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.

include/l4/api/errno.h

@@ -144,6 +144,9 @@
 #define	EOWNERDEAD	130	/* Owner died */
 #define	ENOTRECOVERABLE	131	/* State not recoverable */
 
+/* Codezero specific error codes */
+#define EACTIVE		132	/* Task active */
+
 #ifdef __KERNEL__
 
 /* Should never be seen by user programs */

include/l4/api/exregs.h

@@ -0,0 +1,22 @@
+/*
+ * Exchange registers system call data.
+ *
+ * Copyright (C) 2008 Bahadir Balban
+ */
+#ifndef __EXREGS_H__
+#define __EXREGS_H__
+
+#include <l4/macros.h>
+#include INC_GLUE(syscall.h)
+#include INC_GLUE(context.h)
+#include <l4/types.h>
+
+/* Structure passed by userspace pagers for exchanging registers */
+struct exregs_data {
+	exregs_context_t context;
+	u32 valid_vect;
+};
+
+
+
+#endif /* __EXREGS_H__ */

include/l4/api/thread.h

@@ -1,16 +1,18 @@
 #ifndef __THREAD_H__
 #define __THREAD_H__
 
-#define THREAD_FLAGS_MASK		0x00F0
-
-/* Create new thread, copy given space */
-#define THREAD_CREATE_COPYSPC		0x0010
+#define THREAD_CREATE_MASK		0x00F0
 
 /* Create new thread and new space */
-#define THREAD_CREATE_NEWSPC		0x0020
+#define THREAD_NEW_SPACE		0x0010
+
+/* Create new thread, copy given space */
+#define THREAD_COPY_SPACE		0x0020
 
 /* Create new thread, use given space */
-#define THREAD_CREATE_SAMESPC		0x0030
+#define THREAD_SAME_SPACE		0x0030
+
+
 
 
 #define THREAD_ACTION_MASK		0x000F

include/l4/arch/arm/exception.h

@@ -75,6 +75,17 @@ static inline void irq_local_disable()
 /* This is filled on entry to irq handler, only if a process was interrupted.*/
 extern unsigned int preempted_psr;
 
+#include <l4/generic/tcb.h>
+static inline int task_in_kernel(struct tcb *t)
+{
+	return ((t->context.spsr & ARM_MODE_MASK) == ARM_MODE_SVC) ? 1 : 0;
+}
+
+static inline int task_in_user(struct tcb *t)
+{
+	return !task_in_kernel(t);
+}
+
 static inline int in_kernel()
 {
 	return (((preempted_psr & ARM_MODE_MASK) == ARM_MODE_SVC)) ? 1 : 0;

include/l4/generic/scheduler.h

@@ -34,10 +34,6 @@ static inline struct ktcb *current_task(void)
 #define SCHED_FL_MASK			(SCHED_FL_SLEEP | SCHED_FL_RESUME \
 					 | SCHED_FL_SUSPEND)
 
-#define __IPC_FL_WAIT			4
-#define IPC_FL_WAIT			(1 << __IPC_FL_WAIT)
-#define IPC_FL_MASK			IPC_FL_WAIT
-
 void sched_runqueue_init(void);
 void sched_start_task(struct ktcb *task);
 void sched_resume_task(struct ktcb *task);

include/l4/generic/tcb.h

@@ -13,6 +13,7 @@
 #include INC_GLUE(memory.h)
 #include INC_GLUE(syscall.h)
 #include INC_GLUE(message.h)
+#include INC_GLUE(context.h)
 #include INC_SUBARCH(mm.h)
 
 enum task_state {
@@ -21,32 +22,6 @@ enum task_state {
 	TASK_RUNNABLE	= 2,
 };
 
-/*
- * This describes the user space register context of each task. Simply set them
- * as regular structure fields, and they'll be copied onto real registers upon
- * a context switch. In the ARM case, they're copied from memory to userspace
- * registers using the LDM instruction with ^, no-pc flavor. See ARMARM.
- */
-typedef struct arm_context {
-	u32 spsr;	/* 0x0 */
-	u32 r0;		/* 0x4 */
-	u32 r1;		/* 0x8 */
-	u32 r2;		/* 0xC */
-	u32 r3;		/* 0x10 */
-	u32 r4;		/* 0x14 */
-	u32 r5;		/* 0x18 */
-	u32 r6; 	/* 0x1C */
-	u32 r7;		/* 0x20 */
-	u32 r8;		/* 0x24 */
-	u32 r9;		/* 0x28 */
-	u32 r10;	/* 0x2C */
-	u32 r11;	/* 0x30 */
-	u32 r12;	/* 0x34 */
-	u32 sp;		/* 0x38 */
-	u32 lr;		/* 0x3C */
-	u32 pc;		/* 0x40 */
-} __attribute__((__packed__)) task_context_t;
-
 #define TASK_ID_INVALID			-1
 struct task_ids {
 	l4id_t tid;
@@ -75,7 +50,9 @@ struct ktcb {
 
 	/* Flags to hint scheduler on future task state */
 	unsigned int schedfl;
-	unsigned int flags;
+
+	/* Lock for blocking thread state modifications via a syscall */
+	struct mutex thread_control_lock;
 
 	/* Other related threads */
 	l4id_t pagerid;

include/l4/glue/arm/context.h

@@ -0,0 +1,53 @@
+#ifndef __ARM_CONTEXT_H__
+#define __ARM_CONTEXT_H__
+
+#include <l4/types.h>
+
+/*
+ * This describes the register context of each task. Simply set
+ * them as regular structure fields, and they'll be copied onto
+ * real registers upon a context switch to that task. Normally
+ * exchange_registers() system call is designed for this, whose
+ * input structure is defined further below.
+ */
+typedef struct arm_context {
+	u32 spsr;	/* 0x0 */
+	u32 r0;		/* 0x4 */
+	u32 r1;		/* 0x8 */
+	u32 r2;		/* 0xC */
+	u32 r3;		/* 0x10 */
+	u32 r4;		/* 0x14 */
+	u32 r5;		/* 0x18 */
+	u32 r6; 	/* 0x1C */
+	u32 r7;		/* 0x20 */
+	u32 r8;		/* 0x24 */
+	u32 r9;		/* 0x28 */
+	u32 r10;	/* 0x2C */
+	u32 r11;	/* 0x30 */
+	u32 r12;	/* 0x34 */
+	u32 sp;		/* 0x38 */
+	u32 lr;		/* 0x3C */
+	u32 pc;		/* 0x40 */
+} __attribute__((__packed__)) task_context_t;
+
+
+typedef struct arm_exregs_context {
+	u32 r0;		/* 0x4 */
+	u32 r1;		/* 0x8 */
+	u32 r2;		/* 0xC */
+	u32 r3;		/* 0x10 */
+	u32 r4;		/* 0x14 */
+	u32 r5;		/* 0x18 */
+	u32 r6; 	/* 0x1C */
+	u32 r7;		/* 0x20 */
+	u32 r8;		/* 0x24 */
+	u32 r9;		/* 0x28 */
+	u32 r10;	/* 0x2C */
+	u32 r11;	/* 0x30 */
+	u32 r12;	/* 0x34 */
+	u32 sp;		/* 0x38 */
+	u32 lr;		/* 0x3C */
+	u32 pc;		/* 0x40 */
+} __attribute__((__packed__)) exregs_context_t;
+
+#endif /* __ARM_CONTEXT_H__ */

include/l4/glue/arm/memlayout.h

@@ -68,4 +68,7 @@
 #define KERN_ADDR(x)		((x >= KERNEL_AREA_START) && (x < KERNEL_AREA_END))
 #define USER_ADDR(x)		((x >= USER_AREA_START) && (x < USER_AREA_END))
 
+#define PRIVILEGED_ADDR(x)	(KERN_ADDR(x) || (x >= ARM_HIGH_VECTOR) || \
+				 (x >= IO_AREA_START && x < IO_AREA_END))
+
 #endif /* __MEMLAYOUT_H__ */

include/l4/glue/arm/syscall.h

@@ -2,12 +2,13 @@
  * ARM-specific system call details.
  *
  * Copyright (C) 2007 Bahadir Balban
- *
  */
 
 #ifndef __ARM_GLUE_SYSCALL_H__
 #define __ARM_GLUE_SYSCALL_H__
 
+#include <l4/types.h>
+
 /* Only specific call is the trap that gives back the kip address
  * from which other system calls can be discovered. */
 #define L4_TRAP_KIP			0xB4
@@ -52,7 +53,8 @@ typedef struct msg_regs {
 
 /* NOTE:
  * These references are valid only when they have been explicitly set
- * by a kernel entry point, e.g. a system call, a data abort handler.
+ * by a kernel entry point, e.g. a system call, a data abort handler
+ * that imitates a page fault ipc etc.
  */
 #define KTCB_REF_ARG0(ktcb)	(&(ktcb)->syscall_regs->r0)
 #define KTCB_REF_MR0(ktcb)	(&(ktcb)->syscall_regs->r3)

include/l4/lib/mutex.h

@@ -28,6 +28,7 @@ static inline void mutex_init(struct mutex *mutex)
 	INIT_LIST_HEAD(&mutex->wq.task_list);
 }
 
+int mutex_trylock(struct mutex *mutex);
 void mutex_lock(struct mutex *mutex);
 void mutex_unlock(struct mutex *mutex);
 

include/l4/lib/spinlock.h

@@ -20,7 +20,7 @@ static inline void spin_lock_init(struct spinlock *s)
  */
 static inline void spin_lock(struct spinlock *s)
 {
-	preempt_disable();
+	preempt_disable();	/* This must disable local preempt */
 #if defined(CONFIG_SMP)
 	__spin_lock(&s->lock);
 #endif

include/l4/macros.h

@@ -75,6 +75,9 @@
 #define printk			printf
 #endif
 
+/* Converts an int-sized field offset in a struct into a bit offset in a word */
+#define FIELD_TO_BIT(type, field)	(1 << (offsetof(type, field) >> 2))
+
 /* Functions who may either return a pointer or an error code can use these: */
 #define PTR_ERR(x)		((void *)(x))
 /* checks up to -1000, the rest might be valid pointers!!! E.g. 0xE0000000 */