madvise: Support MADV_WIPEONFORK, MADV_KEEPONFORK and MADV_NORMAL

Change-Id: I1d4cf5affa580d7304dfdc34fa4f1707c0df617c
refs: #1374

kernel/include/mman.h

@@ -54,6 +54,8 @@
 #define	MADV_NOHUGEPAGE		15
 #define	MADV_DONTDUMP		16
 #define	MADV_DODUMP		17
+#define	MADV_WIPEONFORK		18 /* Zero memory on fork, child only */
+#define	MADV_KEEPONFORK		19 /* Undo MADV_WIPEONFORK */
 #define	MADV_HWPOISON		100
 #define	MADV_SOFT_OFFLINE	101
 

kernel/include/process.h

@@ -56,6 +56,7 @@
 #define VR_PAGEOUT	   0x10000000
 #define VR_DONTDUMP	   0x20000000
 #define VR_XPMEM	   0x40000000
+#define VR_WIPEONFORK	   0x80000000
 
 #define	PROT_TO_VR_FLAG(prot)	(((unsigned long)(prot) << 16) & VR_PROT_MASK)
 #define	VRFLAG_PROT_TO_MAXPROT(vrflag)	(((vrflag) & VR_PROT_MASK) << 4)