Re: [PATCH v5 2/2] kasan: call kasan_init_generic in kasan_init

[Sabyrzhan Tasbolatov <snovitoll@gmail.com>]

On Fri, Aug 8, 2025 at 10:07 AM Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
>
>
>
> Le 07/08/2025 à 21:40, Sabyrzhan Tasbolatov a écrit :
> > Call kasan_init_generic() which handles Generic KASAN initialization.
> > For architectures that do not select ARCH_DEFER_KASAN,
> > this will be a no-op for the runtime flag but will
> > print the initialization banner.
> >
> > For SW_TAGS and HW_TAGS modes, their respective init functions will
> > handle the flag enabling, if they are enabled/implemented.
> >
> > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217049
> > Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
> > Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com> # riscv
> > Acked-by: Alexander Gordeev <agordeev@linux.ibm.com> # s390
> > ---
> > Changes in v5:
> > - Unified arch patches into a single one, where we just call
> >       kasan_init_generic()
> > - Added Tested-by tag for riscv (tested the same change in v4)
> > - Added Acked-by tag for s390 (tested the same change in v4)
> > ---
> >   arch/arm/mm/kasan_init.c    | 2 +-
> >   arch/arm64/mm/kasan_init.c  | 4 +---
> >   arch/riscv/mm/kasan_init.c  | 1 +
> >   arch/s390/kernel/early.c    | 3 ++-
> >   arch/x86/mm/kasan_init_64.c | 2 +-
> >   arch/xtensa/mm/kasan_init.c | 2 +-
> >   6 files changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/arm/mm/kasan_init.c b/arch/arm/mm/kasan_init.c
> > index 111d4f70313..c6625e808bf 100644
> > --- a/arch/arm/mm/kasan_init.c
> > +++ b/arch/arm/mm/kasan_init.c
> > @@ -300,6 +300,6 @@ void __init kasan_init(void)
> >       local_flush_tlb_all();
> >
> >       memset(kasan_early_shadow_page, 0, PAGE_SIZE);
> > -     pr_info("Kernel address sanitizer initialized\n");
> >       init_task.kasan_depth = 0;
> > +     kasan_init_generic();
> >   }
> > diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
> > index d541ce45dae..abeb81bf6eb 100644
> > --- a/arch/arm64/mm/kasan_init.c
> > +++ b/arch/arm64/mm/kasan_init.c
> > @@ -399,14 +399,12 @@ void __init kasan_init(void)
> >   {
> >       kasan_init_shadow();
> >       kasan_init_depth();
> > -#if defined(CONFIG_KASAN_GENERIC)
> > +     kasan_init_generic();
> >       /*
> >        * Generic KASAN is now fully initialized.
> >        * Software and Hardware Tag-Based modes still require
> >        * kasan_init_sw_tags() and kasan_init_hw_tags() correspondingly.
> >        */
> > -     pr_info("KernelAddressSanitizer initialized (generic)\n");
> > -#endif
> >   }
> >
> >   #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> > diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
> > index 41c635d6aca..ba2709b1eec 100644
> > --- a/arch/riscv/mm/kasan_init.c
> > +++ b/arch/riscv/mm/kasan_init.c
> > @@ -530,6 +530,7 @@ void __init kasan_init(void)
> >
> >       memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
> >       init_task.kasan_depth = 0;
> > +     kasan_init_generic();
>
> I understood KASAN is really ready to function only once the csr_write()
> and local_flush_tlb_all() below are done. Shouldn't kasan_init_generic()
> be called after it ?

I will try to test this in v6:

        csr_write(CSR_SATP, PFN_DOWN(__pa(swapper_pg_dir)) | satp_mode);
        local_flush_tlb_all();
        kasan_init_generic();

Alexandre Ghiti said [1] it was not a problem, but I will check.

[1] https://lore.kernel.org/all/20c1e656-512e-4424-9d4e-176af18bb7d6@ghiti.fr/

>
> >
> >       csr_write(CSR_SATP, PFN_DOWN(__pa(swapper_pg_dir)) | satp_mode);
> >       local_flush_tlb_all();
> > diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
> > index 9adfbdd377d..544e5403dd9 100644
> > --- a/arch/s390/kernel/early.c
> > +++ b/arch/s390/kernel/early.c
> > @@ -21,6 +21,7 @@
> >   #include <linux/kernel.h>
> >   #include <asm/asm-extable.h>
> >   #include <linux/memblock.h>
> > +#include <linux/kasan.h>
> >   #include <asm/access-regs.h>
> >   #include <asm/asm-offsets.h>
> >   #include <asm/machine.h>
> > @@ -65,7 +66,7 @@ static void __init kasan_early_init(void)
> >   {
> >   #ifdef CONFIG_KASAN
> >       init_task.kasan_depth = 0;
> > -     pr_info("KernelAddressSanitizer initialized\n");
> > +     kasan_init_generic();
> >   #endif
> >   }
> >
> > diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
> > index 0539efd0d21..998b6010d6d 100644
> > --- a/arch/x86/mm/kasan_init_64.c
> > +++ b/arch/x86/mm/kasan_init_64.c
> > @@ -451,5 +451,5 @@ void __init kasan_init(void)
> >       __flush_tlb_all();
> >
> >       init_task.kasan_depth = 0;
> > -     pr_info("KernelAddressSanitizer initialized\n");
> > +     kasan_init_generic();
> >   }
> > diff --git a/arch/xtensa/mm/kasan_init.c b/arch/xtensa/mm/kasan_init.c
> > index f39c4d83173..0524b9ed5e6 100644
> > --- a/arch/xtensa/mm/kasan_init.c
> > +++ b/arch/xtensa/mm/kasan_init.c
> > @@ -94,5 +94,5 @@ void __init kasan_init(void)
> >
> >       /* At this point kasan is fully initialized. Enable error messages. */
> >       current->kasan_depth = 0;
> > -     pr_info("KernelAddressSanitizer initialized\n");
> > +     kasan_init_generic();
> >   }
>