powerpc/mm: enable ARCH_HAS_VM_GET_PAGE_PROT

This defines and exports a platform specific custom vm_get_page_prot() via
subscribing ARCH_HAS_VM_GET_PAGE_PROT.  While here, this also localizes
arch_vm_get_page_prot() as __vm_get_page_prot() and moves it near
vm_get_page_prot().

Link: https://lkml.kernel.org/r/20220414062125.609297-3-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 052e6590f84f..8b474ab32f67 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -7,6 +7,7 @@
 #include <linux/mm_types.h>
 #include <linux/memblock.h>
 #include <linux/memremap.h>
+#include <linux/pkeys.h>
 #include <linux/debugfs.h>
 #include <misc/cxl-base.h>
 
@@ -549,3 +550,19 @@ unsigned long memremap_compat_align(void)
 }
 EXPORT_SYMBOL_GPL(memremap_compat_align);
 #endif
+
+pgprot_t vm_get_page_prot(unsigned long vm_flags)
+{
+	unsigned long prot = pgprot_val(protection_map[vm_flags &
+					(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);
+
+	if (vm_flags & VM_SAO)
+		prot |= _PAGE_SAO;
+
+#ifdef CONFIG_PPC_MEM_KEYS
+	prot |= vmflag_to_pte_pkey_bits(vm_flags);
+#endif
+
+	return __pgprot(prot);
+}
+EXPORT_SYMBOL(vm_get_page_prot);