scripts/gdb: add cpu iterators

The linux kernel provides macro's for iterating against values from the
cpu_list masks.  By providing some commonly used masks, we can mirror
the kernels helper macros with easy to use generators.

Link: http://lkml.kernel.org/r/d045c6599771ada1999d49612ee30fd2f9acf17f.1462865983.git.jan.kiszka@siemens.com
Signed-off-by: Kieran Bingham <kieran.bingham@linaro.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/gdb/linux/cpus.py

@@ -100,6 +100,44 @@ def cpu_list(mask_name):
         yield cpu
 
 
+def each_online_cpu():
+    for cpu in cpu_list("__cpu_online_mask"):
+        yield cpu
+
+
+def each_present_cpu():
+    for cpu in cpu_list("__cpu_present_mask"):
+        yield cpu
+
+
+def each_possible_cpu():
+    for cpu in cpu_list("__cpu_possible_mask"):
+        yield cpu
+
+
+def each_active_cpu():
+    for cpu in cpu_list("__cpu_active_mask"):
+        yield cpu
+
+
+class LxCpus(gdb.Command):
+    """List CPU status arrays
+
+Displays the known state of each CPU based on the kernel masks
+and can help identify the state of hotplugged CPUs"""
+
+    def __init__(self):
+        super(LxCpus, self).__init__("lx-cpus", gdb.COMMAND_DATA)
+
+    def invoke(self, arg, from_tty):
+        gdb.write("Possible CPUs : {}\n".format(list(each_possible_cpu())))
+        gdb.write("Present CPUs  : {}\n".format(list(each_present_cpu())))
+        gdb.write("Online CPUs   : {}\n".format(list(each_online_cpu())))
+        gdb.write("Active CPUs   : {}\n".format(list(each_active_cpu())))
+
+LxCpus()
+
+
 class PerCpu(gdb.Function):
     """Return per-cpu variable.