qemu-3.1.0-rc0: mips emulation hangs when executing invalid instructions

[Alberto Ortega]

QEMU version:
-------------

qemu-3.1.0-rc0 compiled from sources (earlier versions also affected)

Summary:
--------

QEMU MIPS system emulation hangs when trying to execute the following invalid instructions:

71c5a9bf sdbbp 0x716a6
2c4745aa sltiu a3, v0, 0x45aa
f47539fb sdc1 f21, 0x39fb(v1)
5fa5e284 invalid

qemu-system-mips falls under an infinite loop condition and it needs to be ended.

The issue has been reproduced in Ubuntu x64 host running Debian MIPS 32-bits guest with the following command line:

qemu-system-mips -M malta -kernel vmlinux-3.2.0-4-4kc-malta -hda debian_wheezy_mips_standard.qcow2 -append "root=/dev/sda1 console=tty0"

It can also be reproduced using mips-linux-user, in which case throws the following exception:

qemu-mips mips_loop_static.elf
qemu: unhandled CPU exception 0x10 - aborting
pc=0x004a9da0 HI=0x00000003 LO=0x00000002 ds 00e2 004a9da0 0
GPR00: r0 00000000 at fffffff8 v0 004a9da0 v1 004ad000
GPR04: a0 00000001 a1 7fffefc4 a2 7fffefcc a3 00000000
GPR08: t0 004ab854 t1 0ffffffe t2 81010100 t3 2f2f2f2f
GPR12: t4 7ffff1ad t5 004ab090 t6 004ab06c t7 004ab07c
GPR16: s0 00000000 s1 452ac505 s2 00400db4 s3 00400d38
GPR20: s4 00000000 s5 00000000 s6 00000000 s7 00000000
GPR24: t8 004ab0a8 t9 004a9da0 k0 00000000 k1 00000000
GPR28: gp 004b25a0 sp 7fffeec0 s8 7fffeec0 ra 0040041c
CP0 Status 0x24000010 Cause 0x00000000 EPC 0x00000000
    Config0 0x80008482 Config1 0x9e190c8f LLAddr 0xffffffffffffffff
    Config2 0x80000000 Config3 0x00000000
    Config4 0x00000000 Config5 0x00000000
qemu:handle_cpu_signal received signal outside vCPU context @ pc=0x602dbad8

Testcase:
---------

C program to reproduce the problem:

unsigned char code[] = "\x71\xC5\xA9\xBF\x2C\x47\x45\xAA\xF4\x75\x39\xFB\x5F\xA5\xE2\x84";
main()
{
  int (*ret)() = (int(*)())code;
  ret();
}

Also, find a statically compiled ELF attached.

[Philippe Mathieu-Daudé (philmd)]

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'invalid' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/240