lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 1 May 2020 02:02:19 -0700
From:   Max Filippov <jcmvbkbc@...il.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     ira.weiny@...el.com, LKML <linux-kernel@...r.kernel.org>,
        "open list:TENSILICA XTENSA PORT (xtensa)" 
        <linux-xtensa@...ux-xtensa.org>
Subject: Re: xtensa question, was Re: [PATCH V1 00/10] Remove duplicated kmap code

Hi Christoph,

On Fri, May 1, 2020 at 1:46 AM Christoph Hellwig <hch@...radead.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.

-- 
Thanks.
-- Max

Powered by blists - more mailing lists