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Re: [Xen-devel] [PATCH 5/8] kexec: extend hypercall with improved load/unload ops

On Thu, Apr 18, 2013 at 05:29:33PM +0100, David Vrabel wrote:
> On 17/04/13 13:51, Daniel Kiper wrote:
> > On Tue, Apr 16, 2013 at 06:13:07PM +0100, David Vrabel wrote:
> >>
> >>      }
> >>
> >> +    code_page = __map_domain_page(image->control_code_page);
> >> +    memcpy(code_page, kexec_reloc, PAGE_SIZE);
> >
> > memcpy(code_page, kexec_reloc, kexec_reloc_size);
> kexec_reloc_size is absolute symbol and doing this give linker errors.

Yes, it should be changed to something like that:

  .long . - xen_relocate_kernel

Somwhere in xen/include/asm-x86/machine_kexec.h:

extern unsigned int kexec_reloc_size;

> FWIW, Linux also uses a #define'd value for its similar memcpy.

I saw that sometime ago and I think this is a bug.
We should copy only kexec_reloc() code and nothing else.
Otherwise we ask for problems.

I am going to post relevant patches for this and
others kexec issues found in Linux Kernel.

> I have added a link time check that kexec_reloc_size <= PAGE_SIZE.

Good idea but it should be kexec_reloc_size <= KEXEC_CONTROL_PAGE_SIZE.


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