Re: [PATCH 5/9] MIPS: Add numa api support

[Alex Smith <alex.smith@imgtec.com>]

Hi Huacai,

The compat wrappers are needed for all of them for O32/N32 on a 64-bit 
kernel. {get,set}mempolicy, mbind and migrate_pages all copy bitmaps 
to/from user memory. The non-compat versions would behave fine on little 
endian, but the compat versions are needed to convert the 32-bit bitmaps 
to 64-bit on big endian.

move_pages takes an array of pointers, the compat version is needed to 
convert that to 64-bit.

Alex

On 11/04/14 09:21, Huacai Chen wrote:
> Hi, MIPS hackers,
>
> Could anyone help me?
>
> Huacai
>
> On Thu, Apr 10, 2014 at 6:47 PM, Huacai Chen <chenhc@lemote.com> wrote:
>> Hi, David,
>>
>> After some code reading, I have some understanding about compat
>> syscall, please tell me whether I'm correct.
>> 1, compat syscall is only needed by n32/o32 userspace on 64-bit kernel.
>> 2, compat syscall is only needed when there are arguments in pointer type.
>> 3, compat syscall is only needed when pointer arguments are
>> array/struct/union for reading (reading means get_user or
>> copy_from_user), or pointer arguments are array/struct/union/long
>> integer for writing (writing means put_user or copy_to_user).
>>
>> If my understanding is correct, then in this patch, get_mempolicy()
>> need to use the compat version for n32/o32 on 64-bit kernel, mbind()
>> and set_mempolicy() can use the normal version in all cases. But when
>> I reading the X86 code, it seems like only o32 on 64-bit kernel need a
>> compat version (I assume i386/X32/X64 on X86 is the same as
>> o32/n32/n64 on MIPS).
>>
>> Please give some information, thanks.
>>
>> Huacai
>>
>> On Sat, Apr 5, 2014 at 8:54 AM, "陈华才" <chenhc@lemote.com> wrote:
>>> Excuse me, what's the compat version exactly means? Or how to produce a
>>> problem  without a compat version? It seems everything works fine just
>>> with this patch.
>>>
>>> Huacai
>>>
>>>> On 04/04/2014 01:11 AM, Huacai Chen wrote:
>>>>> Enable sys_mbind()/sys_get_mempolicy()/sys_set_mempolicy() for O32, N32,
>>>>> and N64 ABIs.
>>>>>
>>>>> Signed-off-by: Huacai Chen <chenhc@lemote.com>
>>>>
>>>> NACK.
>>>>
>>>> You need compat versions of the syscalls...
>>>>
>>>> Also current migrate_pages and move_pages syscalls need to use the
>>>> compat wrappers for 32-bit ABIs.
>>>>
>>>> David Daney
>>>>
>>>>
>>>>> ---
>>>>>    arch/mips/kernel/scall32-o32.S |    4 ++--
>>>>>    arch/mips/kernel/scall64-64.S  |    4 ++--
>>>>>    arch/mips/kernel/scall64-n32.S |    6 +++---
>>>>>    arch/mips/kernel/scall64-o32.S |    6 +++---
>>>>>    4 files changed, 10 insertions(+), 10 deletions(-)
>>>>>
>>>>> diff --git a/arch/mips/kernel/scall32-o32.S
>>>>> b/arch/mips/kernel/scall32-o32.S
>>>>> index fdc70b4..7f7e2fb 100644
>>>>> --- a/arch/mips/kernel/scall32-o32.S
>>>>> +++ b/arch/mips/kernel/scall32-o32.S
>>>>> @@ -495,8 +495,8 @@ EXPORT(sys_call_table)
>>>>>       PTR     sys_tgkill
>>>>>       PTR     sys_utimes
>>>>>       PTR     sys_mbind
>>>>> -    PTR     sys_ni_syscall                  /* sys_get_mempolicy */
>>>>> -    PTR     sys_ni_syscall                  /* 4270 sys_set_mempolicy */
>>>>> +    PTR     sys_get_mempolicy
>>>>> +    PTR     sys_set_mempolicy               /* 4270 */
>>>>>       PTR     sys_mq_open
>>>>>       PTR     sys_mq_unlink
>>>>>       PTR     sys_mq_timedsend
>>>>> diff --git a/arch/mips/kernel/scall64-64.S
>>>>> b/arch/mips/kernel/scall64-64.S
>>>>> index dd99c328..a4baf06 100644
>>>>> --- a/arch/mips/kernel/scall64-64.S
>>>>> +++ b/arch/mips/kernel/scall64-64.S
>>>>> @@ -347,8 +347,8 @@ EXPORT(sys_call_table)
>>>>>       PTR     sys_tgkill                      /* 5225 */
>>>>>       PTR     sys_utimes
>>>>>       PTR     sys_mbind
>>>>> -    PTR     sys_ni_syscall                  /* sys_get_mempolicy */
>>>>> -    PTR     sys_ni_syscall                  /* sys_set_mempolicy */
>>>>> +    PTR     sys_get_mempolicy
>>>>> +    PTR     sys_set_mempolicy
>>>>>       PTR     sys_mq_open                     /* 5230 */
>>>>>       PTR     sys_mq_unlink
>>>>>       PTR     sys_mq_timedsend
>>>>> diff --git a/arch/mips/kernel/scall64-n32.S
>>>>> b/arch/mips/kernel/scall64-n32.S
>>>>> index f68d2f4..92db19e 100644
>>>>> --- a/arch/mips/kernel/scall64-n32.S
>>>>> +++ b/arch/mips/kernel/scall64-n32.S
>>>>> @@ -339,9 +339,9 @@ EXPORT(sysn32_call_table)
>>>>>       PTR     compat_sys_clock_nanosleep
>>>>>       PTR     sys_tgkill
>>>>>       PTR     compat_sys_utimes               /* 6230 */
>>>>> -    PTR     sys_ni_syscall                  /* sys_mbind */
>>>>> -    PTR     sys_ni_syscall                  /* sys_get_mempolicy */
>>>>> -    PTR     sys_ni_syscall                  /* sys_set_mempolicy */
>>>>> +    PTR     sys_mbind
>>>>> +    PTR     sys_get_mempolicy
>>>>> +    PTR     sys_set_mempolicy
>>>>
>>>> Here
>>>>
>>>>
>>>>>       PTR     compat_sys_mq_open
>>>>>       PTR     sys_mq_unlink                   /* 6235 */
>>>>>       PTR     compat_sys_mq_timedsend
>>>>> diff --git a/arch/mips/kernel/scall64-o32.S
>>>>> b/arch/mips/kernel/scall64-o32.S
>>>>> index 70f6ace..0230429 100644
>>>>> --- a/arch/mips/kernel/scall64-o32.S
>>>>> +++ b/arch/mips/kernel/scall64-o32.S
>>>>> @@ -473,9 +473,9 @@ EXPORT(sys32_call_table)
>>>>>       PTR     compat_sys_clock_nanosleep      /* 4265 */
>>>>>       PTR     sys_tgkill
>>>>>       PTR     compat_sys_utimes
>>>>> -    PTR     sys_ni_syscall                  /* sys_mbind */
>>>>> -    PTR     sys_ni_syscall                  /* sys_get_mempolicy */
>>>>> -    PTR     sys_ni_syscall                  /* 4270 sys_set_mempolicy */
>>>>> +    PTR     sys_mbind
>>>>> +    PTR     sys_get_mempolicy
>>>>> +    PTR     sys_set_mempolicy               /* 4270 */
>>>>
>>>> And Here.
>>>>
>>>>
>>>>>       PTR     compat_sys_mq_open
>>>>>       PTR     sys_mq_unlink
>>>>>       PTR     compat_sys_mq_timedsend
>>>>>
>>>>
>>>>
>>>
>>>
>>>
>