How to load string or floating-point data into registers?

[bstee615]

Hello, thank you for your work on this awesome library! I'd lke to use Qiling to override arguments to a function call with my own values. I'm running on Intel x86_64 instruction set.

This is easy to do for integer types:

from qiling import *

def override_arguments(ql):
  ql.arch.regs.write("edi", 100)
  ql.arch.regs.write("esi", 200)

if __name__ == "__main__":
  rootfs = "/"
  bin_fpath = "a.out"
  ql = Qiling([bin_fpath], rootfs)
  ba = ql.loader.images[0].base
  func_address = 0x1177
  ql.hook_address(override_arguments, ba+func_address)
  ql.run()

And I got it to work for string types, though I'm not sure if this is the best way:

def override_arguments(ql):
  addr = 0x100000 # By the way, what is the best place to allocate memory like this?
  size = len(arg) + 1
  size = ql.mem.align_up(size)
  ql.log.info(f"Reserving {size} bytes")
  ql.mem.map(addr, size)
  ql.log.info(f"Writing {repr(arg)} to 0x{addr:x}")
  ql.mem.string(addr, arg)
  ql.arch.regs.write("edi", addr)

However, I can't figure out how to supply floating-point values. As far as I can tell, the calling convention passes these values in the registers xmm0, xmm1, ... using the movss instruction. If I directly write data to xmm0, the value is printed as 0.0 in the inferior program.

def override_arguments(ql):
  ql.arch.regs.write("xmm0", 50)

I'd appreciate if you can help answer my questions: What's the best way to allocate memory for loading string data? How can I load floating-point values as a function's arguments?