Re: Linux powerpc new system call instruction and ABI

From: Nicholas Piggin <npiggin@gmail.com>
To: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: Rich Felker <dalias@libc.org>,
	Joakim Tjernlund <Joakim.Tjernlund@infinera.com>,
	linux-api@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	Michael Ellerman <mpe@ellerman.id.au>,
	musl@lists.openwall.com,
	Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: Linux powerpc new system call instruction and ABI
Date: Thu, 20 May 2021 17:20:44 +1000	[thread overview]
Message-ID: <1621495199.91bc4mp4tb.astroid@bobo.none> (raw)
In-Reply-To: <20210520025948.GA27081@altlinux.org>

Excerpts from Dmitry V. Levin's message of May 20, 2021 12:59 pm:
> On Thu, May 20, 2021 at 12:45:57PM +1000, Nicholas Piggin wrote:
>> Excerpts from Dmitry V. Levin's message of May 20, 2021 11:06 am:
>> > On Wed, May 19, 2021 at 07:48:47PM -0400, Rich Felker wrote:
>> >> On Wed, May 19, 2021 at 06:09:25PM +0000, Joakim Tjernlund wrote:
>> > [...]
>> >> > W.r.t breaking ABI, isn't that what PowerPC is trying to do with the new syscall I/F? 
>> >> 
>> >> No, it's a new independent interface.
>> > 
>> > Unfortunately, being a new independent interface doesn't mean it isn't
>> > an ABI break.  In fact, it was a severe ABI break, and this thread is
>> > an attempt to find a hotfix.
>> 
>> It is an ABI break, that was known. The ptrace info stuff I fixed with 
>> the patch earlier was obviously a bug in my initial implementation and 
>> not intended (sorry my ptrace testing was not sufficient, and thanks for
>> reporting it, by the way).
> 
> Could you check whether tools/testing/selftests/ptrace/get_syscall_info.c
> passes again with your fix, please?

It does.

Thanks,
Nick

> If yes, then PTRACE_GET_SYSCALL_INFO is fixed.
> 
> By the way, kernel tracing and audit subsystems also use those functions
> from asm/syscall.h and asm/ptrace.h, so your ptrace fix is likely to fix
> these subsystems as well.