Re: [PATCH V4 03/26] powerpc/mm: Move protection_map[] inside the platform

Anshuman Khandual
2022-06-24T05:23:18Z

On 6/24/22 10:48, Christophe Leroy wrote:
>
>
> Le 24/06/2022 à 06:43, Anshuman Khandual a écrit :
>> This moves protection_map[] inside the platform and while here, also enable
>> ARCH_HAS_VM_GET_PAGE_PROT on 32 bit platforms via DECLARE_VM_GET_PAGE_PROT.
>
> Not only 32 bit platforms, also nohash 64 (aka book3e/64)

Sure, will update the commit message.

>
>>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Nicholas Piggin <npiggin@gmail.com>
>> Cc: linuxppc-dev@lists.ozlabs.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> arch/powerpc/Kconfig | 2 +-
>> arch/powerpc/include/asm/pgtable.h | 20 +-------------------
>> arch/powerpc/mm/pgtable.c | 24 ++++++++++++++++++++++++
>> 3 files changed, 26 insertions(+), 20 deletions(-)
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index c2ce2e60c8f0..1035d172c7dd 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -140,7 +140,7 @@ config PPC
>> select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
>> select ARCH_HAS_UACCESS_FLUSHCACHE
>> select ARCH_HAS_UBSAN_SANITIZE_ALL
>> - select ARCH_HAS_VM_GET_PAGE_PROT if PPC_BOOK3S_64
>> + select ARCH_HAS_VM_GET_PAGE_PROT
>> select ARCH_HAVE_NMI_SAFE_CMPXCHG
>> select ARCH_KEEP_MEMBLOCK
>> select ARCH_MIGHT_HAVE_PC_PARPORT
>> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
>> index d564d0ecd4cd..bf98db844579 100644
>> --- a/arch/powerpc/include/asm/pgtable.h
>> +++ b/arch/powerpc/include/asm/pgtable.h
>> @@ -20,25 +20,6 @@ struct mm_struct;
>> #include <asm/nohash/pgtable.h>
>> #endif /* !CONFIG_PPC_BOOK3S */
>>
>> -/* Note due to the way vm flags are laid out, the bits are XWR */
>> -#define __P000 PAGE_NONE
>> -#define __P001 PAGE_READONLY
>> -#define __P010 PAGE_COPY
>> -#define __P011 PAGE_COPY
>> -#define __P100 PAGE_READONLY_X
>> -#define __P101 PAGE_READONLY_X
>> -#define __P110 PAGE_COPY_X
>> -#define __P111 PAGE_COPY_X
>> -
>> -#define __S000 PAGE_NONE
>> -#define __S001 PAGE_READONLY
>> -#define __S010 PAGE_SHARED
>> -#define __S011 PAGE_SHARED
>> -#define __S100 PAGE_READONLY_X
>> -#define __S101 PAGE_READONLY_X
>> -#define __S110 PAGE_SHARED_X
>> -#define __S111 PAGE_SHARED_X
>> -
>> #ifndef __ASSEMBLY__
>>
>> #ifndef MAX_PTRS_PER_PGD
>> @@ -79,6 +60,7 @@ extern void paging_init(void);
>> void poking_init(void);
>>
>> extern unsigned long ioremap_bot;
>> +extern pgprot_t protection_map[16] __ro_after_init;
>>
>> /*
>> * kern_addr_valid is intended to indicate whether an address is a valid
>> diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
>> index e6166b71d36d..618f30d35b17 100644
>> --- a/arch/powerpc/mm/pgtable.c
>> +++ b/arch/powerpc/mm/pgtable.c
>> @@ -472,3 +472,27 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
>> return ret_pte;
>> }
>> EXPORT_SYMBOL_GPL(__find_linux_pte);
>> +
>> +/* Note due to the way vm flags are laid out, the bits are XWR */
>> +pgprot_t protection_map[16] __ro_after_init = {
>
> I can't see any place where protection_map[] gets modified. This could
> be made const.

Sure, will make it a const as in case for many other platforms as well.

>
>> + [VM_NONE] = PAGE_NONE,
>> + [VM_READ] = PAGE_READONLY,
>> + [VM_WRITE] = PAGE_COPY,
>> + [VM_WRITE | VM_READ] = PAGE_COPY,
>> + [VM_EXEC] = PAGE_READONLY_X,
>> + [VM_EXEC | VM_READ] = PAGE_READONLY_X,
>> + [VM_EXEC | VM_WRITE] = PAGE_COPY_X,
>> + [VM_EXEC | VM_WRITE | VM_READ] = PAGE_COPY_X,
>> + [VM_SHARED] = PAGE_NONE,
>> + [VM_SHARED | VM_READ] = PAGE_READONLY,
>> + [VM_SHARED | VM_WRITE] = PAGE_SHARED,
>> + [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
>> + [VM_SHARED | VM_EXEC] = PAGE_READONLY_X,
>> + [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_X,
>> + [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_X,
>> + [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_X
>> +};
>> +
>> +#ifndef CONFIG_PPC_BOOK3S_64
>> +DECLARE_VM_GET_PAGE_PROT
>> +#endif