Dump information about given virtual address

sys/debug/README.md

@@ -18,6 +18,8 @@ you can use following custom commands:
    addresses,
 * `vm_map` - list memory map of process of given pid (when number is given as argument)
   or of current process (when no argument is given)
+* `vm_address` - dump all information about given address in process virtual address space
+  (e.g. `kdump vm_address 3 0x412000` tells about address 0x412000 in vmspace of process 3)
 * `klog` - all log messages currently saved in the kernel,
 * `threads` - all existing threads,
 * `tlb` - Translation Lookaside Buffer with addresses and flags marking if page

sys/debug/kdump.py

@@ -1,4 +1,4 @@
-from .virtmem import VmPhysSeg, VmFreePages, VmMapSeg, PhysMap
+from .virtmem import VmAddress, VmPhysSeg, VmFreePages, VmMapSeg, PhysMap
 from .memory import Vmem, Malloc, MallocStats, PoolStats
 from .cmd import CommandDispatcher
 
@@ -7,6 +7,6 @@ class Kdump(CommandDispatcher):
     """Examine kernel data structures."""
 
     def __init__(self):
-        super().__init__('kdump', [VmPhysSeg(), VmFreePages(), VmMapSeg(),
-                                   PhysMap(), Vmem(), Malloc(), MallocStats(),
-                                   PoolStats()])
+        super().__init__('kdump', [VmAddress(), VmPhysSeg(), VmFreePages(),
+                                   VmMapSeg(), PhysMap(), Vmem(), Malloc(),
+                                   MallocStats(), PoolStats()])

sys/debug/virtmem.py

@@ -96,11 +96,65 @@ def __call__(self, args):
             vm_map = proc.vm_map()
 
         entries = vm_map['entries']
-        table = TextTable(types='itttttt', align='rrrrrrr')
-        table.header(['segment', 'start', 'end', 'prot', 'flags', 'object',
-                      'offset'])
+        table = TextTable(types='ittttt', align='rrrrrr')
+        table.header(['segment', 'start', 'end', 'prot', 'flags', 'object'])
         segments = TailQueue(entries, 'link')
         for idx, seg in enumerate(segments):
             table.add_row([idx, seg['start'], seg['end'], seg['prot'],
-                           seg['flags'], seg['object'], seg['offset']])
+                           seg['flags'], seg['object']])
         print(table)
+
+
+def print_entry(ent):
+    table = TextTable(types='tttttt', align='rrrrrr')
+    table.header(['start', 'end', 'prot', 'flags', 'object', 'offset'])
+    table.add_row([ent['start'], ent['end'], ent['prot'], ent['flags'],
+                   ent['object'], ent['offset']])
+    print(table)
+
+
+def print_addr_in_object(ent, address):
+    offset = ent['offset'] + address - ent['start']
+    obj_addr = ent['object']
+    page = gdb.parse_and_eval(f'vm_object_find_page({obj_addr}, {offset})')
+    if page == 0x0:
+        print(f'There is no page for address {hex(address)} in vm_object')
+        return
+    obj = obj_addr.dereference()
+    print(f'Page found in object ({obj_addr}):\n{obj}')
+
+
+class VmAddress(UserCommand):
+    """List all information about addres in given vm_map"""
+
+    def __init__(self):
+        super().__init__('vm_address')
+
+    def __call__(self, args):
+        args = args.split()
+
+        if len(args) < 2:
+            print("Please give pid and address")
+            return
+
+        pid = int(args[0])
+        address = int(args[1], 16)
+
+        proc = Process.from_pid(pid)
+        if proc is None:
+            print(f'No process of pid {pid}!')
+            return
+
+        PAGESHIFT = 12
+        entries = TailQueue(proc.vm_map()['entries'], 'link')
+        for ent in entries:
+            if address >= ent['start'] and address < ent['end']:
+                print(f'Address in entry {ent.address}')
+                print_entry(ent)
+                # align address
+                address = (address >> PAGESHIFT) << PAGESHIFT
+                obj = ent['object']
+                if obj != 0:
+                    print_addr_in_object(ent, address)
+                return
+        print(f'Adress not found in process {pid} address space.')