Qdb: add command show_args

Author: ucgJhe

qiling/debugger/qdb/branch_predictor/branch_predictor_x8664.py

@@ -98,7 +98,7 @@ def predict(self):
             prophecy.going = jump_reg_table.get(line.mnemonic)(self.ql.arch.regs.ecx)
 
         if prophecy.going:
-            takeaway_list = ["ptr", "dword", "[", "]"]
+            takeaway_list = ["ptr", "dword", "qword", "[", "]"]
 
             if len(line.op_str.split()) > 1:
                 new_line = line.op_str.replace(":", "+")
@@ -114,7 +114,6 @@ def predict(self):
                     if each_reg in new_line:
                         new_line = re.sub(each_reg, hex(self.read_reg(each_reg)), new_line)
 
-
                 prophecy.where = check_and_eval(new_line)
 
             elif line.op_str in self.ql.arch.regs.register_mapping:

qiling/debugger/qdb/qdb.py

@@ -6,9 +6,10 @@
 import cmd
 
 from typing import Optional, Tuple, Union
+from contextlib import contextmanager
 
 from qiling import Qiling
-from qiling.const import QL_OS, QL_ARCH
+from qiling.const import QL_OS, QL_ARCH, QL_ENDIAN
 from qiling.debugger import QlDebugger
 
 from .utils import setup_context_render, setup_branch_predictor, setup_address_marker, SnapshotManager, run_qdb_script
@@ -119,6 +120,15 @@ def _run(self, address: int = 0, end: int = 0, count: int = 0) -> None:
 
         self.ql.emu_start(begin=address, end=end, count=count)
 
+    @contextmanager
+    def _save(self, reg=True, mem=True, hw=False, fd=False, cpu_context=False, os=False, loader=False):
+        """
+        helper function for fetching specific context by emulating instructions
+        """
+        saved_states = self.ql.save(reg=reg, mem=mem)
+        yield self
+        self.ql.restore(saved_states)
+
     def save_reg_dump(func) -> None:
         """
         decorator function for saving register dump
@@ -417,6 +427,96 @@ def do_mark(self, args=""):
 
         qdb_print(QDB_MSG.INFO, f"mark symbol '{sym_name}' at address: 0x{loc:08x} ...")
 
+    @parse_int
+    def do_show_args(self, argc: int = -1):
+        """
+        show arguments of a function call
+        default argc is 2 since we don't know the function definition
+        """
+
+        if argc is None:
+            argc = -1
+
+        elif argc > 16:
+            qdb_print(QDB_MSG.ERROR, 'Maximum argc is 16.')
+            return
+
+        prophecy = self.predictor.predict()
+        if not prophecy.going:
+            qdb_print(QDB_MSG.ERROR, 'Not on a braching instruction currently.')
+            return
+
+        if argc == -1:
+            reg_n, stk_n = 2, 0
+        else:
+            reg_n, stk_n = 4, 0
+            if argc > 4:
+                stk_n = argc - 4
+
+        ptr_size = self.ql.arch.pointersize
+
+        reg_args = []
+        arch_type = self.ql.arch.type
+        if arch_type in (QL_ARCH.MIPS, QL_ARCH.ARM, QL_ARCH.CORTEX_M, QL_ARCH.X8664):
+
+            reg_idx = None
+            if arch_type == QL_ARCH.MIPS:
+                slot_addr = self.cur_addr + ptr_size
+
+                op_str = self.predictor.disasm(slot_addr).op_str
+                # register may be changed due to dealy slot
+                if '$a' in op_str.split(',')[0]:
+                    dst_reg = op_str.split(',')[0].strip('$')
+                    reg_idx = int(dst_reg.strip('a'))
+
+                    # fetch real value by emulating instruction in delay slot
+                    with self._save() as qdb:
+                        qdb._run(slot_addr, 0, count=1)
+                        real_val = self.ql.arch.regs.read(dst_reg)
+
+                reg_names = [f'a{d}'for d in range(reg_n)]
+
+            elif arch_type in (QL_ARCH.ARM, QL_ARCH.CORTEX_M):
+                reg_names = [f'r{d}'for d in range(reg_n)]
+
+            elif arch_type == QL_ARCH.X8664:
+                if argc == -1:
+                    reg_n = 2
+                else:
+                    reg_n = argc
+
+                reg_names = ('rdi', 'rsi', 'rdx', 'rcx', 'r8', 'r9')[:reg_n]
+
+            reg_args = [self.ql.arch.regs.read(reg_name) for reg_name in reg_names]
+            if reg_idx:
+                regs_args.insert(reg_idx, real_val)
+
+            reg_args = list(map(hex, reg_args))
+
+        elif arch_type == QL_ARCH.X86:
+            stk_n = 2 if argc == -1 else argc
+
+        # read arguments on stack
+        if stk_n >= 0:
+            shadow_n = 0
+            base_offset = self.ql.arch.regs.arch_sp
+
+            if arch_type in (QL_ARCH.X86, QL_ARCH.X8664):
+                # shadow 1 pointer size for return address
+                shadow_n = 1
+
+            elif arch_type == QL_ARCH.MIPS:
+                # shadow 4 pointer size for mips
+                shadow_n = 4
+
+            base_offset = self.ql.arch.regs.arch_sp + shadow_n * ptr_size
+            stk_args = [self.ql.mem.read(base_offset+offset*ptr_size, ptr_size) for offset in range(stk_n)]
+            endian = 'little' if self.ql.arch.endian == QL_ENDIAN.EL else 'big'
+            stk_args = list(map(hex, map(lambda x: int.from_bytes(x, endian), stk_args)))
+
+        args = reg_args + stk_args
+        qdb_print(QDB_MSG.INFO, f'args: {args}')
+
     def do_show(self, *args) -> None:
         """
         show some runtime information
@@ -473,6 +573,7 @@ def do_EOF(self, *args) -> None:
     do_r = do_run
     do_s = do_step_in
     do_n = do_step_over
+    do_a = do_show_args
     do_j = do_jump
     do_m = do_mark
     do_q = do_quit