tools/helpers/arch.py

   1 # Copyright 2021 Oliver Smith
   2 # SPDX-License-Identifier: GPL-3.0-or-later
   3 import platform
   4 import logging
   5 import ctypes
   6
   7 def is_32bit_capable():
   8     # man 2 personality
   9     personality = ctypes.CDLL(None).personality
  10     personality.restype = ctypes.c_int
  11     personality.argtypes = [ctypes.c_ulong]
  12     # linux/include/uapi/linux/personality.h
  13     PER_LINUX32 = 0x0008
  14     # mirror e.g. https://github.com/util-linux/util-linux/blob/v2.41/sys-utils/lscpu-cputype.c#L745-L756
  15     pers = personality(PER_LINUX32)
  16     if pers != -1: # success, revert back to previous persona (typically just PER_LINUX, 0x0000)
  17         personality(pers)
  18         return True
  19     return False # unable to "impersonate" 32-bit host, nothing done
  20
  21 def host():
  22     machine = platform.machine()
  23
  24     mapping = {
  25         "i686": "x86",
  26         "x86_64": "x86_64",
  27         "aarch64": "arm64",
  28         "armv7l": "arm",
  29         "armv8l": "arm"
  30     }
  31     if machine in mapping:
  32         return maybe_remap(mapping[machine])
  33     raise ValueError("platform.machine '" + machine + "'"
  34                      " architecture is not supported")
  35
  36 def maybe_remap(target):
  37     if target.startswith("x86"):
  38         with open("/proc/cpuinfo") as f:
  39             cpuinfo = f.read()
  40         if "ssse3" not in cpuinfo:
  41             raise ValueError("x86/x86_64 CPU must support SSSE3!")
  42         if target == "x86_64" and "sse4_2" not in cpuinfo:
  43             logging.info("x86_64 CPU does not support SSE4.2, falling back to x86...")
  44             return "x86"
  45     elif target == "arm64" and platform.architecture()[0] == "32bit":
  46         return "arm"
  47     elif target == "arm64" and not is_32bit_capable():
  48         logging.info("AArch64 CPU does not appear to support AArch32, assuming arm64_only...")
  49         return "arm64_only"
  50
  51     return target