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Date:   Mon, 5 Dec 2022 16:46:18 -0500
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Subject: Re: [PATCH] powerpc/ftrace: fix syscall tracing on PPC64_ELF_ABI_V1
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From:   Michael Jeanson <mjeanson@efficios.com>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Steven Rostedt <rostedt@goodmis.org>
Cc:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Nicholas Piggin <npiggin@gmail.com>,
        Michal Suchanek <msuchanek@suse.de>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
References: <20221201161442.2127231-1-mjeanson@efficios.com>
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On 2022-12-05 15:11, Michael Jeanson wrote:
>>>> Michael Jeanson <mjeanson@efficios.com> writes:
>>>>> In v5.7 the powerpc syscall entry/exit logic was rewritten in C, on
>>>>> PPC64_ELF_ABI_V1 this resulted in the symbols in the syscall table
>>>>> changing from their dot prefixed variant to the non-prefixed ones.
>>>>>
>>>>> Since ftrace prefixes a dot to the syscall names when matching them to
>>>>> build its syscall event list, this resulted in no syscall events being
>>>>> available.
>>>>>
>>>>> Remove the PPC64_ELF_ABI_V1 specific version of
>>>>> arch_syscall_match_sym_name to have the same behavior across all powerpc
>>>>> variants.
>>>>
>>>> This doesn't seem to work for me.
>>>>
>>>> Event with it applied I still don't see anything in
>>>> /sys/kernel/debug/tracing/events/syscalls
>>>>
>>>> Did we break it in some other way recently?
>>>>
>>>> cheers

I did some further testing, my config also enabled KALLSYMS_ALL, when I remove 
it there is indeed no syscall events.