Am Montag, 22 August 2016, 15:22:00 schrieb Dave Young:
> On 08/22/16 at 12:38am, Thiago Jung Bauermann wrote:
> > Am Montag, 22 August 2016, 11:21:35 schrieb Dave Young:
> > > On 08/13/16 at 12:18am, Thiago Jung Bauermann wrote:
> > > > diff --git a/arch/powerpc/kernel/machine_kexec_64.c
> > > > b/arch/powerpc/kernel/machine_kexec_64.c index
> > > > a484a6346146..190c652e49b7 100644
> > > > --- a/arch/powerpc/kernel/machine_kexec_64.c
> > > > +++ b/arch/powerpc/kernel/machine_kexec_64.c
> > > > @@ -490,6 +490,60 @@ int arch_kimage_file_post_load_cleanup(struct
> > > > kimage *image)>
> > > >
> > > > return image->fops->cleanup(image->image_loader_data);
> > > >
> > > > }
> > > >
> > > > +bool kexec_can_hand_over_buffer(void)
> > > > +{
> > > > + return true;
> > > > +}
> > > > +
> > > > +int arch_kexec_add_handover_buffer(struct kimage *image,
> > > > + unsigned long load_addr, unsigned
long
> >
> > size)
> >
> > > > +{
> > > > + image->arch.handover_buffer_addr = load_addr;
> > > > + image->arch.handover_buffer_size = size;
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +int kexec_get_handover_buffer(void **addr, unsigned long *size)
> > > > +{
> > > > + int ret;
> > > > + u64 start_addr, end_addr;
> > > > +
> > > > + ret = of_property_read_u64(of_chosen,
> > > > + "linux,kexec-handover-buffer-
start",
> > > > + &start_addr);
> > > > + if (ret == -EINVAL)
> > > > + return -ENOENT;
> > > > + else if (ret)
> > > > + return -EINVAL;
> > > > +
> > > > + ret = of_property_read_u64(of_chosen,
> > > > "linux,kexec-handover-buffer-end", +
> >
> > &end_addr);
> >
> > > > + if (ret == -EINVAL)
> > > > + return -ENOENT;
> > > > + else if (ret)
> > > > + return -EINVAL;
> > > > +
> > > > + *addr = __va(start_addr);
> > > > + /* -end is the first address after the buffer. */
> > > > + *size = end_addr - start_addr;
> > > > +
> > > > + return 0;
> > > > +}
> > >
> > > This depends on dtb, so if IMA want to extend it to arches like x86 in
> > > the future you will have to think about other way to pass it.
> > >
> > > How about think about a general way now?
> >
> > The only general way I can think of is by adding a kernel command line
> > parameter which the first kernel would pass to the second kernel, but
> > IMHO that is ugly, because such parameter wouldn't be useful to a user,
> > and it would also be something that, from the perspective of the user,
> > would magically appear in the kernel command line of the second
> > kernel...
> Sorry I just brought up the question, actually I have no idea either.
> Maybe we have to do this with arch specific ways..
Actually, I don't think it's possible to avoid arch-specific code because
the first kernel has to put the buffer memory region in a reserved memory
map, and that is arch-specific.
On powerpc, this is done by adding it to the device tree memory reservation
map. On x86, I believe this would be done added to the e820 map.
--
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center
