From: "H. Peter Anvin" <hpa@zytor.com>
To: Arnd Bergmann <arnd@arndb.de>, ksummit-discuss@lists.linuxfoundation.org
Cc: John Stultz <john.stultz@linaro.org>,
lkml <linux-kernel@vger.kernel.org>,
"Joseph S. Myers" <joseph@codesourcery.com>
Subject: Re: [Ksummit-discuss] 2038 Kernel Summit Discussion Fodder
Date: Fri, 18 Sep 2015 17:04:22 -0700 [thread overview]
Message-ID: <55FCA686.601@zytor.com> (raw)
In-Reply-To: <3758173.O0N9ZgmMoN@wuerfel>
On 08/13/2014 01:06 PM, Arnd Bergmann wrote:
> On Wednesday 13 August 2014 03:06:53 Ben Hutchings wrote:
>>> On the kernel side, it also adds more complexity, where we have to add
>>> even more complex compat support for 64bit systems to handle all the
>>> various 32bit applications possible.
>> [...]
>>
>> Didn't we need to do this already to support x32? Have compat ioctls
>> involving time been botched?
>
> AFAICT, every ioctl that involves passing a __kernel_ulong_t or
> __kernel_ulong_t is potentially broken on x32, and this includes
> everything passing a time_t or timespec.
>
> The problem is that the libc ioctl() function ends up in the kernel's
> compat_ioctl handler, which expects the 32-bit ABI, not the 64-bit ABI.
> Most other syscalls in x32 however use the 64-bit ABI.
>
> It works only for drivers that use the same function for .ioctl and
> .compat_ioctl, and that encode the size of the data structure correctly
> in the ioctl command code. I assume this is how we will do it for all
> 32-bit architectures with 64-bit time_t, but on x32 it also concerns
> other types that use __kernel_long_t.
>
OK, super-late reply.
Actually we have by and large dealt with that. Sadly this meant an
increase in the number of paths with conditional ABI.
-hpa
WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: Arnd Bergmann <arnd@arndb.de>, ksummit-discuss@lists.linuxfoundation.org
Cc: Ben Hutchings <ben@decadent.org.uk>,
John Stultz <john.stultz@linaro.org>,
"Joseph S. Myers" <joseph@codesourcery.com>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [Ksummit-discuss] 2038 Kernel Summit Discussion Fodder
Date: Fri, 18 Sep 2015 17:04:22 -0700 [thread overview]
Message-ID: <55FCA686.601@zytor.com> (raw)
In-Reply-To: <3758173.O0N9ZgmMoN@wuerfel>
On 08/13/2014 01:06 PM, Arnd Bergmann wrote:
> On Wednesday 13 August 2014 03:06:53 Ben Hutchings wrote:
>>> On the kernel side, it also adds more complexity, where we have to add
>>> even more complex compat support for 64bit systems to handle all the
>>> various 32bit applications possible.
>> [...]
>>
>> Didn't we need to do this already to support x32? Have compat ioctls
>> involving time been botched?
>
> AFAICT, every ioctl that involves passing a __kernel_ulong_t or
> __kernel_ulong_t is potentially broken on x32, and this includes
> everything passing a time_t or timespec.
>
> The problem is that the libc ioctl() function ends up in the kernel's
> compat_ioctl handler, which expects the 32-bit ABI, not the 64-bit ABI.
> Most other syscalls in x32 however use the 64-bit ABI.
>
> It works only for drivers that use the same function for .ioctl and
> .compat_ioctl, and that encode the size of the data structure correctly
> in the ioctl command code. I assume this is how we will do it for all
> 32-bit architectures with 64-bit time_t, but on x32 it also concerns
> other types that use __kernel_long_t.
>
OK, super-late reply.
Actually we have by and large dealt with that. Sadly this meant an
increase in the number of paths with conditional ABI.
-hpa
next prev parent reply other threads:[~2015-09-19 0:04 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-13 0:01 [Ksummit-discuss] 2038 Kernel Summit Discussion Fodder John Stultz
2014-08-13 2:06 ` Ben Hutchings
2014-08-13 2:06 ` Ben Hutchings
2014-08-13 4:03 ` John Stultz
2014-08-13 4:03 ` John Stultz
2014-08-13 20:06 ` Arnd Bergmann
2014-08-13 20:06 ` Arnd Bergmann
2015-09-19 0:04 ` H. Peter Anvin [this message]
2015-09-19 0:04 ` H. Peter Anvin
2014-08-13 12:05 ` Joseph S. Myers
2014-08-13 12:05 ` Joseph S. Myers
2014-08-13 15:37 ` [Ksummit-discuss] " Joseph S. Myers
2014-08-13 15:37 ` Joseph S. Myers
2014-08-13 15:37 ` Joseph S. Myers
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