong <menglong8.dong@gmail.com>, Jiri Olsa <olsajiri@gmail.com>
Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com,
andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com,
song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org,
sdf@fomichev.me, haoluo@google.com, mattbobrowski@google.com,
rostedt@goodmis.org, mhiramat@kernel.org,
mathieu.desnoyers@efficios.com, leon.hwang@linux.dev,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH RFC bpf-next 3/5] bpf,x86: add tracing session supporting for x86_64
Date: Mon, 20 Oct 2025 16:31:44 +0800 [thread overview]
Message-ID: <6206161.lOV4Wx5bFT@7950hx> (raw)
In-Reply-To: <aPXwlJ57B9egtr8x@krava>
On 2025/10/20 16:19, Jiri Olsa wrote:
> On Sat, Oct 18, 2025 at 10:21:22PM +0800, Menglong Dong wrote:
>
> SNIP
>
> > /* mov rax, qword ptr [rbp - rounded_stack_depth - 8] */
> > #define LOAD_TRAMP_TAIL_CALL_CNT_PTR(stack) \
> > __LOAD_TCC_PTR(-round_up(stack, 8) - 8)
> > @@ -3179,8 +3270,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
> > void *func_addr)
> > {
> > int i, ret, nr_regs = m->nr_args, stack_size = 0;
> > - int regs_off, nregs_off, ip_off, run_ctx_off, arg_stack_off, rbx_off;
> > + int regs_off, nregs_off, session_off, ip_off, run_ctx_off,
> > + arg_stack_off, rbx_off;
> > struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
> > + struct bpf_tramp_links *session = &tlinks[BPF_TRAMP_SESSION];
> > struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
> > struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN];
> > void *orig_call = func_addr;
> > @@ -3222,6 +3315,8 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
> > *
> > * RBP - nregs_off [ regs count ] always
> > *
> > + * RBP - session_off [ session flags ] tracing session
> > + *
> > * RBP - ip_off [ traced function ] BPF_TRAMP_F_IP_ARG flag
> > *
> > * RBP - rbx_off [ rbx value ] always
> > @@ -3246,6 +3341,8 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
> > /* regs count */
> > stack_size += 8;
> > nregs_off = stack_size;
> > + stack_size += 8;
> > + session_off = stack_size;
>
> should this depend on session->nr_links ?
Hmm...my mistake, it should. And this also break the bpf_get_func_ip(),
which I'll fix in the next version.
>
> jirka
>
> >
> > if (flags & BPF_TRAMP_F_IP_ARG)
> > stack_size += 8; /* room for IP address argument */
> > @@ -3345,6 +3442,13 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
> > return -EINVAL;
> > }
> >
> > + if (session->nr_links) {
> > + if (invoke_bpf_session_entry(m, &prog, session, regs_off,
> > + run_ctx_off, session_off,
> > + image, rw_image))
> > + return -EINVAL;
> > + }
> > +
> > if (fmod_ret->nr_links) {
> > branches = kcalloc(fmod_ret->nr_links, sizeof(u8 *),
> > GFP_KERNEL);
> > @@ -3409,6 +3513,15 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
> > }
> > }
> >
> > + if (session->nr_links) {
> > + if (invoke_bpf_session_exit(m, &prog, session, regs_off,
> > + run_ctx_off, session_off,
> > + image, rw_image)) {
> > + ret = -EINVAL;
> > + goto cleanup;
> > + }
> > + }
> > +
> > if (flags & BPF_TRAMP_F_RESTORE_REGS)
> > restore_regs(m, &prog, regs_off);
> >
>
>
next prev parent reply other threads:[~2025-10-20 8:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-18 14:21 [PATCH RFC bpf-next 0/5] bpf: tracing session supporting Menglong Dong
2025-10-18 14:21 ` [PATCH RFC bpf-next 1/5] bpf: add tracing session support Menglong Dong
2025-10-18 14:21 ` [PATCH RFC bpf-next 2/5] bpf: add kfunc bpf_tracing_is_exit for TRACE_SESSION Menglong Dong
2025-10-20 8:19 ` Jiri Olsa
2025-10-20 8:30 ` Menglong Dong
2025-10-18 14:21 ` [PATCH RFC bpf-next 3/5] bpf,x86: add tracing session supporting for x86_64 Menglong Dong
2025-10-19 2:03 ` Menglong Dong
2025-10-20 8:19 ` Jiri Olsa
2025-10-20 8:31 ` Menglong Dong [this message]
2025-10-21 18:16 ` Alexei Starovoitov
2025-10-22 1:05 ` Menglong Dong
2025-10-18 14:21 ` [PATCH RFC bpf-next 4/5] libbpf: add support for tracing session Menglong Dong
2025-10-18 14:21 ` [PATCH RFC bpf-next 5/5] selftests/bpf: add testcases " Menglong Dong
2025-10-20 8:19 ` Jiri Olsa
2025-10-20 8:40 ` Menglong Dong
2025-10-20 8:18 ` [PATCH RFC bpf-next 0/5] bpf: tracing session supporting Jiri Olsa
2025-10-20 8:55 ` Menglong Dong
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