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/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)