Thumb2: Recognizing doubles

[joelreymont]

Version and Platform (required):

• Binary Ninja Version: 3.4.4251-dev, 3f761e0a
• OS: ubuntu
• OS Version: 22.10
• CPU Architecture: x86_64

Code below is loading an 8-byte value into a floating point register.

000020792  93ed047b   vldr    d7, [r3, #0x10]  {data_dd908}  {0xfefa0000}

Why doesn't BN automatically define a double at data_dd908?

\x00\x00\x00\x00\x00\x008C\x00\x00\xfa\xfeB.v\xbf:;\x9e\xbc\x9a\xf7\x0c\xbd\xbd\xfd\xff\xff\xff\xff\xdf?

HLIL thinks I'm dealing with integers

00002078e          q1 = (0 - *(int64_t*)((char*)q1)[8]);

Is this because I implemented VLDR as a regular register load?

	case armv7::ARMV7_VLDR:
		if (instr->format->operandCount == 3)
		{
			uint32_t reg = GetRegisterByIndex(instr->fields[instr->format->operands[1].field0]);
			il.AddInstruction(WriteILOperand(il, instr, 0, il.Load(4, GetMemoryAddress(il, instr, 1, 4, false))));
			il.AddInstruction(il.SetRegister(4, reg, il.Add(4, il.Register(4, reg), ReadILOperand(il, instr, 2))));
		}
		else
		{
			il.AddInstruction(WriteILOperand(il, instr, 0, il.Load(4, GetMemoryAddress(il, instr, 1, 4))));
		}
		break;

[plafosse]

Yes I would assume because the IL isn't loading it as a float

[joelreymont]

How do I make IL treat it as a float then?

…

On Mon, Apr 24, 2023 at 4:03 PM Peter LaFosse ***@***.***> wrote: Yes I would assume because the IL isn't loading it as a float — Reply to this email directly, view it on GitHub <#4262 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAESZ2QU6WJZEXVLLPPWGDXCZ2Y7ANCNFSM6AAAAAAXJRSCK4> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[plafosse]

Something like

il.AddInstruction(WriteILOperand(il, instr, 0, il.FloatConvert(4, il.Load(4, GetMemoryAddress(il, instr, 1, 4)))));

I think.

[plafosse]

For an example of this see: https://github.com/Vector35/arch-x86/blob/5b134ac7da45c009094faf654f613a9ecd11cae8/il.cpp#L286