Added exregs_set_mr() function

Moved all exregs-related calls to libl4 since these are part of the L4 api.

tasks/libl4/include/l4lib/exregs.h

@@ -4,7 +4,7 @@
 #include <l4/api/exregs.h>
 
 void exregs_set_stack(struct exregs_data *s, unsigned long sp);
-void exregs_set_mr_return(struct exregs_data *s, unsigned long retreg);
+void exregs_set_mr(struct exregs_data *s, int offset, unsigned long val);
 void exregs_set_pc(struct exregs_data *s, unsigned long pc);
 void exregs_set_pager(struct exregs_data *s, l4id_t pagerid);
 

tasks/libl4/src/arm/exregs.c

@@ -0,0 +1,45 @@
+/*
+ * Generic to arch-specific interface for
+ * exchange_registers()
+ *
+ * Copyright (C) 2008 Bahadir Balban
+ */
+#include <l4/macros.h>
+#include <l4lib/exregs.h>
+#include INC_GLUE(message.h)
+
+
+void exregs_set_mr(struct exregs_data *s, int offset, unsigned long val)
+{
+	/* Get MR0 */
+	u32 *mr = &s->context.r3;
+
+	/* Sanity check */
+	BUG_ON(offset > MR_TOTAL || offset < 0);
+
+	/* Set MR */
+	mr[offset] = val;
+
+	/* Set valid bit for mr register */
+	s->valid_vect |= offsetof(exregs_context_t, r3) +
+			 (offset * sizeof(int));
+}
+
+void exregs_set_pager(struct exregs_data *s, l4id_t pagerid)
+{
+	s->pagerid = pagerid;
+	s->flags |= EXREGS_SET_PAGER;
+}
+
+void exregs_set_stack(struct exregs_data *s, unsigned long sp)
+{
+	s->context.sp = sp;
+	s->valid_vect |= 1 << (offsetof(exregs_context_t, sp) >> 2);
+}
+
+void exregs_set_pc(struct exregs_data *s, unsigned long pc)
+{
+	s->context.pc = pc;
+	s->valid_vect |= 1 << (offsetof(exregs_context_t, pc) >> 2);
+}
+

tasks/libl4/src/arm/syscalls.S

@@ -65,7 +65,7 @@ BEGIN_PROC(arch_clone)
 	 */
 	cmp	r0, #0			@ Check ipc success
 	blt	ipc_failed
-	cmp	r2, #0			@ Check ipc return register MR_RETURN.
+	cmp	r3, #0			@ Check ipc return register MR_RETURN.
 	blt	clone_failed		@ Ipc was ok but clone() failed.
 	bgt	parent_return		@ It has child pid, goto parent return.
 child:

tasks/mm0/src/arch-arm/exregs.c

@@ -1,27 +0,0 @@
-/*
- * Generic to arch-specific interface for
- * exchange_registers()
- *
- * Copyright (C) 2008 Bahadir Balban
- */
-#include <exregs.h>
-
-
-void exregs_set_pager(struct exregs_data *s, l4id_t pagerid)
-{
-	s->pagerid = pagerid;
-	s->flags |= EXREGS_SET_PAGER;
-}
-
-void exregs_set_stack(struct exregs_data *s, unsigned long sp)
-{
-	s->context.sp = sp;
-	s->valid_vect |= 1 << (offsetof(task_context_t, sp) >> 2);
-}
-
-void exregs_set_pc(struct exregs_data *s, unsigned long pc)
-{
-	s->context.pc = pc;
-	s->valid_vect |= 1 << (offsetof(task_context_t, pc) >> 2);
-}
-

tasks/mm0/src/clone.c

@@ -9,6 +9,7 @@
 #include <mmap.h>
 #include <l4lib/arch/syslib.h>
 #include <l4lib/ipcdefs.h>
+#include <l4lib/exregs.h>
 #include <l4/api/thread.h>
 #include <utcb.h>
 #include <shm.h>
@@ -49,7 +50,9 @@ int vfs_notify_fork(struct tcb *child, struct tcb *parent)
 
 int do_fork(struct tcb *parent)
 {
+	int err;
 	struct tcb *child;
+	struct exregs_data exregs;
 	struct vm_file *utcb_shm;
 	struct task_ids ids = {
 		.tid = TASK_ID_INVALID,
@@ -70,6 +73,12 @@ int do_fork(struct tcb *parent)
 		return 0;
 	}
 
+	/* Set child's fork return value to 0 */
+	memset(&exregs, 0, sizeof(exregs));
+	exregs_set_mr(&exregs, MR_RETURN, 0);
+	if ((err = l4_exchange_registers(&exregs, child->tid)) < 0)
+		BUG();
+
 	/* Create new utcb for child since it can't use its parent's */
 	child->utcb = utcb_vaddr_new();
 

tasks/mm0/src/task.c

@@ -15,6 +15,7 @@
 #include <l4lib/arch/syslib.h>
 #include <l4lib/arch/utcb.h>
 #include <l4lib/ipcdefs.h>
+#include <l4lib/exregs.h>
 #include <lib/addr.h>
 #include <kmalloc/kmalloc.h>
 #include <init.h>
@@ -26,7 +27,6 @@
 #include <task.h>
 #include <shm.h>
 #include <mmap.h>
-#include <exregs.h>
 
 struct tcb_head {
 	struct list_head list;