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Fix qdb support for ARM Cortex-M #1574

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Merged
merged 2 commits into from
Jun 23, 2025
Merged

Fix qdb support for ARM Cortex-M #1574

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b1ad033
Have qdb use xPSR for Cortex M instead of CPSR
elicn Jun 21, 2025
95d7b8f
Generalize code to meet both Cortex A and M
elicn Jun 21, 2025
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6 changes: 5 additions & 1 deletion qiling/debugger/qdb/arch/arch_arm.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,12 +3,14 @@
# Cross Platform and Multi Architecture Advanced Binary Emulation Framework
#

from typing import Dict, Optional
from typing import ClassVar, Dict, Optional

from .arch import Arch


class ArchARM(Arch):
_flags_reg: ClassVar[str] = 'cpsr'

def __init__(self) -> None:
regs = (
'r0', 'r1', 'r2', 'r3',
Expand Down Expand Up @@ -134,6 +136,8 @@ def read_insn(self, address: int) -> Optional[bytearray]:


class ArchCORTEX_M(ArchARM):
_flags_reg: ClassVar[str] = 'xpsr'

def __init__(self):
super().__init__()

Expand Down
14 changes: 7 additions & 7 deletions qiling/debugger/qdb/branch_predictor/branch_predictor_arm.py
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Expand Up @@ -27,11 +27,11 @@ class BranchPredictorARM(BranchPredictor, ArchARM):

stop = 'udf'

def get_cpsr(self) -> Tuple[bool, bool, bool, bool]:
"""Get flags map of CPSR.
def get_cond_flags(self) -> Tuple[bool, bool, bool, bool]:
"""Get condition status flags from CPSR / xPSR.
"""

cpsr = self.read_reg('cpsr')
cpsr = self.read_reg(self._flags_reg)

return (
(cpsr & (0b1 << 28)) != 0, # V, overflow flag
Expand Down Expand Up @@ -122,9 +122,9 @@ def __parse_op(op: ArmOp, *args, **kwargs) -> Optional[int]:

def __is_taken(cc: int) -> Tuple[bool, Tuple[bool, ...]]:
pred = predicate[cc]
cpsr = self.get_cpsr()
flags = self.get_cond_flags()

return pred(*cpsr), cpsr
return pred(*flags), flags

# conditions predicate selector
predicate: Dict[int, Callable[..., bool]] = {
Expand Down Expand Up @@ -215,13 +215,13 @@ def __is_taken(cc: int) -> Tuple[bool, Tuple[bool, ...]]:
where = __parse_op(operands[1], **msize[suffix])

elif iname in binop:
going, cpsr = __is_taken(insn.cc)
going, flags = __is_taken(insn.cc)

if going:
operator = binop[iname]
op1 = __parse_op(operands[1])
op2 = __parse_op(operands[2])
carry = int(cpsr[1])
carry = int(flags[1])

where = (op1 and op2) and operator(op1, op2, carry)

Expand Down
4 changes: 2 additions & 2 deletions qiling/debugger/qdb/render/render_arm.py
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Expand Up @@ -3,7 +3,7 @@
# Cross Platform and Multi Architecture Advanced Binary Emulation Framework
#

from typing import Iterator, Optional
from typing import Iterator

from .render import Render, ContextRender
from ..arch import ArchARM, ArchCORTEX_M
Expand All @@ -15,7 +15,7 @@ class ContextRenderARM(ContextRender, ArchARM):
"""

def print_mode_info(self) -> None:
cpsr = self.read_reg('cpsr')
cpsr = self.read_reg(self._flags_reg)

flags = ArchARM.get_flags(cpsr)
mode = ArchARM.get_mode(cpsr)
Expand Down