Nick Desaulniers writes:
> On Thu, Jun 11, 2020 at 4:53 PM Segher Boessenkool
> wrote:
>>
>> On Thu, Jun 11, 2020 at 03:43:55PM -0700, Nick Desaulniers wrote:
>> > Segher, Cristophe, I suspect Clang is missing support for the %L and %U
>> > output templates [1].
...
>
> IIUC the bug report
On 06/12/2020 09:33 PM, Nick Desaulniers wrote:
IIUC the bug report correctly, it looks like LLVM is failing for the
__put_user_asm2_goto case for -m32. A simple reproducer:
https://godbolt.org/z/jBBF9b
void foo(long long in, long long* out) {
asm volatile(
"stw%X1 %0, %1\n\t"
Hi!
On Fri, Jun 12, 2020 at 02:33:09PM -0700, Nick Desaulniers wrote:
> On Thu, Jun 11, 2020 at 4:53 PM Segher Boessenkool
> wrote:
> > The PowerPC part of
> > https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html#Machine-Constraints
> > (sorry, no anchor) documents %U.
>
> I thought
On Thu, Jun 11, 2020 at 03:43:55PM -0700, Nick Desaulniers wrote:
> Segher, Cristophe, I suspect Clang is missing support for the %L and %U
> output templates [1].
The arch/powerpc kernel first used the %U output modifier in 0c176fa80fdf
(from 2016), and %L in b8b572e1015f (2008).
On Fri, 2020-04-17 at 17:08:51 UTC, Christophe Leroy wrote:
> unsafe_put_user() is designed to take benefit of 'asm goto'.
>
> Instead of using the standard __put_user() approach and branch
> based on the returned error, use 'asm goto' and make the
> exception code branch directly to the error
On Wed, May 06, 2020 at 08:10:57PM +0200, Christophe Leroy wrote:
> Le 06/05/2020 à 19:58, Segher Boessenkool a écrit :
> >> #define __put_user_asm_goto(x, addr, label, op) \
> >>asm volatile goto( \
> >>- "1: " op "%U1%X1
Le 06/05/2020 à 19:58, Segher Boessenkool a écrit :
On Wed, May 06, 2020 at 10:58:55AM +1000, Michael Ellerman wrote:
The "m<>" here is breaking GCC 4.6.3, which we allegedly still support.
[ You shouldn't use 4.6.3, there has been 4.6.4 since a while. And 4.6
is nine years old now.
On Wed, May 06, 2020 at 11:36:00AM +1000, Michael Ellerman wrote:
> >> As far as I understood that's mandatory on recent gcc to get the
> >> pre-update form of the instruction. With older versions "m" was doing
> >> the same, but not anymore.
> >
> > Yes. How much that matters depends on the
On Wed, May 06, 2020 at 10:58:55AM +1000, Michael Ellerman wrote:
> >> The "m<>" here is breaking GCC 4.6.3, which we allegedly still support.
> >
> > [ You shouldn't use 4.6.3, there has been 4.6.4 since a while. And 4.6
> > is nine years old now. Most projects do not support < 4.8 anymore,
Segher Boessenkool writes:
> On Tue, May 05, 2020 at 05:40:21PM +0200, Christophe Leroy wrote:
>> >>+#define __put_user_asm_goto(x, addr, label, op) \
>> >>+ asm volatile goto( \
>> >>+ "1: " op "%U1%X1 %0,%1 # put_user\n"
Segher Boessenkool writes:
> Hi!
>
> On Wed, May 06, 2020 at 12:27:58AM +1000, Michael Ellerman wrote:
>> Christophe Leroy writes:
>> > unsafe_put_user() is designed to take benefit of 'asm goto'.
>> >
>> > Instead of using the standard __put_user() approach and branch
>> > based on the returned
Hi,
Le 05/05/2020 à 16:27, Michael Ellerman a écrit :
Christophe Leroy writes:
unsafe_put_user() is designed to take benefit of 'asm goto'.
Instead of using the standard __put_user() approach and branch
based on the returned error, use 'asm goto' and make the
exception code branch directly
On Tue, May 05, 2020 at 05:40:21PM +0200, Christophe Leroy wrote:
> >>+#define __put_user_asm_goto(x, addr, label, op)\
> >>+ asm volatile goto( \
> >>+ "1: " op "%U1%X1 %0,%1 # put_user\n" \
> >>+
Hi!
On Wed, May 06, 2020 at 12:27:58AM +1000, Michael Ellerman wrote:
> Christophe Leroy writes:
> > unsafe_put_user() is designed to take benefit of 'asm goto'.
> >
> > Instead of using the standard __put_user() approach and branch
> > based on the returned error, use 'asm goto' and make the
>
Christophe Leroy writes:
> unsafe_put_user() is designed to take benefit of 'asm goto'.
>
> Instead of using the standard __put_user() approach and branch
> based on the returned error, use 'asm goto' and make the
> exception code branch directly to the error label. There is
> no code anymore in
unsafe_put_user() is designed to take benefit of 'asm goto'.
Instead of using the standard __put_user() approach and branch
based on the returned error, use 'asm goto' and make the
exception code branch directly to the error label. There is
no code anymore in the fixup section.
This change
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