um/mm: enable ARCH_HAS_VM_GET_PAGE_PROT

This enables ARCH_HAS_VM_GET_PAGE_PROT on the platform and exports
standard vm_get_page_prot() implementation via DECLARE_VM_GET_PAGE_PROT,
which looks up a private and static protection_map[] array. Subsequently
all __SXXX and __PXXX macros can be dropped which are no longer needed.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Anshuman Khandual <[e-mail]>
Cc: Jeff Dike <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Brian Cain <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Christophe Leroy <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Chris Zankel <[e-mail]>
Cc: "David S. Miller" <[e-mail]>
Cc: Dinh Nguyen <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Cc: Guo Ren <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Huacai Chen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: "James E.J. Bottomley" <[e-mail]>
Cc: Jonas Bonn <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Michal Simek <[e-mail]>
Cc: Nicholas Piggin <[e-mail]>
Cc: Palmer Dabbelt <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Paul Walmsley <[e-mail]>
Cc: Richard Henderson <[e-mail]>
Cc: Rich Felker <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Sam Ravnborg <[e-mail]>
Cc: Stafford Horne <[e-mail]>
Cc: Thomas Bogendoerfer <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Cc: Vineet Gupta <[e-mail]>
Cc: WANG Xuerui <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Yoshinori Sato <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

arch/um/Kconfig

···
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_STRNCPY_FROM_USER
 	select ARCH_HAS_STRNLEN_USER
+	select ARCH_HAS_VM_GET_PAGE_PROT
 	select ARCH_NO_PREEMPT
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_SECCOMP_FILTER

arch/um/include/asm/pgtable.h

···
  * Also, write permissions imply read permissions. This is the closest we can
  * get..
  */
-#define __P000	PAGE_NONE
-#define __P001	PAGE_READONLY
-#define __P010	PAGE_COPY
-#define __P011	PAGE_COPY
-#define __P100	PAGE_READONLY
-#define __P101	PAGE_READONLY
-#define __P110	PAGE_COPY
-#define __P111	PAGE_COPY
-
-#define __S000	PAGE_NONE
-#define __S001	PAGE_READONLY
-#define __S010	PAGE_SHARED
-#define __S011	PAGE_SHARED
-#define __S100	PAGE_READONLY
-#define __S101	PAGE_READONLY
-#define __S110	PAGE_SHARED
-#define __S111	PAGE_SHARED
 
 /*
  * ZERO_PAGE is a global shared page that is always zero: used

arch/um/kernel/mem.c

···
 {
 	return kmalloc(size, flags);
 }
+
+static const pgprot_t protection_map[16] = {
+	[VM_NONE]					= PAGE_NONE,
+	[VM_READ]					= PAGE_READONLY,
+	[VM_WRITE]					= PAGE_COPY,
+	[VM_WRITE | VM_READ]				= PAGE_COPY,
+	[VM_EXEC]					= PAGE_READONLY,
+	[VM_EXEC | VM_READ]				= PAGE_READONLY,
+	[VM_EXEC | VM_WRITE]				= PAGE_COPY,
+	[VM_EXEC | VM_WRITE | VM_READ]			= PAGE_COPY,
+	[VM_SHARED]					= PAGE_NONE,
+	[VM_SHARED | VM_READ]				= PAGE_READONLY,
+	[VM_SHARED | VM_WRITE]				= PAGE_SHARED,
+	[VM_SHARED | VM_WRITE | VM_READ]		= PAGE_SHARED,
+	[VM_SHARED | VM_EXEC]				= PAGE_READONLY,
+	[VM_SHARED | VM_EXEC | VM_READ]			= PAGE_READONLY,
+	[VM_SHARED | VM_EXEC | VM_WRITE]		= PAGE_SHARED,
+	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= PAGE_SHARED
+};
+DECLARE_VM_GET_PAGE_PROT

arch/x86/um/mem_32.c

···
 	gate_vma.vm_start = FIXADDR_USER_START;
 	gate_vma.vm_end = FIXADDR_USER_END;
 	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
-	gate_vma.vm_page_prot = __P101;
+	gate_vma.vm_page_prot = PAGE_READONLY;
 
 	return 0;
 }