From: Dave Martin <Dave.Martin@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Peter Collingbourne <pcc@google.com>,
Evgenii Stepanov <eugenis@google.com>,
Kostya Serebryany <kcc@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Will Deacon <will@kernel.org>, Oleg Nesterov <oleg@redhat.com>,
"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Andrey Konovalov <andreyknvl@google.com>,
Richard Henderson <rth@twiddle.net>,
linux-api@vger.kernel.org, Helge Deller <deller@gmx.de>,
David Spickett <david.spickett@linaro.org>
Subject: Re: [PATCH v13 1/8] parisc: Drop parisc special case for __sighandler_t
Date: Wed, 4 Nov 2020 18:00:26 +0000 [thread overview]
Message-ID: <20201104180026.GF6882@arm.com> (raw)
In-Reply-To: <20201104172447.GF28902@gaia>
On Wed, Nov 04, 2020 at 05:24:48PM +0000, Catalin Marinas wrote:
> On Wed, Nov 04, 2020 at 10:54:34AM -0600, Eric W. Biederman wrote:
> > Peter Collingbourne <pcc@google.com> writes:
> > > From: Helge Deller <deller@gmx.de>
> > >
> > > I believe we can and *should* drop this parisc-specific typedef for
> > > __sighandler_t when compiling a 64-bit kernel. The reasons:
> > >
> > > 1. We don't have a 64-bit userspace yet, so nothing (on userspace side)
> > > can break.
> > >
> > > 2. Inside the Linux kernel, this is only used in kernel/signal.c, in
> > > function kernel_sigaction() where the signal handler is compared against
> > > SIG_IGN. SIG_IGN is defined as (__sighandler_t)1), so only the pointers
> > > are compared.
> > >
> > > 3. Even when a 64-bit userspace gets added at some point, I think
> > > __sighandler_t should be defined what it is: a function pointer struct.
> > >
> > > I compiled kernel/signal.c with and without the patch, and the produced code
> > > is identical in both cases.
> > >
> > > Signed-off-by: Helge Deller <deller@gmx.de>
> > > Reviewed-by: Peter Collingbourne <pcc@google.com>
> > > Link:
> > > https://linux-review.googlesource.com/id/I21c43f21b264f339e3aa395626af838646f62d97
> >
> > Peter as you have sent this, this also needs your Signed-off-by.
> >
> > Otherwise this looks reasonable to me.
> > Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
> >
> > While the final bits look like they are still under discussion it looks
> > like the preceding cleanups are pretty solid at this point.
>
> Minor nits, unless you nak the whole approach of SA_FAULTFLAGS and
> SA_UNSUPPORTED ;) (it looks a bit complicated to me but I don't have a
> better idea for a generic implementation).
It is a bit complicated, but we didn't come up with anything better so
far that can cope with the various historical quirks in the signal API.
A bigger overhaul of the whole interface might be a good idea at some
point, but it would probably be a mistake to rush that.
It may be possible to make the SA_UNSUPPORTED stuff a bit more
digestible via libc. I'll try to get a discussion started on that.
[...]
Cheers
---Dave
next prev parent reply other threads:[~2020-11-04 18:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-03 4:09 [PATCH v13 0/8] arm64: expose FAR_EL1 tag bits in siginfo Peter Collingbourne
2020-11-03 4:09 ` [PATCH v13 1/8] parisc: Drop parisc special case for __sighandler_t Peter Collingbourne
2020-11-04 16:54 ` Eric W. Biederman
2020-11-04 17:24 ` Catalin Marinas
2020-11-04 17:36 ` Eric W. Biederman
2020-11-04 18:00 ` Dave Martin [this message]
2020-11-04 20:46 ` Peter Collingbourne
2020-11-03 4:09 ` [PATCH v13 2/8] parisc: start using signal-defs.h Peter Collingbourne
2020-11-04 18:05 ` Eric W. Biederman
2020-11-03 4:09 ` [PATCH v13 3/8] arch: move SA_* definitions to generic headers Peter Collingbourne
2020-11-04 18:47 ` Eric W. Biederman
2020-11-04 20:48 ` Peter Collingbourne
2020-11-03 4:09 ` [PATCH v13 4/8] signal: clear non-uapi flag bits when passing/returning sa_flags Peter Collingbourne
2020-11-03 4:09 ` [PATCH v13 5/8] signal: define the SA_UNSUPPORTED bit in sa_flags Peter Collingbourne
2020-11-03 4:09 ` [PATCH v13 6/8] signal: deduplicate code dealing with common _sigfault fields Peter Collingbourne
2020-11-03 4:09 ` [PATCH v13 7/8] signal: define the field siginfo.si_faultflags Peter Collingbourne
2020-11-03 17:53 ` Catalin Marinas
2020-11-03 18:39 ` Peter Collingbourne
2020-11-04 10:57 ` Dave Martin
2020-11-04 18:23 ` Catalin Marinas
2020-11-04 19:57 ` Peter Collingbourne
2020-11-03 4:09 ` [PATCH v13 8/8] arm64: expose FAR_EL1 tag bits in siginfo Peter Collingbourne
2020-11-03 18:33 ` Catalin Marinas
2020-11-03 19:16 ` Peter Collingbourne
2020-11-04 17:45 ` Catalin Marinas
2020-11-04 18:27 ` Peter Collingbourne
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