From: Anshuman Khandual Subject: mm/mmap: add new config ARCH_HAS_VM_GET_PAGE_PROT Patch series "mm/mmap: Drop arch_vm_get_page_prot() and arch_filter_pgprot()", v7. protection_map[] is an array based construct that translates given vm_flags combination. This array contains page protection map, which is populated by the platform via [__S000 .. __S111] and [__P000 .. __P111] exported macros. Primary usage for protection_map[] is for vm_get_page_prot(), which is used to determine page protection value for a given vm_flags. vm_get_page_prot() implementation, could again call platform overrides arch_vm_get_page_prot() and arch_filter_pgprot(). Some platforms override protection_map[] that was originally built with __SXXX/__PXXX with different runtime values. Currently there are multiple layers of abstraction i.e __SXXX/__PXXX macros , protection_map[], arch_vm_get_page_prot() and arch_filter_pgprot() built between the platform and generic MM, finally defining vm_get_page_prot(). Hence this series proposes to drop later two abstraction levels and instead just move the responsibility of defining vm_get_page_prot() to the platform (still utilizing generic protection_map[] array) itself making it clean and simple. This first introduces ARCH_HAS_VM_GET_PAGE_PROT which enables the platforms to define custom vm_get_page_prot(). This starts converting platforms that define the overrides arch_filter_pgprot() or arch_vm_get_page_prot() which enables for those constructs to be dropped off completely. The series has been inspired from an earlier discuss with Christoph Hellwig https://lore.kernel.org/all/1632712920-8171-1-git-send-email-anshuman.khandual@arm.com/ This patch (of 7): Add a new config ARCH_HAS_VM_GET_PAGE_PROT, which when subscribed enables a given platform to define its own vm_get_page_prot() but still utilizing the generic protection_map[] array. Link: https://lkml.kernel.org/r/20220414062125.609297-1-anshuman.khandual@arm.com Link: https://lkml.kernel.org/r/20220414062125.609297-2-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual Reviewed-by: Christophe Leroy Reviewed-by: Catalin Marinas Suggested-by: Christoph Hellwig Cc: David S. Miller Cc: Ingo Molnar Cc: Khalid Aziz Cc: Michael Ellerman Cc: Paul Mackerras Cc: Thomas Gleixner Cc: Will Deacon Signed-off-by: Andrew Morton --- mm/Kconfig | 3 +++ mm/mmap.c | 2 ++ 2 files changed, 5 insertions(+) --- a/mm/Kconfig~mm-mmap-add-new-config-arch_has_vm_get_page_prot +++ a/mm/Kconfig @@ -765,6 +765,9 @@ config ARCH_HAS_CURRENT_STACK_POINTER config ARCH_HAS_FILTER_PGPROT bool +config ARCH_HAS_VM_GET_PAGE_PROT + bool + config ARCH_HAS_PTE_DEVMAP bool --- a/mm/mmap.c~mm-mmap-add-new-config-arch_has_vm_get_page_prot +++ a/mm/mmap.c @@ -120,6 +120,7 @@ pgprot_t protection_map[16] __ro_after_i [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = __S111 }; +#ifndef CONFIG_ARCH_HAS_VM_GET_PAGE_PROT #ifndef CONFIG_ARCH_HAS_FILTER_PGPROT static inline pgprot_t arch_filter_pgprot(pgprot_t prot) { @@ -136,6 +137,7 @@ pgprot_t vm_get_page_prot(unsigned long return arch_filter_pgprot(ret); } EXPORT_SYMBOL(vm_get_page_prot); +#endif /* CONFIG_ARCH_HAS_VM_GET_PAGE_PROT */ static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) { _