linux-kernel - Re: [PATCH] tracing/probe: Fix bpf_task_fd

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Date:   Tue, 9 Jun 2020 16:12:34 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Jean-Philippe Brucker <jean-philippe@...aro.org>
Cc:     linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        mhiramat@...nel.org, rostedt@...dmis.org, mingo@...hat.com,
        ast@...nel.org, daniel@...earbox.net, kafai@...com,
        songliubraving@...com, yhs@...com, andriin@...com,
        john.fastabend@...il.com, kpsingh@...omium.org
Subject: Re: [PATCH] tracing/probe: Fix bpf_task_fd_query() for kprobes and
 uprobes

On Mon,  8 Jun 2020 14:45:32 +0200
Jean-Philippe Brucker <jean-philippe@...aro.org> wrote:

> Commit 60d53e2c3b75 ("tracing/probe: Split trace_event related data from
> trace_probe") removed the trace_[ku]probe structure from the
> trace_event_call->data pointer. As bpf_get_[ku]probe_info() were
> forgotten in that change, fix them now. These functions are currently
> only used by the bpf_task_fd_query() syscall handler to collect
> information about a perf event.
> 

Oops, good catch!

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>


> Fixes: 60d53e2c3b75 ("tracing/probe: Split trace_event related data from trace_probe")
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@...aro.org>

Cc: stable@...r.kernel.org


Thank you!

> ---
> Found while trying to run the task_fd_query BPF sample. I intend to try
> and move that sample to kselftests since it seems like a useful
> regression test.
> ---
>  kernel/trace/trace_kprobe.c | 2 +-
>  kernel/trace/trace_uprobe.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 35989383ae113..8eeb95e04bf52 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -1629,7 +1629,7 @@ int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
>  	if (perf_type_tracepoint)
>  		tk = find_trace_kprobe(pevent, group);
>  	else
> -		tk = event->tp_event->data;
> +		tk = trace_kprobe_primary_from_call(event->tp_event);
>  	if (!tk)
>  		return -EINVAL;
>  
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 2a8e8e9c1c754..fdd47f99b18fd 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -1412,7 +1412,7 @@ int bpf_get_uprobe_info(const struct perf_event *event, u32 *fd_type,
>  	if (perf_type_tracepoint)
>  		tu = find_probe_event(pevent, group);
>  	else
> -		tu = event->tp_event->data;
> +		tu = trace_uprobe_primary_from_call(event->tp_event);
>  	if (!tu)
>  		return -EINVAL;
>  
> -- 
> 2.27.0
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>