Add pcplist command for printing Linux kernel per-cpu page cache (#1487)

pwndbg/commands/__init__.py

@@ -702,6 +702,7 @@ def load_commands() -> None:
     import pwndbg.commands.onegadget
     import pwndbg.commands.p2p
     import pwndbg.commands.patch
+    import pwndbg.commands.pcplist
     import pwndbg.commands.peda
     import pwndbg.commands.pie
     import pwndbg.commands.plist

pwndbg/commands/pcplist.py

@@ -0,0 +1,60 @@
+from __future__ import annotations
+
+import argparse
+import logging
+
+import gdb
+
+import pwndbg.commands
+import pwndbg.gdblib.memory
+from pwndbg.commands import CommandCategory
+from pwndbg.gdblib.kernel import per_cpu
+from pwndbg.gdblib.kernel.macros import for_each_entry
+
+log = logging.getLogger(__name__)
+
+parser = argparse.ArgumentParser(description="Print Per-CPU page list")
+
+parser.add_argument("zone", type=int, nargs="?", help="")
+# parser.add_argument("list_num", type=int, help="")
+
+
+def print_zone(zone, list_num=None) -> None:
+    print(f"Zone {zone}")
+    pageset_addr = per_cpu(
+        gdb.lookup_global_symbol("contig_page_data").value()["node_zones"][zone]["pageset"]
+    )
+    pageset = pwndbg.gdblib.memory.get_typed_pointer_value(
+        gdb.lookup_type("struct per_cpu_pageset"), pageset_addr
+    )
+    pcp = pageset["pcp"]
+    print("count: ", pcp["count"])
+    print("high: ", pcp["high"])
+    print("")
+    for i in range(4):
+        print(f"pcp.lists[{i}]:")
+
+        count = 0
+        for e in for_each_entry(pcp["lists"][i], "struct page", "lru"):
+            count += 1
+            print(e)
+
+        if count == 0:
+            print("EMPTY")
+        else:
+            print(f"{count} entries")
+
+        print("")
+
+
+@pwndbg.commands.ArgparsedCommand(parser, category=CommandCategory.KERNEL)
+@pwndbg.commands.OnlyWhenQemuKernel
+@pwndbg.commands.OnlyWithKernelDebugSyms
+@pwndbg.commands.OnlyWhenPagingEnabled
+def pcplist(zone=None, list_num=None) -> None:
+    log.warning("This command is a work in progress and may not work as expected.")
+    if zone:
+        print_zone(zone, list_num)
+    else:
+        for i in range(3):
+            print_zone(i)