Re: [PATCH v6 4/4] powerpc: Book3S 64-bit "heavyweight" KASAN support

[Christophe Leroy]

Le 12/02/2020 Ã 11:12, Daniel Axtens a ÃcritÂ:
> Christophe Leroy <christophe.leroy@xxxxxx> writes:
>
> > Le 12/02/2020 Ã 06:47, Daniel Axtens a ÃcritÂ:
> > > diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
> > > index fbff9ff9032e..2911fdd3a6a0 100644
> > > --- a/arch/powerpc/include/asm/kasan.h
> > > +++ b/arch/powerpc/include/asm/kasan.h
> > > @@ -2,6 +2,8 @@
> > >    #ifndef __ASM_KASAN_H
> > >    #define __ASM_KASAN_H
> > >    
> > > +#include <asm/page.h>
> > > +
> > >    #ifdef CONFIG_KASAN
> > >    #define _GLOBAL_KASAN(fn)	_GLOBAL(__##fn)
> > >    #define _GLOBAL_TOC_KASAN(fn)	_GLOBAL_TOC(__##fn)
> > > @@ -14,29 +16,41 @@
> > >    
> > >    #ifndef __ASSEMBLY__
> > >    
> > > -#include <asm/page.h>
> > > -
> > >    #define KASAN_SHADOW_SCALE_SHIFT	3
> > >    
> > >    #define KASAN_SHADOW_START	(KASAN_SHADOW_OFFSET + \
> > >    				 (PAGE_OFFSET >> KASAN_SHADOW_SCALE_SHIFT))
> > >    
> > > +#ifdef CONFIG_KASAN_SHADOW_OFFSET
> > >    #define KASAN_SHADOW_OFFSET	ASM_CONST(CONFIG_KASAN_SHADOW_OFFSET)
> > > +#endif
> > >    
> > > +#ifdef CONFIG_PPC32
> > >    #define KASAN_SHADOW_END	0UL
> > >    
> > > -#define KASAN_SHADOW_SIZE	(KASAN_SHADOW_END - KASAN_SHADOW_START)
> > > +#ifdef CONFIG_KASAN
> > > +void kasan_late_init(void);
> > > +#else
> > > +static inline void kasan_late_init(void) { }
> > > +#endif
> > > +
> > > +#endif
> > > +
> > > +#ifdef CONFIG_PPC_BOOK3S_64
> > > +#define KASAN_SHADOW_END	(KASAN_SHADOW_OFFSET + \
> > > +				 (RADIX_VMEMMAP_END >> KASAN_SHADOW_SCALE_SHIFT))
> > > +
> > > +static inline void kasan_late_init(void) { }
> > > +#endif
> > >    
> > >    #ifdef CONFIG_KASAN
> > >    void kasan_early_init(void);
> > >    void kasan_mmu_init(void);
> > >    void kasan_init(void);
> > > -void kasan_late_init(void);
> > >    #else
> > >    static inline void kasan_init(void) { }
> > >    static inline void kasan_mmu_init(void) { }
> > > -static inline void kasan_late_init(void) { }
> > >    #endif
> >
> > Why modify all this kasan_late_init() stuff ?
> >
> > This function is only called from kasan init_32.c, it is never called by
> > PPC64, so you should not need to modify anything at all.
>
> I got a compile error for a missing symbol. I'll repro it and attach it.

Oops, sorry. I looked too quickly. It is defined in kasan_init_32.c and 
called from mm/mem.c

We don't have a performance issue here, since this is called only once 
during startup. Could you define an empty kasan_late_init() in 
init_book3s_64.c instead ?

Christophe