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    SubjectRe: [RFC V1 04/31] powerpc/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT
    On Fri, Feb 04, 2022 at 08:27:37AM +0530, Anshuman Khandual wrote:
    >
    > On 2/3/22 11:45 PM, Mike Rapoport wrote:
    > > 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.
    >
    > Just to minimize the code churn ! But I will be happy to open code them
    > here (and in other platforms) if that will be preferred.

    I think this will be clearer because all the processing will be at one place.
    Besides, this way include/asm/pgtable.h becomes shorter and less crowded.

    --
    Sincerely yours,
    Mike.

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