arch/metag/kernel/process.c - linux - Git at Google

 /*
  * Copyright (C) 2005,2006,2007,2008,2009,2010,2011 Imagination Technologies
  *
  * This file contains the architecture-dependent parts of process handling.
  *
  */

 #include <linux/errno.h>
 #include <linux/export.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/unistd.h>
 #include <linux/ptrace.h>
 #include <linux/user.h>
 #include <linux/reboot.h>
 #include <linux/elfcore.h>
 #include <linux/fs.h>
 #include <linux/tick.h>
 #include <linux/slab.h>
 #include <linux/mman.h>
 #include <linux/pm.h>
 #include <linux/syscalls.h>
 #include <linux/uaccess.h>
 #include <linux/smp.h>
 #include <asm/core_reg.h>
 #include <asm/user_gateway.h>
 #include <asm/tcm.h>
 #include <asm/traps.h>
 #include <asm/switch_to.h>

 /*
  * Wait for the next interrupt and enable local interrupts
  */
 void arch_cpu_idle(void)
 {
 	int tmp;

 	/*
 	 * Quickly jump straight into the interrupt entry point without actually
 	 * triggering an interrupt. When TXSTATI gets read the processor will
 	 * block until an interrupt is triggered.
 	 */
 	asm volatile (/* Switch into ISTAT mode */
 		      "RTH\n\t"
 		      /* Enable local interrupts */
 		      "MOV	TXMASKI, %1\n\t"
 		      /*
 		       * We can't directly "SWAP PC, PCX", so we swap via a
 		       * temporary. Essentially we do:
 		       *  PCX_new = 1f (the place to continue execution)
 		       *  PC = PCX_old
 		       */
 		      "ADD	%0, CPC0, #(1f-.)\n\t"
 		      "SWAP	PCX, %0\n\t"
 		      "MOV	PC, %0\n"
 		      /* Continue execution here with interrupts enabled */
 		      "1:"
 		      : "=a" (tmp)
 		      : "r" (get_trigger_mask()));
 }

 #ifdef CONFIG_HOTPLUG_CPU
 void arch_cpu_idle_dead(void)
 {
 	cpu_die();
 }
 #endif

 void (*pm_power_off)(void);
 EXPORT_SYMBOL(pm_power_off);

 void (*soc_restart)(char *cmd);
 void (*soc_halt)(void);

 void machine_restart(char *cmd)
 {
 	if (soc_restart)
 		soc_restart(cmd);
 	hard_processor_halt(HALT_OK);
 }

 void machine_halt(void)
 {
 	if (soc_halt)
 		soc_halt();
 	smp_send_stop();
 	hard_processor_halt(HALT_OK);
 }

 void machine_power_off(void)
 {
 	if (pm_power_off)
 		pm_power_off();
 	smp_send_stop();
 	hard_processor_halt(HALT_OK);
 }

 #define FLAG_Z 0x8
 #define FLAG_N 0x4
 #define FLAG_O 0x2
 #define FLAG_C 0x1

 void show_regs(struct pt_regs *regs)
 {
 	int i;
 	const char *AX0_names[] = {"A0StP", "A0FrP"};
 	const char *AX1_names[] = {"A1GbP", "A1LbP"};

 	const char *DX0_names[] = {
 		"D0Re0",
 		"D0Ar6",
 		"D0Ar4",
 		"D0Ar2",
 		"D0FrT",
 		"D0.5 ",
 		"D0.6 ",
 		"D0.7 "
 	};

 	const char *DX1_names[] = {
 		"D1Re0",
 		"D1Ar5",
 		"D1Ar3",
 		"D1Ar1",
 		"D1RtP",
 		"D1.5 ",
 		"D1.6 ",
 		"D1.7 "
 	};

 	show_regs_print_info(KERN_INFO);

 	pr_info(" pt_regs @ %p\n", regs);
 	pr_info(" SaveMask = 0x%04hx\n", regs->ctx.SaveMask);
 	pr_info(" Flags = 0x%04hx (%c%c%c%c)\n", regs->ctx.Flags,
 		regs->ctx.Flags & FLAG_Z ? 'Z' : 'z',
 		regs->ctx.Flags & FLAG_N ? 'N' : 'n',
 		regs->ctx.Flags & FLAG_O ? 'O' : 'o',
 		regs->ctx.Flags & FLAG_C ? 'C' : 'c');
 	pr_info(" TXRPT = 0x%08x\n", regs->ctx.CurrRPT);
 	pr_info(" PC = 0x%08x\n", regs->ctx.CurrPC);

 	/* AX regs */
 	for (i = 0; i < 2; i++) {
 		pr_info(" %s = 0x%08x    ",
 			AX0_names[i],
 			regs->ctx.AX[i].U0);
 		printk(" %s = 0x%08x\n",
 			AX1_names[i],
 			regs->ctx.AX[i].U1);
 	}

 	if (regs->ctx.SaveMask & TBICTX_XEXT_BIT)
 		pr_warn(" Extended state present - AX2.[01] will be WRONG\n");

 	/* Special place with AXx.2 */
 	pr_info(" A0.2  = 0x%08x    ",
 		regs->ctx.Ext.AX2.U0);
 	printk(" A1.2  = 0x%08x\n",
 		regs->ctx.Ext.AX2.U1);

 	/* 'extended' AX regs (nominally, just AXx.3) */
 	for (i = 0; i < (TBICTX_AX_REGS - 3); i++) {
 		pr_info(" A0.%d  = 0x%08x    ", i + 3, regs->ctx.AX3[i].U0);
 		printk(" A1.%d  = 0x%08x\n", i + 3, regs->ctx.AX3[i].U1);
 	}

 	for (i = 0; i < 8; i++) {
 		pr_info(" %s = 0x%08x    ", DX0_names[i], regs->ctx.DX[i].U0);
 		printk(" %s = 0x%08x\n", DX1_names[i], regs->ctx.DX[i].U1);
 	}

 	show_trace(NULL, (unsigned long *)regs->ctx.AX[0].U0, regs);
 }

 /*
  * Copy architecture-specific thread state
  */
 int copy_thread(unsigned long clone_flags, unsigned long usp,
 		unsigned long kthread_arg, struct task_struct *tsk)
 {
 	struct pt_regs *childregs = task_pt_regs(tsk);
 	void *kernel_context = ((void *) childregs +
 				sizeof(struct pt_regs));
 	unsigned long global_base;

 	BUG_ON(((unsigned long)childregs) & 0x7);
 	BUG_ON(((unsigned long)kernel_context) & 0x7);

 	memset(&tsk->thread.kernel_context, 0,
 			sizeof(tsk->thread.kernel_context));

 	tsk->thread.kernel_context = __TBISwitchInit(kernel_context,
 						     ret_from_fork,
 						     0, 0);

 	if (unlikely(tsk->flags & PF_KTHREAD)) {
 		/*
 		 * Make sure we don't leak any kernel data to child's regs
 		 * if kernel thread becomes a userspace thread in the future
 		 */
 		memset(childregs, 0 , sizeof(struct pt_regs));

 		global_base = __core_reg_get(A1GbP);
 		childregs->ctx.AX[0].U1 = (unsigned long) global_base;
 		childregs->ctx.AX[0].U0 = (unsigned long) kernel_context;
 		/* Set D1Ar1=kthread_arg and D1RtP=usp (fn) */
 		childregs->ctx.DX[4].U1 = usp;
 		childregs->ctx.DX[3].U1 = kthread_arg;
 		tsk->thread.int_depth = 2;
 		return 0;
 	}

 	/*
 	 * Get a pointer to where the new child's register block should have
 	 * been pushed.
 	 * The Meta's stack grows upwards, and the context is the the first
 	 * thing to be pushed by TBX (phew)
 	 */
 	*childregs = *current_pt_regs();
 	/* Set the correct stack for the clone mode */
 	if (usp)
 		childregs->ctx.AX[0].U0 = ALIGN(usp, 8);
 	tsk->thread.int_depth = 1;

 	/* set return value for child process */
 	childregs->ctx.DX[0].U0 = 0;

 	/* The TLS pointer is passed as an argument to sys_clone. */
 	if (clone_flags & CLONE_SETTLS)
 		tsk->thread.tls_ptr =
 				(__force void __user *)childregs->ctx.DX[1].U1;

 #ifdef CONFIG_METAG_FPU
 	if (tsk->thread.fpu_context) {
 		struct meta_fpu_context *ctx;

 		ctx = kmemdup(tsk->thread.fpu_context,
 			      sizeof(struct meta_fpu_context), GFP_ATOMIC);
 		tsk->thread.fpu_context = ctx;
 	}
 #endif

 #ifdef CONFIG_METAG_DSP
 	if (tsk->thread.dsp_context) {
 		struct meta_ext_context *ctx;
 		int i;

 		ctx = kmemdup(tsk->thread.dsp_context,
 			      sizeof(struct meta_ext_context), GFP_ATOMIC);
 		for (i = 0; i < 2; i++)
 			ctx->ram[i] = kmemdup(ctx->ram[i], ctx->ram_sz[i],
 					      GFP_ATOMIC);
 		tsk->thread.dsp_context = ctx;
 	}
 #endif

 	return 0;
 }

 #ifdef CONFIG_METAG_FPU
 static void alloc_fpu_context(struct thread_struct *thread)
 {
 	thread->fpu_context = kzalloc(sizeof(struct meta_fpu_context),
 				      GFP_ATOMIC);
 }

 static void clear_fpu(struct thread_struct *thread)
 {
 	thread->user_flags &= ~TBICTX_FPAC_BIT;
 	kfree(thread->fpu_context);
 	thread->fpu_context = NULL;
 }
 #else
 static void clear_fpu(struct thread_struct *thread)
 {
 }
 #endif

 #ifdef CONFIG_METAG_DSP
 static void clear_dsp(struct thread_struct *thread)
 {
 	if (thread->dsp_context) {
 		kfree(thread->dsp_context->ram[0]);
 		kfree(thread->dsp_context->ram[1]);

 		kfree(thread->dsp_context);

 		thread->dsp_context = NULL;
 	}

 	__core_reg_set(D0.8, 0);
 }
 #else
 static void clear_dsp(struct thread_struct *thread)
 {
 }
 #endif

 struct task_struct *__sched __switch_to(struct task_struct *prev,
 					struct task_struct *next)
 {
 	TBIRES to, from;

 	to.Switch.pCtx = next->thread.kernel_context;
 	to.Switch.pPara = prev;

 #ifdef CONFIG_METAG_FPU
 	if (prev->thread.user_flags & TBICTX_FPAC_BIT) {
 		struct pt_regs *regs = task_pt_regs(prev);
 		TBIRES state;

 		state.Sig.SaveMask = prev->thread.user_flags;
 		state.Sig.pCtx = &regs->ctx;

 		if (!prev->thread.fpu_context)
 			alloc_fpu_context(&prev->thread);
 		if (prev->thread.fpu_context)
 			__TBICtxFPUSave(state, prev->thread.fpu_context);
 	}
 	/*
 	 * Force a restore of the FPU context next time this process is
 	 * scheduled.
 	 */
 	if (prev->thread.fpu_context)
 		prev->thread.fpu_context->needs_restore = true;
 #endif


 	from = __TBISwitch(to, &prev->thread.kernel_context);

 	/* Restore TLS pointer for this process. */
 	set_gateway_tls(current->thread.tls_ptr);

 	return (struct task_struct *) from.Switch.pPara;
 }

 void flush_thread(void)
 {
 	clear_fpu(&current->thread);
 	clear_dsp(&current->thread);
 }

 /*
  * Free current thread data structures etc.
  */
 void exit_thread(void)
 {
 	clear_fpu(&current->thread);
 	clear_dsp(&current->thread);
 }

 /* TODO: figure out how to unwind the kernel stack here to figure out
  * where we went to sleep. */
 unsigned long get_wchan(struct task_struct *p)
 {
 	return 0;
 }

 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 {
 	/* Returning 0 indicates that the FPU state was not stored (as it was
 	 * not in use) */
 	return 0;
 }

 #ifdef CONFIG_METAG_USER_TCM

 #define ELF_MIN_ALIGN	PAGE_SIZE

 #define ELF_PAGESTART(_v) ((_v) & ~(unsigned long)(ELF_MIN_ALIGN-1))
 #define ELF_PAGEOFFSET(_v) ((_v) & (ELF_MIN_ALIGN-1))
 #define ELF_PAGEALIGN(_v) (((_v) + ELF_MIN_ALIGN - 1) & ~(ELF_MIN_ALIGN - 1))

 #define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)

 unsigned long __metag_elf_map(struct file *filep, unsigned long addr,
 			      struct elf_phdr *eppnt, int prot, int type,
 			      unsigned long total_size)
 {
 	unsigned long map_addr, size;
 	unsigned long page_off = ELF_PAGEOFFSET(eppnt->p_vaddr);
 	unsigned long raw_size = eppnt->p_filesz + page_off;
 	unsigned long off = eppnt->p_offset - page_off;
 	unsigned int tcm_tag;
 	addr = ELF_PAGESTART(addr);
 	size = ELF_PAGEALIGN(raw_size);

 	/* mmap() will return -EINVAL if given a zero size, but a
 	 * segment with zero filesize is perfectly valid */
 	if (!size)
 		return addr;

 	tcm_tag = tcm_lookup_tag(addr);

 	if (tcm_tag != TCM_INVALID_TAG)
 		type &= ~MAP_FIXED;

 	/*
 	* total_size is the size of the ELF (interpreter) image.
 	* The _first_ mmap needs to know the full size, otherwise
 	* randomization might put this image into an overlapping
 	* position with the ELF binary image. (since size < total_size)
 	* So we first map the 'big' image - and unmap the remainder at
 	* the end. (which unmap is needed for ELF images with holes.)
 	*/
 	if (total_size) {
 		total_size = ELF_PAGEALIGN(total_size);
 		map_addr = vm_mmap(filep, addr, total_size, prot, type, off);
 		if (!BAD_ADDR(map_addr))
 			vm_munmap(map_addr+size, total_size-size);
 	} else
 		map_addr = vm_mmap(filep, addr, size, prot, type, off);

 	if (!BAD_ADDR(map_addr) && tcm_tag != TCM_INVALID_TAG) {
 		struct tcm_allocation *tcm;
 		unsigned long tcm_addr;

 		tcm = kmalloc(sizeof(*tcm), GFP_KERNEL);
 		if (!tcm)
 			return -ENOMEM;

 		tcm_addr = tcm_alloc(tcm_tag, raw_size);
 		if (tcm_addr != addr) {
 			kfree(tcm);
 			return -ENOMEM;
 		}

 		tcm->tag = tcm_tag;
 		tcm->addr = tcm_addr;
 		tcm->size = raw_size;

 		list_add(&tcm->list, &current->mm->context.tcm);

 		eppnt->p_vaddr = map_addr;
 		if (copy_from_user((void *) addr, (void __user *) map_addr,
 				   raw_size))
 			return -EFAULT;
 	}

 	return map_addr;
 }
 #endif
	/*
	* Copyright (C) 2005,2006,2007,2008,2009,2010,2011 Imagination Technologies
	*
	* This file contains the architecture-dependent parts of process handling.
	*
	*/

	#include <linux/errno.h>
	#include <linux/export.h>
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/unistd.h>
	#include <linux/ptrace.h>
	#include <linux/user.h>
	#include <linux/reboot.h>
	#include <linux/elfcore.h>
	#include <linux/fs.h>
	#include <linux/tick.h>
	#include <linux/slab.h>
	#include <linux/mman.h>
	#include <linux/pm.h>
	#include <linux/syscalls.h>
	#include <linux/uaccess.h>
	#include <linux/smp.h>
	#include <asm/core_reg.h>
	#include <asm/user_gateway.h>
	#include <asm/tcm.h>
	#include <asm/traps.h>
	#include <asm/switch_to.h>

	/*
	* Wait for the next interrupt and enable local interrupts
	*/
	void arch_cpu_idle(void)
	{
	int tmp;

	/*
	* Quickly jump straight into the interrupt entry point without actually
	* triggering an interrupt. When TXSTATI gets read the processor will
	* block until an interrupt is triggered.
	*/
	asm volatile (/* Switch into ISTAT mode */
	"RTH\n\t"
	/* Enable local interrupts */
	"MOV TXMASKI, %1\n\t"
	/*
	* We can't directly "SWAP PC, PCX", so we swap via a
	* temporary. Essentially we do:
	* PCX_new = 1f (the place to continue execution)
	* PC = PCX_old
	*/
	"ADD %0, CPC0, #(1f-.)\n\t"
	"SWAP PCX, %0\n\t"
	"MOV PC, %0\n"
	/* Continue execution here with interrupts enabled */
	"1:"
	: "=a" (tmp)
	: "r" (get_trigger_mask()));
	}

	#ifdef CONFIG_HOTPLUG_CPU
	void arch_cpu_idle_dead(void)
	{
	cpu_die();
	}
	#endif

	void (*pm_power_off)(void);
	EXPORT_SYMBOL(pm_power_off);

	void (soc_restart)(char cmd);
	void (*soc_halt)(void);

	void machine_restart(char *cmd)
	{
	if (soc_restart)
	soc_restart(cmd);
	hard_processor_halt(HALT_OK);
	}

	void machine_halt(void)
	{
	if (soc_halt)
	soc_halt();
	smp_send_stop();
	hard_processor_halt(HALT_OK);
	}

	void machine_power_off(void)
	{
	if (pm_power_off)
	pm_power_off();
	smp_send_stop();
	hard_processor_halt(HALT_OK);
	}

	#define FLAG_Z 0x8
	#define FLAG_N 0x4
	#define FLAG_O 0x2
	#define FLAG_C 0x1

	void show_regs(struct pt_regs *regs)
	{
	int i;
	const char *AX0_names[] = {"A0StP", "A0FrP"};
	const char *AX1_names[] = {"A1GbP", "A1LbP"};

	const char *DX0_names[] = {
	"D0Re0",
	"D0Ar6",
	"D0Ar4",
	"D0Ar2",
	"D0FrT",
	"D0.5 ",
	"D0.6 ",
	"D0.7 "
	};

	const char *DX1_names[] = {
	"D1Re0",
	"D1Ar5",
	"D1Ar3",
	"D1Ar1",
	"D1RtP",
	"D1.5 ",
	"D1.6 ",
	"D1.7 "
	};

	show_regs_print_info(KERN_INFO);

	pr_info(" pt_regs @ %p\n", regs);
	pr_info(" SaveMask = 0x%04hx\n", regs->ctx.SaveMask);
	pr_info(" Flags = 0x%04hx (%c%c%c%c)\n", regs->ctx.Flags,
	regs->ctx.Flags & FLAG_Z ? 'Z' : 'z',
	regs->ctx.Flags & FLAG_N ? 'N' : 'n',
	regs->ctx.Flags & FLAG_O ? 'O' : 'o',
	regs->ctx.Flags & FLAG_C ? 'C' : 'c');
	pr_info(" TXRPT = 0x%08x\n", regs->ctx.CurrRPT);
	pr_info(" PC = 0x%08x\n", regs->ctx.CurrPC);

	/* AX regs */
	for (i = 0; i < 2; i++) {
	pr_info(" %s = 0x%08x ",
	AX0_names[i],
	regs->ctx.AX[i].U0);
	printk(" %s = 0x%08x\n",
	AX1_names[i],
	regs->ctx.AX[i].U1);
	}

	if (regs->ctx.SaveMask & TBICTX_XEXT_BIT)
	pr_warn(" Extended state present - AX2.[01] will be WRONG\n");

	/* Special place with AXx.2 */
	pr_info(" A0.2 = 0x%08x ",
	regs->ctx.Ext.AX2.U0);
	printk(" A1.2 = 0x%08x\n",
	regs->ctx.Ext.AX2.U1);

	/* 'extended' AX regs (nominally, just AXx.3) */
	for (i = 0; i < (TBICTX_AX_REGS - 3); i++) {
	pr_info(" A0.%d = 0x%08x ", i + 3, regs->ctx.AX3[i].U0);
	printk(" A1.%d = 0x%08x\n", i + 3, regs->ctx.AX3[i].U1);
	}

	for (i = 0; i < 8; i++) {
	pr_info(" %s = 0x%08x ", DX0_names[i], regs->ctx.DX[i].U0);
	printk(" %s = 0x%08x\n", DX1_names[i], regs->ctx.DX[i].U1);
	}

	show_trace(NULL, (unsigned long *)regs->ctx.AX[0].U0, regs);
	}

	/*
	* Copy architecture-specific thread state
	*/
	int copy_thread(unsigned long clone_flags, unsigned long usp,
	unsigned long kthread_arg, struct task_struct *tsk)
	{
	struct pt_regs *childregs = task_pt_regs(tsk);
	void kernel_context = ((void ) childregs +
	sizeof(struct pt_regs));
	unsigned long global_base;

	BUG_ON(((unsigned long)childregs) & 0x7);
	BUG_ON(((unsigned long)kernel_context) & 0x7);

	memset(&tsk->thread.kernel_context, 0,
	sizeof(tsk->thread.kernel_context));

	tsk->thread.kernel_context = __TBISwitchInit(kernel_context,
	ret_from_fork,
	0, 0);

	if (unlikely(tsk->flags & PF_KTHREAD)) {
	/*
	* Make sure we don't leak any kernel data to child's regs
	* if kernel thread becomes a userspace thread in the future
	*/
	memset(childregs, 0 , sizeof(struct pt_regs));

	global_base = __core_reg_get(A1GbP);
	childregs->ctx.AX[0].U1 = (unsigned long) global_base;
	childregs->ctx.AX[0].U0 = (unsigned long) kernel_context;
	/* Set D1Ar1=kthread_arg and D1RtP=usp (fn) */
	childregs->ctx.DX[4].U1 = usp;
	childregs->ctx.DX[3].U1 = kthread_arg;
	tsk->thread.int_depth = 2;
	return 0;
	}

	/*
	* Get a pointer to where the new child's register block should have
	* been pushed.
	* The Meta's stack grows upwards, and the context is the the first
	* thing to be pushed by TBX (phew)
	*/
	childregs = current_pt_regs();
	/* Set the correct stack for the clone mode */
	if (usp)
	childregs->ctx.AX[0].U0 = ALIGN(usp, 8);
	tsk->thread.int_depth = 1;

	/* set return value for child process */
	childregs->ctx.DX[0].U0 = 0;

	/* The TLS pointer is passed as an argument to sys_clone. */
	if (clone_flags & CLONE_SETTLS)
	tsk->thread.tls_ptr =
	(__force void __user *)childregs->ctx.DX[1].U1;

	#ifdef CONFIG_METAG_FPU
	if (tsk->thread.fpu_context) {
	struct meta_fpu_context *ctx;

	ctx = kmemdup(tsk->thread.fpu_context,
	sizeof(struct meta_fpu_context), GFP_ATOMIC);
	tsk->thread.fpu_context = ctx;
	}
	#endif

	#ifdef CONFIG_METAG_DSP
	if (tsk->thread.dsp_context) {
	struct meta_ext_context *ctx;
	int i;

	ctx = kmemdup(tsk->thread.dsp_context,
	sizeof(struct meta_ext_context), GFP_ATOMIC);
	for (i = 0; i < 2; i++)
	ctx->ram[i] = kmemdup(ctx->ram[i], ctx->ram_sz[i],
	GFP_ATOMIC);
	tsk->thread.dsp_context = ctx;
	}
	#endif

	return 0;
	}

	#ifdef CONFIG_METAG_FPU
	static void alloc_fpu_context(struct thread_struct *thread)
	{
	thread->fpu_context = kzalloc(sizeof(struct meta_fpu_context),
	GFP_ATOMIC);
	}

	static void clear_fpu(struct thread_struct *thread)
	{
	thread->user_flags &= ~TBICTX_FPAC_BIT;
	kfree(thread->fpu_context);
	thread->fpu_context = NULL;
	}
	#else
	static void clear_fpu(struct thread_struct *thread)
	{
	}
	#endif

	#ifdef CONFIG_METAG_DSP
	static void clear_dsp(struct thread_struct *thread)
	{
	if (thread->dsp_context) {
	kfree(thread->dsp_context->ram[0]);
	kfree(thread->dsp_context->ram[1]);

	kfree(thread->dsp_context);

	thread->dsp_context = NULL;
	}

	__core_reg_set(D0.8, 0);
	}
	#else
	static void clear_dsp(struct thread_struct *thread)
	{
	}
	#endif

	struct task_struct __sched __switch_to(struct task_struct prev,
	struct task_struct *next)
	{
	TBIRES to, from;

	to.Switch.pCtx = next->thread.kernel_context;
	to.Switch.pPara = prev;

	#ifdef CONFIG_METAG_FPU
	if (prev->thread.user_flags & TBICTX_FPAC_BIT) {
	struct pt_regs *regs = task_pt_regs(prev);
	TBIRES state;

	state.Sig.SaveMask = prev->thread.user_flags;
	state.Sig.pCtx = &regs->ctx;

	if (!prev->thread.fpu_context)
	alloc_fpu_context(&prev->thread);
	if (prev->thread.fpu_context)
	__TBICtxFPUSave(state, prev->thread.fpu_context);
	}
	/*
	* Force a restore of the FPU context next time this process is
	* scheduled.
	*/
	if (prev->thread.fpu_context)
	prev->thread.fpu_context->needs_restore = true;
	#endif


	from = __TBISwitch(to, &prev->thread.kernel_context);

	/* Restore TLS pointer for this process. */
	set_gateway_tls(current->thread.tls_ptr);

	return (struct task_struct *) from.Switch.pPara;
	}

	void flush_thread(void)
	{
	clear_fpu(&current->thread);
	clear_dsp(&current->thread);
	}

	/*
	* Free current thread data structures etc.
	*/
	void exit_thread(void)
	{
	clear_fpu(&current->thread);
	clear_dsp(&current->thread);
	}

	/* TODO: figure out how to unwind the kernel stack here to figure out
	* where we went to sleep. */
	unsigned long get_wchan(struct task_struct *p)
	{
	return 0;
	}

	int dump_fpu(struct pt_regs regs, elf_fpregset_t fpu)
	{
	/* Returning 0 indicates that the FPU state was not stored (as it was
	* not in use) */
	return 0;
	}

	#ifdef CONFIG_METAG_USER_TCM

	#define ELF_MIN_ALIGN PAGE_SIZE

	#define ELF_PAGESTART(_v) ((_v) & ~(unsigned long)(ELF_MIN_ALIGN-1))
	#define ELF_PAGEOFFSET(_v) ((_v) & (ELF_MIN_ALIGN-1))
	#define ELF_PAGEALIGN(_v) (((_v) + ELF_MIN_ALIGN - 1) & ~(ELF_MIN_ALIGN - 1))

	#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)

	unsigned long __metag_elf_map(struct file *filep, unsigned long addr,
	struct elf_phdr *eppnt, int prot, int type,
	unsigned long total_size)
	{
	unsigned long map_addr, size;
	unsigned long page_off = ELF_PAGEOFFSET(eppnt->p_vaddr);
	unsigned long raw_size = eppnt->p_filesz + page_off;
	unsigned long off = eppnt->p_offset - page_off;
	unsigned int tcm_tag;
	addr = ELF_PAGESTART(addr);
	size = ELF_PAGEALIGN(raw_size);

	/* mmap() will return -EINVAL if given a zero size, but a
	* segment with zero filesize is perfectly valid */
	if (!size)
	return addr;

	tcm_tag = tcm_lookup_tag(addr);

	if (tcm_tag != TCM_INVALID_TAG)
	type &= ~MAP_FIXED;

	/*
	* total_size is the size of the ELF (interpreter) image.
	* The _first_ mmap needs to know the full size, otherwise
	* randomization might put this image into an overlapping
	* position with the ELF binary image. (since size < total_size)
	* So we first map the 'big' image - and unmap the remainder at
	* the end. (which unmap is needed for ELF images with holes.)
	*/
	if (total_size) {
	total_size = ELF_PAGEALIGN(total_size);
	map_addr = vm_mmap(filep, addr, total_size, prot, type, off);
	if (!BAD_ADDR(map_addr))
	vm_munmap(map_addr+size, total_size-size);
	} else
	map_addr = vm_mmap(filep, addr, size, prot, type, off);

	if (!BAD_ADDR(map_addr) && tcm_tag != TCM_INVALID_TAG) {
	struct tcm_allocation *tcm;
	unsigned long tcm_addr;

	tcm = kmalloc(sizeof(*tcm), GFP_KERNEL);
	if (!tcm)
	return -ENOMEM;

	tcm_addr = tcm_alloc(tcm_tag, raw_size);
	if (tcm_addr != addr) {
	kfree(tcm);
	return -ENOMEM;
	}

	tcm->tag = tcm_tag;
	tcm->addr = tcm_addr;
	tcm->size = raw_size;

	list_add(&tcm->list, &current->mm->context.tcm);

	eppnt->p_vaddr = map_addr;
	if (copy_from_user((void ) addr, (void __user ) map_addr,
	raw_size))
	return -EFAULT;
	}

	return map_addr;
	}
	#endif