GDB: Improve debugging options for VM subsystem

Author: franciscozdo

sys/debug/__init__.py

@@ -10,6 +10,7 @@
 from .sync import CondVar, Mutex
 from .thread import Kthread, Thread, CurrentThread
 from .events import stop_handler
+from .virtmem import VmInfo
 
 
 def addPrettyPrinters():
@@ -32,6 +33,7 @@ def addPrettyPrinters():
 Kthread()
 Ktrace()
 Kgmon()
+VmInfo()
 
 # Functions
 CurrentThread()

sys/debug/kdump.py

@@ -1,4 +1,3 @@
-from .virtmem import VmPhysSeg, VmFreePages, VmMapSeg, PhysMap
 from .memory import Vmem, MallocStats, PoolStats
 from .cmd import CommandDispatcher
 
@@ -7,6 +6,7 @@ class Kdump(CommandDispatcher):
     """Examine kernel data structures."""
 
     def __init__(self):
-        super().__init__('kdump', [VmPhysSeg(), VmFreePages(), VmMapSeg(),
-                                   PhysMap(), Vmem(), MallocStats(),
-                                   PoolStats()])
+        super().__init__('kdump', [Vmem(),
+                                   MallocStats(),
+                                   PoolStats(),
+                                   ])

sys/debug/proc.py

@@ -1,9 +1,10 @@
 import gdb
 
-from .cmd import SimpleCommand, AutoCompleteMixin
+from .cmd import SimpleCommand
 from .utils import TextTable, global_var
 from .struct import GdbStructMeta, TailQueue, enum
 from .thread import Thread
+from .vm_map import VmMap
 from .sync import Mutex
 
 
@@ -12,6 +13,7 @@ class Process(metaclass=GdbStructMeta):
     __cast__ = {'p_pid': int,
                 'p_lock': Mutex,
                 'p_thread': Thread,
+                'p_uspace': VmMap,
                 'p_state': enum}
 
     @staticmethod
@@ -32,6 +34,12 @@ def list_all(cls):
         dead = TailQueue(global_var('zombie_list'), 'p_all')
         return map(cls, list(alive) + list(dead))
 
+    @classmethod
+    def find_by_pid(cls, pid):
+        for p in cls.list_all():
+            if p.p_pid == pid:
+                return p
+
     def __repr__(self):
         return 'proc{pid=%d}' % self.p_pid
 

sys/debug/utils.py

@@ -9,6 +9,10 @@ def cast(value, typename):
     return value.cast(gdb.lookup_type(typename))
 
 
+def cast_ptr(value, typename):
+    return value.cast(gdb.lookup_type(typename).pointer())
+
+
 def local_var(name):
     return gdb.newest_frame().read_var(name)
 
@@ -21,6 +25,29 @@ def relpath(path):
     return path.rsplit('sys/')[-1]
 
 
+def get_arch():
+    try:
+        _ = gdb.parse_and_eval('aarch64_init')
+        return 'aarch64'
+    except gdb.error:
+        pass
+
+    try:
+        _ = gdb.parse_and_eval('riscv_init')
+        return 'riscv'
+    except gdb.error:
+        pass
+
+    try:
+        _ = gdb.parse_and_eval('mips_init')
+        return 'mips'
+    except gdb.error:
+        pass
+
+    print('Current architecture is not supported')
+    raise KeyError
+
+
 # calculates address of ret instruction within function body (MIPS specific)
 def func_ret_addr(name):
     s = gdb.execute('disass thread_create', to_string=True)

sys/debug/virtmem.py

@@ -1,43 +1,179 @@
-import gdb
-
 from .struct import TailQueue
-from .cmd import UserCommand
+from .cmd import UserCommand, CommandDispatcher
 from .cpu import TLBLo
-from .utils import TextTable, global_var, cast
+from .utils import TextTable, global_var, cast_ptr, get_arch
+from .proc import Process
 
 
 PM_NQUEUES = 16
 
 
-class PhysMap(UserCommand):
-    """List active page entries in kernel pmap"""
+class VmInfo(CommandDispatcher):
+    """Examine virtual memory data structures."""
+
     def __init__(self):
-        super().__init__('pmap')
+        super().__init__('vm', [DumpPmap('kernel'),
+                                DumpPmap('user'),
+                                VmMapDump(),
+                                SegmentInfo(''),
+                                SegmentInfo('proc'),
+                                VmPhysSeg(),
+                                VmFreePages(),
+                                ])
+
+
+def _print_mips_pmap(pmap):
+    pdp = cast_ptr(pmap['pde'], 'pde_t')
+    table = TextTable(types='ttttt', align='rrrrr')
+    table.header(['vpn', 'pte0', 'pte1', 'pte2', 'pte3'])
+    for i in range(1024):
+        pde = TLBLo(pdp[i])
+        if not pde.valid:
+            continue
+        ptp = cast_ptr(pde.ppn, 'pte_t')
+        pte = [TLBLo(ptp[j]) for j in range(1024)]
+        for j in range(0, 1024, 4):
+            if not any(pte.valid for pte in pte[j:j+4]):
+                continue
+            pte4 = [str(pte) if pte.valid else '-' for pte in pte[j:j+4]]
+            table.add_row(['{:8x}'.format((i << 22) + (j << 12)),
+                           pte4[0], pte4[1], pte4[2], pte4[3]])
+    print(table)
+
+
+class DumpPmap(UserCommand):
+    """List active page entries in user pmap"""
+
+    def __init__(self, typ):
+        command = 'pmap_' + typ
+        if command not in ('pmap_user', 'pmap_kernel'):
+            print(f'{command} command not supported')
+            return
+        self.command = command
+        super().__init__(command)
 
     def __call__(self, args):
-        pdp = global_var('kernel_pmap')['pde']
-        table = TextTable(types='ttttt', align='rrrrr')
-        table.header(['vpn', 'pte0', 'pte1', 'pte2', 'pte3'])
-        for i in range(1024):
-            pde = TLBLo(pdp[i])
-            if not pde.valid:
-                continue
-            ptp = pde.ppn.cast(gdb.lookup_type('pte_t').pointer())
-            pte = [TLBLo(ptp[j]) for j in range(1024)]
-            for j in range(0, 1024, 4):
-                if not any(pte.valid for pte in pte[j:j+4]):
-                    continue
-                pte4 = [str(pte) if pte.valid else '-' for pte in pte[j:j+4]]
-                table.add_row(['{:8x}'.format((i << 22) + (j << 12)),
-                               pte4[0], pte4[1], pte4[2], pte4[3]])
+        if self.command == 'pmap_kernel':
+            pmap = global_var('kernel_pmap')
+        else:
+            args = args.split()
+            if len(args) == 0:
+                proc = Process.from_current()
+            else:
+                pid = int(args[0])
+                proc = Process.find_by_pid(pid)
+                if proc is None:
+                    print(f'Process {pid} not found')
+                    return
+            pmap = proc.p_uspace.pmap
+
+        arch = get_arch()
+        if arch == 'mips':
+            _print_mips_pmap(pmap)
+        else:
+            print(f"Can't print {arch} pmap")
+
+
+class VmMapDump(UserCommand):
+    """List segments describing virtual address space"""
+
+    def __init__(self):
+        super().__init__('map')
+
+    def __call__(self, args):
+        args = args.split()
+        if len(args) == 0:
+            proc = Process.from_current()
+        else:
+            pid = int(args[0])
+            proc = Process.find_by_pid(pid)
+            if proc is None:
+                print(f'Process {pid} not found')
+                return
+
+        entries = proc.p_uspace.get_entries()
+
+        table = TextTable(types='ittttt', align='rrrrrr')
+        table.header(['segment', 'start', 'end', 'prot', 'flags', 'amap'])
+        for idx, seg in enumerate(entries):
+            table.add_row([idx, hex(seg.start), hex(seg.end), seg.prot,
+                           seg.flags, seg.aref])
         print(table)
 
 
+class SegmentInfo(UserCommand):
+    """Show info about i-th segment in proc vm_map"""
+
+    def __init__(self, typ):
+        command = f"segment{'_' if typ != '' else ''}{typ}"
+        if command not in ['segment', 'segment_proc']:
+            print(f'{command} command not supported')
+            return
+        self.command = command
+        super().__init__(command)
+
+    def _print_segment(self, seg, pid, id):
+        print('Segment {} in proc {}'.format(id, pid))
+        print('Range: {:#08x}-{:#08x} ({:d} pages)'.format(seg.start,
+                                                           seg.end,
+                                                           seg.pages))
+        print('Prot:  {}'.format(seg.prot))
+        print('Flags: {}'.format(seg.flags))
+        amap = seg.amap
+        if amap:
+            print('Amap:        {}'.format(seg.amap_ptr))
+            print('Amap offset: {}'.format(seg.amap_offset))
+            print('Amap slots:  {}'.format(amap.slots))
+            print('Amap refs:   {}'.format(amap.ref_cnt))
+
+            # TODO: show used pages/anons
+        else:
+            print('Amap: NULL')
+
+    def __call__(self, args):
+        args = args.split()
+        if self.command == 'segment':
+            if len(args) < 1:
+                print('require argument (segment)')
+                return
+            proc = Process.from_current()
+        else:
+            if len(args) < 2:
+                print('require 2 arguments (pid and segment)')
+                return
+
+            pid = int(args[0])
+            proc = Process.find_by_pid(pid)
+            if proc is None:
+                print(f'Process {pid} not found')
+                return
+            args = args[1:]
+
+        entries = proc.p_uspace.get_entries()
+
+        segment = int(args[0], 0)
+
+        if segment < 4096:
+            # Lookup by id
+            if segment > len(entries):
+                print(f'Segment {segment} does not exist!')
+                return
+            self._print_segment(entries[segment], proc.p_pid, segment)
+        else:
+            # Lookup by address
+            addr = segment
+            for idx, e in enumerate(entries):
+                if e.start <= addr and addr < e.end:
+                    self._print_segment(e, proc.p_pid, idx)
+                    return
+            print(f'Segment with address {addr} not found')
+
+
 class VmPhysSeg(UserCommand):
     """List physical memory segments managed by vm subsystem"""
 
     def __init__(self):
-        super().__init__('vm_physseg')
+        super().__init__('physseg')
 
     def __call__(self, args):
         table = TextTable(types='ittit', align='rrrrr')
@@ -53,7 +189,7 @@ class VmFreePages(UserCommand):
     """List free pages known to vm subsystem"""
 
     def __init__(self):
-        super().__init__('vm_freepages')
+        super().__init__('freepages')
 
     def __call__(self, args):
         table = TextTable(align='rrl', types='iit')
@@ -71,24 +207,3 @@ def __call__(self, args):
         segments = TailQueue(global_var('seglist'), 'seglink')
         pages = int(sum(seg['npages'] for seg in segments if not seg['used']))
         print('Used pages count: {}'.format(pages - free_pages))
-
-
-class VmMapSeg(UserCommand):
-    """List segments describing virtual address space"""
-
-    def __init__(self):
-        super().__init__('vm_map')
-
-    def __call__(self, args):
-        vm_map = gdb.parse_and_eval('vm_map_user()')
-        if vm_map == 0:
-            print('No active user vm_map!')
-            return
-        entries = vm_map['entries']
-        table = TextTable(types='ittttt', align='rrrrrr')
-        table.header(['segment', 'start', 'end', 'prot', 'flags', 'amap'])
-        segments = TailQueue(entries, 'link')
-        for idx, seg in enumerate(segments):
-            table.add_row([idx, seg['start'], seg['end'], seg['prot'],
-                           seg['flags'], seg['aref']])
-        print(table)