On Fri, Sep 24, 2021 at 11:30 AM Anshuman Khandual
<anshuman.khandual@xxxxxxx> wrote:
>
> Hello Guo,
>
> On 9/22/21 1:48 AM, guoren@xxxxxxxxxx wrote:
> > From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> >
> > The __Pxxx/__Sxxx macros are only for init protection_map[]. All
>
> s/init protection_map[]/protection_map[] int/
^^^
Okay, protection_map[] init
>
> Or rephrase with something similar.
>
> > usage of them in linux should come from protection_map array.
>
> Agreed.
>
> >
> > Becasue a lot of architectures would re-initilize protection_map[]
>
> s/Becasue/Because/
>
> ./scripts/checkpatch.pl ./0001-mm-debug_vm_pgtable-Don-t-use-__P000-directly.patch
> WARNING: 'Becasue' may be misspelled - perhaps 'Because'?
> #9:
> Becasue a lot of architectures would re-initilize protection_map[]
> ^^^^^^^
>
> total: 0 errors, 1 warnings, 15 lines checked
I would use checkpatch.pl next time, thx.
>
> > array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.
> >
> > Using __P000 maybe won't cause bug because hw would deny access
>
> Not very clear. Could you please rephrase.
Using __P000 directly wouldn't equal protection_map[0] in many arches,
but the reason why it didn't cause the problem is the hardware ignores
the other bits when prot-attribute is denied.
>
> > with PROT_NONE permission, but it's not rigorous.
>
> Agreed.
>
> >
> > Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > ---
> > mm/debug_vm_pgtable.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> > index 1403639302e4..a6ebbf6e53dd 100644
> > --- a/mm/debug_vm_pgtable.c
> > +++ b/mm/debug_vm_pgtable.c
> > @@ -1104,13 +1104,13 @@ 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
> > + * __P000 (protection_map[0]) will help create page table entries with
>
> Please just replace __P000 and __S000 with protection_map[0] and
> protection_map[8] respectively. Also reformat this comment section
> if required.
>
> > * 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;
> >
>
> With the above changes in place.
>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
