linux-kernel - Re: [PATCH V2] mm: debug_vm_pgtable: Don't use _

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Date:   Mon, 27 Sep 2021 14:21:41 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux-MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH V2] mm: debug_vm_pgtable: Don't use __P000 directly

Got it, thanks!

On Mon, Sep 27, 2021 at 10:16 AM Anshuman Khandual
<anshuman.khandual@....com> wrote:
>
>
>
> On 9/24/21 11:38 AM, guoren@...nel.org wrote:
> > From: Guo Ren <guoren@...ux.alibaba.com>
> >
> > The __Pxxx/__Sxxx macros are only for protection_map[] init. All
> > usage of them in linux should come from protection_map array.
> >
> > Because a lot of architectures would re-initilize protection_map[]
> > array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.
> >
> > Using __P000 is not rigorous.
> >
> > Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> > Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>
>
>
> >
> > ---
> >
> > Changes since V2:
> >  - s/init protection_map[]/protection_map[] init/
> >  - s/Becasue/Because/
> >  - Remove unclear part
> >  - Replace __P000 and __S000 with protection_map[0] and
> >    protection_map[8]
> > ---
> >  mm/debug_vm_pgtable.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> > index 1403639302e4..228e3954b90c 100644
> > --- a/mm/debug_vm_pgtable.c
> > +++ b/mm/debug_vm_pgtable.c
> > @@ -1104,13 +1104,14 @@ static int __init init_args(struct pgtable_debug_args *args)
> >       /*
> >        * Initialize the debugging data.
> >        *
> > -      * __P000 (or even __S000) will help create page table entries with
> > -      * PROT_NONE permission as required for pxx_protnone_tests().
> > +      * protection_map[0] (or even protection_map[8]) will help create
> > +      * page table entries with PROT_NONE permission as required for
> > +      * pxx_protnone_tests().
> >        */
> >       memset(args, 0, sizeof(*args));
> >       args->vaddr              = get_random_vaddr();
> >       args->page_prot          = vm_get_page_prot(VMFLAGS);
> > -     args->page_prot_none     = __P000;
> > +     args->page_prot_none     = protection_map[0];
> >       args->is_contiguous_page = false;
> >       args->pud_pfn            = ULONG_MAX;
> >       args->pmd_pfn            = ULONG_MAX;
> >



-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/