Meta: Add GDB pretty printers

Meta/debug-kernel.sh

@@ -8,7 +8,9 @@
 # remote on localhost:1234. So point our debugger there, and inform
 # the debugger which binary to load symbols, etc from.
 #
-$SERENITY_KERNEL_DEBUGGER \
+exec $SERENITY_KERNEL_DEBUGGER \
  -ex "file $(dirname "$0")/../Build/${SERENITY_ARCH:-i686}/Kernel/Kernel" \
  -ex 'set arch i386:intel' \
- -ex 'target remote localhost:1234'
+ -ex 'target remote localhost:1234' \
+ -ex "source $(dirname "$0")/serenity_gdb.py" \
+ "$@"

Meta/serenity.sh

@@ -201,7 +201,8 @@ run_gdb() {
  if [ -n "$KERNEL_CMD_LINE" ]; then
  export SERENITY_KERNEL_CMDLINE="$KERNEL_CMD_LINE"
  fi
- gdb "$BUILD_DIR/Kernel/Kernel" -ex 'target remote :1234' "${GDB_ARGS[@]}" -ex cont
+ sleep 1
+ "$(get_top_dir)/Meta/debug-kernel.sh" "${GDB_ARGS[@]}" -ex cont
  fi
 }
 

Meta/serenity_gdb.py

@@ -0,0 +1,274 @@
+# Copyright (c) 2021, Gunnar Beutner <[email protected]>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice, this
+# list of conditions and the following disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright notice,
+# this list of conditions and the following disclaimer in the documentation
+# and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import gdb
+import gdb.types
+import re
+
+
+class AKAtomic:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ return self.val["m_value"]
+
+
+class AKDistinctNumeric:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ return self.val["m_value"]
+
+
+class AKRefCounted:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ return self.val["m_ref_count"]
+
+
+class AKString:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ if int(self.val["m_impl"]["m_bits"]["m_value"]) == 0:
+ return '""'
+ else:
+ impl = AKRefPtr(self.val["m_impl"]).get_pointee().dereference()
+ return AKStringImpl(impl).to_string()
+
+
+class AKStringView:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ if int(self.val["m_length"]) == 0:
+ return '""'
+ else:
+ characters = self.val["m_characters"]
+ str_type = characters.type.target().array(self.val["m_length"]).pointer()
+ return str(characters.cast(str_type).dereference())
+
+
+def get_field_unalloced(val, member, type):
+ # Trying to access a variable-length field seems to fail with
+ # Python Exception <class 'gdb.error'> value requires 4294967296 bytes, which is more than max-value-size
+ # This works around that issue.
+ return gdb.parse_and_eval(f"*({type}*)(({val.type.name}*){int(val.address)})->{member}")
+
+
+class AKStringImpl:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ if int(self.val["m_length"]) == 0:
+ return '""'
+ else:
+ str_type = gdb.lookup_type("char").array(self.val["m_length"])
+ return get_field_unalloced(self.val, "m_inline_buffer", str_type)
+
+
+class AKOwnPtr:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ return self.val.type.name
+
+ def children(self):
+ return [('*', self.val["m_ptr"])]
+
+
+class AKRefPtr:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ return self.val.type.name
+
+ def get_pointee(self):
+ inner_type = self.val.type.template_argument(0)
+ inner_type_ptr = inner_type.pointer()
+ return self.val["m_bits"]["m_value"].cast(inner_type_ptr)
+
+ def children(self):
+ return [('*', self.get_pointee())]
+
+
+class AKVector:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ return f'{self.val.type.name} of len {int(self.val["m_size"])}'
+
+ def children(self):
+ vec_len = int(self.val["m_size"])
+
+ if vec_len == 0:
+ return []
+
+ outline_buf = self.val["m_outline_buffer"]
+
+ inner_type_ptr = self.val.type.template_argument(0).pointer()
+
+ if int(outline_buf) != 0:
+ elements = outline_buf.cast(inner_type_ptr)
+ else:
+ elements = get_field_unalloced(self.val, "m_inline_buffer_storage", inner_type_ptr)
+
+ return [(f"[{i}]", elements[i]) for i in range(vec_len)]
+
+
+class AKHashMapPrettyPrinter:
+ def __init__(self, val):
+ self.val = val
+
+ @staticmethod
+ def _iter_hashtable(val, cb):
+ entry_type_ptr = val.type.template_argument(0).pointer()
+ buckets = val["m_buckets"]
+ for i in range(0, val["m_capacity"]):
+ bucket = buckets[i]
+ if bucket["used"]:
+ cb(bucket["storage"].cast(entry_type_ptr))
+
+ @staticmethod
+ def _iter_hashmap(val, cb):
+ table = val["m_table"]
+ AKHashMapPrettyPrinter._iter_hashtable(table, lambda entry: cb(entry["key"], entry["value"]))
+
+ def to_string(self):
+ return self.val.type.name
+
+ def children(self):
+ elements = []
+
+ def cb(key, value):
+ nonlocal elements
+ elements.append((f"[{key}]", value))
+
+ AKHashMapPrettyPrinter._iter_hashmap(self.val, cb)
+ return elements
+
+
+class VirtualAddress:
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ return self.val["m_address"]
+
+
+class SerenityPrettyPrinterLocator(gdb.printing.PrettyPrinter):
+ def __init__(self):
+ super(SerenityPrettyPrinterLocator, self).__init__("serenity_pretty_printers", [])
+
+ self.re = re.compile('^([^<]+)(<.*>)?$')
+
+ def __call__(self, val):
+ type = gdb.types.get_basic_type(val.type)
+ typename = str(type.tag)
+
+ match = self.re.match(typename)
+ if not match:
+ return None
+
+ klass = match.group(1)
+
+ if klass == 'AK::Atomic':
+ return AKAtomic(val)
+ elif klass == 'AK::DistinctNumeric':
+ return AKDistinctNumeric(val)
+ elif klass == 'AK::HashMap':
+ return AKHashMapPrettyPrinter(val)
+ elif klass == 'AK::RefCounted':
+ return AKRefCounted(val)
+ elif klass == 'AK::RefPtr':
+ return AKRefPtr(val)
+ elif klass == 'AK::OwnPtr':
+ return AKOwnPtr(val)
+ elif klass == 'AK::NonnullRefPtr':
+ return AKRefPtr(val)
+ elif klass == 'AK::String':
+ return AKString(val)
+ elif klass == 'AK::StringView':
+ return AKStringView(val)
+ elif klass == 'AK::StringImpl':
+ return AKStringImpl(val)
+ elif klass == 'AK::Vector':
+ return AKVector(val)
+ elif klass == 'VirtualAddress':
+ return VirtualAddress(val)
+
+
+gdb.printing.register_pretty_printer(None, SerenityPrettyPrinterLocator(), replace=True)
+
+
+class FindThreadCmd(gdb.Command):
+ """
+ Find SerenityOS thread for the specified TID.
+ find_thread TID
+ """
+
+ def __init__(self):
+ super(FindThreadCmd, self).__init__(
+ "find_thread", gdb.COMMAND_USER
+ )
+
+ def _find_thread(self, tid):
+ threads = gdb.parse_and_eval("Kernel::Thread::g_tid_map")
+ thread = None
+
+ def cb(key, value):
+ nonlocal thread
+ if int(key["m_value"]) == tid:
+ thread = value
+
+ AKHashMapPrettyPrinter._iter_hashmap(threads, cb)
+ return thread
+
+ def complete(self, text, word):
+ return gdb.COMPLETE_SYMBOL
+
+ def invoke(self, args, from_tty):
+ argv = gdb.string_to_argv(args)
+ if len(argv) == 0:
+ gdb.write("Argument required (TID).\n")
+ return
+ tid = int(argv[0])
+ thread = self._find_thread(tid)
+ if not thread:
+ gdb.write(f"No thread with TID {tid} found.\n")
+ else:
+ gdb.write(f"{thread}\n")
+
+
+FindThreadCmd()