[RFC v2] Decode UFFDIO_* ioctls

[Dmitry V. Levin]

On Fri, Apr 29, 2016 at 08:32:47PM +0100, Dr. David Alan Gilbert wrote:
> * Dmitry V. Levin (ldv at altlinux.org) wrote:
> > On Sat, Apr 23, 2016 at 05:39:42AM +0300, Dmitry V. Levin wrote:
> > > On Fri, Apr 22, 2016 at 07:02:08PM +0100, Dr. David Alan Gilbert (git) wrote:
> > [...]
> > > >    don't use my decode_flags64 - I guess I should be using printflags
> > > >        but printflags uses struct xlat and they're both unsigned int
> > > >        where I'm dealing in uint64_t's; perhaps if I just rework
> > > >        printflags/xlat it'll all work ???
> > > 
> > > With regards to printing 64-bit flags, see the thread starting at
> > > https://sourceforge.net/p/strace/mailman/message/34979546/
> > 
> > The change of struct xlat is in, you can now generate xlat files filled
> > with 64-bit values by using "#val_type uint64_t" directive, and print
> > 64-bit values using e.g. printxval64() and printflags64().
> 
> Thanks;  it's not 100% happy yet; I was trying to use the 1<< notation
> and ended up with this minor fix:
> 
> diff --git a/xlat.h b/xlat.h
> index 64141b3..2f7643c 100644
> --- a/xlat.h
> +++ b/xlat.h
> @@ -10,7 +10,7 @@ struct xlat {
>  # define XLAT(val)                     { (unsigned)(val), #val }
>  # define XLAT_PAIR(val, str)           { (unsigned)(val), str  }
>  # define XLAT_TYPE(type, val)          {     (type)(val), #val }
> -# define XLAT_TYPE_PAIR(val, str)      {     (type)(val), str  }
> +# define XLAT_TYPE_PAIR(type, val, str)        {     (type)(val), str  }
>  # define XLAT_END                      {               0, 0    }

Oops.  Fixed, thanks.

> however, that's not enough, because the '1' is the wrong type,
> we really need ((type)1) << thing
> and I'm not too sure what the best way of fixing that in gen.sh is;
> you can see it getting that wrong in UFFDIO_API:
> 
> ioctl(4, UFFDIO_API, {api=0xaa, features.in=0, features.out=0, ioctls=_UFFDIO_REGISTER|_UFFDIO_UNREGISTER|0x8000000000000000}) = 0

I've changed gen.sh to generate 1ULL<<val,
it will hopefully work in all cases.

> +			tprintf(", {dst=%#" PRI__x64 ", src=%#" PRI__x64
> +				", len=%" PRI__u64, ", mode=",
> +				uc.dst, uc.src, uc.len);

The comma after PRI__u64 makes gcc -Werror very unhappy,
and rightly so.  Try to configure build with --enable-gcc-Werror.

> --- /dev/null
> +++ b/xlat/uffd_register_ioctl_flags.in
> @@ -0,0 +1,5 @@
> +#val_type uint64_t
> +1<< _UFFDIO_WAKE
> +1<< _UFFDIO_COPY
> +1<< _UFFDIO_ZEROPAGE
> +

gen.sh doesn't handle space characters after 1<< properly (yet).
git am complains about empty line at EOF.

> --- /dev/null
> +++ b/xlat/uffd_zeropage_flags.in
> @@ -0,0 +1,3 @@
> +#val_type uint64_t
> +UFFDIO_ZEROPAGE_MODE_DONTWAKE
> +

git am complains about this as well.


-- 
ldv
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