Re: [PATCH] disable ptrace BookE interface for PowerPC server processors

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> Date: Fri, 25 May 2012 00:49:39 -0300
> From: Edjunior Barbosa Machado <emachado@linux.vnet.ibm.com>
> 
> On 05/22/2012 02:34 PM, Mark Kettenis wrote:
> 
> > But how are you going to handle this when that functionality does
> > become available?  
> 
> 
> Thanks for the feedback and sorry for the late reply. I was discussing
> with the kernel developer responsible for the next version of the ptrace
> booke interface and he proposed that the 'features' field from the
> struct ppc_debug_info returned by ptrace PPC_PTRACE_GETHWDBGINFO call
> could be used to check if its availability. According to him, this field
> is currently 0 for servers, but once the new ptrace interface becomes
> functional, it will return the flag PPC_DEBUG_FEATURE_DATA_BP_RANGE
> enabled. Moreover, this change will not affect the behavior on embedded
> processors (which already has PPC_DEBUG_FEATURE_DATA_BP_RANGE and
> PPC_DEBUG_FEATURE_DATA_BP_MASK enabled).
> 
> Please consider the new version of the patch below.

Certainly makes more sense to me ;)

> gdb/
> 2012-25-05  Edjunior Machado  <emachado@linux.vnet.ibm.com>
> 
> 	* ppc-linux-nat.c (have_ptrace_booke_interface): disable ptrace booke
> 	interface for powerpc server processors if not available in kernel.
> 
> diff --git a/gdb/ppc-linux-nat.c b/gdb/ppc-linux-nat.c
> index 34c40b4..9ffcf88 100644
> --- a/gdb/ppc-linux-nat.c
> +++ b/gdb/ppc-linux-nat.c
> @@ -1421,17 +1421,18 @@ have_ptrace_booke_interface (void)
>        /* Check for kernel support for BOOKE debug registers.  */
>        if (ptrace (PPC_PTRACE_GETHWDBGINFO, tid, 0, &booke_debug_info) >= 0)
>  	{
> -	  have_ptrace_booke_interface = 1;
> -	  max_slots_number = booke_debug_info.num_instruction_bps
> -	    + booke_debug_info.num_data_bps
> -	    + booke_debug_info.num_condition_regs;
> -	}
> -      else
> -	{
> -	  /* Old school interface and no BOOKE debug registers support.  */
> -	  have_ptrace_booke_interface = 0;
> -	  memset (&booke_debug_info, 0, sizeof (struct ppc_debug_info));
> +	  if (booke_debug_info.features)
> +	    {
> +	      have_ptrace_booke_interface = 1;
> +	      max_slots_number = booke_debug_info.num_instruction_bps
> +	        + booke_debug_info.num_data_bps
> +	        + booke_debug_info.num_condition_regs;
> +	      return have_ptrace_booke_interface;
> +	    }
>  	}
> +      /* Old school interface and no BOOKE debug registers support.  */
> +      have_ptrace_booke_interface = 0;
> +      memset (&booke_debug_info, 0, sizeof (struct ppc_debug_info));
>      }
>  
>    return have_ptrace_booke_interface;
> 
>