[PATCH v6 12/26] mm: Introduce arch_calc_vm_flag_bits()

[Catalin Marinas]

From: Kevin Brodsky <Kevin.Brodsky at arm.com>

Similarly to arch_calc_vm_prot_bits(), introduce a dummy
arch_calc_vm_flag_bits() invoked from calc_vm_flag_bits(). This macro
can be overridden by architectures to insert specific VM_* flags derived
from the mmap() MAP_* flags.

Signed-off-by: Kevin Brodsky <Kevin.Brodsky at arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
---

Notes:
    v6:
    - Added comment on where the arch code should define overriding arch_*
      macros (asm/mman.h).
    
    v2:
    - Updated the comment above arch_calc_vm_prot_bits().
    - Changed author since this patch had already been posted (internally).

 include/linux/mman.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/linux/mman.h b/include/linux/mman.h
index 4b08e9c9c538..9ea3f95faa90 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -74,13 +74,18 @@ static inline void vm_unacct_memory(long pages)
 }
 
 /*
- * Allow architectures to handle additional protection bits
+ * Allow architectures to handle additional protection and flag bits. The
+ * overriding macros must be defined in the arch-specific asm/mman.h file.
  */
 
 #ifndef arch_calc_vm_prot_bits
 #define arch_calc_vm_prot_bits(prot, pkey) 0
 #endif
 
+#ifndef arch_calc_vm_flag_bits
+#define arch_calc_vm_flag_bits(flags) 0
+#endif
+
 #ifndef arch_vm_get_page_prot
 #define arch_vm_get_page_prot(vm_flags) __pgprot(0)
 #endif
@@ -131,7 +136,8 @@ calc_vm_flag_bits(unsigned long flags)
 	return _calc_vm_trans(flags, MAP_GROWSDOWN,  VM_GROWSDOWN ) |
 	       _calc_vm_trans(flags, MAP_DENYWRITE,  VM_DENYWRITE ) |
 	       _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    ) |
-	       _calc_vm_trans(flags, MAP_SYNC,	     VM_SYNC      );
+	       _calc_vm_trans(flags, MAP_SYNC,	     VM_SYNC      ) |
+	       arch_calc_vm_flag_bits(flags);
 }
 
 unsigned long vm_commit_limit(void);