From: "H. Peter Anvin" <hpa@zytor.com>
To: Stefani Seibold <stefani@seibold.net>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de,
mingo@redhat.com, ak@linux.intel.com, aarcange@redhat.com,
john.stultz@linaro.org, luto@amacapital.net, xemul@parallels.com,
gorcunov@openvz.org, andriy.shevchenko@linux.intel.com
Subject: Re: [PATCH 6/6] Add 32 bit VDSO support for 32 and 64 bit kernels
Date: Tue, 18 Dec 2012 10:44:22 -0800 [thread overview]
Message-ID: <50D0B986.7020009@zytor.com> (raw)
In-Reply-To: <1355849558.26967.24.camel@wall-e>
On 12/18/2012 08:52 AM, Stefani Seibold wrote:
>
> Pardon, i never disregarded nor i have agreed that this is going to be a
> part of the VDSO. I currently have also no idea how to do this and i see
> no need at the moment to do this revamp. The 64 bit VDSO lives since
> more than 6 years with this kind of implementation.
>
It was part of this discussion thread, about how to best manage the
address space. Fixed addresses are a major problem, and introducing new
ones are extremely undesirable.
Hence I wrote:
> IMO it seems this is making it way more complicated than it is. Just
> make sure you have a section in the vdso where you can map in a data
> page with the symbols in the right offsets. Extra points for doing
> magic so that it is at the beginning or end, but I think that might
> be harder than necessary.
Basically, make the vvar and hpet pages part of the vdso page list.
Optionally they can be mapped without the MAYWRITE option -- in fact, we
could easily split the vdso into an executable area which gets MAYWRITE
to be able to set breakpoints and a data area which doesn't -- but that
is a minor tweak IMO.
> You asked me to do the VDSO 32 bit stuff for the IA32_EMULATION, before
> it is ready for inclusion into the kernel. Thats exactly what i did. I
> spend the whole weekend of my spare time to do this implementation. Now
> we have them all.
>
> The patch works perfectly, all issues are solved:
>
> - Calling conventions
> - ABI transformations
> - System call gateway for X86 32 bit
> - Mapping of the FIXMAP and HPET into the lower 32 bit address space for
> IA32_EMULATION
> - Support for 32 bit programs in 32 kernel and 64 bit kernel
> - One VDSO source for all
>
> If you prefer an other solutions, its okay. There are many ways to code
> things. But for now i think it is a good step ahead. That is what i
> currently can provide.
This is good. We have some time anyway to get this ready for the 3.9
merge window.
-hpa
next prev parent reply other threads:[~2012-12-18 18:45 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-18 9:40 [PATCH 0/6] Add 32 bit VDSO time function support stefani
2012-12-18 9:40 ` [PATCH 1/6] Move out seqcount from seqlock.h stefani
2012-12-18 9:40 ` [PATCH 2/6] Make vsyscall_gtod_data handling x86 generic stefani
2012-12-18 9:40 ` [PATCH 3/6] Make vsyscall_gtod_data compatible with 32 bit VDSO stefani
2012-12-18 9:40 ` [PATCH 4/6] Add new base function _install_special_mapping() to mmap.c stefani
2012-12-18 9:40 ` [PATCH 5/6] Cleanup header files to build a proper 32 bit VDSO stefani
2012-12-18 9:40 ` [PATCH 6/6] Add 32 bit VDSO support for 32 and 64 bit kernels stefani
2012-12-18 16:17 ` H. Peter Anvin
2012-12-18 16:52 ` Stefani Seibold
2012-12-18 18:44 ` H. Peter Anvin [this message]
2012-12-18 20:32 ` Stefani Seibold
2012-12-18 20:37 ` Andy Lutomirski
2012-12-18 22:24 ` H. Peter Anvin
2012-12-20 7:41 ` Stefani Seibold
2012-12-20 16:17 ` H. Peter Anvin
2012-12-20 17:53 ` Stefani Seibold
2012-12-20 18:21 ` H. Peter Anvin
2012-12-20 18:23 ` H.J. Lu
2012-12-20 18:35 ` Roland McGrath
2012-12-20 18:40 ` H. Peter Anvin
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