From: Jiri Olsa <olsajiri@gmail.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jiri Olsa <olsajiri@gmail.com>,
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>, Sven Schnelle <svens@linux.ibm.com>,
Alexei Starovoitov <ast@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>, Guo Ren <guoren@kernel.org>
Subject: Re: [PATCH v5 04/12] fprobe: Use ftrace_regs in fprobe entry handler
Date: Tue, 26 Sep 2023 00:14:33 +0200 [thread overview]
Message-ID: <ZRIGSTTTYADzP7QU@krava> (raw)
In-Reply-To: <20230925211515.41d26a160c546c7bce08ac64@kernel.org>
On Mon, Sep 25, 2023 at 09:15:15PM +0900, Masami Hiramatsu wrote:
> Hi Jiri,
>
> On Mon, 25 Sep 2023 12:41:59 +0200
> Jiri Olsa <olsajiri@gmail.com> wrote:
>
> > On Sun, Sep 24, 2023 at 10:36:36PM +0900, Masami Hiramatsu (Google) wrote:
> > > From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > >
> > > This allows fprobes to be available with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
> > > instead of CONFIG_DYNAMIC_FTRACE_WITH_REGS, then we can enable fprobe
> > > on arm64.
> > >
> > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > Acked-by: Florent Revest <revest@chromium.org>
> >
> > I was getting bpf selftests failures with this patchset and when
> > bisecting I'm getting crash when running on top of this change
>
> Thanks for bisecting!
>
> >
> > looks like it's missing some of the regs NULL checks added later?
>
> yeah, if the RIP (arch_rethook_prepare+0x0/0x30) is correct,
>
> void arch_rethook_prepare(struct rethook_node *rh, struct ftrace_regs *fregs, bool mcount)
>
> RSI (the 2nd argument) is NULL. This means fregs == NULL and caused the crash.
> I think ftrace_get_regs(fregs) for the entry handler may return NULL.
>
> Ah,
>
> @@ -182,7 +182,7 @@ static void fprobe_init(struct fprobe *fp)
> fp->ops.func = fprobe_kprobe_handler;
> else
> fp->ops.func = fprobe_handler;
> - fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
> + fp->ops.flags |= FTRACE_OPS_FL_SAVE_ARGS;
> }
>
> static int fprobe_init_rethook(struct fprobe *fp, int num)
>
> This may cause the issue, it should keep REGS at this point (this must be done in
> [9/12]). But after applying [9/12], it shouldn't be a problem...
>
> Let me check it again.
that helped with the crash, I'll continue bisecting to find out
where it breaks the tests
thanks,
jirka
next prev parent reply other threads:[~2023-09-25 22:14 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-24 13:35 [PATCH v5 00/12] tracing: fprobe: rethook: Use ftrace_regs instead of pt_regs Masami Hiramatsu (Google)
2023-09-24 13:35 ` [PATCH v5 01/12] riscv: ftrace: Fix to pass correct ftrace_regs to ftrace_func_t functions Masami Hiramatsu (Google)
2023-09-24 13:36 ` [PATCH v5 02/12] Documentation: probes: Add a new ret_ip callback parameter Masami Hiramatsu (Google)
2023-09-24 13:36 ` [PATCH v5 03/12] tracing: Add a comment about the requirements of the ftrace_regs Masami Hiramatsu (Google)
2023-09-24 13:36 ` [PATCH v5 04/12] fprobe: Use ftrace_regs in fprobe entry handler Masami Hiramatsu (Google)
2023-09-25 10:41 ` Jiri Olsa
2023-09-25 12:15 ` Masami Hiramatsu
2023-09-25 22:14 ` Jiri Olsa [this message]
2023-09-26 0:20 ` Masami Hiramatsu
2023-09-26 7:23 ` Jiri Olsa
2023-09-26 11:49 ` Jiri Olsa
2023-09-26 14:47 ` Masami Hiramatsu
2023-09-24 13:36 ` [PATCH v5 05/12] tracing: Expose ftrace_regs regardless of CONFIG_FUNCTION_TRACER Masami Hiramatsu (Google)
2023-09-24 13:37 ` [PATCH v5 06/12] fprobe: rethook: Use ftrace_regs in fprobe exit handler and rethook Masami Hiramatsu (Google)
2023-09-24 13:37 ` [PATCH v5 07/12] tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs Masami Hiramatsu (Google)
2023-09-24 13:37 ` [PATCH v5 08/12] tracing: Add ftrace_fill_perf_regs() for perf event Masami Hiramatsu (Google)
2023-09-24 13:37 ` [PATCH v5 09/12] tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS Masami Hiramatsu (Google)
2023-09-24 13:37 ` [PATCH v5 10/12] bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled Masami Hiramatsu (Google)
2023-09-24 13:38 ` [PATCH v5 11/12] Documentation: probes: Update fprobe document to use ftrace_regs Masami Hiramatsu (Google)
2023-09-24 13:38 ` [PATCH v5 12/12] Documentation: tracing: Add a note about argument and retval access Masami Hiramatsu (Google)
2023-09-29 1:21 ` [PATCH v5 00/12] tracing: fprobe: rethook: Use ftrace_regs instead of pt_regs Masami Hiramatsu
2023-09-30 0:12 ` Alexei Starovoitov
2023-09-30 9:14 ` Masami Hiramatsu
2023-10-02 15:39 ` Masami Hiramatsu
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