Re: [PATCH v8 03/13] kexec_file,x86,powerpc: factor out kexec_file_ops functions

From: AKASHI Takahiro
Date: Wed Feb 28 2018 - 22:18:15 EST


On Wed, Feb 28, 2018 at 08:38:00PM +0800, Dave Young wrote:
> On 02/26/18 at 07:01pm, AKASHI Takahiro wrote:
> > On Fri, Feb 23, 2018 at 05:24:59PM +0800, Dave Young wrote:
> > > Hi AKASHI,
> > >
> > > On 02/22/18 at 08:17pm, AKASHI Takahiro wrote:
> > > > As arch_kexec_kernel_*_{probe,load}(), arch_kimage_file_post_load_cleanup()
> > > > and arch_kexec_kernel_verify_sg can be parameterized with a kexec_file_ops
> > > > array and now duplicated among some architectures, let's factor them out.
> > > >
> > > > Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
> > > > Cc: Dave Young <dyoung@xxxxxxxxxx>
> > > > Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
> > > > Cc: Baoquan He <bhe@xxxxxxxxxx>
> > > > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > > > Cc: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
> > > > ---
> > > > arch/powerpc/include/asm/kexec.h | 2 +-
> > > > arch/powerpc/kernel/kexec_elf_64.c | 2 +-
> > > > arch/powerpc/kernel/machine_kexec_file_64.c | 39 ++------------------
> > > > arch/x86/include/asm/kexec-bzimage64.h | 2 +-
> > > > arch/x86/kernel/kexec-bzimage64.c | 2 +-
> > > > arch/x86/kernel/machine_kexec_64.c | 45 +----------------------
> > > > include/linux/kexec.h | 15 ++++----
> > > > kernel/kexec_file.c | 57 +++++++++++++++++++++++++++--
> > > > 8 files changed, 70 insertions(+), 94 deletions(-)
> > > >
> > >
> > > [snip]
> > >
> > > > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> > > > index 990adae52151..a6d14a768b3e 100644
> > > > --- a/kernel/kexec_file.c
> > > > +++ b/kernel/kexec_file.c
> > > > @@ -26,34 +26,83 @@
> > > > #include <linux/vmalloc.h>
> > > > #include "kexec_internal.h"
> > > >
> > > > +const __weak struct kexec_file_ops * const kexec_file_loaders[] = {NULL};
> > > > +
> > > > #ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
> > > > static int kexec_calculate_store_digests(struct kimage *image);
> > > > #else
> > > > static int kexec_calculate_store_digests(struct kimage *image) { return 0; };
> > > > #endif
> > > >
> > > > +int _kexec_kernel_image_probe(struct kimage *image, void *buf,
> > > > + unsigned long buf_len)
> > > > +{
> > > > + const struct kexec_file_ops * const *fops;
> > > > + int ret = -ENOEXEC;
> > > > +
> > > > + for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
> > > > + ret = (*fops)->probe(buf, buf_len);
> > > > + if (!ret) {
> > > > + image->fops = *fops;
> > > > + return ret;
> > > > + }
> > > > + }
> > > > +
> > > > + return ret;
> > > > +}
> > > > +
> > > > /* Architectures can provide this probe function */
> > > > int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> > > > unsigned long buf_len)
> > > > {
> > > > - return -ENOEXEC;
> > > > + return _kexec_kernel_image_probe(image, buf, buf_len);
> > >
> > >
> > > I vaguely remember previously I suggest split the _kexec_kernel_image_probe
> > > because arch code can call them, and common code also use it like above.
> > > But in your new series I do not find where else calls this function
> > > except the common code arch_kexec_kernel_image_probe. If nobody use
> > > them then it is not worth to split them out, it is better to just embed
> > > them in the __weak functions.
> >
> > Powerpc's arch_kexec_kernel_image_probe() uses
> > _kexec_kekrnel_image_probe() as it needs an extra check to rule out
> > crash dump for now.
>
> Oops, I missed that, but what about other similar functions? Such as:
> _kexec_kernel_image_load
> _kimage_file_post_load_cleanup
> _kexec_kernel_verify_sig

Current no users.
Given those functions are so simple, we could go either way.

-Takahiro AKASHI


> >
> > Thanks,
> > -Takahiro AKASHI
> >
> >
> > > Ditto for other similar functions.
> > >
> > > [snip]
> > >
> > > Thanks
> > > Dave
>
> Thanks
> Dave