Re: [PATCH 07/15] parisc: use generic sys_fanotify_mark implementation

["Arnd Bergmann" <arnd@arndb.de>]

On Fri, Jun 21, 2024, at 07:26, LEROY Christophe wrote:
> Le 20/06/2024 à 23:21, Helge Deller a écrit :
>> [Vous ne recevez pas souvent de courriers de deller@gmx.de. Découvrez
>> pourquoi ceci est important à
>> https://aka.ms/LearnAboutSenderIdentification ]
>>
>> On 6/20/24 18:23, Arnd Bergmann wrote:
>>> From: Arnd Bergmann <arnd@arndb.de>
>>>
>>> The sys_fanotify_mark() syscall on parisc uses the reverse word order
>>> for the two halves of the 64-bit argument compared to all syscalls on
>>> all 32-bit architectures. As far as I can tell, the problem is that
>>> the function arguments on parisc are sorted backwards (26, 25, 24, 23,
>>> ...) compared to everyone else,
>>
>> r26 is arg0, r25 is arg1, and so on.
>> I'm not sure I would call this "sorted backwards".
>> I think the reason is simply that hppa is the only 32-bit big-endian
>> arch left...
>
> powerpc/32 is big-endian: r3 is arg0, r4 is arg1, ... r10 is arg7.

Right, I'm pretty sure the ordering is the same on arm, mips,
s390, m68k, openrisc, sh and sparc when running 32-bit big-endian
code.

It's more likely to be related to the upward growing stack.
I checked the gcc sources and found that out of the 50 supported
architectures, ARGS_GROW_DOWNWARD is set on everything except
for gcn, stormy16 and  32-bit parisc. The other two are
little-endian though. STACK_GROWS_DOWNWARD in turn is set on
everything other than parisc (both 32-bit and 64-bit).

      Arnd