llvm dev - Aug 2013 - [LLVMdev] Fix crash in llvm_gcda_emit_arcs()

Hi,

I've been seeing a crash in llvm_gcda_emit_arcs() on x86_64.  The crash
occurs executing a movdqa instruction with an unaligned src address.  The
attached patch to the compiler-rt project fixes the problem by using
memcpy() to read data from the write_buffer[] in GCDAProfiling.c.

This is my first patch submission to llvm so please let me know if I've
missed any steps.  I'm not on the mailing list so please include me on any
replies.

I haven't run the tests on this change but would be happy to do so if
someone could point me to documentation on how to do so.  I couldn't find
testing instructions linked from http://llvm.org/docs/DeveloperPolicy.html.
 I have built the change and run it with the programs I was testing
originally.  With this change the crash no longer occurs.

Thanks,
Joseph Kain
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Bill, could you take a look at this? I don't have a checkout of 
compiler-rt that builds.

It seems obviously-correct to me, but I wish it did a compare against 
cur_buffer_size to make sure it's in range.

Nick

Joseph Kain wrote:
> Hi,
>
> I've been seeing a crash in llvm_gcda_emit_arcs() on x86_64.  The crash
> occurs executing a movdqa instruction with an unaligned src address.
>   The attached patch to the compiler-rt project fixes the problem by
> using memcpy() to read data from the write_buffer[] in GCDAProfiling.c.
>
> This is my first patch submission to llvm so please let me know if I've
> missed any steps.  I'm not on the mailing list so please include me on
> any replies.
>
> I haven't run the tests on this change but would be happy to do so if
> someone could point me to documentation on how to do so.  I couldn't
> find testing instructions linked from
> http://llvm.org/docs/DeveloperPolicy.html.  I have built the change and
> run it with the programs I was testing originally.  With this change the
> crash no longer occurs.
>
> Thanks,
> Joseph Kain
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

Hi Nick,

Thanks for looking over my patch.  I'd be happy to add the compare against
cur_buffer_size.  I'll try to write up such a change today and then send a
new patch to the list.

Joseph Kain


On Thu, Sep 5, 2013 at 1:37 AM, Nick Lewycky <nicholas at mxc.ca> wrote:
> Bill, could you take a look at this? I don't have a checkout of
> compiler-rt that builds.
>
> It seems obviously-correct to me, but I wish it did a compare against
> cur_buffer_size to make sure it's in range.
>
> Nick
>
> Joseph Kain wrote:
>
>> Hi,
>>
>> I've been seeing a crash in llvm_gcda_emit_arcs() on x86_64.  The
crash
>> occurs executing a movdqa instruction with an unaligned src address.
>>   The attached patch to the compiler-rt project fixes the problem by
>> using memcpy() to read data from the write_buffer[] in GCDAProfiling.c.
>>
>> This is my first patch submission to llvm so please let me know if
I've
>> missed any steps.  I'm not on the mailing list so please include me
on
>> any replies.
>>
>> I haven't run the tests on this change but would be happy to do so
if
>> someone could point me to documentation on how to do so.  I
couldn't
>> find testing instructions linked from
>>
http://llvm.org/docs/**DeveloperPolicy.html<http://llvm.org/docs/DeveloperPolicy.html>.
>>  I have built the change and
>> run it with the programs I was testing originally.  With this change
the
>> crash no longer occurs.
>>
>> Thanks,
>> Joseph Kain
>>
>>
>> ______________________________**_________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>
http://lists.cs.uiuc.edu/**mailman/listinfo/llvmdev<http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>
>>
>
>

-- 
Joseph Kain
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