patches/old/mm-mmap-drop-protection_map.patch

From: Anshuman Khandual <anshuman.khandual@arm.com>
Subject: mm/mmap: drop protection_map[]

There are no other users for protection_map[].  Hence just drop this array
construct and instead define __vm_get_page_prot() which will provide page
protection map based on vm_flags combination switch.

Link: https://lkml.kernel.org/r/1645425519-9034-12-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h |    6 ----
 mm/mmap.c          |   61 ++++++++++++++++++++++++++++---------------
 2 files changed, 41 insertions(+), 26 deletions(-)

--- a/include/linux/mm.h~mm-mmap-drop-protection_map
+++ a/include/linux/mm.h
@@ -419,12 +419,6 @@ extern unsigned int kobjsize(const void
 #define VM_FLAGS_CLEAR	(ARCH_VM_PKEY_FLAGS | VM_ARCH_CLEAR)
 
 /*
- * mapping from the currently active vm_flags protection bits (the
- * low four bits) to a page protection mask..
- */
-extern pgprot_t protection_map[16];
-
-/*
  * The default fault flags that should be used by most of the
  * arch-specific page fault handlers.
  */
--- a/mm/mmap.c~mm-mmap-drop-protection_map
+++ a/mm/mmap.c
@@ -102,24 +102,6 @@ static void unmap_region(struct mm_struc
  *								w: (no) no
  *								x: (yes) yes
  */
-pgprot_t protection_map[16] __ro_after_init = {
-	[VM_NONE]					= __P000,
-	[VM_READ]					= __P001,
-	[VM_WRITE]					= __P010,
-	[VM_WRITE | VM_READ]				= __P011,
-	[VM_EXEC]					= __P100,
-	[VM_EXEC | VM_READ]				= __P101,
-	[VM_EXEC | VM_WRITE]				= __P110,
-	[VM_EXEC | VM_WRITE | VM_READ]			= __P111,
-	[VM_SHARED]					= __S000,
-	[VM_SHARED | VM_READ]				= __S001,
-	[VM_SHARED | VM_WRITE]				= __S010,
-	[VM_SHARED | VM_WRITE | VM_READ]		= __S011,
-	[VM_SHARED | VM_EXEC]				= __S100,
-	[VM_SHARED | VM_EXEC | VM_READ]			= __S101,
-	[VM_SHARED | VM_EXEC | VM_WRITE]		= __S110,
-	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= __S111
-};
 
 #ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
 static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
@@ -128,10 +110,49 @@ static inline pgprot_t arch_filter_pgpro
 }
 #endif
 
+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 __P000;
+	case VM_READ:
+		return __P001;
+	case VM_WRITE:
+		return __P010;
+	case VM_READ | VM_WRITE:
+		return __P011;
+	case VM_EXEC:
+		return __P100;
+	case VM_EXEC | VM_READ:
+		return __P101;
+	case VM_EXEC | VM_WRITE:
+		return __P110;
+	case VM_EXEC | VM_READ | VM_WRITE:
+		return __P111;
+	case VM_SHARED:
+		return __S000;
+	case VM_SHARED | VM_READ:
+		return __S001;
+	case VM_SHARED | VM_WRITE:
+		return __S010;
+	case VM_SHARED | VM_READ | VM_WRITE:
+		return __S011;
+	case VM_SHARED | VM_EXEC:
+		return __S100;
+	case VM_SHARED | VM_EXEC | VM_READ:
+		return __S101;
+	case VM_SHARED | VM_EXEC | VM_WRITE:
+		return __S110;
+	case VM_SHARED | VM_EXEC | VM_READ | VM_WRITE:
+		return __S111;
+	default:
+		BUILD_BUG();
+	}
+}
+
 pgprot_t vm_get_page_prot(unsigned long vm_flags)
 {
-	pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
-				(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
+	pgprot_t ret = __pgprot(pgprot_val(__vm_get_page_prot(vm_flags)) |
 			pgprot_val(arch_vm_get_page_prot(vm_flags)));
 
 	return arch_filter_pgprot(ret);
_