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SubjectRe: [RFC V1 04/31] powerpc/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT
On Mon, Jan 24, 2022 at 06:26:41PM +0530, Anshuman Khandual wrote:
> This defines and exports a platform specific custom vm_get_page_prot() via
> subscribing ARCH_HAS_VM_GET_PAGE_PROT. Subsequently all __SXXX and __PXXX
> macros can be dropped which are no longer needed. While here, this also
> localizes arch_vm_get_page_prot() as powerpc_vm_get_page_prot().
>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/include/asm/mman.h | 3 +-
> arch/powerpc/include/asm/pgtable.h | 19 ------------
> arch/powerpc/mm/mmap.c | 47 ++++++++++++++++++++++++++++++
> 4 files changed, 49 insertions(+), 21 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index b779603978e1..ddb4a3687c05 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -135,6 +135,7 @@ 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
> select ARCH_HAVE_NMI_SAFE_CMPXCHG
> select ARCH_KEEP_MEMBLOCK
> select ARCH_MIGHT_HAVE_PC_PARPORT
> diff --git a/arch/powerpc/include/asm/mman.h b/arch/powerpc/include/asm/mman.h
> index 7cb6d18f5cd6..7b10c2031e82 100644
> --- a/arch/powerpc/include/asm/mman.h
> +++ b/arch/powerpc/include/asm/mman.h
> @@ -24,7 +24,7 @@ static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
> }
> #define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)
>
> -static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags)
> +static inline pgprot_t powerpc_vm_get_page_prot(unsigned long vm_flags)
> {
> #ifdef CONFIG_PPC_MEM_KEYS
> return (vm_flags & VM_SAO) ?
> @@ -34,7 +34,6 @@ static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags)
> return (vm_flags & VM_SAO) ? __pgprot(_PAGE_SAO) : __pgprot(0);
> #endif
> }
> -#define arch_vm_get_page_prot(vm_flags) arch_vm_get_page_prot(vm_flags)
>
> static inline bool arch_validate_prot(unsigned long prot, unsigned long addr)
> {
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index d564d0ecd4cd..3cbb6de20f9d 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
> diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
> index c475cf810aa8..7f05e7903bd2 100644
> --- a/arch/powerpc/mm/mmap.c
> +++ b/arch/powerpc/mm/mmap.c
> @@ -254,3 +254,50 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
> mm->get_unmapped_area = arch_get_unmapped_area_topdown;
> }
> }
> +
> +static inline pgprot_t __vm_get_page_prot(unsigned long vm_flags)
> +{
> + switch (vm_flags & (VM_READ | VM_WRITE | VM_EXEC | VM_SHARED)) {
> + case VM_NONE:
> + return PAGE_NONE;
> + case VM_READ:
> + return PAGE_READONLY;
> + case VM_WRITE:
> + return PAGE_COPY;
> + case VM_READ | VM_WRITE:
> + return PAGE_COPY;
> + case VM_EXEC:
> + return PAGE_READONLY_X;
> + case VM_EXEC | VM_READ:
> + return PAGE_READONLY_X;
> + case VM_EXEC | VM_WRITE:
> + return PAGE_COPY_X;
> + case VM_EXEC | VM_READ | VM_WRITE:
> + return PAGE_COPY_X;
> + case VM_SHARED:
> + return PAGE_NONE;
> + case VM_SHARED | VM_READ:
> + return PAGE_READONLY;
> + case VM_SHARED | VM_WRITE:
> + return PAGE_SHARED;
> + case VM_SHARED | VM_READ | VM_WRITE:
> + return PAGE_SHARED;
> + case VM_SHARED | VM_EXEC:
> + return PAGE_READONLY_X;
> + case VM_SHARED | VM_EXEC | VM_READ:
> + return PAGE_READONLY_X;
> + case VM_SHARED | VM_EXEC | VM_WRITE:
> + return PAGE_SHARED_X;
> + case VM_SHARED | VM_EXEC | VM_READ | VM_WRITE:
> + return PAGE_SHARED_X;
> + default:
> + BUILD_BUG();
> + }
> +}
> +
> +pgprot_t vm_get_page_prot(unsigned long vm_flags)
> +{
> + return __pgprot(pgprot_val(__vm_get_page_prot(vm_flags)) |
> + pgprot_val(powerpc_vm_get_page_prot(vm_flags)));

Any reason to keep powerpc_vm_get_page_prot() rather than open code it
here?

This applies to other architectures that implement arch_vm_get_page_prot()
and/or arch_filter_pgprot() as well.

> +}
> +EXPORT_SYMBOL(vm_get_page_prot);
> --
> 2.25.1
>
>

--
Sincerely yours,
Mike.

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