Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: generic uaccess.h | Date | Fri, 24 Jul 2009 11:20:22 +0200 |
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On Friday 24 July 2009, Michal Simek wrote: > I have just look at asm-generic uaccess.h and there is one thing which > seems to me wrong. > > For put_user macro - you use __copy_to_user but you have for 64bit case > ifdef CONFIG_64BIT > but look at fs/eventfd: eventfd_read function. At least for this > function(syscall) is necessary "return" 64bit > value on 32bit machines too. > IMHO that ifdef CONFIG_64BIT shouldn't be there. > > What do you think? > If you agree with me, I'll generate proper patch with description.
The code was intentional, because 32 bit architectures normally don't acces u64 values efficiently. I would expect the memcpy to produce better object code in that case. Did you see an actual bug in my version or are you only guessing that the assignment should work better than the memcpy?
What object code do you get with
int test(unsigned long long __user *out, unsigned long long in) { return put_user(in, ptr); }
in both cases?
Arnd <><
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