hmp: Pass monitor to mon_get_cpu_env()

hmp: Pass monitor to mon_get_cpu_env()

mon_get_cpu_env() is indirectly called monitor_parse_arguments() where
the current monitor isn't set yet. Instead of using monitor_cur_env(),
explicitly pass the Monitor pointer to the function.

Without this fix, an HMP command like "x $pc" crashes like this:

  #0  0x0000555555caa01f in mon_get_cpu_sync (mon=0x0, synchronize=true) at ../monitor/misc.c:270
  #1  0x0000555555caa141 in mon_get_cpu (mon=0x0) at ../monitor/misc.c:294
  #2  0x0000555555caa158 in mon_get_cpu_env () at ../monitor/misc.c:299
  #3  0x0000555555b19739 in monitor_get_pc (mon=0x555556ad2de0, md=0x5555565d2d40 <monitor_defs+1152>, val=0) at ../target/i386/monitor.c:607
  #4  0x0000555555cadbec in get_monitor_def (mon=0x555556ad2de0, pval=0x7fffffffc208, name=0x7fffffffc220 "pc") at ../monitor/misc.c:1681
  #5  0x000055555582ec4f in expr_unary (mon=0x555556ad2de0) at ../monitor/hmp.c:387
  #6  0x000055555582edbb in expr_prod (mon=0x555556ad2de0) at ../monitor/hmp.c:421
  #7  0x000055555582ee79 in expr_logic (mon=0x555556ad2de0) at ../monitor/hmp.c:455
  #8  0x000055555582eefe in expr_sum (mon=0x555556ad2de0) at ../monitor/hmp.c:484
  #9  0x000055555582efe8 in get_expr (mon=0x555556ad2de0, pval=0x7fffffffc418, pp=0x7fffffffc408) at ../monitor/hmp.c:511
  #10 0x000055555582fcd4 in monitor_parse_arguments (mon=0x555556ad2de0, endp=0x7fffffffc890, cmd=0x555556675b50 <hmp_cmds+7920>) at ../monitor/hmp.c:876
  #11 0x00005555558306a8 in handle_hmp_command (mon=0x555556ad2de0, cmdline=0x555556ada452 "$pc") at ../monitor/hmp.c:1087
  #12 0x000055555582df14 in monitor_command_cb (opaque=0x555556ad2de0, cmdline=0x555556ada450 "x $pc", readline_opaque=0x0) at ../monitor/hmp.c:47

After this fix, nothing is left in monitor_parse_arguments() that can
indirectly call monitor_cur(), so the fix is complete.

Fixes: ff04108a0e36e822519c517bd3bddbc1c7747c18
Reported-by: lichun <lichun@ruijie.com.cn>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20201113114326.97663-4-kwolf@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>