From: David Laight
> Sent: 23 October 2020 22:52
...
> Could do_put_user() do an initial check for 64 bit
> then expand a different #define that contains the actual
> code passing either "a" or "A" for the constriant.
>
> Apart from another level of indirection nothing is duplicated.
This code
On October 23, 2020 2:52:16 PM PDT, David Laight
wrote:
>From: Linus Torvalds
>> Sent: 23 October 2020 22:11
>>
>> On Fri, Oct 23, 2020 at 2:00 PM wrote:
>> >
>> > There is no same reason to mess around with hacks when we are
>talking about dx:ax, though.
>>
>> Sure there is.
>>
>> "A"
On October 23, 2020 2:11:19 PM PDT, Linus Torvalds
wrote:
>On Fri, Oct 23, 2020 at 2:00 PM wrote:
>>
>> There is no same reason to mess around with hacks when we are talking
>about dx:ax, though.
>
>Sure there is.
>
>"A" doesn't actually mean %edx:%eax like you seem to think.
>
>It actually
From: Linus Torvalds
> Sent: 23 October 2020 22:11
>
> On Fri, Oct 23, 2020 at 2:00 PM wrote:
> >
> > There is no same reason to mess around with hacks when we are talking about
> > dx:ax, though.
>
> Sure there is.
>
> "A" doesn't actually mean %edx:%eax like you seem to think.
>
> It
On Fri, Oct 23, 2020 at 2:00 PM wrote:
>
> There is no same reason to mess around with hacks when we are talking about
> dx:ax, though.
Sure there is.
"A" doesn't actually mean %edx:%eax like you seem to think.
It actually means %eax OR %edx, and then if given a 64-bit value, it
will use the
On October 23, 2020 1:55:22 PM PDT, Linus Torvalds
wrote:
>Thanks, applied.
>
>On Fri, Oct 23, 2020 at 1:32 PM Rasmus Villemoes
> wrote:
>>
>> I'm wondering if one would also need to make __ptr_pu and __ret_pu
>> explicitly "%"_ASM_CX".
>
>No, the "c"/"0" thing is much better, and makes it
Thanks, applied.
On Fri, Oct 23, 2020 at 1:32 PM Rasmus Villemoes
wrote:
>
> I'm wondering if one would also need to make __ptr_pu and __ret_pu
> explicitly "%"_ASM_CX".
No, the "c"/"0" thing is much better, and makes it properly atomic wrt
the actual asm.
As mentioned to Andy, the "register
On October 23, 2020 1:42:39 PM PDT, Andy Lutomirski wrote:
>On Fri, Oct 23, 2020 at 1:32 PM Rasmus Villemoes
> wrote:
>>
>> Quoting
>> https://gcc.gnu.org/onlinedocs/gcc/Local-Register-Variables.html:
>>
>> You can define a local register variable and associate it with a
>> specified
On Fri, Oct 23, 2020 at 1:42 PM Andy Lutomirski wrote:
>
> This looks like the patch is an improvement, but this is still IMO
> likely to be very fragile. Can we just do the size-dependent "a" vs
> "A" selection method instead? Sure, it's a little more code, but it
> will be Obviously Correct.
On Fri, Oct 23, 2020 at 1:32 PM Rasmus Villemoes
wrote:
>
> Quoting
> https://gcc.gnu.org/onlinedocs/gcc/Local-Register-Variables.html:
>
> You can define a local register variable and associate it with a
> specified register...
>
> The only supported use for this feature is to specify
Quoting
https://gcc.gnu.org/onlinedocs/gcc/Local-Register-Variables.html:
You can define a local register variable and associate it with a
specified register...
The only supported use for this feature is to specify registers for
input and output operands when calling Extended asm (see
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