Towards finishing exchange_registers()

- Added mutex_trylock()
- Implemented most of exchange_registers()
- thread_control() now needs a lock for operations that can modify thread context.
- thread_start() does not initialise scheduler flags, now done in thread_create.

TODO:
- Fork/clone'ed threads should retain their context in tcb, not syscall stack.
- exchange_registers() calls in userspace need cleaning up.

tasks/libl4/include/l4lib/arch-arm/syscalls.h

@@ -59,10 +59,10 @@ typedef int (*__l4_ipc_control_t)(unsigned int action, l4id_t blocked_sender,
 extern __l4_ipc_control_t __l4_ipc_control;
 int l4_ipc_control(unsigned int, l4id_t blocked_sender, u32 blocked_tag);
 
-typedef int (*__l4_exchange_registers_t)(unsigned int pc, unsigned int sp,
+typedef int (*__l4_exchange_registers_t)(void *exregs_struct,
 					 l4id_t pager, l4id_t tid);
 extern __l4_exchange_registers_t __l4_exchange_registers;
-int l4_exchange_registers(unsigned int pc, unsigned int sp, int pager, l4id_t tid);
+int l4_exchange_registers(void *exregs_struct, l4id_t pager, l4id_t tid);
 
 typedef int (*__l4_kmem_control_t)(unsigned long pfn, int npages, int grant);
 extern __l4_kmem_control_t __l4_kmem_control;

tasks/libl4/src/arm/syscalls.S

@@ -186,7 +186,7 @@ END_PROC(l4_space_control)
 
 /*
  * Sets registers of a thread and its pager.
- * @r0 = pc to set, @r1 = sp to set  @r2 = pager id, @r3 = tid of thread.
+ * @r0 = ptr to exchange_registers structure, @r1 = pager id, @r2 = tid of thread.
  */
 BEGIN_PROC(l4_exchange_registers)
 	stmfd	sp!, {lr}

tasks/mm0/include/exregs.h

@@ -0,0 +1,22 @@
+#ifndef __MM0_EXREGS_H__
+#define __MM0_EXREGS_H__
+
+#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_pc(struct exregs_data *s, unsigned long pc);
+
+/*
+exregs_set_stack(unsigned long sp)
+exregs_set_pc(unsigned long pc)
+exregs_set_return(unsigned long retreg)
+exregs_set_arg0(unsigned long arg0)
+exregs_set_mr0(unsigned long mr0)
+exregs_set_mr_sender(unsigned long sender)
+exregs_set_mr_return(unsigned long retreg)
+exregs_set_all(unsigned long arg0, unsigned long arg1, unsigned long arg2, unsigned long arg3,
+	       unsigned long sp, unsigned long pc, u32 valid_vector, l4id_t pager);
+*/
+
+#endif /* __MM0_EXREGS_H__ */

tasks/mm0/main.c

@@ -168,7 +168,7 @@ int self_spawn(void)
 	ids.tgid = self->tgid;
 
 	/* Create a new L4 thread in current thread's address space. */
-	self_child = task_create(self, &ids, THREAD_CREATE_SAMESPC,
+	self_child = task_create(self, &ids, THREAD_SAME_SPACE,
 				 TCB_SHARED_VM | TCB_SHARED_FILES);
 
 	if (IS_ERR(self_child = tcb_alloc_init(TCB_SHARED_VM

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

@@ -0,0 +1,21 @@
+/*
+ * Generic to arch-specific interface for
+ * exchange_registers()
+ *
+ * Copyright (C) 2008 Bahadir Balban
+ */
+#include <exregs.h>
+
+
+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

@@ -64,7 +64,7 @@ int do_fork(struct tcb *parent)
 	 * Create a new L4 thread with parent's page tables
 	 * kernel stack and kernel-side tcb copied
 	 */
-	if (IS_ERR(child = task_create(parent, &ids, THREAD_CREATE_COPYSPC,
+	if (IS_ERR(child = task_create(parent, &ids, THREAD_COPY_SPACE,
 			    	       TCB_NO_SHARING))) {
 		l4_ipc_return((int)child);
 		return 0;
@@ -121,7 +121,6 @@ int sys_clone(l4id_t sender, void *child_stack, unsigned int flags)
 	struct task_ids ids;
 	struct vm_file *utcb_shm;
 	struct tcb *parent, *child;
-	unsigned long stack, stack_size;
 
 	BUG_ON(!(parent = find_task(sender)));
 
@@ -129,7 +128,7 @@ int sys_clone(l4id_t sender, void *child_stack, unsigned int flags)
 	ids.spid = parent->spid;
 	ids.tgid = parent->tgid;
 
-	if (IS_ERR(child = task_create(parent, &ids, THREAD_CREATE_SAMESPC,
+	if (IS_ERR(child = task_create(parent, &ids, THREAD_SAME_SPACE,
 			    	       TCB_SHARED_VM | TCB_SHARED_FILES))) {
 		l4_ipc_return((int)child);
 		return 0;

tasks/mm0/src/task.c

@@ -26,6 +26,7 @@
 #include <task.h>
 #include <shm.h>
 #include <mmap.h>
+#include <exregs.h>
 
 struct tcb_head {
 	struct list_head list;
@@ -303,6 +304,7 @@ int task_setup_registers(struct tcb *task, unsigned int pc,
 			 unsigned int sp, l4id_t pager)
 {
 	int err;
+	struct exregs_data regs;
 
 	/* Set up task's registers to default. */
 	if (!sp)
@@ -313,7 +315,9 @@ int task_setup_registers(struct tcb *task, unsigned int pc,
 		pager = self_tid();
 
 	/* Set up the task's thread details, (pc, sp, pager etc.) */
-	if ((err = l4_exchange_registers(pc, sp, pager, task->tid) < 0)) {
+	exregs_set_stack(&regs, sp);
+	exregs_set_pc(&regs, pc);
+	if ((err = l4_exchange_registers(&regs, pager, task->tid) < 0)) {
 		printf("l4_exchange_registers failed with %d.\n", err);
 		return err;
 	}
@@ -367,7 +371,7 @@ int task_exec(struct vm_file *f, unsigned long task_region_start,
 	struct tcb *task;
 	int err;
 
-	if (IS_ERR(task = task_create(0, ids, THREAD_CREATE_NEWSPC,
+	if (IS_ERR(task = task_create(0, ids, THREAD_NEW_SPACE,
 				      TCB_NO_SHARING)))
 		return (int)task;