From: Andy Lutomirski <luto@kernel•org>
To: Christopher Covington <cov@codeaurora•org>,
Catalin Marinas <catalin.marinas@arm•com>,
criu@openvz•org, Laurent Dufour <ldufour@linux•vnet.ibm.com>,
Will Deacon <Will.Deacon@arm•com>,
Benjamin Herrenschmidt <benh@kernel•crashing.org>,
Paul Mackerras <paulus@samba•org>,
Michael Ellerman <mpe@ellerman•id.au>,
Arnd Bergmann <arnd@arndb•de>,
linux-arm-kernel@lists•infradead.org,
linux-kernel@vger•kernel.org, linuxppc-dev@lists•ozlabs.org,
linux-arch@vger•kernel.org, linux-mm@kvack•org,
dsafonov@virtuozzo•com
Subject: Re: VDSO unmap and remap support for additional architectures
Date: Thu, 28 Apr 2016 11:53:22 -0700 [thread overview]
Message-ID: <2ce7203f-305c-6edf-0ef9-448c141cb103@kernel.org> (raw)
In-Reply-To: <1461856737-17071-1-git-send-email-cov@codeaurora.org>
On 04/28/2016 08:18 AM, Christopher Covington wrote:
> Please take a look at the following prototype of sharing the PowerPC
> VDSO unmap and remap code with other architectures. I've only hooked
> up arm64 to begin with. If folks think this is a reasonable approach I
> can work on 32 bit ARM as well. Not hearing back from an earlier
> request for guidance [1], I simply dove in and started hacking.
> Laurent's test case [2][3] is a compelling illustration of whether VDSO
> remap works or not on a given architecture.
I think there's a much nicer way:
https://lkml.kernel.org/r/1461584223-9418-1-git-send-email-dsafonov@virtuozzo.com
Could arm64 and ppc use this approach? These arch_xyz hooks are gross.
Also, at some point, possibly quite soon, x86 will want a way for user code to ask the kernel to map a specific vdso variant at a specific address. Could we perhaps add a new pair of syscalls:
struct vdso_info {
unsigned long space_needed_before;
unsigned long space_needed_after;
unsigned long alignment;
};
long vdso_get_info(unsigned int vdso_type, struct vdso_info *info);
long vdso_remap(unsigned int vdso_type, unsigned long addr, unsigned int flags);
#define VDSO_X86_I386 0
#define VDSO_X86_64 1
#define VDSO_X86_X32 2
// etc.
vdso_remap will map the vdso of the chosen type such at AT_SYSINFO_EHDR lines up with addr. It will use up to space_needed_before bytes before that address and space_needed_after after than address. It will also unmap the old vdso (or maybe only do that if some flag is set).
On x86, mremap is *not* sufficient for everything that's needed, because some programs will need to change the vdso type.
--Andy
next prev parent reply other threads:[~2016-04-28 18:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20151202121918.GA4523@arm.com>
2016-04-28 15:18 ` VDSO unmap and remap support for additional architectures Christopher Covington
2016-04-28 15:18 ` [RFC 1/5] powerpc: Rename context.vdso_base to context.vdso Christopher Covington
2016-05-02 1:05 ` Balbir Singh
2016-05-04 21:21 ` Christopher Covington
2016-04-28 15:18 ` [RFC 2/5] mm/powerpc: Make VDSO unmap generic Christopher Covington
2016-04-28 15:18 ` [RFC 3/5] mm/powerpc: Make VDSO remap generic Christopher Covington
2016-04-28 15:18 ` [RFC 4/5] arm64: Use unsigned long for vdso Christopher Covington
2016-04-28 15:18 ` [RFC 5/5] arm64: Gain VDSO unmap and remap powers Christopher Covington
2016-04-28 18:53 ` Andy Lutomirski [this message]
2016-04-29 13:22 ` VDSO unmap and remap support for additional architectures Christopher Covington
2016-04-29 13:55 ` Dmitry Safonov
2016-05-03 21:37 ` Christopher Covington
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2ce7203f-305c-6edf-0ef9-448c141cb103@kernel.org \
--to=luto@kernel$(echo .)org \
--cc=Will.Deacon@arm$(echo .)com \
--cc=arnd@arndb$(echo .)de \
--cc=benh@kernel$(echo .)crashing.org \
--cc=catalin.marinas@arm$(echo .)com \
--cc=cov@codeaurora$(echo .)org \
--cc=criu@openvz$(echo .)org \
--cc=dsafonov@virtuozzo$(echo .)com \
--cc=ldufour@linux$(echo .)vnet.ibm.com \
--cc=linux-arch@vger$(echo .)kernel.org \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linux-mm@kvack$(echo .)org \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
--cc=mpe@ellerman$(echo .)id.au \
--cc=paulus@samba$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox