[RFC v2] Decode UFFDIO_* ioctls

[Dmitry V. Levin]

On Wed, May 04, 2016 at 06:00:58PM +0100, Dr. David Alan Gilbert wrote:
> * Dmitry V. Levin (ldv at altlinux.org) wrote:
> > On Tue, May 03, 2016 at 08:23:43PM +0100, Dr. David Alan Gilbert wrote:
> > [...]
> > > > > --- /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.
> > > 
> > > Fixed. Hmm, I've removed the spaces, but the output I'm getting is:
> > > [pid  9644] ioctl(20, UFFDIO_REGISTER{range={start=0x7ff674200000, len=0x40000}, mode=UFFDIO_REGISTER_MODE_MISSING, ioctls=_UFFDIO_WAKE|_UFFDIO_COPY|_UFFDIO_ZEROPAGE}) = 0
> > > 
> > > shouldn't I be seeing 1ull<<_UFFDIO_WAKE | 1ull << _UFFDIO_COPY etc?
> > 
> > We have just a few users of this feature, and these users seem to be OK
> > with the current behaviour, which means we probably need another syntax
> > for this case.
> 
> Hmm this is confusing; I see icmp flags are one of the options;
> so strace ping:
> 
> setsockopt(3, SOL_RAW, ICMP_FILTER, ~(ICMP_ECHOREPLY|ICMP_DEST_UNREACH|ICMP_SOURCE_QUENCH|ICMP_REDIRECT|ICMP_TIME_EXCEEDED|ICMP_PARAMETERPROB), 4) = 0
> 
> if we look at the source for ping:
>         struct icmp_filter filt;
>         filt.data = ~((1<<ICMP_SOURCE_QUENCH)|
>                       (1<<ICMP_DEST_UNREACH)|
>                       (1<<ICMP_TIME_EXCEEDED)|
>                       (1<<ICMP_PARAMETERPROB)|
>                       (1<<ICMP_REDIRECT)|
>                       (1<<ICMP_ECHOREPLY));
>         if (setsockopt(icmp_sock, SOL_RAW, ICMP_FILTER, (char*)&filt, sizeof(filt)) == -1)
> 
> so I reckon the current decode is wrong; however, it is more readable
> and if we prefer readable I'm happy to stick with it.

I think the output should be both correct and readable
so parser of ICMP_FILTER argument needs a fix.


-- 
ldv
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.strace.io/pipermail/strace-devel/attachments/20160504/d0376d0c/attachment.bin>