[PATCH] Common PROT_xxx -> VM_xxx mapping

This moves the mapping of PROT_* bits to VM_* bits from mmap.c to the
common header file <linux/mman.h>.  The mapping is needed for mprotect
too.

1 files changed, 29 insertions, 0 deletions

diff --git a/include/linux/mman.h b/include/linux/mman.h
index a8956f6588ad..cfb6ac61bbde 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -2,6 +2,7 @@
 #define _LINUX_MMAN_H
 
 #include <linux/config.h>
+#include <linux/mm.h>
 
 #include <asm/atomic.h>
 #include <asm/mman.h>
@@ -27,4 +28,32 @@ static inline void vm_unacct_memory(long pages)
 	vm_acct_memory(-pages);
 }
 
+/* Optimisation macro. */
+#define _calc_vm_trans(x,bit1,bit2) \
+  ((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \
+   : ((x) & (bit1)) / ((bit1) / (bit2)))
+
+/*
+ * Combine the mmap "prot" argument into "vm_flags" used internally.
+ */
+static inline unsigned long
+calc_vm_prot_bits(unsigned long prot)
+{
+	return _calc_vm_trans(prot, PROT_READ,  VM_READ ) |
+	       _calc_vm_trans(prot, PROT_WRITE, VM_WRITE) |
+	       _calc_vm_trans(prot, PROT_EXEC,  VM_EXEC );
+}
+
+/*
+ * Combine the mmap "flags" argument into "vm_flags" used internally.
+ */
+static inline unsigned long
+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_EXECUTABLE, VM_EXECUTABLE) |
+	       _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    );
+}
+
 #endif /* _LINUX_MMAN_H */