linux-kernel - Re: [PATCH] selftests/ftrace: Disable multiple

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Date:   Tue, 5 Jan 2021 19:15:18 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Steven Rostedt <rostedt@...dmis.org>, shuah@...nel.org,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] selftests/ftrace: Disable multiple_kprobes test on
 powerpc

On Tue, 5 Jan 2021 19:01:56 +0900
Masami Hiramatsu <mhiramat@...nel.org> wrote:

> On Tue,  5 Jan 2021 12:27:30 +0530
> "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com> wrote:
> 
> > Not all symbols are blacklisted on powerpc. Disable multiple_kprobes
> > test until that is sorted, so that rest of ftrace and kprobe selftests
> > can be run.
> 
> This looks good to me, but could you try to find the functions
> which should be blocked from kprobes?
> (Usually, the function which are involved in the sw-breakpoint
>  handling, including locks etc.)

Ah, OK. 
I wonder why CONFIG_KPROBE_EVENTS_ON_NOTRACE=n doesn't help, it
was ignored if the arch doesn't support CONFIG_KPROBES_ON_FTRACE.

Naveen, could you try to run this test case with following patch
on powerpc?

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index b911e9f6d9f5..241a55313476 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -433,7 +433,7 @@ static int disable_trace_kprobe(struct trace_event_call *call,
        return 0;
 }
 
-#if defined(CONFIG_KPROBES_ON_FTRACE) && \
+#if defined(CONFIG_FUNCTION_TRACER) && \
        !defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE)
 static bool __within_notrace_func(unsigned long addr)
 {

Of course you need to enable CONFIG_FUNCTION_TRACER=y, but it may
pass the test.

Thank you,

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