From: Christoph Hellwig <hch@infradead.org>
To: Max Filippov <jcmvbkbc@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>,
ira.weiny@intel.com, LKML <linux-kernel@vger.kernel.org>,
"open list:TENSILICA XTENSA PORT (xtensa)"
<linux-xtensa@linux-xtensa.org>
Subject: Re: xtensa question, was Re: [PATCH V1 00/10] Remove duplicated kmap code
Date: Fri, 1 May 2020 02:19:33 -0700 [thread overview]
Message-ID: <20200501091933.GA3084@infradead.org> (raw)
In-Reply-To: <CAMo8Bf+Mvvg_f1-33iQhTqZPVw1civX94KS2mf4uSkcpEVx55Q@mail.gmail.com>
On Fri, May 01, 2020 at 02:02:19AM -0700, Max Filippov wrote:
> Hi Christoph,
>
> On Fri, May 1, 2020 at 1:46 AM Christoph Hellwig <hch@infradead.org> wrote:
> > any idea why xtensa uses PAGE_KERNEL_EXEC instead of PAGE_KERNEL
> > for kmap_prot? Mapping all mapped highmem as executable seems rather
> > dangerous.
>
> I sure do: to allow instruction cache flushing when writing to high user
> pages temporarily mapped with kmap. Instruction cache management
> opcodes that operate on virtual addresses would raise an exception if
> the address is not executable.
Seems like this should use kmap_atomic_prot with PAGE_KERNEL_EXEC just
for that case. Which of course didn't exist on xtensa so far, but with
this series will.
next prev parent reply other threads:[~2020-05-01 9:19 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 20:38 [PATCH V1 00/10] Remove duplicated kmap code ira.weiny
2020-04-30 20:38 ` [PATCH V1 01/10] arch/kmap: Remove BUG_ON() ira.weiny
2020-05-01 8:35 ` Christoph Hellwig
2020-04-30 20:38 ` [PATCH V1 02/10] arch/xtensa: Move kmap build bug out of the way ira.weiny
2020-05-01 8:36 ` Christoph Hellwig
2020-04-30 20:38 ` [PATCH V1 03/10] arch/kmap: Remove redundant arch specific kmaps ira.weiny
2020-05-01 8:37 ` Christoph Hellwig
2020-04-30 20:38 ` [PATCH V1 04/10] arch/kunmap: Remove duplicate kunmap implementations ira.weiny
2020-05-01 8:38 ` Christoph Hellwig
2020-04-30 20:38 ` [PATCH V1 05/10] arch/kmap_atomic: Consolidate duplicate code ira.weiny
2020-05-01 2:09 ` Al Viro
2020-05-01 8:39 ` Christoph Hellwig
2020-04-30 20:38 ` [PATCH V1 06/10] arch/kunmap_atomic: " ira.weiny
2020-05-01 8:39 ` Christoph Hellwig
2020-04-30 20:38 ` [PATCH V1 07/10] arch/kmap: Ensure kmap_prot visibility ira.weiny
2020-05-01 8:44 ` sparc-related comment, to " Christoph Hellwig
2020-05-01 15:35 ` Ira Weiny
2020-04-30 20:38 ` [PATCH V1 08/10] arch/kmap: Don't hard code kmap_prot values ira.weiny
2020-05-01 2:16 ` Al Viro
2020-05-01 8:47 ` Christoph Hellwig
2020-04-30 20:38 ` [PATCH V1 09/10] arch/kmap: Define kmap_atomic_prot() for all arch's ira.weiny
2020-05-01 2:37 ` Al Viro
2020-05-01 3:20 ` Al Viro
2020-05-03 3:11 ` Ira Weiny
2020-05-01 8:48 ` Christoph Hellwig
2020-04-30 20:38 ` [PATCH V1 10/10] drm: Remove drm specific kmap_atomic code ira.weiny
2020-05-01 7:23 ` Christian König
2020-05-01 8:49 ` Christoph Hellwig
2020-05-01 2:29 ` [PATCH V1 00/10] Remove duplicated kmap code Michael Ellerman
2020-05-01 8:46 ` xtensa question, was " Christoph Hellwig
2020-05-01 9:02 ` Max Filippov
2020-05-01 9:19 ` Christoph Hellwig [this message]
2020-05-01 9:50 ` Max Filippov
2020-05-01 8:54 ` Christoph Hellwig
2020-05-01 17:18 ` Ira Weiny
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