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[RFA 3/3] Implement support for PowerPC BookE masked watchpoints


Hi Uli,

Thanks for your review and suggestions!

[ This patch depends on two patches that I'm posting as replies to your
message too so that they'll be grouped together. ]

On Thu, 2011-02-17 at 15:40 +0100, Ulrich Weigand wrote:
> Thiago Jung Bauermann wrote:
> The effect is that GDB will parse the expression, create the list of
> memory regions it needs to watch to implement its high-level semantics.
> Then, it will just add the mask to each of the addresses generated
> in that manner.  It seems to me that in general, the effects of what
> will actually happen now are hard to predict, and will generally not
> be what the user expects.
> 
> Of course, the feature *can* be used in ways the user understands,
> like in the example you show in the documentation:
>    watch *0xdeadbeef mask 0xffffff00
> 
> But if used in a more complex way, like
>    watch p->x mask 0xffffff00
> for some local variable p, this doesn't seem to have very useful
> (or even well-defined) semantics ...

This isn't a problem for PowerPC because there are only two hardware
watchpoint registers, and both will be needed to set up a masked
watchpoint (one for the address, the other for the mask). So the command
you mention above would fail since it would need more registers than
that. But I agree that in general it's a problem.

> Now, I'm not sure how exactly the GDB command line syntax ought to
> be modified to implement this.  But most fundamentally, we should
> go away from specifying "the value of an expression", and rather
> go to specifying a memory region via address and mask.
> 
> We've recently added the -location feature that already prevents
> GDB from fully tracking the expression, but rather just evaluate
> it one time for its address.   Maybe one simple fix could be to
> restrict the "mask" feature to watch -location (or have the 
> presence of "mask" automatically imply -location, or maybe have
> instead a new keyword -masked-location or so).

-location is indeed a good fit for this patch. I don't think we need a
separate -masked-location keyword, so in this patch I made the mask
parameter imply -location. Do you think this addresses your concerns
regarding the semantics of masked watchpoints?

> However, even so there are still differences: even with -location,
> GDB watchpoint code will still treat a watchpoint as refering to
> one value, and track it (e.g. remember the value we saw last time;
> re-evaluate it each time execution stops etc.).  This is really
> not appropriate for the masked watchpoint case, because we do not
> *have* any contiguous region that would define any single value.
> Therefore, it seems to me that all this code ought to be disabled
> for masked watchpoints.

Indeed. With this new patch, the only place that evaluates the
watchpoint expression is update_watchpoint. This is necessary because
the resulting value chain is then used to create the bp_locations and
also by can_use_hardware_watchpoint when deciding whether to set a
software or hardware watchpoint.

I could manually create a bp_location for masked watchpoints and
implement a version of can_use_hardware_watchpoint just for masked
watchpoints, but is it worth the extra special casing and complexity in
update_watchpoint?

> A couple of more specific comments on the patch:
> 
> > @@ -1518,10 +1522,26 @@ update_watchpoint (struct breakpoint *b, int reparse)
> >  	      target_resources_ok = target_can_use_hardware_watchpoint
> >  		    (bp_hardware_watchpoint, i, other_type_used);
> >  	      if (target_resources_ok <= 0)
> > -		b->type = bp_watchpoint;
> > +		{
> > +		  if (orig_type == bp_hardware_watchpoint
> > +		      && b->ops && b->ops->works_in_software_mode
> > +		      && !b->ops->works_in_software_mode (b))
> > +		    error (_("This watchpoint cannot be used "
> > +			     "in software mode."));
> > +		  else
> > +		    b->type = bp_watchpoint;
> > +		}
> >  	    }
> >  	  else
> > -	    b->type = bp_watchpoint;
> > +	    {
> > +	      if (b->type == bp_hardware_watchpoint
> > +		  && b->ops && b->ops->works_in_software_mode
> > +		  && !b->ops->works_in_software_mode (b))
> > +		error (_("This watchpoint cannot be used "
> > +			 "in software mode."));
> > +	      else
> > +		b->type = bp_watchpoint;
> > +	    }
> 
> What is the point of checking the original type?  If works_in_software_mode
> returns false, the original type couldn't have been a software watchpoint
> anyway, could it?

Right, removed.

> >  	   print_it_typical.  */
> >  	/* FIXME: how breakpoint can ever be NULL here?  */
> >  	if (b != NULL && b->ops != NULL && b->ops->print_it != NULL)
> > -	  return b->ops->print_it (b);
> > +	  return b->ops->print_it (b, bs->old_val);
> >  	else
> >  	  return print_it_typical (bs);
> >        }
> 
> I don't understand this change.  You add the "old_val" argument to the
> print_it routine, and the new instance of print_it for masked watchpoints
> then uses it (for what purpose?) ...  But for masked watchpoints, the
> whole concept of its "value", new or old, doesn't make sense to start
> with ...

I added it for two reasons. First, because I thought it made sense to
make available to print_it implementations the same information that
print_it_typical uses itself. Also, I wasn't sure how important is this
code in print_it_masked_watchpoint which I borrowed from
print_it_typical:

+    case bp_access_watchpoint:
+      if (old_val != NULL)
+       annotate_watchpoint (b->number);

So I decided to keep it. In this version I removed the old_val argument
and the call to annotate_watchpoint.

> > @@ -3761,6 +3796,11 @@ watchpoint_check (void *p)
> >  	  b->val_valid = 1;
> >  	  return WP_VALUE_CHANGED;
> >  	}
> > +      else if (is_masked_watchpoint (b))
> > +	/* Since we don't know the exact trigger address (from
> > +	   stopped_data_address), just tell the user we've triggered
> > +	   a mask watchpoint.  */
> > +	return WP_VALUE_CHANGED;
> 
> This goes back to the issue discussed above: this should not even
> attempt to "compute the old value" which doesn't make sense for a
> masked watchpoint.  Instead, it should simply report a stop to the
> user whenever the hardware reports a hit.

Right. This was solved simply by doing the is_masked_watchpoint check
before fetching the watchpoint value.

> > +static void
> > +print_one_detail_masked_watchpoint (const struct breakpoint *b,
> > +				    struct ui_out *uiout)
> > +{
> > +  ui_out_text (uiout, "\tmask ");
> > +
> > +  /* I don't know whether it's possible to get here without a b->loc,
> > +     but we can handle the situation.  */
> > +  if (b->loc)
> > +    ui_out_field_core_addr (uiout, "mask", b->loc->gdbarch, b->hw_wp_mask);
> > +  else
> > +    ui_out_field_string (uiout, "mask", core_addr_to_string (b->hw_wp_mask));
> 
> I think we should enforce that there is always exactly one location on
> masked watchpoints, just like we do e.g. for catchpoints.

Ok, with -location now we are guaranteed to have only one location.
Fixed.

> > +/* Implement the "print_recreate" breakpoint_ops method for
> > +   masked hardware watchpoints.  */
> > +
> > +static void
> > +print_recreate_masked_watchpoint (struct breakpoint *b, struct ui_file *fp)
> > +{
> > +  char tmp[40];
> > +
> > +  switch (b->type)
> > +    {
> > +    case bp_hardware_watchpoint:
> > +      fprintf_unfiltered (fp, "watch");
> > +      break;
> > +    case bp_read_watchpoint:
> > +      fprintf_unfiltered (fp, "rwatch");
> > +      break;
> > +    case bp_access_watchpoint:
> > +      fprintf_unfiltered (fp, "awatch");
> > +      break;
> > +    default:
> > +      internal_error (__FILE__, __LINE__,
> > +		      _("Invalid hardware watchpoint type."));
> > +    }
> > +
> > +  sprintf_vma (tmp, b->hw_wp_mask);
> > +  fprintf_unfiltered (fp, " %s mask 0x%s", b->exp_string, tmp);
> 
> Depending on the discussion on command syntax this may need to change anyway,
> but even with the current syntax, it ignores any -location flag that may have
> been given initially ...

Since mask now implies -location, no change is needed here anymore.

> > @@ -8540,7 +8832,14 @@ watch_command_1 (char *arg, int accessflag, int from_tty,
> >      b->exp_string = savestring (exp_start, exp_end - exp_start);
> >    b->val = val;
> >    b->val_valid = 1;
> > -  b->ops = &watchpoint_breakpoint_ops;
> > +
> > +  if (use_mask)
> > +    {
> > +      b->hw_wp_mask = hw_wp_mask;
> > +      b->ops = &masked_watchpoint_breakpoint_ops;
> > +    }
> > +  else
> > +    b->ops = &watchpoint_breakpoint_ops;
> 
> We shouldn't compute an intial value or set val_valid for masked watchpoints.

Fixed.

> > +/* Insert a new masked watchpoint at ADDR using the mask MASK.
> > +   RW may be hw_read for a read watchpoint, hw_write for a write watchpoint
> > +   or hw_access for an access watchpoint.  Returns 0 on success and throws
> > +   an error on failure.  */
> > +
> > +static int
> > +ppc_linux_insert_mask_watchpoint (struct target_ops *ops, CORE_ADDR addr,
> > +				  CORE_ADDR mask, int rw)
> > +{
> > +  ptid_t ptid;
> > +  struct lwp_info *lp;
> > +  struct ppc_hw_breakpoint p;
> > +
> > +  gdb_assert (have_ptrace_booke_interface ());
> > +
> > +  if ((mask & 0xC0000000) != 0xC0000000)
> > +    error (_("\
> > +The given mask covers kernel address space and cannot be used.\n\
> > +You have to delete the masked watchpoint to continue the debugging session."));
> 
> Huh, this interface seems a bit odd.  Shouldn't such watchpoints be rejected
> right from the start, using something like the region_ok_for_watchpoint
> callback?
>
> > +/* Return the number of registers needed for a masked hardware watchpoint.  */
> > +
> > +static int
> > +ppc_linux_masked_watch_num_registers (struct target_ops *target)
> > +{
> > +  return ((have_ptrace_booke_interface ()
> > +	   && booke_debug_info.features & PPC_DEBUG_FEATURE_DATA_BP_MASK)?
> > +	  2 : -1);
> > +}
> 
> So maybe this interface ought to get parameters to be able to check
> whether specific watchpoints are valid?

Ok, it now gets an addr and mask parameter, and returns -2 if the region
is rejected.

> >        INHERIT (to_insert_watchpoint, t);
> >        INHERIT (to_remove_watchpoint, t);
> > +      /* Do not inherit to_insert_mask_watchpoint.  */
> > +      /* Do not inherit to_remove_mask_watchpoint.  */
> 
> Why should this differ between regular and masked watchpoints?  Shouldn't
> they either both use inheritance or none?

This was discussed and settled in the ranged watchpoints patch, so I
didn't change it here.

Tested without regressions on ppc-linux, ppc64-linux and i386-linux. Ok?
-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center


2011-04-18  Sergio Durigan Junior  <sergiodj@linux.vnet.ibm.com>
	    Thiago Jung Bauermann  <bauerman@br.ibm.com>

	Implement support for PowerPC BookE masked watchpoints.

gdb/
	*NEWS: Mention masked watchpoint support.  Create "Changed commands"
	section.
	* breakpoint.h (struct breakpoint_ops) <works_in_software_mode>: New
	method.  Initialize to NULL in all existing breakpoint_ops instances.
	(struct breakpoint) <hw_wp_mask>: New field.
	* breakpoint.c (is_masked_watchpoint): Add prototype.
	(update_watchpoint): Don't set b->val for masked watchpoints.  Call
	breakpoint's breakpoint_ops.works_in_software_mode if available.
	(watchpoints_triggered): Handle the case of a hardware masked
	watchpoint trigger.
	(watchpoint_check): Likewise.
	(works_in_software_mode_watchpoint): New function.
	(insert_masked_watchpoint, remove_masked_watchpoint)
	(resources_needed_masked_watchpoint)
	(works_in_software_mode_masked_watchpoint, print_it_masked_watchpoint)
	(print_one_detail_masked_watchpoint, print_mention_masked_watchpoint)
	(print_recreate_masked_watchpoint, is_masked_watchpoint): New
	functions.
	(masked_watchpoint_breakpoint_ops): New structure.
	(watch_command_1): Check for the existence of the `mask' parameter.
	Set b->ops according to the type of hardware watchpoint being created.
	* ppc-linux-nat.c (ppc_linux_insert_mask_watchpoint)
	(ppc_linux_remove_mask_watchpoint)
	(ppc_linux_masked_watch_num_registers): New functions.
	(_initialize_ppc_linux_nat): Initialize to_insert_mask_watchpoint,
	to_remove_mask_watchpoint and to_masked_watch_num_registers.
	* target.c (update_current_target): Mention to_insert_mask_watchpoint,
	to_remove_mask_watchpoint, and to_masked_watch_num_registers.
	(target_insert_mask_watchpoint, target_remove_mask_watchpoint)
	(target_masked_watch_num_registers): New functions.
	* target.h (struct target_ops) <to_insert_mask_watchpoint>,
	<to_remove_mask_watchpoint>, <to_masked_watch_num_registers>: New
	methods.
	(target_insert_mask_watchpoint, target_remove_mask_watchpoint)
	(target_masked_watch_num_registers): Add prototypes.

gdb/doc/
	* gdb.texinfo (Set Watchpoints): Document mask parameter.
	(PowerPC Embedded): Document masked watchpoints.


diff --git a/gdb/NEWS b/gdb/NEWS
index a673d7a..5a68154 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,20 @@
 
 *** Changes since GDB 7.3
 
+* When natively debugging programs on PowerPC BookE processors running
+  a Linux kernel version 2.6.34 or later, GDB supports masked hardware
+  watchpoints, which specify a mask in addition to an address to watch.
+  The mask specifies that some bits of an address (the bits which are
+  reset in the mask) should be ignored when matching the address accessed
+  by the inferior against the watchpoint address.  See the "PowerPC Embedded"
+  section in the user manual for more details.
+
+* Changed commands
+
+watch EXPRESSION mask MASK_VALUE
+  The watch command now supports the mask argument which allows creation
+  of masked watchpoints, if the current architecture supports this feature.
+
 *** Changes in GDB 7.3
 
 * GDB has a new command: "thread find [REGEXP]".
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 0a0b09f..c91df6f 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -10951,6 +10951,7 @@ static struct breakpoint_ops catch_exception_breakpoint_ops =
   NULL, /* remove */
   NULL, /* breakpoint_hit */
   NULL, /* resources_needed */
+  NULL, /* works_in_software_mode */
   print_it_catch_exception,
   print_one_catch_exception,
   NULL, /* print_one_detail */
@@ -10991,6 +10992,7 @@ static struct breakpoint_ops catch_exception_unhandled_breakpoint_ops = {
   NULL, /* remove */
   NULL, /* breakpoint_hit */
   NULL, /* resources_needed */
+  NULL, /* works_in_software_mode */
   print_it_catch_exception_unhandled,
   print_one_catch_exception_unhandled,
   NULL, /* print_one_detail */
@@ -11029,6 +11031,7 @@ static struct breakpoint_ops catch_assert_breakpoint_ops = {
   NULL, /* remove */
   NULL, /* breakpoint_hit */
   NULL, /* resources_needed */
+  NULL, /* works_in_software_mode */
   print_it_catch_assert,
   print_one_catch_assert,
   NULL, /* print_one_detail */
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 2bfdfb0..7d01737 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -224,6 +224,8 @@ static void disable_trace_command (char *, int);
 
 static void trace_pass_command (char *, int);
 
+static int is_masked_watchpoint (const struct breakpoint *b);
+
 /* Assuming we're creating a static tracepoint, does S look like a
    static tracepoint marker spec ("-m MARKER_ID")?  */
 #define is_marker_spec(s)						\
@@ -1345,8 +1347,10 @@ update_watchpoint (struct breakpoint *b, int reparse)
       /* Avoid setting b->val if it's already set.  The meaning of
 	 b->val is 'the last value' user saw, and we should update
 	 it only if we reported that last value to user.  As it
-	 happens, the code that reports it updates b->val directly.  */
-      if (!b->val_valid)
+	 happens, the code that reports it updates b->val directly.
+	 We don't keep track of the memory value for masked
+	 watchpoints.  */
+      if (!b->val_valid && !is_masked_watchpoint (b))
 	{
 	  b->val = v;
 	  b->val_valid = 1;
@@ -1437,19 +1441,23 @@ update_watchpoint (struct breakpoint *b, int reparse)
 		    (bp_hardware_watchpoint, i, other_type_used);
 	      if (target_resources_ok <= 0)
 		{
-		  if (target_resources_ok == 0
-		      && b->type != bp_hardware_watchpoint)
+		  /* If there's no works_in_software_mode method, we
+		     assume that the watchpoint works in software mode.  */
+		  int sw_mode = (!b->ops || !b->ops->works_in_software_mode
+				 || b->ops->works_in_software_mode (b));
+
+		  if (target_resources_ok == 0 && !sw_mode)
 		    error (_("Target does not support this type of "
 			     "hardware watchpoint."));
-		  else if (target_resources_ok < 0
-		      && b->type != bp_hardware_watchpoint)
-		    error (_("Target can only support one kind "
-			     "of HW watchpoint at a time."));
+		  else if (target_resources_ok < 0 && !sw_mode)
+		    error (_("There are not enough available hardware "
+			     "resources for this watchpoint."));
 		  else
 		    b->type = bp_watchpoint;
 		}
 	    }
-	  else if (b->type != bp_hardware_watchpoint)
+	  else if (b->ops && b->ops->works_in_software_mode
+		   && !b->ops->works_in_software_mode (b))
 	    error (_("Expression cannot be implemented with "
 		     "read/access watchpoint."));
 	  else
@@ -3695,15 +3703,30 @@ watchpoints_triggered (struct target_waitstatus *ws)
 
 	b->watchpoint_triggered = watch_triggered_no;
 	for (loc = b->loc; loc; loc = loc->next)
-	  /* Exact match not required.  Within range is
-	     sufficient.  */
-	  if (target_watchpoint_addr_within_range (&current_target,
-						   addr, loc->address,
-						   loc->length))
-	    {
-	      b->watchpoint_triggered = watch_triggered_yes;
-	      break;
-	    }
+	  {
+	    CORE_ADDR newaddr, start;
+
+	    if (is_masked_watchpoint (loc->owner))
+	      {
+		newaddr = addr & loc->owner->hw_wp_mask;
+		start = loc->address & loc->owner->hw_wp_mask;
+	      }
+	    else
+	      {
+		newaddr = addr;
+		start = loc->address;
+	      }
+
+	    /* Exact match not required.  Within range is
+	       sufficient.  */
+	    if (target_watchpoint_addr_within_range (&current_target,
+						     newaddr, start,
+						     loc->length))
+	      {
+		b->watchpoint_triggered = watch_triggered_yes;
+		break;
+	      }
+	  }
       }
 
   return 1;
@@ -3800,9 +3823,16 @@ watchpoint_check (void *p)
          might be in the middle of evaluating a function call.  */
 
       int pc = 0;
-      struct value *mark = value_mark ();
+      struct value *mark;
       struct value *new_val;
 
+      if (is_masked_watchpoint (b))
+	/* Since we don't know the exact trigger address (from
+	   stopped_data_address), just tell the user we've triggered
+	   a mask watchpoint.  */
+	return WP_VALUE_CHANGED;
+
+      mark = value_mark ();
       fetch_subexp_value (b->exp, &pc, &new_val, NULL, NULL);
 
       /* We use value_equal_contents instead of value_equal because
@@ -6306,6 +6336,7 @@ static struct breakpoint_ops catch_fork_breakpoint_ops =
   remove_catch_fork,
   breakpoint_hit_catch_fork,
   NULL, /* resources_needed */
+  NULL, /* works_in_software_mode */
   print_it_catch_fork,
   print_one_catch_fork,
   NULL, /* print_one_detail */
@@ -6404,6 +6435,7 @@ static struct breakpoint_ops catch_vfork_breakpoint_ops =
   remove_catch_vfork,
   breakpoint_hit_catch_vfork,
   NULL, /* resources_needed */
+  NULL, /* works_in_software_mode */
   print_it_catch_vfork,
   print_one_catch_vfork,
   NULL, /* print_one_detail */
@@ -6691,6 +6723,7 @@ static struct breakpoint_ops catch_syscall_breakpoint_ops =
   remove_catch_syscall,
   breakpoint_hit_catch_syscall,
   NULL, /* resources_needed */
+  NULL, /* works_in_software_mode */
   print_it_catch_syscall,
   print_one_catch_syscall,
   NULL, /* print_one_detail */
@@ -6847,6 +6880,7 @@ static struct breakpoint_ops catch_exec_breakpoint_ops =
   remove_catch_exec,
   breakpoint_hit_catch_exec,
   NULL, /* resources_needed */
+  NULL, /* works_in_software_mode */
   print_it_catch_exec,
   print_one_catch_exec,
   NULL, /* print_one_detail */
@@ -8479,6 +8513,7 @@ static struct breakpoint_ops ranged_breakpoint_ops =
   NULL, /* remove */
   breakpoint_hit_ranged_breakpoint,
   resources_needed_ranged_breakpoint,
+  NULL, /* works_in_software_mode */
   print_it_ranged_breakpoint,
   print_one_ranged_breakpoint,
   print_one_detail_ranged_breakpoint,
@@ -8785,6 +8820,15 @@ resources_needed_watchpoint (const struct bp_location *bl)
   return target_region_ok_for_hw_watchpoint (bl->address, length);
 }
 
+/* Implement the "works_in_software_mode" breakpoint_ops method for
+   hardware watchpoints.  */
+
+int
+works_in_software_mode_watchpoint (const struct breakpoint *b)
+{
+  return b->type == bp_hardware_watchpoint;
+}
+
 /* The breakpoint_ops structure to be used in hardware watchpoints.  */
 
 static struct breakpoint_ops watchpoint_breakpoint_ops =
@@ -8793,6 +8837,7 @@ static struct breakpoint_ops watchpoint_breakpoint_ops =
   remove_watchpoint,
   NULL, /* breakpoint_hit */
   resources_needed_watchpoint,
+  works_in_software_mode_watchpoint,
   NULL, /* print_it */
   NULL, /* print_one */
   NULL, /* print_one_detail */
@@ -8800,6 +8845,200 @@ static struct breakpoint_ops watchpoint_breakpoint_ops =
   NULL  /* print_recreate */
 };
 
+/* Implement the "insert" breakpoint_ops method for
+   masked hardware watchpoints.  */
+
+static int
+insert_masked_watchpoint (struct bp_location *bl)
+{
+  return target_insert_mask_watchpoint (bl->address, bl->owner->hw_wp_mask,
+					bl->watchpoint_type);
+}
+
+/* Implement the "remove" breakpoint_ops method for
+   masked hardware watchpoints.  */
+
+static int
+remove_masked_watchpoint (struct bp_location *bl)
+{
+  return target_remove_mask_watchpoint (bl->address, bl->owner->hw_wp_mask,
+				        bl->watchpoint_type);
+}
+
+/* Implement the "resources_needed" breakpoint_ops method for
+   masked hardware watchpoints.  */
+
+static int
+resources_needed_masked_watchpoint (const struct bp_location *bl)
+{
+  return target_masked_watch_num_registers (bl->address,
+					    bl->owner->hw_wp_mask);
+}
+
+/* Implement the "works_in_software_mode" breakpoint_ops method for
+   masked hardware watchpoints.  */
+
+static int
+works_in_software_mode_masked_watchpoint (const struct breakpoint *b)
+{
+  return 0;
+}
+
+/* Implement the "print_it" breakpoint_ops method for
+   masked hardware watchpoints.  */
+
+static enum print_stop_action
+print_it_masked_watchpoint (struct breakpoint *b)
+{
+  struct ui_stream *stb;
+  struct cleanup *old_chain;
+
+  /* Masked watchpoints have only one location.  */
+  gdb_assert (b->loc && b->loc->next == NULL);
+
+  stb = ui_out_stream_new (uiout);
+  old_chain = make_cleanup_ui_out_stream_delete (stb);
+
+  switch (b->type)
+    {
+    case bp_hardware_watchpoint:
+      annotate_watchpoint (b->number);
+      if (ui_out_is_mi_like_p (uiout))
+	ui_out_field_string
+	  (uiout, "reason",
+	   async_reason_lookup (EXEC_ASYNC_WATCHPOINT_TRIGGER));
+      break;
+
+    case bp_read_watchpoint:
+      if (ui_out_is_mi_like_p (uiout))
+	ui_out_field_string
+	  (uiout, "reason",
+	   async_reason_lookup (EXEC_ASYNC_READ_WATCHPOINT_TRIGGER));
+      break;
+
+    case bp_access_watchpoint:
+      if (ui_out_is_mi_like_p (uiout))
+	ui_out_field_string
+	  (uiout, "reason",
+	   async_reason_lookup (EXEC_ASYNC_ACCESS_WATCHPOINT_TRIGGER));
+      break;
+    default:
+      internal_error (__FILE__, __LINE__,
+		      _("Invalid hardware watchpoint type."));
+    }
+
+  mention (b);
+  ui_out_text (uiout, _("\n\
+Check the underlying instruction at PC for the memory\n\
+address and value which triggered this watchpoint.\n"));
+  ui_out_text (uiout, "\n");
+
+  do_cleanups (old_chain);
+
+  /* More than one watchpoint may have been triggered.  */
+  return PRINT_UNKNOWN;
+}
+
+/* Implement the "print_one_detail" breakpoint_ops method for
+   masked hardware watchpoints.  */
+
+static void
+print_one_detail_masked_watchpoint (const struct breakpoint *b,
+				    struct ui_out *uiout)
+{
+  /* Masked watchpoints have only one location.  */
+  gdb_assert (b->loc && b->loc->next == NULL);
+
+  ui_out_text (uiout, "\tmask ");
+  ui_out_field_core_addr (uiout, "mask", b->loc->gdbarch, b->hw_wp_mask);
+  ui_out_text (uiout, "\n");
+}
+
+/* Implement the "print_mention" breakpoint_ops method for
+   masked hardware watchpoints.  */
+
+static void
+print_mention_masked_watchpoint (struct breakpoint *b)
+{
+  struct cleanup *ui_out_chain;
+
+  switch (b->type)
+    {
+    case bp_hardware_watchpoint:
+      ui_out_text (uiout, "Masked hardware watchpoint ");
+      ui_out_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "wpt");
+      break;
+    case bp_read_watchpoint:
+      ui_out_text (uiout, "Masked hardware read watchpoint ");
+      ui_out_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "hw-rwpt");
+      break;
+    case bp_access_watchpoint:
+      ui_out_text (uiout, "Masked hardware access (read/write) watchpoint ");
+      ui_out_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "hw-awpt");
+      break;
+    default:
+      internal_error (__FILE__, __LINE__,
+		      _("Invalid hardware watchpoint type."));
+    }
+
+  ui_out_field_int (uiout, "number", b->number);
+  ui_out_text (uiout, ": ");
+  ui_out_field_string (uiout, "exp", b->exp_string);
+  do_cleanups (ui_out_chain);
+}
+
+/* Implement the "print_recreate" breakpoint_ops method for
+   masked hardware watchpoints.  */
+
+static void
+print_recreate_masked_watchpoint (struct breakpoint *b, struct ui_file *fp)
+{
+  char tmp[40];
+
+  switch (b->type)
+    {
+    case bp_hardware_watchpoint:
+      fprintf_unfiltered (fp, "watch");
+      break;
+    case bp_read_watchpoint:
+      fprintf_unfiltered (fp, "rwatch");
+      break;
+    case bp_access_watchpoint:
+      fprintf_unfiltered (fp, "awatch");
+      break;
+    default:
+      internal_error (__FILE__, __LINE__,
+		      _("Invalid hardware watchpoint type."));
+    }
+
+  sprintf_vma (tmp, b->hw_wp_mask);
+  fprintf_unfiltered (fp, " %s mask 0x%s", b->exp_string, tmp);
+}
+
+/* The breakpoint_ops structure to be used in masked hardware watchpoints.  */
+
+static struct breakpoint_ops masked_watchpoint_breakpoint_ops =
+{
+  insert_masked_watchpoint,
+  remove_masked_watchpoint,
+  NULL, /* breakpoint_hit */
+  resources_needed_masked_watchpoint,
+  works_in_software_mode_masked_watchpoint,
+  print_it_masked_watchpoint,
+  NULL, /* print_one */
+  print_one_detail_masked_watchpoint,
+  print_mention_masked_watchpoint,
+  print_recreate_masked_watchpoint
+};
+
+/* Tell whether the given watchpoint is a masked hardware watchpoint.  */
+
+static int
+is_masked_watchpoint (const struct breakpoint *b)
+{
+  return b->ops == &masked_watchpoint_breakpoint_ops;
+}
+
 /* accessflag:  hw_write:  watch write, 
                 hw_read:   watch read, 
 		hw_access: watch access (read or write) */
@@ -8815,73 +9054,97 @@ watch_command_1 (char *arg, int accessflag, int from_tty,
   struct frame_info *frame;
   char *exp_start = NULL;
   char *exp_end = NULL;
-  char *tok, *id_tok_start, *end_tok;
-  int toklen;
+  char *tok, *end_tok;
+  int toklen = -1;
   char *cond_start = NULL;
   char *cond_end = NULL;
   enum bptype bp_type;
   int thread = -1;
   int pc = 0;
+  /* Flag to indicate whether we are going to use masks for
+     the hardware watchpoint.  */
+  int use_mask = 0;
+  CORE_ADDR mask = 0;
 
   /* Make sure that we actually have parameters to parse.  */
   if (arg != NULL && arg[0] != '\0')
     {
-      toklen = strlen (arg); /* Size of argument list.  */
+      char *value_start;
 
-      /* Points tok to the end of the argument list.  */
-      tok = arg + toklen - 1;
+      /* Look for "parameter value" pairs at the end
+	 of the arguments string.  */
+      for (tok = arg + strlen (arg) - 1; tok > arg; tok--)
+	{
+	  /* Skip whitespace at the end of the argument list.  */
+	  while (tok > arg && (*tok == ' ' || *tok == '\t'))
+	    tok--;
+
+	  /* Find the beginning of the last token.
+	     This is the value of the parameter.  */
+	  while (tok > arg && (*tok != ' ' && *tok != '\t'))
+	    tok--;
+	  value_start = tok + 1;
+
+	  /* Skip whitespace.  */
+	  while (tok > arg && (*tok == ' ' || *tok == '\t'))
+	    tok--;
+
+	  end_tok = tok;
+
+	  /* Find the beginning of the second to last token.
+	     This is the parameter itself.  */
+	  while (tok > arg && (*tok != ' ' && *tok != '\t'))
+	    tok--;
+	  tok++;
+	  toklen = end_tok - tok + 1;
+
+	  if (toklen == 6 && !strncmp (tok, "thread", 6))
+	    {
+	      /* At this point we've found a "thread" token, which means
+		 the user is trying to set a watchpoint that triggers
+		 only in a specific thread.  */
+	      char *endp;
 
-      /* Go backwards in the parameters list.  Skip the last
-         parameter.  If we're expecting a 'thread <thread_num>'
-         parameter, this should be the thread identifier.  */
-      while (tok > arg && (*tok == ' ' || *tok == '\t'))
-        tok--;
-      while (tok > arg && (*tok != ' ' && *tok != '\t'))
-        tok--;
+	      if (thread != -1)
+		error(_("You can specify only one thread."));
 
-      /* Points end_tok to the beginning of the last token.  */
-      id_tok_start = tok + 1;
+	      /* Extract the thread ID from the next token.  */
+	      thread = strtol (value_start, &endp, 0);
 
-      /* Go backwards in the parameters list.  Skip one more
-         parameter.  If we're expecting a 'thread <thread_num>'
-         parameter, we should reach a "thread" token.  */
-      while (tok > arg && (*tok == ' ' || *tok == '\t'))
-        tok--;
+	      /* Check if the user provided a valid numeric value for the
+		 thread ID.  */
+	      if (*endp != ' ' && *endp != '\t' && *endp != '\0')
+		error (_("Invalid thread ID specification %s."), value_start);
 
-      end_tok = tok;
+	      /* Check if the thread actually exists.  */
+	      if (!valid_thread_id (thread))
+		error (_("Unknown thread %d."), thread);
+	    }
+	  else if (toklen == 4 && !strncmp (tok, "mask", 4))
+	    {
+	      /* We've found a "mask" token, which means the user wants to
+		 create a hardware watchpoint that is going to have the mask
+		 facility.  */
+	      struct value *mask_value, *mark;
 
-      while (tok > arg && (*tok != ' ' && *tok != '\t'))
-        tok--;
+	      if (use_mask)
+		error(_("You can specify only one mask."));
 
-      /* Move the pointer forward to skip the whitespace and
-         calculate the length of the token.  */
-      tok++;
-      toklen = end_tok - tok;
+	      use_mask = just_location = 1;
 
-      if (toklen >= 1 && strncmp (tok, "thread", toklen) == 0)
-        {
-          /* At this point we've found a "thread" token, which means
-             the user is trying to set a watchpoint that triggers
-             only in a specific thread.  */
-          char *endp;
-
-          /* Extract the thread ID from the next token.  */
-          thread = strtol (id_tok_start, &endp, 0);
-
-          /* Check if the user provided a valid numeric value for the
-             thread ID.  */
-          if (*endp != ' ' && *endp != '\t' && *endp != '\0')
-            error (_("Invalid thread ID specification %s."), id_tok_start);
-
-          /* Check if the thread actually exists.  */
-          if (!valid_thread_id (thread))
-            error (_("Unknown thread %d."), thread);
-
-          /* Truncate the string and get rid of the thread <thread_num>
-             parameter before the parameter list is parsed by the
-             evaluate_expression() function.  */
-          *tok = '\0';
-        }
+	      mark = value_mark ();
+	      mask_value = parse_to_comma_and_eval (&value_start);
+	      mask = value_as_address (mask_value);
+	      value_free_to_mark (mark);
+	    }
+	  else
+	    /* We didn't recognize what we found.  We should stop here.  */
+	    break;
+
+	  /* Truncate the string and get rid of the "parameter value" pair before
+	     the arguments string is parsed by the parse_exp_1 function.  */
+	  *tok = '\0';
+	}
     }
 
   /* Parse the rest of the arguments.  */
@@ -8912,10 +9175,22 @@ watch_command_1 (char *arg, int accessflag, int from_tty,
 
   if (just_location)
     {
+      int ret;
+
       exp_valid_block = NULL;
       val = value_addr (result);
       release_value (val);
       value_free_to_mark (mark);
+
+      if (use_mask)
+	{
+	  ret = target_masked_watch_num_registers (value_as_address (val),
+						   mask);
+	  if (ret == -1)
+	    error (_("This target does not support masked watchpoints."));
+	  else if (ret == -2)
+	    error (_("Invalid mask or memory region."));
+	}
     }
   else if (val != NULL)
     release_value (val);
@@ -9013,9 +9288,18 @@ watch_command_1 (char *arg, int accessflag, int from_tty,
     }
   else
     b->exp_string = savestring (exp_start, exp_end - exp_start);
-  b->val = val;
-  b->val_valid = 1;
-  b->ops = &watchpoint_breakpoint_ops;
+
+  if (use_mask)
+    {
+      b->hw_wp_mask = mask;
+      b->ops = &masked_watchpoint_breakpoint_ops;
+    }
+  else
+    {
+      b->val = val;
+      b->val_valid = 1;
+      b->ops = &watchpoint_breakpoint_ops;
+    }
 
   if (cond_start)
     b->cond_string = savestring (cond_start, cond_end - cond_start);
@@ -9550,6 +9834,7 @@ static struct breakpoint_ops gnu_v3_exception_catchpoint_ops = {
   NULL, /* remove */
   NULL, /* breakpoint_hit */
   NULL, /* resources_needed */
+  NULL, /* works_in_software_mode */
   print_it_exception_catchpoint,
   print_one_exception_catchpoint,
   NULL, /* print_one_detail */
diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index bf827e5..ccd7c3c 100644
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -410,6 +410,11 @@ struct breakpoint_ops
      the breakpoint or watchpoint needs one debug register.  */
   int (*resources_needed) (const struct bp_location *);
 
+  /* Tell whether we can downgrade from a hardware watchpoint to a software
+     one.  If not, the user will not be able to enable the watchpoint when
+     there are not enough hardware resources available.  */
+  int (*works_in_software_mode) (const struct breakpoint *);
+
   /* The normal print routine for this breakpoint, called when we
      hit it.  */
   enum print_stop_action (*print_it) (struct breakpoint *);
@@ -651,6 +656,9 @@ struct breakpoint
 
     /* Whether this watchpoint is exact (see target_exact_watchpoints).  */
     int exact;
+
+    /* The mask address for a masked hardware watchpoint.  */
+    CORE_ADDR hw_wp_mask;
   };
 
 typedef struct breakpoint *breakpoint_p;
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index c71d664..b1fb0ff 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -3727,7 +3727,7 @@ watchpoints, which do not slow down the running of your program.
 
 @table @code
 @kindex watch
-@item watch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]}
+@item watch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]} @r{[}mask @var{maskvalue}@r{]}
 Set a watchpoint for an expression.  @value{GDBN} will break when the
 expression @var{expr} is written into by the program and its value
 changes.  The simplest (and the most popular) use of this command is
@@ -3738,12 +3738,17 @@ to watch the value of a single variable:
 @end smallexample
 
 If the command includes a @code{@r{[}thread @var{threadnum}@r{]}}
-clause, @value{GDBN} breaks only when the thread identified by
+argument, @value{GDBN} breaks only when the thread identified by
 @var{threadnum} changes the value of @var{expr}.  If any other threads
 change the value of @var{expr}, @value{GDBN} will not break.  Note
 that watchpoints restricted to a single thread in this way only work
 with Hardware Watchpoints.
 
+The @code{@r{[}mask @var{maskvalue}@r{]}} argument allows creation
+of masked watchpoints, if the current architecture supports this
+feature.  (Currently, this is only available on PowerPC Embedded
+architecture, see @ref{PowerPC Embedded}.)
+
 Ordinarily a watchpoint respects the scope of variables in @var{expr}
 (see below).  The @code{-location} argument tells @value{GDBN} to
 instead watch the memory referred to by @var{expr}.  In this case,
@@ -3754,12 +3759,12 @@ result does not have an address, then @value{GDBN} will print an
 error.
 
 @kindex rwatch
-@item rwatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]}
+@item rwatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]} @r{[}mask @var{maskvalue}@r{]}
 Set a watchpoint that will break when the value of @var{expr} is read
 by the program.
 
 @kindex awatch
-@item awatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]}
+@item awatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]} @r{[}mask @var{maskvalue}@r{]}
 Set a watchpoint that will break when @var{expr} is either read from
 or written into by the program.
 
@@ -18742,6 +18747,23 @@ region using one of the following commands (@pxref{Expressions}):
 (@value{GDBP}) watch @{char[@var{length}]@} @var{address}
 @end smallexample
 
+PowerPC embedded processors support masked watchpoints.
+
+A @dfn{masked watchpoint} specifies a mask in addition to an address
+to watch.  The mask specifies that some bits of an address (the bits
+which are reset in the mask) should be ignored when matching the
+address accessed by the inferior against the watchpoint address.
+Thus, a masked watchpoint watches many addresses
+simultaneously---those addresses whose unmasked bits are identical
+to the unmasked bits in the watchpoint address.
+
+To set a masked watchpoint in @value{GDBN}, use the @code{mask} argument in
+the @code{watch} command (@pxref{Set Watchpoints}), as in:
+
+@smallexample
+(@value{GDBP}) watch *0xdeadbeef mask 0xffffff00
+@end smallexample
+
 @cindex ranged breakpoint
 PowerPC embedded processors support hardware accelerated
 @dfn{ranged breakpoints}.  A ranged breakpoint stops execution of
diff --git a/gdb/ppc-linux-nat.c b/gdb/ppc-linux-nat.c
index 6f11715..d20a288 100644
--- a/gdb/ppc-linux-nat.c
+++ b/gdb/ppc-linux-nat.c
@@ -1739,6 +1739,64 @@ get_trigger_type (int rw)
   return t;
 }
 
+/* Insert a new masked watchpoint at ADDR using the mask MASK.
+   RW may be hw_read for a read watchpoint, hw_write for a write watchpoint
+   or hw_access for an access watchpoint.  Returns 0 on success and throws
+   an error on failure.  */
+
+static int
+ppc_linux_insert_mask_watchpoint (struct target_ops *ops, CORE_ADDR addr,
+				  CORE_ADDR mask, int rw)
+{
+  ptid_t ptid;
+  struct lwp_info *lp;
+  struct ppc_hw_breakpoint p;
+
+  gdb_assert (have_ptrace_booke_interface ());
+
+  p.version = PPC_DEBUG_CURRENT_VERSION;
+  p.trigger_type = get_trigger_type (rw);
+  p.addr_mode = PPC_BREAKPOINT_MODE_MASK;
+  p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE;
+  p.addr = addr;
+  p.addr2 = mask;
+  p.condition_value = 0;
+
+  ALL_LWPS (lp, ptid)
+    booke_insert_point (&p, TIDGET (ptid));
+
+  return 0;
+}
+
+/* Remove a masked watchpoint at ADDR with the mask MASK.
+   RW may be hw_read for a read watchpoint, hw_write for a write watchpoint
+   or hw_access for an access watchpoint.  Returns 0 on success and throws
+   an error on failure.  */
+
+static int
+ppc_linux_remove_mask_watchpoint (struct target_ops *ops, CORE_ADDR addr,
+				  CORE_ADDR mask, int rw)
+{
+  ptid_t ptid;
+  struct lwp_info *lp;
+  struct ppc_hw_breakpoint p;
+
+  gdb_assert (have_ptrace_booke_interface ());
+
+  p.version = PPC_DEBUG_CURRENT_VERSION;
+  p.trigger_type = get_trigger_type (rw);
+  p.addr_mode = PPC_BREAKPOINT_MODE_MASK;
+  p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE;
+  p.addr = addr;
+  p.addr2 = mask;
+  p.condition_value = 0;
+
+  ALL_LWPS (lp, ptid)
+    booke_remove_point (&p, TIDGET (ptid));
+
+  return 0;
+}
+
 /* Check whether we have at least one free DVC register.  */
 static int
 can_use_watchpoint_cond_accel (void)
@@ -2224,6 +2282,27 @@ ppc_linux_watchpoint_addr_within_range (struct target_ops *target,
   return start <= addr + mask && start + length - 1 >= addr;
 }
 
+/* Return the number of registers needed for a masked hardware watchpoint.  */
+
+static int
+ppc_linux_masked_watch_num_registers (struct target_ops *target,
+				      CORE_ADDR addr, CORE_ADDR mask)
+{
+  if (!have_ptrace_booke_interface ()
+	   || (booke_debug_info.features & PPC_DEBUG_FEATURE_DATA_BP_MASK) == 0)
+    return -1;
+  else if ((mask & 0xC0000000) != 0xC0000000)
+    {
+      warning (_("\
+The given mask covers kernel address space and cannot be used.\n\
+You have to delete the masked watchpoint to continue the debugging session."));
+
+      return -2;
+    }
+  else
+    return 2;
+}
+
 static void
 ppc_linux_store_inferior_registers (struct target_ops *ops,
 				    struct regcache *regcache, int regno)
@@ -2438,11 +2517,14 @@ _initialize_ppc_linux_nat (void)
   t->to_region_ok_for_hw_watchpoint = ppc_linux_region_ok_for_hw_watchpoint;
   t->to_insert_watchpoint = ppc_linux_insert_watchpoint;
   t->to_remove_watchpoint = ppc_linux_remove_watchpoint;
+  t->to_insert_mask_watchpoint = ppc_linux_insert_mask_watchpoint;
+  t->to_remove_mask_watchpoint = ppc_linux_remove_mask_watchpoint;
   t->to_stopped_by_watchpoint = ppc_linux_stopped_by_watchpoint;
   t->to_stopped_data_address = ppc_linux_stopped_data_address;
   t->to_watchpoint_addr_within_range = ppc_linux_watchpoint_addr_within_range;
   t->to_can_accel_watchpoint_condition
     = ppc_linux_can_accel_watchpoint_condition;
+  t->to_masked_watch_num_registers = ppc_linux_masked_watch_num_registers;
   t->to_ranged_break_num_registers = ppc_linux_ranged_break_num_registers;
 
   t->to_read_description = ppc_linux_read_description;
diff --git a/gdb/target.c b/gdb/target.c
index a032052..5028247 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -597,6 +597,8 @@ update_current_target (void)
       /* Do not inherit to_ranged_break_num_registers.  */
       INHERIT (to_insert_watchpoint, t);
       INHERIT (to_remove_watchpoint, t);
+      /* Do not inherit to_insert_mask_watchpoint.  */
+      /* Do not inherit to_remove_mask_watchpoint.  */
       INHERIT (to_stopped_data_address, t);
       INHERIT (to_have_steppable_watchpoint, t);
       INHERIT (to_have_continuable_watchpoint, t);
@@ -604,6 +606,7 @@ update_current_target (void)
       INHERIT (to_watchpoint_addr_within_range, t);
       INHERIT (to_region_ok_for_hw_watchpoint, t);
       INHERIT (to_can_accel_watchpoint_condition, t);
+      /* Do not inherit to_masked_watch_num_registers.  */
       INHERIT (to_terminal_init, t);
       INHERIT (to_terminal_inferior, t);
       INHERIT (to_terminal_ours_for_output, t);
@@ -3492,6 +3495,75 @@ target_verify_memory (const gdb_byte *data, CORE_ADDR memaddr, ULONGEST size)
   tcomplain ();
 }
 
+/* The documentation for this function is in its prototype declaration in
+   target.h.  */
+
+int
+target_insert_mask_watchpoint (CORE_ADDR addr, CORE_ADDR mask, int rw)
+{
+  struct target_ops *t;
+
+  for (t = current_target.beneath; t != NULL; t = t->beneath)
+    if (t->to_insert_mask_watchpoint != NULL)
+      {
+	int ret;
+
+	ret = t->to_insert_mask_watchpoint (t, addr, mask, rw);
+
+	if (targetdebug)
+	  fprintf_unfiltered (gdb_stdlog, "\
+target_insert_mask_watchpoint (%s, %s, %d) = %d\n",
+			      core_addr_to_string (addr),
+			      core_addr_to_string (mask), rw, ret);
+
+	return ret;
+      }
+
+  return 1;
+}
+
+/* The documentation for this function is in its prototype declaration in
+   target.h.  */
+
+int
+target_remove_mask_watchpoint (CORE_ADDR addr, CORE_ADDR mask, int rw)
+{
+  struct target_ops *t;
+
+  for (t = current_target.beneath; t != NULL; t = t->beneath)
+    if (t->to_remove_mask_watchpoint != NULL)
+      {
+	int ret;
+
+	ret = t->to_remove_mask_watchpoint (t, addr, mask, rw);
+
+	if (targetdebug)
+	  fprintf_unfiltered (gdb_stdlog, "\
+target_remove_mask_watchpoint (%s, %s, %d) = %d\n",
+			      core_addr_to_string (addr),
+			      core_addr_to_string (mask), rw, ret);
+
+	return ret;
+      }
+
+  return 1;
+}
+
+/* The documentation for this function is in its prototype declaration
+   in target.h.  */
+
+int
+target_masked_watch_num_registers (CORE_ADDR addr, CORE_ADDR mask)
+{
+  struct target_ops *t;
+
+  for (t = current_target.beneath; t != NULL; t = t->beneath)
+    if (t->to_masked_watch_num_registers != NULL)
+      return t->to_masked_watch_num_registers (t, addr, mask);
+
+  return -1;
+}
+
 /* The documentation for this function is in its prototype declaration
    in target.h.  */
 
diff --git a/gdb/target.h b/gdb/target.h
index f0b2e43..ef15022 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -459,6 +459,10 @@ struct target_ops
     int (*to_remove_watchpoint) (CORE_ADDR, int, int, struct expression *);
     int (*to_insert_watchpoint) (CORE_ADDR, int, int, struct expression *);
 
+    int (*to_insert_mask_watchpoint) (struct target_ops *,
+				      CORE_ADDR, CORE_ADDR, int);
+    int (*to_remove_mask_watchpoint) (struct target_ops *,
+				      CORE_ADDR, CORE_ADDR, int);
     int (*to_stopped_by_watchpoint) (void);
     int to_have_steppable_watchpoint;
     int to_have_continuable_watchpoint;
@@ -472,6 +476,8 @@ struct target_ops
 
     int (*to_can_accel_watchpoint_condition) (CORE_ADDR, int, int,
 					      struct expression *);
+    int (*to_masked_watch_num_registers) (struct target_ops *,
+					  CORE_ADDR, CORE_ADDR);
     void (*to_terminal_init) (void);
     void (*to_terminal_inferior) (void);
     void (*to_terminal_ours_for_output) (void);
@@ -1349,6 +1355,20 @@ extern char *target_thread_name (struct thread_info *);
 #define	target_remove_watchpoint(addr, len, type, cond) \
      (*current_target.to_remove_watchpoint) (addr, len, type, cond)
 
+/* Insert a new masked watchpoint at ADDR using the mask MASK.
+   RW may be hw_read for a read watchpoint, hw_write for a write watchpoint
+   or hw_access for an access watchpoint.  Returns 0 for success, 1 if
+   masked watchpoints are not supported, -1 for failure.  */
+
+extern int target_insert_mask_watchpoint (CORE_ADDR, CORE_ADDR, int);
+
+/* Remove a masked watchpoint at ADDR with the mask MASK.
+   RW may be hw_read for a read watchpoint, hw_write for a write watchpoint
+   or hw_access for an access watchpoint.  Returns 0 for success, non-zero
+   for failure.  */
+
+extern int target_remove_mask_watchpoint (CORE_ADDR, CORE_ADDR, int);
+
 #define target_insert_hw_breakpoint(gdbarch, bp_tgt) \
      (*current_target.to_insert_hw_breakpoint) (gdbarch, bp_tgt)
 
@@ -1382,6 +1402,12 @@ extern int target_ranged_break_num_registers (void);
 #define target_can_accel_watchpoint_condition(addr, len, type, cond) \
   (*current_target.to_can_accel_watchpoint_condition) (addr, len, type, cond)
 
+/* Return number of debug registers needed for a masked watchpoint,
+   -1 if masked watchpoints are not supported or -2 if the given address
+   and mask combination cannot be used.  */
+
+extern int target_masked_watch_num_registers (CORE_ADDR addr, CORE_ADDR mask);
+
 /* Target can execute in reverse?  */
 #define target_can_execute_reverse \
      (current_target.to_can_execute_reverse ? \



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