Re: [PATCH v16 10/13] arch/arm: enable task isolation functionality

[Chris Metcalf]

On 11/3/2017 1:23 PM, Russell King - ARM Linux wrote:
> On Fri, Nov 03, 2017 at 01:04:49PM -0400, Chris Metcalf wrote:
> > From: Francis Giraldeau <francis.giraldeau@xxxxxxxxx>
> >
> > This patch is a port of the task isolation functionality to the arm 32-bit
> > architecture. The task isolation needs an additional thread flag that
> > requires to change the entry assembly code to accept a bitfield larger than
> > one byte.  The constants _TIF_SYSCALL_WORK and _TIF_WORK_MASK are now
> > defined in the literal pool. The rest of the patch is straightforward and
> > reflects what is done on other architectures.
> >
> > To avoid problems with the tst instruction in the v7m build, we renumber
> > TIF_SECCOMP to bit 8 and let TIF_TASK_ISOLATION use bit 7.
> After a bit of digging (which could've been saved if our patch format
> contained information about what kernel version this patch was
> generated against) it turns out that this patch will not apply since
> commit 73ac5d6a2b6ac ("arm/syscalls: Check address limit on user-mode
> return") has been applied, which means the TIF numbers have changed
> as well as the assembly code that your patch touches.
>
> My guess is that this patch was generated from a 4.13 kernel, so
> misses the 4.14-rc1 changes.  Since we're potentially about to start
> the merge window for 4.15 this weekend, the timing of this doesn't
> work well either.

What patch failure did you see? The patch is based against 4.14-rc4, so 
while
it's a few weeks out of date, it does include the commit you reference.

> Once 4.15-rc1 has been published, please rebase against that version
> and resend.

Sure. I was hoping to eke out a little bit of attention from kernel 
developers
before the merge window actually opens :)

--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com