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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     "Dmitry V. Levin" <ldv@altlinux.org>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Breno Leitao <leitao@debian.org>,
        Andy Lutomirski <luto@kernel.org>,
        Eugene Syromyatnikov <esyr@redhat.com>,
        Elvira Khabirova <lineprinter@altlinux.org>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] powerpc/ptrace: replace ptrace_report_syscall() with a tracehook call
In-Reply-To: <20181207011946.GA18558@altlinux.org>
References: <20181116121701.14359da0@akathisia> <87ftw12nyn.fsf@concordia.ellerman.id.au> <20181119210139.GA8360@altlinux.org> <87efbe166y.fsf@concordia.ellerman.id.au> <20181203031823.GE11573@altlinux.org> <20181207011946.GA18558@altlinux.org>
Date:   Fri, 07 Dec 2018 22:12:49 +1100
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"Dmitry V. Levin" <ldv@altlinux.org> writes:

> On Mon, Dec 03, 2018 at 06:18:23AM +0300, Dmitry V. Levin wrote:
>> From: Elvira Khabirova <lineprinter@altlinux.org>
>> 
>> Arch code should use tracehook_*() helpers, as documented
>> in include/linux/tracehook.h,
>> ptrace_report_syscall() is not expected to be used outside that file.
>> 
>> Co-authored-by: Dmitry V. Levin <ldv@altlinux.org>
>> Fixes: 5521eb4bca2d ("powerpc/ptrace: Add support for PTRACE_SYSEMU")
>> Signed-off-by: Elvira Khabirova <lineprinter@altlinux.org>
>> Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
>> ---
>> v4: rewritten to call tracehook_report_syscall_entry() once, compile-tested
>> v3: add a descriptive comment
>> v2: explicitly ignore tracehook_report_syscall_entry() return code
>> 
>>  arch/powerpc/kernel/ptrace.c | 54 +++++++++++++++++++++++-------------
>>  1 file changed, 35 insertions(+), 19 deletions(-)
>
> Sorry, this patch does not work, please ignore it.

Hmm OK. Why exactly?

I wrote more or less the same patch, although I used a temporary bool.

> However, the bug blocks PTRACE_GET_SYSCALL_INFO, so please fix it.

Sorry, didn't realise it was blocking you.

> I'm going to use
> 	if (tracehook_report_syscall_entry(regs))
> 		return -1;
> 	return -1;
> in the series until you have a better fix.

Yeah that's fine by me. I could send that to Linus for 4.20 if you want
me to, otherwise I'm fine for you to carry it in your series.

cheers