vm: Separate mmap regions.

Add support for compact address layout.  This feature can be enabled
through the ac_layout=1 boot option.

Change-Id: Ie20b808fce32b5c54d0a7e7210e0084a540e9613

minix/kernel/arch/earm/pre_init.c

@@ -275,12 +275,12 @@ void get_parameters(kinfo_t *cbi, char *bootargs)
 	mb_set_param(cbi->param_buf, BOARDVARNAME,(char *)get_board_name(machine.board_id) , cbi);
 	
 
-	/* round user stack down to leave a gap to catch kernel
+	/* move user stack/data down to leave a gap to catch kernel
 	 * stack overflow; and to distinguish kernel and user addresses
 	 * at a glance (0xf.. vs 0xe..) 
 	 */
-	cbi->user_sp &= 0xF0000000;
+	cbi->user_sp = USR_STACKTOP;
-	cbi->user_end = cbi->user_sp;
+	cbi->user_end = USR_DATATOP;
 
 	/* kernel bytes without bootstrap code/data that is currently
 	 * still needed but will be freed after bootstrapping.

minix/kernel/arch/i386/pre_init.c

@@ -157,12 +157,12 @@ void get_parameters(u32_t ebx, kinfo_t *cbi)
         mb_set_param(cbi->param_buf, ARCHVARNAME, (char *)get_board_arch_name(BOARD_ID_INTEL), cbi);
 	mb_set_param(cbi->param_buf, BOARDVARNAME,(char *)get_board_name(BOARD_ID_INTEL) , cbi);
 
-	/* round user stack down to leave a gap to catch kernel
+	/* move user stack/data down to leave a gap to catch kernel
 	 * stack overflow; and to distinguish kernel and user addresses
 	 * at a glance (0xf.. vs 0xe..) 
 	 */
-	cbi->user_sp &= 0xF0000000;
+	cbi->user_sp = USR_STACKTOP;
-	cbi->user_end = cbi->user_sp;
+	cbi->user_end = USR_DATATOP;
 
 	/* kernel bytes without bootstrap code/data that is currently
 	 * still needed but will be freed after bootstrapping.

minix/kernel/const.h

@@ -30,4 +30,25 @@
 /* for kputc() */
 #define END_OF_KMESS	0
 
+/* User limits. */
+#ifndef USR_DATATOP
+#ifndef _MINIX_MAGIC
+#define USR_DATATOP 0xF0000000
+#else
+#define USR_DATATOP 0xE0000000	/* TODO: is this necessary? */
+#endif
+#endif
+
+#ifndef USR_STACKTOP
+#define USR_STACKTOP USR_DATATOP
+#endif
+
+#ifndef USR_DATATOP_COMPACT
+#define USR_DATATOP_COMPACT USR_DATATOP
+#endif
+
+#ifndef USR_STACKTOP_COMPACT
+#define USR_STACKTOP_COMPACT 0x50000000
+#endif
+
 #endif /* CONST_H */

minix/kernel/main.c

@@ -426,6 +426,13 @@ void cstart()
   if(!value || system_hz < 2 || system_hz > 50000)	/* sanity check */
 	system_hz = DEFAULT_HZ;
 
+  /* Get memory parameters. */
+  value = env_get("ac_layout");
+  if(value && atoi(value)) {
+        kinfo.user_sp = (vir_bytes) USR_STACKTOP_COMPACT;
+        kinfo.user_end = (vir_bytes) USR_DATATOP_COMPACT;
+  }
+
   DEBUGEXTRA(("cstart\n"));
 
   /* Record miscellaneous information for user-space servers. */

minix/servers/vm/mmap.c

@@ -75,7 +75,7 @@ static struct vir_region *mmap_region(struct vmproc *vmp, vir_bytes addr,
 
 	if (!vr) {
 		/* No address given or address already in use. */
-		vr = map_page_region(vmp, VM_PAGE_SIZE, VM_DATATOP, len,
+		vr = map_page_region(vmp, VM_MMAPBASE, VM_MMAPTOP, len,
 			vrflags, mfflags, mt);
 	}
 
@@ -349,7 +349,7 @@ int do_map_phys(message *m)
 	if(len % VM_PAGE_SIZE)
 		len += VM_PAGE_SIZE - (len % VM_PAGE_SIZE);
 
-	if(!(vr = map_page_region(vmp, 0, VM_DATATOP, len, 
+	if(!(vr = map_page_region(vmp, VM_MMAPBASE, VM_MMAPTOP, len,
 		VR_DIRECT | VR_WRITABLE, 0, &mem_type_directphys))) {
 		return ENOMEM;
 	}
@@ -419,8 +419,8 @@ int do_remap(message *m)
 		vr = map_page_region(dvmp, da, 0, size, flags, 0,
 			&mem_type_shared);
 	else
-		vr = map_page_region(dvmp, 0, VM_DATATOP, size, flags, 0,
+		vr = map_page_region(dvmp, VM_MMAPBASE, VM_MMAPTOP, size,
-			&mem_type_shared);
+			flags, 0, &mem_type_shared);
 
 	if(!vr) {
 		printf("VM: re-map of shared area failed\n");

minix/servers/vm/vm.h

@@ -63,7 +63,20 @@
 
 /* And what is the highest addressable piece of memory? */
 #define VM_DATATOP	kernel_boot_info.user_end
+
 #define VM_STACKTOP	kernel_boot_info.user_sp
 
+/* Live update will work only with magic instrumentation. Live update requires
+ * strict separation of regions within the process to succeed. Therefore,
+ * apply this strict separation only if magic instrumentation is used.
+ * Otherwise, do not place such limitations on processes.
+ */
+#ifdef _MINIX_MAGIC
+#define VM_MMAPTOP	(VM_STACKTOP-DEFAULT_STACK_LIMIT)
+#define VM_MMAPBASE	(VM_MMAPTOP/2)
+#else
+#define VM_MMAPTOP	VM_DATATOP
+#define VM_MMAPBASE	VM_PAGE_SIZE
 #endif
 
+#endif