Re: [PATCH 2/6] x86: Simplify compat syscall userspace allocation

From: Gabriel Krisman Bertazi
Date: Sat Sep 12 2020 - 03:54:13 EST


Christoph Hellwig <hch@xxxxxx> writes:

> On Sat, Sep 12, 2020 at 03:05:49AM -0400, Gabriel Krisman Bertazi wrote:
>> When allocating user memory space for a compat system call, don't
>> consider whether the originating code is IA32 or X32, just allocate from
>> a safe region for both, beyond the redzone. This should be safe for
>> IA32, and has the benefit of avoiding TIF_IA32, which we want to drop.
>
> This doesn't look wrong, by why bother (maybe Ccing me on the whole
> seris as you always should instead of sending annoying out of context
> single patches would have told..).

Hi Chris,

Thanks for the quick reply. sorry and I will make sure to cc you for the
rest of the series if this spin again. The reason is the removal of
TIF_IA32 to reclaim some bits in the ti flags.

If you want to see the rest of it immediately: <https://lkml.org/lkml/2020/9/12/28>

> We will hopefully kill off compat_alloc_user_space in the next few
> merge windows..

I plan to kill TIF_IA32 hopefully in the next merge window, to
facilitate other work I'm doing and I wouldn't like to wait for other
stuff, since this is trivial enough. Can I get your reviewed-by here?

Thanks,

--
Gabriel Krisman Bertazi