Re: [PATCH 2/7] signal: factor copy_siginfo_to_external32 from copy_siginfo_to_user32

Christophe Leroy
2020-04-28T07:45:58Z

Le 28/04/2020 à 09:09, Christoph Hellwig a écrit :
> On Mon, Apr 27, 2020 at 03:40:50PM -0700, Andrew Morton wrote:
>>> https://www.spinics.net/lists/kernel/msg3473847.html
>>> https://www.spinics.net/lists/kernel/msg3473840.html
>>> https://www.spinics.net/lists/kernel/msg3473843.html
>>
>> OK, but that doesn't necessitate the above monstrosity? How about
>>
>> static int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
>> const struct kernel_siginfo *from, bool x32_ABI)
>> {
>> struct compat_siginfo new;
>> copy_siginfo_to_external32(&new, from);
>> ...
>> }
>>
>> int copy_siginfo_to_user32(struct compat_siginfo __user *to,
>> const struct kernel_siginfo *from)
>> {
>> #if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION)
>> return __copy_siginfo_to_user32(to, from, in_x32_syscall());
>> #else
>> return __copy_siginfo_to_user32(to, from, 0);
>> #endif
>> }
>>
>> Or something like that - I didn't try very hard. We know how to do
>> this stuff, and surely this thing isn't how!
>
> I guess that might be a worthwhile middle ground. Still not a fan of
> all these ifdefs..
>

Can't we move the small X32 specific part out of
__copy_siginfo_to_user32(), in an arch specific helper that voids for
other architectures ?

Something like:

if (!arch_special_something(&new, from)) {
new.si_utime = from->si_utime;
new.si_stime = from->si_stime;
}

Then the arch_special_something() does what it wants in x86 and returns
1, and for architectures not implementating it, a generic version return
0 all the time.

Christophe