commit da0f3f5df02d660fe08f2789eabfcc41d6efe5a5
parent bf50144b57dbddac57a47ade8a2da68f149e465e
Author: deurzen <m.deurzen@tum.de>
Date: Sun, 7 Feb 2021 13:38:43 +0100
implements critical value handling, debug refactoring
Diffstat:
1 file changed, 72 insertions(+), 41 deletions(-)
diff --git a/project/extract_sizeret.py b/project/extract_sizeret.py
@@ -3,6 +3,7 @@
import gdb
import re
import json
+from enum import IntEnum
# allocator |-> register containing size argument
break_arg = {
@@ -23,16 +24,20 @@ break_arg_access = {
"kmem_cache_alloc_node": ("rdi", "struct kmem_cache *", "object_size"),
}
-# { type -> [field chain] }
-# Make sure each entry in a field chain is a pointer,
-# as it is dereferenced to obtain the next field
-watch_write_field_chain = {
+# { type |-> [(access chain, critical value)] }
+#
+# Make sure each entry in an access chain (apart from the last entry)
+# is a pointer, as it is dereferenced to obtain the next field
+#
+# If `critical_value` is set to None, any changes to the field are reported
+watch_write_access_chain = {
"struct task_struct *": [
# (((struct task_struct *)<address>)->real_cred)->uid
- ["real_cred", "uid"],
+ (["real_cred", "uid"], 0),
]
}
+avail_hw_breakpoints = 4
watchpoints = {}
n_watchpoints = 0
@@ -52,7 +57,13 @@ mem_map = {}
size_at_entry = None
-debug = True
+class DebugLevel(IntEnum):
+ __order__ = 'WARN INFO TRACE'
+ WARN = 0
+ INFO = 1
+ TRACE = 2
+
+debug_level = DebugLevel.INFO
class RkPrintMem(gdb.Command):
def __init__(self):
@@ -71,12 +82,12 @@ RkPrintMem()
class RkDebug(gdb.Command):
def __init__(self):
- super(RkDebug, self).__init__("rk-debug", gdb.COMMAND_USER)
+ super(RkDebug, self).__init__("rk-debug_level", gdb.COMMAND_USER)
def invoke(self, arg, from_tty):
- global debug
- debug = not debug
- print(f"Debug messages set to {debug}")
+ global debug_level
+ debug_level = DebugLevel((int(debug_level) + 1) % len(list(map(int, DebugLevel))))
+ print(f"debug_level messages set to {debug_level.name}")
RkDebug()
@@ -110,9 +121,10 @@ class EntryExitBreakpoint(gdb.Breakpoint):
gdb.Breakpoint.__init__(self, b)
def stop(self):
+ global avail_hw_breakpoints
global watchpoints
global n_watchpoints
- global watch_write_field_chain
+ global watch_write_access_chain
global mem_map
frame = gdb.newest_frame()
@@ -139,20 +151,22 @@ class EntryExitBreakpoint(gdb.Breakpoint):
mem_map[address] = (type, size, caller)
- if type[7:] in watch_write_field_chain:
- field_chains = watch_write_field_chain[type[7:]]
- for field_chain in field_chains:
- if n_watchpoints + len(field_chain) <= 4:
+ if type[7:] in watch_write_access_chain:
+ access_chains = watch_write_access_chain[type[7:]]
+ for access_chain, critical_value in access_chains:
+ if n_watchpoints + len(access_chain) <= avail_hw_breakpoints:
+ watchpoint = WriteWatchpoint(address, type[7:], access_chain, critical_value)
+
if address in watchpoints:
- watchpoints[address].append(WriteWatchpoint(address, type[7:], field_chain))
+ watchpoints[address].append(watchpoint)
else:
- watchpoints[address] = [WriteWatchpoint(address, type[7:], field_chain)]
+ watchpoints[address] = [watchpoint]
- n_watchpoints += len(field_chain)
- if n_watchpoints >= 4:
+ n_watchpoints += len(access_chain)
+ if n_watchpoints >= avail_hw_breakpoints:
break
- if debug:
+ if debug_level >= DebugLevel.TRACE:
print("Allocating", (type, size, caller), "at", hex(address))
return False
@@ -173,7 +187,9 @@ class EntryExitBreakpoint(gdb.Breakpoint):
elif frame.name() in break_arg_access:
(reg, type, field) = break_arg_access[frame.name()]
- size = int(gdb.execute(f"p (({type})${reg})->{field}", to_string=True).strip().split(" ")[2])
+ size = int(gdb.execute(f"p (({type})${reg})->{field}",
+ to_string=True).strip().split(" ")[2])
+
if size > 0:
size_at_entry = size
return None
@@ -216,7 +232,7 @@ class FreeBreakpoint(gdb.Breakpoint):
global watchpoints
global n_watchpoints
global free_funcs
- global debug
+ global debug_level
frame = gdb.newest_frame()
@@ -230,14 +246,17 @@ class FreeBreakpoint(gdb.Breakpoint):
if address in watchpoints:
for watchpoint in watchpoints[address]:
- print("Deleting watchpoint on", watchpoint.current_chain, "which is at", hex(address))
+ if debug_level >= DebugLevel.INFO:
+ print("Deleting watchpoint on", watchpoint.current_chain,
+ "which is at", hex(address))
+
watchpoint.delete()
- n_watchpoints -= len(watchpoint.field_chain)
+ n_watchpoints -= len(watchpoint.access_chain)
del(watchpoints[address])
if address in mem_map:
- if debug:
+ if debug_level >= DebugLevel.TRACE:
print("Freeing", mem_map[address], "at", hex(address))
mem_map.pop(address)
@@ -246,48 +265,60 @@ class FreeBreakpoint(gdb.Breakpoint):
class WriteWatchpoint(gdb.Breakpoint):
address = None
type = None
- field_chain = None
+ access_chain = None
+ critical_value = None
previous_value = None
previous_value_print = None
- def __init__(self, address, type, field_chain):
+ def __init__(self, address, type, access_chain, critical_value):
global watchpoints
self.address = address
self.type = type
- self.field_chain = field_chain
+ self.access_chain = access_chain
+ self.critical_value = critical_value
current_chain = f"(({type}){hex(address)})"
- for field in field_chain:
+ for field in access_chain:
current_chain = "(" + current_chain + "->" + field + ")"
self.previous_value = self.get_value(current_chain)
self.previous_value_print = self.get_value_print(current_chain)
- print("Setting watchpoint on", current_chain, "which is at", hex(address))
+ if debug_level >= DebugLevel.INFO:
+ print("Setting watchpoint on", current_chain, "which is at", hex(address))
+
self.current_chain = current_chain
gdb.Breakpoint.__init__(self, current_chain, internal=True, type=gdb.BP_WATCHPOINT)
def stop(self):
current_chain = f"(({self.type}){hex(self.address)})"
- for field in self.field_chain:
+ for field in self.access_chain:
current_chain = "(" + current_chain + "->" + field + ")"
current_value = self.get_value(current_chain)
- if self.previous_value is not None and self.previous_value != current_value:
- current_value_print = self.get_value_print(current_chain)
+ current_value_print = self.get_value_print(current_chain)
- print(current_chain, "changed from", self.previous_value_print,
- "to", current_value_print)
+ if self.previous_value is not None and current_value is not None:
+ if self.previous_value != current_value:
+ if debug_level >= DebugLevel.INFO:
+ print(current_chain, "changed from", self.previous_value_print,
+ "to", current_value_print)
- self.previous_value = current_value
- self.previous_value_print = current_value_print
+ if debug_level >= DebugLevel.WARN:
+ current_value = int.from_bytes(bytes(current_value), "little")
+ if current_value == self.critical_value:
+ print(f"WARNING: critical value {self.critical_value} set to {current_chain}")
+
+ self.previous_value = current_value
+ self.previous_value_print = current_value_print
return False
def get_value_print(self, name):
try:
- return "\n".join([line.strip() for line in gdb.execute(f"p {name}", to_string=True).strip().split("\n")[1:-1]])
+ return "\n".join([line.strip() for line in
+ gdb.execute(f"p {name}", to_string=True).strip().split("\n")[1:-1]])
except:
return None
@@ -295,17 +326,17 @@ class WriteWatchpoint(gdb.Breakpoint):
try:
size = int(gdb.parse_and_eval(f"sizeof({name})"))
except:
- return 0
+ return None
try:
address = int(gdb.execute(f"p &({name})", to_string = True).strip().split(" ")[-1], 16)
except:
- return 0
+ return None
try:
return gdb.selected_inferior().read_memory(address, size)
except:
- return 0
+ return None
class Stage3():
breakpoints = []
