[RFC] kexec_file: Add support for purgatory built as PIE

[Eric W. Biederman]

Baoquan He <bhe at redhat.com> writes:

> On 11/02/16 at 04:00am, Thiago Jung Bauermann wrote:
>> Hello,
>> 
>> The kexec_file code currently builds the purgatory as a partially linked object 
>> (using ld -r). Is there a particular reason to use that instead of a position 
>> independent executable (PIE)?
>
> It's taken as "-r", relocatable in user space kexec-tools too originally.
> I think Vivek just keeps it the same when moving into kernel.

At least on x86 using just -r removed the need for a GOT and all of the
other nasty dynamic relocatable bits, that are not needed when the you
don't want to share your text bits with the page cache.

I can see reaons for refactoring code but I expect PIE expecutables need
a GOT and all of that pain in the neck stuff that can just be avoided by
building the code to run at an absolute address.

So far I have not seen ELF relocations that are difficult to process.

Eric