Re: [Xen-devel] [PATCH LIVEPATCH-BUILD-TOOLS 2/2] Remove section alignment requirement

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 09/06/17 17:38, Konrad Rzeszutek Wilk wrote:
> On Fri, Jun 09, 2017 at 05:03:36PM +0100, Ross Lagerwall wrote:
>> Remove the requirement that section twins have the same alignment. The
>> section alignment of the patched section is respected by the loader in
>> Xen so it shouldn't matter if the original section alignment was
>> different.
> Why would we have different section aligment for the same twins?
>
> I understand the change here - if for example the original code
> had:
>
>  .rodata.str.1
>
> [I think I got the section name right - that should be a string
> generated with 1 byte alignment, say 'a'].
>
> But the new patch has a new one:
>
>  .rodata.str.2
>
> ['a' -> 'ab']
>
> Is that what we are fixing here?

Functions also have alignment.  For reasons best known to the compiler,
the fix for XSA-213 caused the alignment of arch_do_multicall_call() to
change from 1 to 16.

The build tools choked on this, but the result is legitimate, and did
work fine.

~Andrew

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