Re: [RFC6 PATCH v6 00/21] ILP32 for ARM64 - LTP results

[Andrew Pinski <pinskia@gmail.com>]

On Fri, Apr 22, 2016 at 8:37 PM, Zhangjian (Bamvor)
<bamvor.zhangjian@huawei.com> wrote:
> Hi, Yury
>
>
> On 2016/4/6 6:44, Yury Norov wrote:
>>
>> There are about 20 failing tests of 782 in lite scenario.
>> float_bessel
>> float_exp_log
>> float_iperb
>> float_power
>> float_trigo
>> pipeio_1
>> pipeio_3
>> pipeio_5
>> pipeio_8
>> abort01
>> clone02
>> kill11
>> mmap16
>> open12
>> pause01
>> rename11
>> rmdir02
>> umount2_01
>> umount2_02
>> umount2_03
>> utime06
>> mtest06
>>
>> The list is rough because some tests fail not every time.
>>
>> Tests abort01 and kill11 fail for lp64 too, so maybe there's
>> a reason unrelated to ilp32 itself.
>>
>> float_xxx tests fail because they call unwind() from signal context,
>> and GCC for ilp32 has problem with it, as Andrew told.
>
> Is there some progress about this issue. When we talk about unwind
> functions, do you mean the function in libgcc?
>
> We encountered another issue(abort not segfault) which also called
> pthread_cancel(). The test code is in the attachment. Here is the
> backtrace:

Yes this was a known issue I knew about.  I have a patch GCC to fix
this.  Basically REG_VALUE_IN_UNWIND_CONTEXT needs to be defined while
building libgcc to support the correct unwind information.
I will be posting a GCC patch to fix this tomorrow.  This was a bug
even in the original set of ilp32 patches.  I only finally was able to
sit down and fix it today.


Thanks,
Andrew

>
> ```
> Program received signal SIGABRT, Aborted.
> [Switching to Thread 0xf77ee330 (LWP 2958)]
> 0x000000000040f5bc in raise (sig=sig@entry=6)
>     at ../sysdeps/unix/sysv/linux/raise.c:55
> 55      ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
> (gdb) bt
> #0  0x000000000040f5bc in raise (sig=sig@entry=6)
>     at ../sysdeps/unix/sysv/linux/raise.c:55
> #1  0x000000000040f884 in abort () at abort.c:89
>
> #2  0x00000000004073b4 in uw_update_context_1 (
>     context=context@entry=0xf77ec820, fs=fs@entry=0xf77ebec8)
> at /home/GCC-Build/p660/p660_build_dir/src/gcc-4.9/libgcc/unwind-dw2.c:1430
>
> #3  0x00000000004078c0 in uw_update_context
> (context=context@entry=0xf77ec820,
>     fs=fs@entry=0xf77ebec8)
>    at
> /home/GCC-Build/p660/p660_build_dir/src/gcc-4.9/libgcc/unwind-dw2.c:1506
> #4  0x0000000000407a9c in uw_advance_context (fs=0xf77ebec8,
>     context=0xf77ec820)
>     at
> /home/GCC-Build/p660/p660_build_dir/src/gcc-4.9/libgcc/unwind-dw2.c:1529
> #5  _Unwind_ForcedUnwind_Phase2 (exc=exc@entry=0xf77ee580,
>     context=context@entry=0xf77ec820)
>     at /home/GCC-Build/p660/p660_build_dir/src/gcc-4.9/libgcc/unwind.inc:185
> #6  0x0000000000408228 in _Unwind_ForcedUnwind (exc=0xf77ee580,
>     stop=stop@entry=0x405440 <unwind_stop>, stop_argument=0xf77eddd8)
>     at /home/GCC-Build/p660/p660_build_dir/src/gcc-4.9/libgcc/unwind.inc:207
> #7  0x00000000004055c4 in __pthread_unwind (buf=<optimized out>)
>     at unwind.c:126
> #8  0x00000000004050b4 in __do_cancel () at ./pthreadP.h:283
> #9  sigcancel_handler (sig=<optimized out>, si=<optimized out>,
>     ctx=<optimized out>) at nptl-init.c:225
> ---Type <return> to continue, or q <return> to quit---
> #10 <signal handler called>
>
> #11 0x0000000000000000 in ?? ()
>
> #12 0x0000000000423084 in __select (nfds=-66661, readfds=<optimized out>,
>     writefds=<optimized out>, exceptfds=<optimized out>, timeout=0x0)
>     at ../sysdeps/unix/sysv/linux/generic/select.c:45
> #13 0x0000000000400604 in TEST_TaskDelay (
>     uiMillSecs=<error reading variable: can't compute CFA for this frame>)
>     at test-cancel.c:18
> #14 0x0000000000400680 in printids (
>     s=<error reading variable: can't compute CFA for this frame>)
>     at test-cancel.c:38
> #15 0x00000000004006d0 in thr_fn (
>     arg=<error reading variable: can't compute CFA for this frame>)
>     at test-cancel.c:49
> #16 0x0000000000401b28 in start_thread (arg=0x4a3000) at
> pthread_create.c:335
> #17 0x0000000000401b28 in start_thread (arg=0x4a3000) at
> pthread_create.c:335
> Backtrace stopped: previous frame identical to this frame (corrupt stack?)
> ```
>
> Such abort is raise by the following code:
> ```
> static void
> uw_update_context_1 (struct _Unwind_Context *context, _Unwind_FrameState
> *fs)
> {
> //...
>   /* Compute this frame's CFA.  */
>   switch (fs->regs.cfa_how)
>     {
>     case CFA_REG_OFFSET:
>       cfa = _Unwind_GetPtr (&orig_context, fs->regs.cfa_reg);
>       cfa += fs->regs.cfa_offset;
>       break;
>
>     case CFA_EXP:
>       {
>         const unsigned char *exp = fs->regs.cfa_exp;
>         _uleb128_t len;
>
>         exp = read_uleb128 (exp, &len);
>         cfa = (void *) (_Unwind_Ptr)
>           execute_stack_op (exp, exp + len, &orig_context, 0);
>         break;
>       }
>
>     default:
>       gcc_unreachable ();
>     }
>   context->cfa = cfa;
> //...
> }
> ``
>
> Any suggestion is appreciated.
>
> CC gcc mailing list. Sorry if it is off topic.
>
> Regards
>
> Bamvor
>
>
>
>
>> pipeio_x tests are very unstable and may fail randomly. I strongly
>> suspect race conditions, as they all work like a charm if pinned to
>> single CPU with taskset. Probably, race is the reason of clone02 too.
>> Though I'm not sure, is the race in kernel, glibc or test itself.
>>
>> But I know for sure that pause01 fails due to test design:
>>         if (setitimer(ITIMER_REAL, &it, NULL)) // For 1000us
>>                 tst_brkm(TBROK | TERRNO, NULL, "setitimer() failed");
>>
>>         TEST(pause());
>>
>> As setitimer() and pause() calls are not atomic, alarm may come before
>> pause()
>> is called, and be silently dropped by the handler. Next pause() call hangs
>> test forever. I already reported to LTP list.
>>
>> open12, rename11, rmdir02, mmap16, mtest06 - all call mkfs tool, and it
>> returns
>> error code. I didn't investigate it much yet.
>>
>> umount02_x, utime06 - cannot reproduce out of scenario, even run it in
>> infinite
>> loop - they work fine.
>>
>> Full test log is attached.
>>
>> Yury
>>
>