lrdp-v2: Add radix_tree_lookup_element_v2 for new radix tree parsing

As of Linux Kernel 4.9, radix tree lookup by element has changed to use
shift instead of height. Update radix tree lookup to reflect this change.

Change-Id: I22a86af719a679c462a463fc9ac92154636f57c7

linux-ramdump-parser-v2/parsers/irqstate.py

@@ -70,6 +70,50 @@ class IrqParse(RamParser):
                 print_out_str(
                     '{0:4} {1} {2:30} {3:10}'.format(irqnum, irq_stats_str, name, chip_name))
 
+    def shift_to_maxindex(self, shift):
+        radix_tree_map_shift = 6
+        radix_tree_map_size = 1 << radix_tree_map_shift
+        return (radix_tree_map_size << shift) - 1
+
+    def is_internal_node(self, addr):
+        radix_tree_entry_mask = 0x3
+        radix_tree_internal_node = 0x1
+        return (addr & radix_tree_entry_mask) == radix_tree_internal_node
+
+    def entry_to_node(self, addr):
+        return addr & 0xfffffffffffffffe
+
+    def radix_tree_lookup_element_v2(self, ram_dump, root_addr, index):
+        rnode_offset = ram_dump.field_offset('struct radix_tree_root', 'rnode')
+        rnode_shift_offset = ram_dump.field_offset('struct radix_tree_node', 'shift')
+        slots_offset = ram_dump.field_offset('struct radix_tree_node', 'slots')
+        pointer_size = ram_dump.sizeof('struct radix_tree_node *')
+        maxindex = 0
+        # if CONFIG_BASE_SMALL=0: radix_tree_map_shift = 6
+        radix_tree_map_shift = 6
+        radix_tree_map_mask = 0x3f
+
+        rnode_addr = ram_dump.read_word(root_addr + rnode_offset)
+        if self.is_internal_node(rnode_addr):
+            node_addr = self.entry_to_node(rnode_addr)
+            shift = ram_dump.read_byte(node_addr + rnode_shift_offset)
+            maxindex = self.shift_to_maxindex(shift)
+
+        if index > maxindex:
+            return None
+
+        while self.is_internal_node(rnode_addr):
+            parent_addr = self.entry_to_node(rnode_addr)
+            parent_shift = ram_dump.read_byte(parent_addr + rnode_shift_offset)
+            offset = (index >> parent_shift) & radix_tree_map_mask
+            rnode_addr = ram_dump.read_word(parent_addr + slots_offset +
+                (offset * pointer_size))
+
+        if rnode_addr is 0:
+            return None
+
+        return rnode_addr
+
     def radix_tree_lookup_element(self, ram_dump, root_addr, index):
         rnode_offset = ram_dump.field_offset('struct radix_tree_root', 'rnode')
         if (ram_dump.kernel_version[0], ram_dump.kernel_version[1]) >= (3, 18):
@@ -140,11 +184,19 @@ class IrqParse(RamParser):
         if nr_irqs > 50000:
             return
 
+        major, minor, patch = ram_dump.kernel_version
         for i in range(0, nr_irqs):
-            irq_desc = self.radix_tree_lookup_element(
-                ram_dump, irq_desc_tree, i)
+
+            if (major, minor) >= (4, 9):
+                irq_desc = self.radix_tree_lookup_element_v2(
+                    ram_dump, irq_desc_tree, i)
+            else:
+                irq_desc = self.radix_tree_lookup_element(
+                    ram_dump, irq_desc_tree, i)
+
             if irq_desc is None:
                 continue
+
             irqnum = ram_dump.read_int(irq_desc + irq_data_offset + irq_num_offset)
             irqcount = ram_dump.read_int(irq_desc + irq_count_offset)
             action = ram_dump.read_word(irq_desc + irq_action_offset)