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SubjectRe: [PATCH v3 03/10] kexec_file: factor out arch_kexec_kernel_*() from x86, powerpc
HI AKASHI,
On 09/22/17 at 04:58pm, AKASHI Takahiro wrote:
> Hi Dave,
>
[snip]

> > > /*
> > > * Apply purgatory relocations.
> > > *
> > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> > > index dd056fab9e35..4a2b24d94e04 100644
> > > --- a/include/linux/kexec.h
> > > +++ b/include/linux/kexec.h
> > > @@ -134,6 +134,26 @@ struct kexec_file_ops {
> > > #endif
> > > };
> > >
> > > +int kexec_kernel_image_probe(struct kimage *image, void *buf,
> > > + unsigned long buf_len);
> > > +void *kexec_kernel_image_load(struct kimage *image);
> > > +int kexec_kernel_post_load_cleanup(struct kimage *image);
> > > +int kexec_kernel_verify_sig(struct kimage *image, void *buf,
> > > + unsigned long buf_len);
> > > +
> > > +#ifndef arch_kexec_kernel_image_probe
> > > +#define arch_kexec_kernel_image_probe kexec_kernel_image_probe
> > > +#endif
> > > +#ifndef arch_kexec_kernel_image_load
> > > +#define arch_kexec_kernel_image_load kexec_kernel_image_load
> > > +#endif
> > > +#ifndef arch_kimage_file_post_load_cleanup
> > > +#define arch_kimage_file_post_load_cleanup kexec_kernel_post_load_cleanup
> > > +#endif
> > > +#ifndef arch_kexec_kernel_verify_sig
> > > +#define arch_kexec_kernel_verify_sig kexec_kernel_verify_sig
> > > +#endif
> > > +
> > > /**
> > > * struct kexec_buf - parameters for finding a place for a buffer in memory
> > > * @image: kexec image in which memory to search.
> > > @@ -276,12 +296,6 @@ int crash_shrink_memory(unsigned long new_size);
> > > size_t crash_get_memory_size(void);
> > > void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
> > >
> > > -int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> > > - unsigned long buf_len);
> > > -void * __weak arch_kexec_kernel_image_load(struct kimage *image);
> > > -int __weak arch_kimage_file_post_load_cleanup(struct kimage *image);
> > > -int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> > > - unsigned long buf_len);
> >
> > I thought we can keep using the __weak function in common code and drop
> > the arch functions, no need the #ifndef arch_kexec_kernel_image_probe
> > and the function renaming stuff. But I did not notice the powerpc
> > _probe function checks KEXEC_ON_CRASH, that should be checked earlier
> > and we can fail out early if not supported, but I have no idea
> > how to do it gracefully for now.
> >
> > Also for x86 _load function it cleanups image->arch.elf_headers, it can
> > not be dropped simply.
>
> Yeah, arm64 post_load_cleanup function also has some extra stuff.
> See my patch #7/8.

But the x86 cleanup was dropped silently, can you add it in x86
post_load_cleanup as well?

>
> > Consider the above two issues, maybe you can keep the powerpc
> > version of _probe() and x86 version of _load(), and still copy the common code
> > to kexec_file.c weak functions.
>
> It was exactly what I made before submitting v3, but I changed
> my mind a bit. My intension is to prevent the code being duplicated
> even though it has only a few lines of code.
>
> I agree that '#ifndef arch_kexec_kernel_image_probe' in kexec.h would be
> quite ugly, but similar usages can be spotted in the kernel source.
>
> That said if you don't like it at all, I defer to you.

I understand your concern, maybe still use a weak function for
arch_kexec_kernel_image_*, and they call the kexec_kernel_image_* in
kexec_file.c common code.

Like in general code:

int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
unsigned long buf_len)
{
return kexec_kernel_image_probe(image, buf, buf_len);
}

In architechture code it can add other code and call
kexec_kernel_image_*

It looks a bit better than the #ifdef way.

[snip]

>
> Thanks,
> -Takahiro AKASHI
>

Thanks
Dave

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