x86/traps: replace plain numbers

... 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>

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 322ebf44b3f2e2fe6c5421c04dfdfd9076498c6c..ec324b0ec709646459791bc2f1ac5a0b8840c458 100644 (file)
--- 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, unsigned int reg, unsigned long value)
          * 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;

diff --git a/xen/include/asm-x86/debugreg.h b/xen/include/asm-x86/debugreg.h
index a5b28383912e93ec3be9b1784cee509de3581392..c57914efc6e81eac5f6c948cf26f374c68a930ca 100644 (file)
--- 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