From: Sven Schnelle <svens@linux.ibm.com>
To: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Florent Revest <revest@chromium.org>,
linux-trace-kernel@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Jiri Olsa <jolsa@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Alan Maguire <alan.maguire@oracle.com>,
Mark Rutland <mark.rutland@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v4 4/9] fprobe: rethook: Use ftrace_regs in fprobe exit handler and rethook
Date: Mon, 11 Sep 2023 09:55:09 +0200 [thread overview]
Message-ID: <yt9dy1hdi1pe.fsf@linux.ibm.com> (raw)
In-Reply-To: <20230909232435.dfa15f93f1c5eef5b229a7d2@kernel.org> (Masami Hiramatsu's message of "Sat, 9 Sep 2023 23:24:35 +0900")
Masami Hiramatsu (Google) <mhiramat@kernel.org> writes:
>> > IOW, it is ftrace save regs/restore regs code issue. I need to check how the
>> > function_graph implements it.
>>
>> gpr2-gpr14 are always saved in ftrace_caller/ftrace_regs_caller(),
>> regardless of the FTRACE_WITH_REGS flags. The only difference is that
>> without the FTRACE_WITH_REGS flag the program status word (psw) is not
>> saved because collecting that is a rather expensive operation.
>
> Thanks for checking that! So s390 will recover those saved registers
> even if FTRACE_WITH_REGS flag is not set? (I wonder what is the requirement
> of the ftrace_regs when returning from ftrace_call() without
> FTRACE_WITH_REGS?)
Yes, it will recover these in all cases.
>>
>> I used the following commands to test rethook (is that the correct
>> testcase?)
>>
>> #!/bin/bash
>> cd /sys/kernel/tracing
>>
>> echo 'r:icmp_rcv icmp_rcv' >kprobe_events
>> echo 1 >events/kprobes/icmp_rcv/enable
>> ping -c 1 127.0.0.1
>> cat trace
>
> No, the kprobe will path pt_regs to rethook.
> Cna you run
>
> echo "f:icmp_rcv%return icmp_rcv" >> dynamic_events
Ah, ok. Seems to work as well:
ping-481 [001] ..s2. 53.918480: icmp_rcv: (ip_protocol_deliver_rcu+0x42/0x218 <- icmp_rcv)
ping-481 [001] ..s2. 53.918491: icmp_rcv: (ip_protocol_deliver_rcu+0x42/0x218 <- icmp_rcv)
next prev parent reply other threads:[~2023-09-11 7:56 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-23 15:15 [PATCH v4 0/9] bpf: fprobe: rethook: Use ftrace_regs instead of pt_regs Masami Hiramatsu (Google)
2023-08-23 15:15 ` [PATCH v4 1/9] Documentation: probes: Add a new ret_ip callback parameter Masami Hiramatsu (Google)
2023-08-25 16:11 ` Florent Revest
2023-08-23 15:15 ` [PATCH v4 2/9] fprobe: Use fprobe_regs in fprobe entry handler Masami Hiramatsu (Google)
2023-08-25 16:11 ` Florent Revest
2023-08-23 15:16 ` [PATCH v4 3/9] tracing: Expose ftrace_regs regardless of CONFIG_FUNCTION_TRACER Masami Hiramatsu (Google)
2023-08-23 15:16 ` [PATCH v4 4/9] fprobe: rethook: Use ftrace_regs in fprobe exit handler and rethook Masami Hiramatsu (Google)
2023-08-25 16:12 ` Florent Revest
2023-09-04 13:40 ` Masami Hiramatsu
2023-09-05 7:17 ` Sven Schnelle
2023-09-05 13:36 ` Masami Hiramatsu
2023-09-05 16:30 ` Steven Rostedt
2023-09-06 0:06 ` Masami Hiramatsu
2023-09-06 6:49 ` Sven Schnelle
2023-09-09 14:24 ` Masami Hiramatsu
2023-09-11 7:55 ` Sven Schnelle [this message]
2023-09-11 14:15 ` Masami Hiramatsu
2023-08-23 15:16 ` [PATCH v4 5/9] ftrace: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs Masami Hiramatsu (Google)
2023-08-25 21:49 ` Andrii Nakryiko
2023-08-26 1:56 ` Masami Hiramatsu
2023-09-05 19:50 ` Andrii Nakryiko
2023-09-06 0:28 ` Masami Hiramatsu
2023-09-08 22:56 ` Andrii Nakryiko
2023-08-23 15:16 ` [PATCH v4 6/9] tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS Masami Hiramatsu (Google)
2023-08-25 16:12 ` Florent Revest
2023-08-26 3:38 ` Masami Hiramatsu
2023-08-30 7:20 ` Masami Hiramatsu
2023-08-23 15:16 ` [PATCH v4 7/9] bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled Masami Hiramatsu (Google)
2023-08-23 15:16 ` [PATCH v4 8/9] Documentations: probes: Update fprobe document to use ftrace_regs Masami Hiramatsu (Google)
2023-08-23 15:17 ` [PATCH v4 9/9] Documentation: tracing: Add a note about argument and retval access Masami Hiramatsu (Google)
2023-08-25 16:12 ` Florent Revest
2023-08-25 16:11 ` [PATCH v4 0/9] bpf: fprobe: rethook: Use ftrace_regs instead of pt_regs Florent Revest
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