From: Mark Rutland <mark.rutland@arm.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Chris Metcalf <cmetcalf@ezchip.com>,
Gilad Ben Yossef <giladb@ezchip.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Christoph Lameter <cl@linux.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v9 08/13] arch/arm64: adopt prepare_exit_to_usermode() model from x86
Date: Tue, 5 Jan 2016 18:01:02 +0000 [thread overview]
Message-ID: <20160105180101.GA29455@leverpostej> (raw)
In-Reply-To: <CALCETrUyB5dHn0OQwwYwB28pEDqMeGmnFv1mQLfHXhW-4YWCjg@mail.gmail.com>
On Mon, Jan 04, 2016 at 02:31:42PM -0800, Andy Lutomirski wrote:
> On Mon, Jan 4, 2016 at 12:33 PM, Mark Rutland <mark.rutland@arm.com> wrote:
> > Hi,
> >
> > On Mon, Jan 04, 2016 at 02:34:46PM -0500, Chris Metcalf wrote:
> >> This change is a prerequisite change for TASK_ISOLATION but also
> >> stands on its own for readability and maintainability.
> >
> > I have also been looking into converting the userspace return path from
> > assembly to C [1], for the latter two reasons. Based on that, I have a
> > couple of comments.
> >
>
> >
> > [1] https://git.kernel.org/cgit/linux/kernel/git/mark/linux.git/log/?h=arm64/entry-deasm
>
> Neat!
>
> In case you want to compare notes, I have a branch with the entire
> syscall path on x86 in C except for cleanly separated asm fast path
> optimizations:
>
> https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/log/?h=x86/entry_compat
It was in fact your x86 effort that inspired me to look at this!
Thanks for the pointer, I'm almost certainly going to steal an idea or
two.
Currently it looks like arm64's conversion will be less painful than
that for x86 as the entry assembly is smaller and relatively uniform.
It looks like all but the register save/restore is possible in C.
That said, I have yet to stress/validate everything with tracing, irq
debugging, and so on, so my confidence may be misplaced.
Thanks,
Mark.
next prev parent reply other threads:[~2016-01-05 18:01 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-04 19:34 [PATCH v9 00/13] support "task_isolation" mode for nohz_full Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 01/13] vmstat: provide a function to quiet down the diff processing Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 02/13] vmstat: add vmstat_idle function Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 03/13] lru_add_drain_all: factor out lru_add_drain_needed Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 04/13] task_isolation: add initial support Chris Metcalf
2016-01-19 15:42 ` Frederic Weisbecker
2016-01-19 20:45 ` Chris Metcalf
2016-01-28 0:28 ` Frederic Weisbecker
2016-01-29 18:18 ` Chris Metcalf
2016-01-30 21:11 ` Frederic Weisbecker
2016-02-11 19:24 ` Chris Metcalf
2016-03-04 12:56 ` Frederic Weisbecker
2016-03-09 19:39 ` Chris Metcalf
2016-04-08 13:56 ` Frederic Weisbecker
2016-04-08 16:34 ` Chris Metcalf
2016-04-12 18:41 ` Chris Metcalf
2016-04-22 13:16 ` Frederic Weisbecker
2016-04-25 20:36 ` Chris Metcalf
2016-05-26 1:07 ` Frederic Weisbecker
2016-06-03 19:32 ` Chris Metcalf
2016-06-29 15:18 ` Frederic Weisbecker
2016-07-01 20:59 ` Chris Metcalf
2016-07-05 14:41 ` Frederic Weisbecker
2016-07-05 17:47 ` Christoph Lameter
2016-01-04 19:34 ` [PATCH v9 05/13] task_isolation: support PR_TASK_ISOLATION_STRICT mode Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 06/13] task_isolation: add debug boot flag Chris Metcalf
2016-01-04 22:52 ` Steven Rostedt
2016-01-04 23:42 ` Chris Metcalf
2016-01-05 13:42 ` Steven Rostedt
2016-01-04 19:34 ` [PATCH v9 07/13] arch/x86: enable task isolation functionality Chris Metcalf
2016-01-04 21:02 ` [PATCH v9bis " Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 08/13] arch/arm64: adopt prepare_exit_to_usermode() model from x86 Chris Metcalf
2016-01-04 20:33 ` Mark Rutland
2016-01-04 21:01 ` Chris Metcalf
2016-01-05 17:21 ` Mark Rutland
2016-01-05 17:33 ` [PATCH 1/2] arm64: entry: remove pointless SPSR mode check Mark Rutland
2016-01-06 12:15 ` Catalin Marinas
2016-01-05 17:33 ` [PATCH 2/2] arm64: factor work_pending state machine to C Mark Rutland
2016-01-05 18:53 ` Chris Metcalf
2016-01-06 12:30 ` Catalin Marinas
2016-01-06 12:47 ` Mark Rutland
2016-01-06 13:43 ` Mark Rutland
2016-01-06 14:17 ` Catalin Marinas
2016-01-04 22:31 ` [PATCH v9 08/13] arch/arm64: adopt prepare_exit_to_usermode() model from x86 Andy Lutomirski
2016-01-05 18:01 ` Mark Rutland [this message]
2016-01-04 19:34 ` [PATCH v9 09/13] arch/arm64: enable task isolation functionality Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 10/13] arch/tile: adopt prepare_exit_to_usermode() model from x86 Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 11/13] arch/tile: move user_exit() to early kernel entry sequence Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 12/13] arch/tile: enable task isolation functionality Chris Metcalf
2016-01-04 19:34 ` [PATCH v9 13/13] arm, tile: turn off timer tick for oneshot_stopped state Chris Metcalf
2016-01-11 21:15 ` [PATCH v9 00/13] support "task_isolation" mode for nohz_full Chris Metcalf
2016-01-12 10:07 ` Will Deacon
2016-01-12 17:49 ` Chris Metcalf
2016-01-13 10:44 ` Ingo Molnar
2016-01-13 21:19 ` Chris Metcalf
2016-01-20 13:27 ` Mark Rutland
2016-01-12 10:53 ` Ingo Molnar
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