[PATCH] jump_label: align jump_entry table to at least 4-bytes

David Daney
2017-02-27T23:34:44Z

On 02/27/2017 02:50 PM, Jason Baron wrote:
>
>
> On 02/27/2017 05:45 PM, David Daney wrote:
>> On 02/27/2017 02:36 PM, Steven Rostedt wrote:
>>> On Mon, 27 Feb 2017 14:21:21 -0800
>>> David Daney <ddaney@caviumnetworks.com> wrote:
>>>
>>>> See attached for mips. It seems to do the right thing.
>>>>
>>>> I leave it as an exercise to the reader to fix the other architectures.
>>>>
>>>> Consult your own binutils experts to verify that what I say is true.
>>>
>>> It may still just be safer to do the pointers instead. That way we
>>> don't need to worry about some strange arch or off by one binutils
>>> messing it up.
>>
>> Obviously it is your choice, but this is bog standard ELF linking. In
>> theory even the arrays of power-of-2 sized objects should also supply an
>> entity size. Think __ex_table and its ilk.
>>
>>
>> The benefit of supplying an entsize is that you don't have to change the
>> structure of the existing code and risk breaking something in the
>> process.
>>
>> David Daney
>>
>>
>
> Thanks for the suggestion! I would like to see if this resolves the ppc
> issue we had. I'm attaching a powerpc patch based on your suggestion.
> Hopefully, Sachin can try it.
>

If there are problems, you could try something like:

$ find . -name \*\.o | xargs mips64-octeon-linux-gnu-readelf -eW | grep
'File:\| __jump_table'
File: ./drivers/firmware/built-in.o
File: ./drivers/built-in.o
[3249] __jump_table PROGBITS 0000000000000000 1838c8
0022c8 18 WAM 0 0 8
File: ./drivers/spi/built-in.o
[82] __jump_table PROGBITS 0000000000000000 008cb0 000048
18 WAM 0 0 8
File: ./drivers/spi/spi-cavium-octeon.o
File: ./drivers/spi/spi-cavium.o
File: ./drivers/spi/spi.o
.
.
.

Look for files where the size of the __jump_table section is not a
integer multiple of the entsize.

> Thanks,
>
> -Jason