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

[Igor Kovalenko]

On Mon, Apr 11, 2011 at 12:00 AM, Artyom Tarasenko <address@hidden> wrote:
> On Sun, Apr 10, 2011 at 9:41 PM, Igor Kovalenko
> <address@hidden> wrote:
>> On Sun, Apr 10, 2011 at 11:37 PM, Artyom Tarasenko <address@hidden> wrote:
>>> On Sun, Apr 10, 2011 at 8:52 PM, Igor Kovalenko
>>> <address@hidden> wrote:
>>>> 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?
>>>>
>>>> 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?
>>>
>>> Hard to say. With a breakpoint set qemu doesn't crash.
>>> The breakpoint shows the change from 0x14->0x16.
>>> So the only difference is that interrupts are getting enabled. No
>>> register bank change.
>>> (And now also no cpu_check_irqs(env) call, because I commented it out.)
>>>
>>> But given there was a Data Access MMU Miss, I would expect there must
>>> have beeb a PS_MG switch.
>>>
>>> Also the breakpoint makes tcg to cut the translation block before the wrpr:
>>>
>>> IN:
>>> 0x00000000011fea18:  rdpr  %tick, %o5
>>> 0x00000000011fea1c:  cmp  %o2, %o4
>>> 0x00000000011fea20:  be  %icc, 0x11fea18
>>> 0x00000000011fea24:  ldub  [ %o0 ], %o4
>>> --------------
>>> IN:
>>> 0x00000000011fea28:  brz,pn   %o4, 0x11fe9f4
>>> --------------
>>> IN:
>>> 0x00000000011fea2c:  wrpr  %g0, %g1, %pstate
>>> --------------
>>> IN:
>>> 0x00000000011fea30:  retl
>>> --------------
>>> IN:
>>> 0x00000000011fea30:  retl
>>> 0x00000000011fea34:  sub  %o5, %o3, %o0
>>>
>>
>> You can try enabling DEBUG_PSTATE to see which bits are changed.
>
> I put an additional DPRINTF in the helper and it doesn't get executed
> at 11fea2c. Only at 11fe9f4 (0x16->0x14).

In such cases I would run with -d in_asm,int to have more data to
compare two runs.
May the patch attached help a bit to add verbose pstate output.

Do you have public test case?
It is possible to code this delay slot write test but real issue may
be corruption elsewhere.

-- 
Kind regards,
Igor V. Kovalenko

sparc64-dump-pstate-verbose
Description: Binary data