From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH 3/4] x86/traps: replace plain numbers
Date: Thu, 22 Jan 2015 14:45:48 +0000
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To: Jan Beulich <JBeulich@suse.com>, xen-devel <xen-devel@lists.xenproject.org>
Cc: Keir Fraser <keir@xen.org>
List-Id: xen-devel@lists.xenproject.org

On 22/01/15 14:00, Jan Beulich wrote:
> ... making the code better document itself. No functional change
> intended.
>
> Note that for now (as we don't support RTM yet) DR_STATUS_RESERVED_ONE
> and its users don't take DR_NOT_RTM into consideration yet.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

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

>
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -531,9 +531,9 @@ static void instruction_done(
>      regs->eflags &= ~X86_EFLAGS_RF;
>      if ( bpmatch || (regs->eflags & X86_EFLAGS_TF) )
>      {
> -        current->arch.debugreg[6] |= bpmatch | 0xffff0ff0;
> +        current->arch.debugreg[6] |= bpmatch | DR_STATUS_RESERVED_ONE;
>          if ( regs->eflags & X86_EFLAGS_TF )
> -            current->arch.debugreg[6] |= 0x4000;
> +            current->arch.debugreg[6] |= DR_STEP;
>          do_guest_trap(TRAP_debug, regs, 0);
>      }
>  }
> @@ -3872,8 +3872,8 @@ long set_debugreg(struct vcpu *v, unsign
>           * DR6: Bits 4-11,16-31 reserved (set to 1).
>           *      Bit 12 reserved (set to 0).
>           */
> -        value &= 0xffffefff; /* reserved bits => 0 */
> -        value |= 0xffff0ff0; /* reserved bits => 1 */
> +        value &= ~DR_STATUS_RESERVED_ZERO; /* reserved bits => 0 */
> +        value |=  DR_STATUS_RESERVED_ONE;  /* reserved bits => 1 */
>          if ( v == curr ) 
>              write_debugreg(6, value);
>          break;
> --- a/xen/include/asm-x86/debugreg.h
> +++ b/xen/include/asm-x86/debugreg.h
> @@ -21,6 +21,8 @@
>  #define DR_STEP         (0x4000)        /* single-step */
>  #define DR_SWITCH       (0x8000)        /* task switch */
>  #define DR_NOT_RTM      (0x10000)       /* clear: #BP inside RTM region */
> +#define DR_STATUS_RESERVED_ZERO (~0xffffeffful) /* Reserved, read as zero */
> +#define DR_STATUS_RESERVED_ONE  0xffff0ff0ul /* Reserved, read as one */
>  
>  /* Now define a bunch of things for manipulating the control register.
>     The top two bytes of the control register consist of 4 fields of 4
>
>
>