Re: [ANNOUNCEMENT] mesa 11.0.9-2

[Jon Turney <jon.turney@dronecode.org.uk>]

On 31/05/2016 18:03, Jon Turney wrote:
> On 13/04/2016 03:33, Yaakov Selkowitz wrote:
>> On 2016-04-12 10:20, Marco Atzeri wrote:
>>> $ cd /usr/lib/mesa-demos
>>> $ ./quad-clip.exe
>>> GL_RENDERER   = Gallium 0.4 on llvmpipe (LLVM 3.7, 256 bits)
>>> GL_VERSION    = 3.0 Mesa 11.0.9
>>> GL_VENDOR     = VMware, Inc.
>>> Segmentation fault (core dumped)
>>
>> I can reproduce this on 32-bit but not 64-bit, and the same happens with
>> 11.1.2.  It may be an issue with LLVM 3.7 (11.0.9-1 was built with 3.5)
>> but without a useful backtrace it will be hard to pin down.
>
> gdb can successfully backtrace this, with today's cygwin snapshot.
>
> Both examples of the crash provided by Marco show very similar symptoms.
>
> Unfortunately, the backtrace stops at llvm_pipeline_generic() calling
> into some JIT-ed code.  The faulting is at an insertps instruction with
> what looks like a bogus absolute address.
>
> So I guess this some is an llvm issue, possibly with some address
> computation which doesn't give the right result on 32 bit?
>
>> # gdb ./quad-clip
>> [...]
>> (gdb) r
>> [...]
>> Program received signal SIGSEGV, Segmentation fault.
>> 0x7fdf00c1 in ?? ()
[...]
>> /usr/src/debug/mesa-demos-8.3.0-1/src/trivial/quad-clip.c:137
>> (gdb) disassemble 0x7fdf00b1,0x7fdf00d2
>> Dump of assembler code from 0x7fdf00b1 to 0x7fdf00d2:
>>    0x7fdf00b1:  insertps $0x10,0x4(%eax,%edi,1),%xmm0
>>    0x7fdf00b9:  insertps $0x20,0x8(%eax,%edi,1),%xmm0
>> => 0x7fdf00c1:  insertps $0x30,0xfffeff34,%xmm0
>>    0x7fdf00cb:  mov    (%esi),%eax
>>    0x7fdf00cd:  mul    %ecx

After staring this a bit more, I see that this is the offset to the data 
to load, apparently being used as an absolute address

This seems to be the case with other addresses in the JIT-ed code,  so 
perhaps there is some problem preventing relocations being applied...


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