Re: [Qemu-devel] tcg/tcg.c:1892: tcg fatal error

[Igor Kovalenko]

On Sun, Apr 10, 2011 at 10:35 PM, Artyom Tarasenko <address@hidden> wrote:
> On Sun, Apr 10, 2011 at 7:57 PM, Blue Swirl <address@hidden> wrote:
>> On Sun, Apr 10, 2011 at 8:48 PM, Artyom Tarasenko <address@hidden> wrote:
>>> On Sun, Apr 10, 2011 at 4:44 PM, Blue Swirl <address@hidden> wrote:
>>>> On Sun, Apr 10, 2011 at 5:09 PM, Artyom Tarasenko <address@hidden> wrote:
>>>>> On Sun, Apr 10, 2011 at 3:24 PM, Aurelien Jarno <address@hidden> wrote:
>>>>>> On Sun, Apr 10, 2011 at 02:29:59PM +0200, Artyom Tarasenko wrote:
>>>>>>> Trying to boot some proprietary OS I get qemu-system-sparc64 crash with 
>>>>>>> a
>>>>>>>
>>>>>>> tcg/tcg.c:1892: tcg fatal error
>>>>>>>
>>>>>>> error message.
>>>>>>>
>>>>>>> It looks like it can be a platform independent bug though, because
>>>>>>> when a '-singlestep' option IS present, qemu doesn't crash and seems
>>>>>>> to translate the code properly.
>>>>>>>
>>>>>>> (gdb) bt
>>>>>>> #0  0x00000032c2e327f5 in raise () from /lib64/libc.so.6
>>>>>>> #1  0x00000032c2e33fd5 in abort () from /lib64/libc.so.6
>>>>>>> #2  0x000000000051933d in tcg_reg_alloc_call (s=<value optimized out>,
>>>>>>> def=0x89d340, opc=INDEX_op_call, args=0x10acc98, dead_iargs=3) at
>>>>>>> qemu/tcg/tcg.c:1892
>>>>>>> #3  0x000000000051a557 in tcg_gen_code_common (s=0x10b8940,
>>>>>>> gen_code_buf=0x40338b60 "address@hidden 3\355I\211\256\220") at
>>>>>>> qemu/tcg/tcg.c:2099
>>>>>>> #4  tcg_gen_code (s=0x10b8940, gen_code_buf=0x40338b60 "address@hidden
>>>>>>> 3\355I\211\256\220") at qemu/tcg/tcg.c:2142
>>>>>>> #5  0x00000000004d38f1 in cpu_sparc_gen_code (env=0x10cce10,
>>>>>>> tb=0x7fffe91bc218, gen_code_size_ptr=0x7fffffffd9b4) at
>>>>>>> qemu/translate-all.c:93
>>>>>>> #6  0x00000000004d1fd7 in tb_gen_code (env=0x10cce10, pc=18868776,
>>>>>>> cs_base=18868780, flags=15, cflags=0) at qemu/exec.c:989
>>>>>>> #7  0x00000000004d4029 in tb_find_slow (env1=<value optimized out>) at
>>>>>>> qemu/cpu-exec.c:167
>>>>>>> #8  tb_find_fast (env1=<value optimized out>) at cpu-exec.c:194
>>>>>>> #9  cpu_sparc_exec (env1=<value optimized out>) at qemu/cpu-exec.c:556
>>>>>>> #10 0x0000000000408868 in tcg_cpu_exec () at qemu/cpus.c:1066
>>>>>>> #11 cpu_exec_all () at qemu/cpus.c:1102
>>>>>>> #12 0x000000000053c756 in main_loop (argc=<value optimized out>,
>>>>>>> argv=<value optimized out>, envp=<value optimized out>) at
>>>>>>> qemu/vl.c:1430
>>>>>>>
>>>>>>> I inspected ts->val_type causing the abort() case and it turned out to 
>>>>>>> be 0.
>>>>>>>
>>>>>>> The last lines of qemu.log (without -singlestep)
>>>>>>> IN:
>>>>>>> 0x00000000011fe9f0:  rdpr  %pstate, %g1
>>>>>>> 0x00000000011fe9f4:  wrpr  %g1, 2, %pstate
>>>>>>> --------------
>>>>>>> IN:
>>>>>>> 0x00000000011fe9f8:  ldub  [ %o0 ], %o1
>>>>>>> 0x00000000011fe9fc:  mov  %o1, %o2
>>>>>>> 0x00000000011fea00:  rdpr  %tick, %o3
>>>>>>> 0x00000000011fea04:  cmp  %o1, %o2
>>>>>>> 0x00000000011fea08:  be  %icc, 0x11fea00
>>>>>>> 0x00000000011fea0c:  ldub  [ %o0 ], %o2
>>>>>>>
>>>>>>> Search PC...
>>>>>>> Search PC...
>>>>>>> Search PC...
>>>>>>> Search PC...
>>>>>>> Search PC...
>>>>>>> Search PC...
>>>>>>> --------------
>>>>>>> IN:
>>>>>>> 0x00000000011fe9f8:  ldub  [ %o0 ], %o1
>>>>>>> 0x00000000011fe9fc:  mov  %o1, %o2
>>>>>>> 0x00000000011fea00:  rdpr  %tick, %o3
>>>>>>> 0x00000000011fea04:  cmp  %o1, %o2
>>>>>>> 0x00000000011fea08:  be  %icc, 0x11fea00
>>>>>>> 0x00000000011fea0c:  ldub  [ %o0 ], %o2
>>>>>>>
>>>>>>> 110521: Data Access MMU Miss (v=0068) pc=00000000011fe9f8
>>>>>>> npc=00000000011fe9fc SP=000000000180ae41
>>>>>>> pc: 00000000011fe9f8  npc: 00000000011fe9fc
>>>>>>>
>>>>>>> IN:
>>>>>>> 0x00000000011fea00:  rdpr  %tick, %o3
>>>>>>> 0x00000000011fea04:  cmp  %o1, %o2
>>>>>>> 0x00000000011fea08:  be  %icc, 0x11fea00
>>>>>>> 0x00000000011fea0c:  ldub  [ %o0 ], %o2
>>>>>>> --------------
>>>>>>> IN:
>>>>>>> 0x00000000011fea10:  brz,pn   %o2, 0x11fe9f8
>>>>>>> 0x00000000011fea14:  mov  %o2, %o4
>>>>>>> --------------
>>>>>>> IN:
>>>>>>> 0x00000000011fea18:  rdpr  %tick, %o5
>>>>>>> 0x00000000011fea1c:  cmp  %o2, %o4
>>>>>>> 0x00000000011fea20:  be  %icc, 0x11fea18
>>>>>>> 0x00000000011fea24:  ldub  [ %o0 ], %o4
>>>>>>> --------------
>>>>>>> IN:
>>>>>>> 0x00000000011fea28:  brz,pn   %o4, 0x11fe9f4
>>>>>>> 0x00000000011fea2c:  wrpr  %g0, %g1, %pstate
>>>>>>> <EOF>
>>>>>>>
>>>>>>> The crash is 100% reproducible and happens always on the same place,
>>>>>>> so it's probably a pure TCG issue, not related on getting the
>>>>>>> external/timer interrupts.
>>>>>>>
>>>>>>> Do you need any additional info?
>>>>>>>
>>>>>>
>>>>>> What would be interesting would be to get the corresponding TCG code
>>>>>> from qemu.log (-d op,op_opt).
>>>>>
>>>>>
>>>>> OP:
>>>>>  ---- 0x11fea28
>>>>>  ld_i64 tmp6,regwptr,$0x20
>>>>>  movi_i64 cond,$0x0
>>>>>  movi_i64 tmp8,$0x0
>>>>>  brcond_i64 tmp6,tmp8,ne,$0x0
>>>>>  movi_i64 cond,$0x1
>>>>>  set_label $0x0
>>>>>
>>>>>  ---- 0x11fea2c
>>>>>  movi_i64 tmp7,$0x0
>>>>>  xor_i64 tmp0,tmp7,g1
>>>>>  movi_i64 pc,$0x11fea2c
>>>>>  movi_i64 tmp8,$compute_psr
>>>>>  call tmp8,$0x0,$0
>>>>>  movi_i64 tmp8,$0x0
>>>>>  brcond_i64 cond,tmp8,eq,$0x1
>>>>>  movi_i64 npc,$0x11fe9f4
>>>>>  br $0x2
>>>>>  set_label $0x1
>>>>>  movi_i64 npc,$0x11fea30
>>>>>  set_label $0x2
>>>>>  movi_i64 tmp8,$wrpstate
>>>>>  call tmp8,$0x0,$0,tmp0
>>>>>  mov_i64 pc,npc
>>>>>  movi_i64 tmp8,$0x4
>>>>>  add_i64 npc,npc,tmp8
>>>>>  exit_tb $0x0
>>>>>
>>>>> OP after liveness analysis:
>>>>>  ---- 0x11fea28
>>>>>  ld_i64 tmp6,regwptr,$0x20
>>>>>  movi_i64 cond,$0x0
>>>>>  movi_i64 tmp8,$0x0
>>>>>  brcond_i64 tmp6,tmp8,ne,$0x0
>>>>>  movi_i64 cond,$0x1
>>>>>  set_label $0x0
>>>>>
>>>>>  ---- 0x11fea2c
>>>>>  nopn $0x2,$0x2
>>>>>  nopn $0x3,$0x68,$0x3
>>>>>  movi_i64 pc,$0x11fea2c
>>>>>  movi_i64 tmp8,$compute_psr
>>>>>  call tmp8,$0x0,$0
>>>>>  movi_i64 tmp8,$0x0
>>>>>  brcond_i64 cond,tmp8,eq,$0x1
>>>>>  movi_i64 npc,$0x11fe9f4
>>>>>  br $0x2
>>>>>  set_label $0x1
>>>>>  movi_i64 npc,$0x11fea30
>>>>>  set_label $0x2
>>>>>  movi_i64 tmp8,$wrpstate
>>>>>  call tmp8,$0x0,$0,tmp0
>>>>>  mov_i64 pc,npc
>>>>>  movi_i64 tmp8,$0x4
>>>>>  add_i64 npc,npc,tmp8
>>>>>  exit_tb $0x0
>>>>>  end
>>>>>
>>>>> Does it mean the last block is processed correctly and the crash
>>>>> happens on the next instruction which doesn't make it to the log?
>>>>> The next instruction would be a
>>>>>
>>>>> 0x00000000011fea30:  retl
>>>>>
>>>>> Since it's a branch instruction I guess this would also be a tcg block 
>>>>> boundary.
>>>>
>>>> Because abort() was called from tcg_reg_alloc_call, I'd say 'retl'
>>>> (synthetic op for 'jmpl %o8 + 8, %g0') was the problem.
>>>
>>> Any idea why? retl is not a rare instruction...
>>
>> Sorry, calls are generated for helpers, so it's not 'jmpl' but the
>> call to wrpstate helper.
>
> And why it doesn't happen in a singlestep mode?
> I tried to comment out
> cpu_check_irqs(env);
> in the helper_wrpstate but it made no difference. The only suspicious
> thing left is register bank switching. Is it safe to switch register
> banks in the helper function? Shouldn't we end the translation block
> before?
>
> --
> Regards,
> Artyom Tarasenko
>
> solaris/sparc under qemu blog: http://tyom.blogspot.com/
>
>

Not sure if I have seen write to pstate in delay slot, but switching
globals with PS_AG appears to be safe.
Do you know which bits are changed in the pstate?

-- 
Kind regards,
Igor V. Kovalenko