linux-kernel - Re: [RFC5 PATCH v6 00/21] ILP32 for ARM64

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Message-ID: <56FA816D.60101@huawei.com>
Date:	Tue, 29 Mar 2016 21:21:49 +0800
From:	"Zhangjian (Bamvor)" <bamvor.zhangjian@...wei.com>
To:	Yury Norov <ynorov@...iumnetworks.com>,
	Arnd Bergmann <arnd@...db.de>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	Andreas Schwab <schwab@...e.de>, <young.liuyang@...wei.com>,
	<pinskia@...il.com>, <Prasun.Kapoor@...iumnetworks.com>,
	<catalin.marinas@....com>, <broonie@...nel.org>,
	"jijun (D)" <jijun2@...wei.com>, <heiko.carstens@...ibm.com>,
	<linux-kernel@...r.kernel.org>, <agraf@...e.de>,
	<klimov.linux@...il.com>, <jan.dakinevich@...il.com>,
	<joseph@...esourcery.com>, <gaoyongliang@...wei.com>,
	<schwidefsky@...ibm.com>, <Nathan_Lynch@...tor.com>,
	Bamvor Zhang Jian <bamvor.zhangjian@...aro.org>,
	<christoph.muellner@...obroma-systems.com>,
	"Zhangjian (Bamvor)" <bamvor.zhangjian@...wei.com>
Subject: Re: [RFC5 PATCH v6 00/21] ILP32 for ARM64

Hi, Yury

On 2016/3/29 20:01, Yury Norov wrote:
> On Tue, Mar 29, 2016 at 12:58:25PM +0200, Arnd Bergmann wrote:
>> On Saturday 26 March 2016 20:36:43 Zhangjian wrote:
>>> Hi, Arnd
>>>
>>> On 2016/3/21 17:43, Arnd Bergmann wrote:
>>>> On Monday 21 March 2016 10:07:49 Andreas Schwab wrote:
>>>>> This patch may fix a few LTP tests.
>>>>>
>>>>
>>>> Thanks for analyzing.
>>>>
>>>>> diff --git a/sysdeps/unix/sysv/linux/aarch64/bits/fcntl.h b/sysdeps/unix/sysv/linux/aarch64/bits/fcntl.h
>>>>> index 3631903..d1010db 100644
>>>>> --- a/sysdeps/unix/sysv/linux/aarch64/bits/fcntl.h
>>>>> +++ b/sysdeps/unix/sysv/linux/aarch64/bits/fcntl.h
>>>>> @@ -25,18 +25,29 @@
>>>>>    #define __O_NOFOLLOW	0100000
>>>>>    #define __O_DIRECT	0200000
>>>>>
>>>>> -#define __O_LARGEFILE	0
>>>>> +#ifdef __ILP32__
>>>>> +# define __O_LARGEFILE	0400000
>>>>> +#else
>>>>> +# define __O_LARGEFILE	0
>>>>> +#endif
>>>>>
>>>>
>>>> I guess this means I screwed up when I said I'd merged the kernel patch
>>>> that Yury did to fix it, sorry about that.
>>>>
>>>> We need the patch to make all new architecture in the kernel default to
>>>> O_LARGEFILE, and not do this in user space. I'd suggest now to keep the
>>>> patches as part of the ILP32 series after all, to make sure they are
>>>> merged at the point when they are needed.
>>>
>>> I am a little bit confuse about off_t. In "[PATCH 08/33] 32-bit
>>> ABI: introduce ARCH_32BIT_OFF_T config option", it mentioned that all
>>> the new 32bit architecture should use 64bit off_t.
>>
>> Ah, so it is part of the series. I had not checked that here.
>>
>
> I'm preparing new submission now.
Cool:)
 > I can join off_t, s390 and ilp32
> patchsets. It seems, they will not be grabbed separately anyway, so
> this may decrease confusions like this.
>
> Arnd?
I am curious which one is more easily to get ack:p
>
>>> Should we define off_t in aarch64(for both ilp32 and lp64) in
>>> typesize.h as following?
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/aarch64/bits/typesizes.h b/sysdeps/unix/sysv/linux/aarch64/bits/typesizes.h
>>> index 7073493..13b77c5 100644
>>> --- a/sysdeps/unix/sysv/linux/aarch64/bits/typesizes.h
>>> +++ b/sysdeps/unix/sysv/linux/aarch64/bits/typesizes.h
>>> @@ -33,7 +33,7 @@
>>>    #define __INO64_T_TYPE         __UQUAD_TYPE
>>>    #define __MODE_T_TYPE          __U32_TYPE
>>>    #define __NLINK_T_TYPE         __U32_TYPE
>>> -#define __OFF_T_TYPE           __SLONGWORD_TYPE
>>> +#define __OFF_T_TYPE           __SQUAD_TYPE
>>>    #define __OFF64_T_TYPE         __SQUAD_TYPE
>>>    #define __PID_T_TYPE           __S32_TYPE
>>>    #define __RLIM_T_TYPE          __ULONGWORD_TYPE
>>>
>>> Then we could remove the __USE_FILE_OFFSET64 in stat.h and fcnt.h in
>>> aarch64. And truncate and ftruncate is same as truncate64 and
>>> ftruncate64.
>>
>> I don't know what the glibc developers prefer, but I think the
>> result needs to be something like that: either __OFF_T_TYPE is
>> defined as you write above as a 64-bit type, or the user-visible
>> off_t typedef unconditionally uses __OFF64_T_TYPE rather than
>> __OFF_T_TYPE.
>>
>
> I'm not the glibc developer as well, but I think it's OK.
IIUC, it is usually what glibc does.
If we want to define off_t to 64bit in ilp32, the follow syscall may
need to define as non-compat too:
sys_fadvise64
sys_sendfile
sys_sendfile64
sys_lseek
sys_splice
sys_sync_file_range2
sys_truncate
sys_ftruncate

Regards

Bamvor

>
>>> Otherwise we need to handle the pad like yury do it in
>>> stat.h, and we need to handle the bigendian as well:
>>
>> I see.
>>
>>> @@ -35,12 +35,21 @@ struct stat
>>>      {
>>>        __dev_t st_dev;			/* Device.  */
>>>    #ifdef __ILP32__
>>> +
>>> +#if !defined(__AARCH64EB__)
>>>        unsigned int __st_ino_pad;
>>> +#endif
>>> +
>>>    # ifndef __USE_FILE_OFFSET64
>>>        __ino_t st_ino;			/* File serial number.	*/
>>>    # else
>>>        __ino_t __st_ino;			/* 32bit file serial number.	*/
>>>    # endif
>>> +
>>> +#if defined(__AARCH64EB__)
>>> +    unsigned int __st_ino_pad;
>>> +#endif
>>> +
>>>    #else
>>
>> This would indeed be silly, we really don't want anyone
>> to access the old __st_ino field or the 32-bit version of
>> the offset here.
>>
>> 	Arnd