Re: [PATCH v5 03/10] powerpc: introduce kimage_vaddr to store the kernel base

[Jason Yan]

On 2019/8/7 21:03, Michael Ellerman wrote:
> Jason Yan <yanaijie@xxxxxxxxxx> writes:
> > Now the kernel base is a fixed value - KERNELBASE. To support KASLR, we
> > need a variable to store the kernel base.
> >
> > Signed-off-by: Jason Yan <yanaijie@xxxxxxxxxx>
> > Cc: Diana Craciun <diana.craciun@xxxxxxx>
> > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > Cc: Christophe Leroy <christophe.leroy@xxxxxx>
> > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> > Cc: Paul Mackerras <paulus@xxxxxxxxx>
> > Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> > Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxx>
> > Reviewed-by: Diana Craciun <diana.craciun@xxxxxxx>
> > Tested-by: Diana Craciun <diana.craciun@xxxxxxx>
> > ---
> >   arch/powerpc/include/asm/page.h | 2 ++
> >   arch/powerpc/mm/init-common.c   | 2 ++
> >   2 files changed, 4 insertions(+)
> >
> > diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
> > index 0d52f57fca04..60a68d3a54b1 100644
> > --- a/arch/powerpc/include/asm/page.h
> > +++ b/arch/powerpc/include/asm/page.h
> > @@ -315,6 +315,8 @@ void arch_free_page(struct page *page, int order);
> >   
> >   struct vm_area_struct;
> >   
> > +extern unsigned long kimage_vaddr;
> > +
> >   #include <asm-generic/memory_model.h>
> >   #endif /* __ASSEMBLY__ */
> >   #include <asm/slice.h>
> > diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
> > index 152ae0d21435..d4801ce48dc5 100644
> > --- a/arch/powerpc/mm/init-common.c
> > +++ b/arch/powerpc/mm/init-common.c
> > @@ -25,6 +25,8 @@ phys_addr_t memstart_addr = (phys_addr_t)~0ull;
> >   EXPORT_SYMBOL_GPL(memstart_addr);
> >   phys_addr_t kernstart_addr;
> >   EXPORT_SYMBOL_GPL(kernstart_addr);
> > +unsigned long kimage_vaddr = KERNELBASE;
> > +EXPORT_SYMBOL_GPL(kimage_vaddr);
>
> The names of the #defines and variables we use for these values are not
> very consistent already, but using kimage_vaddr makes it worse I think.
>
> Isn't this going to have the same value as kernstart_addr, but the
> virtual rather than physical address?

Yes, that's true.

> If so kernstart_virt_addr would seem better.

OK, I will take kernstart_virt_addr if no better name appears.

> cheers
>
> .