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

[Chouinard, Luc]

ACK - and thanks!

> -----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)) {
> 
> 
> --
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