Re: [PATCH v4 2/2] x86/hvm: clean up segment validation

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 22/11/13 14:21, Jan Beulich wrote:
> Use _SEGMENT_* instead of plain numbers where feasible.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

>
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -2259,7 +2259,7 @@ static int hvm_load_segment_selector(
>          desc = *pdesc;
>  
>          /* Segment present in memory? */
> -        if ( !(desc.b & (1u<<15)) )
> +        if ( !(desc.b & _SEGMENT_P) )
>          {
>              fault_type = TRAP_no_segment;
>              goto unmap_and_fail;
> @@ -2277,7 +2277,7 @@ static int hvm_load_segment_selector(
>          {
>          case x86_seg_cs:
>              /* Code segment? */
> -            if ( !(desc.b & (1u<<11)) )
> +            if ( !(desc.b & _SEGMENT_CODE) )
>                  goto unmap_and_fail;
>              /* Non-conforming segment: check DPL against RPL. */
>              if ( !(desc.b & _SEGMENT_EC) && (dpl != rpl) )
> @@ -2285,19 +2285,19 @@ static int hvm_load_segment_selector(
>              break;
>          case x86_seg_ss:
>              /* Writable data segment? */
> -            if ( (desc.b & (5u<<9)) != (1u<<9) )
> +            if ( (desc.b & (_SEGMENT_CODE|_SEGMENT_WR)) != _SEGMENT_WR )
>                  goto unmap_and_fail;
>              if ( (dpl != cpl) || (dpl != rpl) )
>                  goto unmap_and_fail;
>              break;
>          case x86_seg_ldtr:
>              /* LDT system segment? */
> -            if ( (desc.b & (15u<<8)) != (2u<<8) )
> +            if ( (desc.b & _SEGMENT_TYPE) != (2u<<8) )
>                  goto unmap_and_fail;
>              goto skip_accessed_flag;
>          default:
>              /* Readable code or data segment? */
> -            if ( (desc.b & (5u<<9)) == (4u<<9) )
> +            if ( (desc.b & (_SEGMENT_CODE|_SEGMENT_WR)) == _SEGMENT_CODE )
>                  goto unmap_and_fail;
>              /*
>               * Data or non-conforming code segment:
>
>
>