[Crash-utility] [PATCH] sial: Fix processing of bitfields on bigendian systems

[Dave Anderson]

----- "Luc Chouinard" <Luc.Chouinard at trueposition.com> wrote:

> ACK - and thanks!

Can you attach an actual patch that I can download and apply?

Thanks,
  Dave

> 
> > -----Original Message-----
> > From: crash-utility-bounces at redhat.com [mailto:crash-utility-
> > bounces at redhat.com] On Behalf Of Michael Holzheu
> > Sent: Wednesday, September 16, 2009 1:45 PM
> > To: Chouinard, Luc
> > Cc: wein at de.ibm.com; crash
> > Subject: [Crash-utility] [PATCH] sial: Fix processing of bitfields
> on
> > bigendian systems
> > 
> > Hi Luc,
> > 
> > The processing of bit fields on big endian systems in sial is
> currently
> > broken, because the bits are not copied to the correct position and
> are
> > not shifted the right way.
> > 
> > To fix this, the following patch does the processing on big endian
> > systems as follows:
> > 1. sial_exemem(): Copy complete bit field to the "end" (right) of
> the
> >    long long variable.
> > 2. get_bit_value(): Shift the bits of the bit field member right to
> >    the "end" of the long long variable. This results in the value
> of
> >    the requested bitfield member.
> > 
> > Michael
> > ---
> >  extensions/libsial/sial_member.c |    7 +++++--
> >  extensions/libsial/sial_type.c   |    6 +++++-
> >  2 files changed, 10 insertions(+), 3 deletions(-)
> > 
> > Index: crash-4.0.9/extensions/libsial/sial_member.c
> > ===================================================================
> > --- crash-4.0.9.orig/extensions/libsial/sial_member.c
> > +++ crash-4.0.9/extensions/libsial/sial_member.c
> > @@ -236,10 +236,13 @@ srcpos_t p;
> >  		}
> >  		/* bit field gymnastic */
> >  		else if(stm->m.nbits) {
> > -
> >  			ull value=0;
> > +			void *target = &value;
> > +
> > +			if (__BYTE_ORDER != __LITTLE_ENDIAN)
> > +				target = target + (sizeof(value) -
> stm->m.size);
> > 
> > -			API_GETMEM(m->mem+stm->m.offset, &value,
> stm->m.size);
> > +			API_GETMEM(m->mem+stm->m.offset, target,
> stm->m.size);
> >  			get_bit_value(value, stm->m.nbits, stm->m.fbit,
> stm-
> > >m.size, v);
> >  			/* no mempos for bit fields ... */
> > 
> > Index: crash-4.0.9/extensions/libsial/sial_type.c
> > ===================================================================
> > --- crash-4.0.9.orig/extensions/libsial/sial_type.c
> > +++ crash-4.0.9/extensions/libsial/sial_type.c
> > @@ -287,7 +287,11 @@ get_bit_value(ull val, int nbits, int bo
> >          else {
> >                  mask = ((1 << nbits) - 1);
> >          }
> > -        val = val >> boff;
> > +
> > +	if (__BYTE_ORDER == __LITTLE_ENDIAN)
> > +		val = val >> boff;
> > +	else
> > +		val = val >> (vnbits - boff - nbits);
> >  	val &= mask;
> > 
> >  	if(issigned(v)) {
> > 
> > 
> > --
> > Crash-utility mailing list
> > Crash-utility at redhat.com
> > https://www.redhat.com/mailman/listinfo/crash-utility
> 
> 
> 
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