#!/usr/bin/env python3
# read_va.py - dump a guest process's memory at a VA (GPU VAs of UVM sysmem
# objects are usually also valid CPU VAs in the owning process).
#
# Usage:
#   sudo python3 read_va.py <pid> <va-hex> [len] [--u32]
#
# --u32 prints one little-endian u32 per line (method-stream friendly).
import os
import sys


def main():
    if len(sys.argv) < 3:
        print(__doc__)
        return 1
    pid = int(sys.argv[1])
    va = int(sys.argv[2], 16)
    ln = 256
    as_u32 = False
    for a in sys.argv[3:]:
        if a == '--u32':
            as_u32 = True
        else:
            ln = int(a, 0)

    found = False
    with open('/proc/%d/maps' % pid) as f:
        for line in f:
            rng = line.split()[0]
            a, b = rng.split('-')
            if int(a, 16) <= va < int(b, 16):
                print('MAP: %s' % line.strip())
                found = True
                break
    if not found:
        print('VA 0x%x not in maps' % va)

    mem = os.open('/proc/%d/mem' % pid, os.O_RDONLY)
    try:
        data = os.pread(mem, ln, va)
    except OSError as e:
        print('read error: %s' % e)
        return 1
    finally:
        os.close(mem)

    if as_u32:
        for i in range(0, len(data) - 3, 4):
            print('+0x%03x: 0x%08x' %
                  (i, int.from_bytes(data[i:i + 4], 'little')))
    else:
        for i in range(0, len(data), 16):
            chunk = data[i:i + 16]
            hexs = ' '.join('%02x' % b for b in chunk)
            print('+0x%03x: %s' % (i, hexs))
    return 0


if __name__ == '__main__':
    sys.exit(main())