From: "H. Peter Anvin" <hpa@zytor.com>
To: stefani@seibold.net, gregkh@linuxfoundation.org,
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
Cc: Martin.Runge@rohde-schwarz.com, Andreas.Brief@rohde-schwarz.com
Subject: Re: [PATCH 4/4] Add 32 bit VDSO time support for 64 bit kernel
Date: Sat, 01 Feb 2014 12:29:01 -0800 [thread overview]
Message-ID: <52ED590D.8090208@zytor.com> (raw)
In-Reply-To: <1391268756-10766-5-git-send-email-stefani@seibold.net>
On 02/01/2014 07:32 AM, stefani@seibold.net wrote:
>
> This kind of type hacking could be prevent in the future by doing a call to the
> 64 bit code by the following sequence:
>
> - Compile the arch/x86/vdso/vclock_gettime.c as 64 bit, but only generate
> the assembler output.
> - Next compile a 32 bit object by including the 64 bit vclock_gettime.s
> prefixed with .code64
> - At least we need a trampolin code which invokes the 64 bit code and do
> the API conversation (64 bit longs to 32 bit longs), like the
> followig snipped:
>
Honestly, I think the overhead of the mode switch would ruin a lot of
the advantages with the vdso.
-hpa
prev parent reply other threads:[~2014-02-01 20:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-01 15:32 [PATCH 0/4] Add 32 bit VDSO time function support stefani
2014-02-01 15:32 ` [PATCH 1/4] Make vsyscall_gtod_data handling x86 generic stefani
2014-02-01 23:40 ` Andy Lutomirski
2014-02-01 15:32 ` [PATCH 2/4] Add new func _install_special_mapping() to mmap.c stefani
2014-02-01 15:32 ` [PATCH 3/4] Add 32 bit VDSO time support for 32 bit kernel stefani
2014-02-01 23:59 ` Andy Lutomirski
2014-02-02 0:26 ` H. Peter Anvin
2014-02-02 0:30 ` Andy Lutomirski
2014-02-02 0:41 ` H. Peter Anvin
2014-02-02 0:56 ` H. Peter Anvin
2014-02-03 21:11 ` Roland McGrath
2014-02-02 11:20 ` Stefani Seibold
2014-02-02 15:25 ` H. Peter Anvin
2014-02-01 15:32 ` [PATCH 4/4] Add 32 bit VDSO time support for 64 " stefani
2014-02-01 20:29 ` H. Peter Anvin [this message]
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