powerpc/watchpoint: Disable all available watchpoints when !dawr_force_enable

Instead of disabling only first watchpoint, disable all available
watchpoints while clearing dawr_force_enable.

Callback function is used only for disabling watchpoint, rename it
to disable_dawrs_cb(). And null_brk parameter is not really required
while disabling watchpoint, remove it.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-9-ravi.bangoria@linux.ibm.com

arch/powerpc/kernel/dawr.c

@@ -50,9 +50,13 @@ int set_dawr(int nr, struct arch_hw_breakpoint *brk)
 	return 0;
 }
 
-static void set_dawr_cb(void *info)
+static void disable_dawrs_cb(void *info)
 {
-	set_dawr(0, info);
+	struct arch_hw_breakpoint null_brk = {0};
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++)
+		set_dawr(i, &null_brk);
 }
 
 static ssize_t dawr_write_file_bool(struct file *file,
@@ -74,7 +78,7 @@ static ssize_t dawr_write_file_bool(struct file *file,
 
 	/* If we are clearing, make sure all CPUs have the DAWR cleared */
 	if (!dawr_force_enable)
-		smp_call_function(set_dawr_cb, &null_brk, 0);
+		smp_call_function(disable_dawrs_cb, NULL, 0);
 
 	return rc;
 }