linux-kernel - Re: [PATCH v3 07/12] kasan/loongarch: select ARCH_DEFER_KASAN and call kasan_init

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Message-ID: <CACzwLxgjKz-bc1w4SvGu-EeoMvK9Dh=2WpB-A_zC-u7H38QqVg@mail.gmail.com>
Date: Tue, 22 Jul 2025 19:09:07 +0500
From: Sabyrzhan Tasbolatov <snovitoll@...il.com>
To: Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc: hca@...ux.ibm.com, christophe.leroy@...roup.eu, andreyknvl@...il.com, 
	agordeev@...ux.ibm.com, akpm@...ux-foundation.org, glider@...gle.com, 
	dvyukov@...gle.com, kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org, 
	loongarch@...ts.linux.dev, linuxppc-dev@...ts.ozlabs.org, 
	linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org, 
	linux-um@...ts.infradead.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 07/12] kasan/loongarch: select ARCH_DEFER_KASAN and
 call kasan_init_generic

On Tue, Jul 22, 2025 at 4:00 AM Andrey Ryabinin <ryabinin.a.a@...il.com> wrote:
>
>
>
> On 7/17/25 4:27 PM, Sabyrzhan Tasbolatov wrote:
>
> > diff --git a/arch/loongarch/include/asm/kasan.h b/arch/loongarch/include/asm/kasan.h
> > index 62f139a9c87..0e50e5b5e05 100644
> > --- a/arch/loongarch/include/asm/kasan.h
> > +++ b/arch/loongarch/include/asm/kasan.h
> > @@ -66,7 +66,6 @@
> >  #define XKPRANGE_WC_SHADOW_OFFSET    (KASAN_SHADOW_START + XKPRANGE_WC_KASAN_OFFSET)
> >  #define XKVRANGE_VC_SHADOW_OFFSET    (KASAN_SHADOW_START + XKVRANGE_VC_KASAN_OFFSET)
> >
> > -extern bool kasan_early_stage;
> >  extern unsigned char kasan_early_shadow_page[PAGE_SIZE];
> >
> >  #define kasan_mem_to_shadow kasan_mem_to_shadow
> > @@ -75,12 +74,6 @@ void *kasan_mem_to_shadow(const void *addr);
> >  #define kasan_shadow_to_mem kasan_shadow_to_mem
> >  const void *kasan_shadow_to_mem(const void *shadow_addr);
> >
> > -#define kasan_arch_is_ready kasan_arch_is_ready
> > -static __always_inline bool kasan_arch_is_ready(void)
> > -{
> > -     return !kasan_early_stage;
> > -}
> > -
> >  #define addr_has_metadata addr_has_metadata
> >  static __always_inline bool addr_has_metadata(const void *addr)
> >  {
> > diff --git a/arch/loongarch/mm/kasan_init.c b/arch/loongarch/mm/kasan_init.c
> > index d2681272d8f..cf8315f9119 100644
> > --- a/arch/loongarch/mm/kasan_init.c
> > +++ b/arch/loongarch/mm/kasan_init.c
> > @@ -40,11 +40,9 @@ static pgd_t kasan_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
> >  #define __pte_none(early, pte) (early ? pte_none(pte) : \
> >  ((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page)))
> >
> > -bool kasan_early_stage = true;
> > -
> >  void *kasan_mem_to_shadow(const void *addr)
> >  {
> > -     if (!kasan_arch_is_ready()) {
> > +     if (!kasan_enabled()) {
>
> This doesn't make sense, !kasan_enabled() is compile-time check which is always false here.

I should've used `!kasan_shadow_initialized()` check here which provides
the needed runtime behavior that kasan_early_stage used to provide.
Will do in v4. Thanks!

>
> >               return (void *)(kasan_early_shadow_page);
> >       } else {
> >               unsigned long maddr = (unsigned long)addr;