arch/sparc/kernel/process.c - kernel/msm-4.19 - Gitiles

 /*  linux/arch/sparc/kernel/process.c
  *
  *  Copyright (C) 1995, 2008 David S. Miller (davem@davemloft.net)
  *  Copyright (C) 1996 Eddie C. Dost   (ecd@skynet.be)
  */

 /*
  * This file handles the architecture-dependent parts of process handling..
  */

 #include <stdarg.h>

 #include <linux/errno.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/stddef.h>
 #include <linux/ptrace.h>
 #include <linux/slab.h>
 #include <linux/user.h>
 #include <linux/smp.h>
 #include <linux/reboot.h>
 #include <linux/delay.h>
 #include <linux/pm.h>
 #include <linux/init.h>

 #include <asm/auxio.h>
 #include <asm/oplib.h>
 #include <asm/uaccess.h>
 #include <asm/system.h>
 #include <asm/page.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
 #include <asm/delay.h>
 #include <asm/processor.h>
 #include <asm/psr.h>
 #include <asm/elf.h>
 #include <asm/prom.h>
 #include <asm/unistd.h>

 /*
  * Power management idle function
  * Set in pm platform drivers (apc.c and pmc.c)
  */
 void (*pm_idle)(void);

 /*
  * Power-off handler instantiation for pm.h compliance
  * This is done via auxio, but could be used as a fallback
  * handler when auxio is not present-- unused for now...
  */
 void (*pm_power_off)(void) = machine_power_off;
 EXPORT_SYMBOL(pm_power_off);

 /*
  * sysctl - toggle power-off restriction for serial console
  * systems in machine_power_off()
  */
 int scons_pwroff = 1;

 extern void fpsave(unsigned long *, unsigned long *, void *, unsigned long *);

 struct task_struct *last_task_used_math = NULL;
 struct thread_info *current_set[NR_CPUS];

 #ifndef CONFIG_SMP

 #define SUN4C_FAULT_HIGH 100

 /*
  * the idle loop on a Sparc... ;)
  */
 void cpu_idle(void)
 {
 	/* endless idle loop with no priority at all */
 	for (;;) {
 		if (ARCH_SUN4C) {
 			static int count = HZ;
 			static unsigned long last_jiffies;
 			static unsigned long last_faults;
 			static unsigned long fps;
 			unsigned long now;
 			unsigned long faults;

 			extern unsigned long sun4c_kernel_faults;
 			extern void sun4c_grow_kernel_ring(void);

 			local_irq_disable();
 			now = jiffies;
 			count -= (now - last_jiffies);
 			last_jiffies = now;
 			if (count < 0) {
 				count += HZ;
 				faults = sun4c_kernel_faults;
 				fps = (fps + (faults - last_faults)) >> 1;
 				last_faults = faults;
 #if 0
 				printk("kernel faults / second = %ld\n", fps);
 #endif
 				if (fps >= SUN4C_FAULT_HIGH) {
 					sun4c_grow_kernel_ring();
 				}
 			}
 			local_irq_enable();
 		}

 		if (pm_idle) {
 			while (!need_resched())
 				(*pm_idle)();
 		} else {
 			while (!need_resched())
 				cpu_relax();
 		}
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
 		check_pgt_cache();
 	}
 }

 #else

 /* This is being executed in task 0 'user space'. */
 void cpu_idle(void)
 {
         set_thread_flag(TIF_POLLING_NRFLAG);
 	/* endless idle loop with no priority at all */
 	while(1) {
 		while (!need_resched())
 			cpu_relax();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
 		check_pgt_cache();
 	}
 }

 #endif

 /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
 void machine_halt(void)
 {
 	local_irq_enable();
 	mdelay(8);
 	local_irq_disable();
 	prom_halt();
 	panic("Halt failed!");
 }

 void machine_restart(char * cmd)
 {
 	char *p;

 	local_irq_enable();
 	mdelay(8);
 	local_irq_disable();

 	p = strchr (reboot_command, '\n');
 	if (p) *p = 0;
 	if (cmd)
 		prom_reboot(cmd);
 	if (*reboot_command)
 		prom_reboot(reboot_command);
 	prom_feval ("reset");
 	panic("Reboot failed!");
 }

 void machine_power_off(void)
 {
 #ifdef CONFIG_SUN_AUXIO
 	if (auxio_power_register &&
 	    (strcmp(of_console_device->type, "serial") || scons_pwroff))
 		*auxio_power_register |= AUXIO_POWER_OFF;
 #endif
 	machine_halt();
 }

 #if 0

 static DEFINE_SPINLOCK(sparc_backtrace_lock);

 void __show_backtrace(unsigned long fp)
 {
 	struct reg_window *rw;
 	unsigned long flags;
 	int cpu = smp_processor_id();

 	spin_lock_irqsave(&sparc_backtrace_lock, flags);

 	rw = (struct reg_window *)fp;
         while(rw && (((unsigned long) rw) >= PAGE_OFFSET) &&
             !(((unsigned long) rw) & 0x7)) {
 		printk("CPU[%d]: ARGS[%08lx,%08lx,%08lx,%08lx,%08lx,%08lx] "
 		       "FP[%08lx] CALLER[%08lx]: ", cpu,
 		       rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
 		       rw->ins[4], rw->ins[5],
 		       rw->ins[6],
 		       rw->ins[7]);
 		printk("%pS\n", (void *) rw->ins[7]);
 		rw = (struct reg_window *) rw->ins[6];
 	}
 	spin_unlock_irqrestore(&sparc_backtrace_lock, flags);
 }

 #define __SAVE __asm__ __volatile__("save %sp, -0x40, %sp\n\t")
 #define __RESTORE __asm__ __volatile__("restore %g0, %g0, %g0\n\t")
 #define __GET_FP(fp) __asm__ __volatile__("mov %%i6, %0" : "=r" (fp))

 void show_backtrace(void)
 {
 	unsigned long fp;

 	__SAVE; __SAVE; __SAVE; __SAVE;
 	__SAVE; __SAVE; __SAVE; __SAVE;
 	__RESTORE; __RESTORE; __RESTORE; __RESTORE;
 	__RESTORE; __RESTORE; __RESTORE; __RESTORE;

 	__GET_FP(fp);

 	__show_backtrace(fp);
 }

 #ifdef CONFIG_SMP
 void smp_show_backtrace_all_cpus(void)
 {
 	xc0((smpfunc_t) show_backtrace);
 	show_backtrace();
 }
 #endif

 void show_stackframe(struct sparc_stackf *sf)
 {
 	unsigned long size;
 	unsigned long *stk;
 	int i;

 	printk("l0: %08lx l1: %08lx l2: %08lx l3: %08lx "
 	       "l4: %08lx l5: %08lx l6: %08lx l7: %08lx\n",
 	       sf->locals[0], sf->locals[1], sf->locals[2], sf->locals[3],
 	       sf->locals[4], sf->locals[5], sf->locals[6], sf->locals[7]);
 	printk("i0: %08lx i1: %08lx i2: %08lx i3: %08lx "
 	       "i4: %08lx i5: %08lx fp: %08lx i7: %08lx\n",
 	       sf->ins[0], sf->ins[1], sf->ins[2], sf->ins[3],
 	       sf->ins[4], sf->ins[5], (unsigned long)sf->fp, sf->callers_pc);
 	printk("sp: %08lx x0: %08lx x1: %08lx x2: %08lx "
 	       "x3: %08lx x4: %08lx x5: %08lx xx: %08lx\n",
 	       (unsigned long)sf->structptr, sf->xargs[0], sf->xargs[1],
 	       sf->xargs[2], sf->xargs[3], sf->xargs[4], sf->xargs[5],
 	       sf->xxargs[0]);
 	size = ((unsigned long)sf->fp) - ((unsigned long)sf);
 	size -= STACKFRAME_SZ;
 	stk = (unsigned long *)((unsigned long)sf + STACKFRAME_SZ);
 	i = 0;
 	do {
 		printk("s%d: %08lx\n", i++, *stk++);
 	} while ((size -= sizeof(unsigned long)));
 }
 #endif

 void show_regs(struct pt_regs *r)
 {
 	struct reg_window *rw = (struct reg_window *) r->u_regs[14];

         printk("PSR: %08lx PC: %08lx NPC: %08lx Y: %08lx    %s\n",
 	       r->psr, r->pc, r->npc, r->y, print_tainted());
 	printk("PC: <%pS>\n", (void *) r->pc);
 	printk("%%G: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 	       r->u_regs[0], r->u_regs[1], r->u_regs[2], r->u_regs[3],
 	       r->u_regs[4], r->u_regs[5], r->u_regs[6], r->u_regs[7]);
 	printk("%%O: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 	       r->u_regs[8], r->u_regs[9], r->u_regs[10], r->u_regs[11],
 	       r->u_regs[12], r->u_regs[13], r->u_regs[14], r->u_regs[15]);
 	printk("RPC: <%pS>\n", (void *) r->u_regs[15]);

 	printk("%%L: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 	       rw->locals[0], rw->locals[1], rw->locals[2], rw->locals[3],
 	       rw->locals[4], rw->locals[5], rw->locals[6], rw->locals[7]);
 	printk("%%I: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
 	       rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
 	       rw->ins[4], rw->ins[5], rw->ins[6], rw->ins[7]);
 }

 /*
  * The show_stack is an external API which we do not use ourselves.
  * The oops is printed in die_if_kernel.
  */
 void show_stack(struct task_struct *tsk, unsigned long *_ksp)
 {
 	unsigned long pc, fp;
 	unsigned long task_base;
 	struct reg_window *rw;
 	int count = 0;

 	if (tsk != NULL)
 		task_base = (unsigned long) task_stack_page(tsk);
 	else
 		task_base = (unsigned long) current_thread_info();

 	fp = (unsigned long) _ksp;
 	do {
 		/* Bogus frame pointer? */
 		if (fp < (task_base + sizeof(struct thread_info)) ||
 		    fp >= (task_base + (PAGE_SIZE << 1)))
 			break;
 		rw = (struct reg_window *) fp;
 		pc = rw->ins[7];
 		printk("[%08lx : ", pc);
 		printk("%pS ] ", (void *) pc);
 		fp = rw->ins[6];
 	} while (++count < 16);
 	printk("\n");
 }

 void dump_stack(void)
 {
 	unsigned long *ksp;

 	__asm__ __volatile__("mov	%%fp, %0"
 			     : "=r" (ksp));
 	show_stack(current, ksp);
 }

 EXPORT_SYMBOL(dump_stack);

 /*
  * Note: sparc64 has a pretty intricated thread_saved_pc, check it out.
  */
 unsigned long thread_saved_pc(struct task_struct *tsk)
 {
 	return task_thread_info(tsk)->kpc;
 }

 /*
  * Free current thread data structures etc..
  */
 void exit_thread(void)
 {
 #ifndef CONFIG_SMP
 	if(last_task_used_math == current) {
 #else
 	if (test_thread_flag(TIF_USEDFPU)) {
 #endif
 		/* Keep process from leaving FPU in a bogon state. */
 		put_psr(get_psr() | PSR_EF);
 		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
 #ifndef CONFIG_SMP
 		last_task_used_math = NULL;
 #else
 		clear_thread_flag(TIF_USEDFPU);
 #endif
 	}
 }

 void flush_thread(void)
 {
 	current_thread_info()->w_saved = 0;

 #ifndef CONFIG_SMP
 	if(last_task_used_math == current) {
 #else
 	if (test_thread_flag(TIF_USEDFPU)) {
 #endif
 		/* Clean the fpu. */
 		put_psr(get_psr() | PSR_EF);
 		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
 #ifndef CONFIG_SMP
 		last_task_used_math = NULL;
 #else
 		clear_thread_flag(TIF_USEDFPU);
 #endif
 	}

 	/* Now, this task is no longer a kernel thread. */
 	current->thread.current_ds = USER_DS;
 	if (current->thread.flags & SPARC_FLAG_KTHREAD) {
 		current->thread.flags &= ~SPARC_FLAG_KTHREAD;

 		/* We must fixup kregs as well. */
 		/* XXX This was not fixed for ti for a while, worked. Unused? */
 		current->thread.kregs = (struct pt_regs *)
 		    (task_stack_page(current) + (THREAD_SIZE - TRACEREG_SZ));
 	}
 }

 static inline struct sparc_stackf __user *
 clone_stackframe(struct sparc_stackf __user *dst,
 		 struct sparc_stackf __user *src)
 {
 	unsigned long size, fp;
 	struct sparc_stackf *tmp;
 	struct sparc_stackf __user *sp;

 	if (get_user(tmp, &src->fp))
 		return NULL;

 	fp = (unsigned long) tmp;
 	size = (fp - ((unsigned long) src));
 	fp = (unsigned long) dst;
 	sp = (struct sparc_stackf __user *)(fp - size);

 	/* do_fork() grabs the parent semaphore, we must release it
 	 * temporarily so we can build the child clone stack frame
 	 * without deadlocking.
 	 */
 	if (__copy_user(sp, src, size))
 		sp = NULL;
 	else if (put_user(fp, &sp->fp))
 		sp = NULL;

 	return sp;
 }

 asmlinkage int sparc_do_fork(unsigned long clone_flags,
                              unsigned long stack_start,
                              struct pt_regs *regs,
                              unsigned long stack_size)
 {
 	unsigned long parent_tid_ptr, child_tid_ptr;
 	unsigned long orig_i1 = regs->u_regs[UREG_I1];
 	long ret;

 	parent_tid_ptr = regs->u_regs[UREG_I2];
 	child_tid_ptr = regs->u_regs[UREG_I4];

 	ret = do_fork(clone_flags, stack_start,
 		      regs, stack_size,
 		      (int __user *) parent_tid_ptr,
 		      (int __user *) child_tid_ptr);

 	/* If we get an error and potentially restart the system
 	 * call, we're screwed because copy_thread() clobbered
 	 * the parent's %o1.  So detect that case and restore it
 	 * here.
 	 */
 	if ((unsigned long)ret >= -ERESTART_RESTARTBLOCK)
 		regs->u_regs[UREG_I1] = orig_i1;

 	return ret;
 }

 /* Copy a Sparc thread.  The fork() return value conventions
  * under SunOS are nothing short of bletcherous:
  * Parent -->  %o0 == childs  pid, %o1 == 0
  * Child  -->  %o0 == parents pid, %o1 == 1
  *
  * NOTE: We have a separate fork kpsr/kwim because
  *       the parent could change these values between
  *       sys_fork invocation and when we reach here
  *       if the parent should sleep while trying to
  *       allocate the task_struct and kernel stack in
  *       do_fork().
  * XXX See comment above sys_vfork in sparc64. todo.
  */
 extern void ret_from_fork(void);

 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
 		unsigned long unused,
 		struct task_struct *p, struct pt_regs *regs)
 {
 	struct thread_info *ti = task_thread_info(p);
 	struct pt_regs *childregs;
 	char *new_stack;

 #ifndef CONFIG_SMP
 	if(last_task_used_math == current) {
 #else
 	if (test_thread_flag(TIF_USEDFPU)) {
 #endif
 		put_psr(get_psr() | PSR_EF);
 		fpsave(&p->thread.float_regs[0], &p->thread.fsr,
 		       &p->thread.fpqueue[0], &p->thread.fpqdepth);
 #ifdef CONFIG_SMP
 		clear_thread_flag(TIF_USEDFPU);
 #endif
 	}

 	/*
 	 *  p->thread_info         new_stack   childregs
 	 *  !                      !           !             {if(PSR_PS) }
 	 *  V                      V (stk.fr.) V  (pt_regs)  { (stk.fr.) }
 	 *  +----- - - - - - ------+===========+============={+==========}+
 	 */
 	new_stack = task_stack_page(p) + THREAD_SIZE;
 	if (regs->psr & PSR_PS)
 		new_stack -= STACKFRAME_SZ;
 	new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
 	memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
 	childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);

 	/*
 	 * A new process must start with interrupts closed in 2.5,
 	 * because this is how Mingo's scheduler works (see schedule_tail
 	 * and finish_arch_switch). If we do not do it, a timer interrupt hits
 	 * before we unlock, attempts to re-take the rq->lock, and then we die.
 	 * Thus, kpsr|=PSR_PIL.
 	 */
 	ti->ksp = (unsigned long) new_stack;
 	ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
 	ti->kpsr = current->thread.fork_kpsr | PSR_PIL;
 	ti->kwim = current->thread.fork_kwim;

 	if(regs->psr & PSR_PS) {
 		extern struct pt_regs fake_swapper_regs;

 		p->thread.kregs = &fake_swapper_regs;
 		new_stack += STACKFRAME_SZ + TRACEREG_SZ;
 		childregs->u_regs[UREG_FP] = (unsigned long) new_stack;
 		p->thread.flags |= SPARC_FLAG_KTHREAD;
 		p->thread.current_ds = KERNEL_DS;
 		memcpy(new_stack, (void *)regs->u_regs[UREG_FP], STACKFRAME_SZ);
 		childregs->u_regs[UREG_G6] = (unsigned long) ti;
 	} else {
 		p->thread.kregs = childregs;
 		childregs->u_regs[UREG_FP] = sp;
 		p->thread.flags &= ~SPARC_FLAG_KTHREAD;
 		p->thread.current_ds = USER_DS;

 		if (sp != regs->u_regs[UREG_FP]) {
 			struct sparc_stackf __user *childstack;
 			struct sparc_stackf __user *parentstack;

 			/*
 			 * This is a clone() call with supplied user stack.
 			 * Set some valid stack frames to give to the child.
 			 */
 			childstack = (struct sparc_stackf __user *)
 				(sp & ~0x7UL);
 			parentstack = (struct sparc_stackf __user *)
 				regs->u_regs[UREG_FP];

 #if 0
 			printk("clone: parent stack:\n");
 			show_stackframe(parentstack);
 #endif

 			childstack = clone_stackframe(childstack, parentstack);
 			if (!childstack)
 				return -EFAULT;

 #if 0
 			printk("clone: child stack:\n");
 			show_stackframe(childstack);
 #endif

 			childregs->u_regs[UREG_FP] = (unsigned long)childstack;
 		}
 	}

 #ifdef CONFIG_SMP
 	/* FPU must be disabled on SMP. */
 	childregs->psr &= ~PSR_EF;
 #endif

 	/* Set the return value for the child. */
 	childregs->u_regs[UREG_I0] = current->pid;
 	childregs->u_regs[UREG_I1] = 1;

 	/* Set the return value for the parent. */
 	regs->u_regs[UREG_I1] = 0;

 	if (clone_flags & CLONE_SETTLS)
 		childregs->u_regs[UREG_G7] = regs->u_regs[UREG_I3];

 	return 0;
 }

 /*
  * fill in the fpu structure for a core dump.
  */
 int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
 {
 	if (used_math()) {
 		memset(fpregs, 0, sizeof(*fpregs));
 		fpregs->pr_q_entrysize = 8;
 		return 1;
 	}
 #ifdef CONFIG_SMP
 	if (test_thread_flag(TIF_USEDFPU)) {
 		put_psr(get_psr() | PSR_EF);
 		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
 		if (regs != NULL) {
 			regs->psr &= ~(PSR_EF);
 			clear_thread_flag(TIF_USEDFPU);
 		}
 	}
 #else
 	if (current == last_task_used_math) {
 		put_psr(get_psr() | PSR_EF);
 		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
 		if (regs != NULL) {
 			regs->psr &= ~(PSR_EF);
 			last_task_used_math = NULL;
 		}
 	}
 #endif
 	memcpy(&fpregs->pr_fr.pr_regs[0],
 	       &current->thread.float_regs[0],
 	       (sizeof(unsigned long) * 32));
 	fpregs->pr_fsr = current->thread.fsr;
 	fpregs->pr_qcnt = current->thread.fpqdepth;
 	fpregs->pr_q_entrysize = 8;
 	fpregs->pr_en = 1;
 	if(fpregs->pr_qcnt != 0) {
 		memcpy(&fpregs->pr_q[0],
 		       &current->thread.fpqueue[0],
 		       sizeof(struct fpq) * fpregs->pr_qcnt);
 	}
 	/* Zero out the rest. */
 	memset(&fpregs->pr_q[fpregs->pr_qcnt], 0,
 	       sizeof(struct fpq) * (32 - fpregs->pr_qcnt));
 	return 1;
 }

 /*
  * sparc_execve() executes a new program after the asm stub has set
  * things up for us.  This should basically do what I want it to.
  */
 asmlinkage int sparc_execve(struct pt_regs *regs)
 {
 	int error, base = 0;
 	char *filename;

 	/* Check for indirect call. */
 	if(regs->u_regs[UREG_G1] == 0)
 		base = 1;

 	filename = getname((char __user *)regs->u_regs[base + UREG_I0]);
 	error = PTR_ERR(filename);
 	if(IS_ERR(filename))
 		goto out;
 	error = do_execve(filename,
 			  (char __user * __user *)regs->u_regs[base + UREG_I1],
 			  (char __user * __user *)regs->u_regs[base + UREG_I2],
 			  regs);
 	putname(filename);
 out:
 	return error;
 }

 /*
  * This is the mechanism for creating a new kernel thread.
  *
  * NOTE! Only a kernel-only process(ie the swapper or direct descendants
  * who haven't done an "execve()") should use this: it will work within
  * a system call from a "real" process, but the process memory space will
  * not be freed until both the parent and the child have exited.
  */
 pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 {
 	long retval;

 	__asm__ __volatile__("mov %4, %%g2\n\t"    /* Set aside fn ptr... */
 			     "mov %5, %%g3\n\t"    /* and arg. */
 			     "mov %1, %%g1\n\t"
 			     "mov %2, %%o0\n\t"    /* Clone flags. */
 			     "mov 0, %%o1\n\t"     /* usp arg == 0 */
 			     "t 0x10\n\t"          /* Linux/Sparc clone(). */
 			     "cmp %%o1, 0\n\t"
 			     "be 1f\n\t"           /* The parent, just return. */
 			     " nop\n\t"            /* Delay slot. */
 			     "jmpl %%g2, %%o7\n\t" /* Call the function. */
 			     " mov %%g3, %%o0\n\t" /* Get back the arg in delay. */
 			     "mov %3, %%g1\n\t"
 			     "t 0x10\n\t"          /* Linux/Sparc exit(). */
 			     /* Notreached by child. */
 			     "1: mov %%o0, %0\n\t" :
 			     "=r" (retval) :
 			     "i" (__NR_clone), "r" (flags | CLONE_VM | CLONE_UNTRACED),
 			     "i" (__NR_exit),  "r" (fn), "r" (arg) :
 			     "g1", "g2", "g3", "o0", "o1", "memory", "cc");
 	return retval;
 }

 unsigned long get_wchan(struct task_struct *task)
 {
 	unsigned long pc, fp, bias = 0;
 	unsigned long task_base = (unsigned long) task;
         unsigned long ret = 0;
 	struct reg_window *rw;
 	int count = 0;

 	if (!task || task == current ||
             task->state == TASK_RUNNING)
 		goto out;

 	fp = task_thread_info(task)->ksp + bias;
 	do {
 		/* Bogus frame pointer? */
 		if (fp < (task_base + sizeof(struct thread_info)) ||
 		    fp >= (task_base + (2 * PAGE_SIZE)))
 			break;
 		rw = (struct reg_window *) fp;
 		pc = rw->ins[7];
 		if (!in_sched_functions(pc)) {
 			ret = pc;
 			goto out;
 		}
 		fp = rw->ins[6] + bias;
 	} while (++count < 16);

 out:
 	return ret;
 }
	/* linux/arch/sparc/kernel/process.c
	*
	* Copyright (C) 1995, 2008 David S. Miller (davem@davemloft.net)
	* Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
	*/

	/*
	* This file handles the architecture-dependent parts of process handling..
	*/

	#include <stdarg.h>

	#include <linux/errno.h>
	#include <linux/module.h>
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/stddef.h>
	#include <linux/ptrace.h>
	#include <linux/slab.h>
	#include <linux/user.h>
	#include <linux/smp.h>
	#include <linux/reboot.h>
	#include <linux/delay.h>
	#include <linux/pm.h>
	#include <linux/init.h>

	#include <asm/auxio.h>
	#include <asm/oplib.h>
	#include <asm/uaccess.h>
	#include <asm/system.h>
	#include <asm/page.h>
	#include <asm/pgalloc.h>
	#include <asm/pgtable.h>
	#include <asm/delay.h>
	#include <asm/processor.h>
	#include <asm/psr.h>
	#include <asm/elf.h>
	#include <asm/prom.h>
	#include <asm/unistd.h>

	/*
	* Power management idle function
	* Set in pm platform drivers (apc.c and pmc.c)
	*/
	void (*pm_idle)(void);

	/*
	* Power-off handler instantiation for pm.h compliance
	* This is done via auxio, but could be used as a fallback
	* handler when auxio is not present-- unused for now...
	*/
	void (*pm_power_off)(void) = machine_power_off;
	EXPORT_SYMBOL(pm_power_off);

	/*
	* sysctl - toggle power-off restriction for serial console
	* systems in machine_power_off()
	*/
	int scons_pwroff = 1;

	extern void fpsave(unsigned long , unsigned long , void , unsigned long );

	struct task_struct *last_task_used_math = NULL;
	struct thread_info *current_set[NR_CPUS];

	#ifndef CONFIG_SMP

	#define SUN4C_FAULT_HIGH 100

	/*
	* the idle loop on a Sparc... ;)
	*/
	void cpu_idle(void)
	{
	/* endless idle loop with no priority at all */
	for (;;) {
	if (ARCH_SUN4C) {
	static int count = HZ;
	static unsigned long last_jiffies;
	static unsigned long last_faults;
	static unsigned long fps;
	unsigned long now;
	unsigned long faults;

	extern unsigned long sun4c_kernel_faults;
	extern void sun4c_grow_kernel_ring(void);

	local_irq_disable();
	now = jiffies;
	count -= (now - last_jiffies);
	last_jiffies = now;
	if (count < 0) {
	count += HZ;
	faults = sun4c_kernel_faults;
	fps = (fps + (faults - last_faults)) >> 1;
	last_faults = faults;
	#if 0
	printk("kernel faults / second = %ld\n", fps);
	#endif
	if (fps >= SUN4C_FAULT_HIGH) {
	sun4c_grow_kernel_ring();
	}
	}
	local_irq_enable();
	}

	if (pm_idle) {
	while (!need_resched())
	(*pm_idle)();
	} else {
	while (!need_resched())
	cpu_relax();
	}
	preempt_enable_no_resched();
	schedule();
	preempt_disable();
	check_pgt_cache();
	}
	}

	#else

	/* This is being executed in task 0 'user space'. */
	void cpu_idle(void)
	{
	set_thread_flag(TIF_POLLING_NRFLAG);
	/* endless idle loop with no priority at all */
	while(1) {
	while (!need_resched())
	cpu_relax();
	preempt_enable_no_resched();
	schedule();
	preempt_disable();
	check_pgt_cache();
	}
	}

	#endif

	/* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
	void machine_halt(void)
	{
	local_irq_enable();
	mdelay(8);
	local_irq_disable();
	prom_halt();
	panic("Halt failed!");
	}

	void machine_restart(char * cmd)
	{
	char *p;

	local_irq_enable();
	mdelay(8);
	local_irq_disable();

	p = strchr (reboot_command, '\n');
	if (p) *p = 0;
	if (cmd)
	prom_reboot(cmd);
	if (*reboot_command)
	prom_reboot(reboot_command);
	prom_feval ("reset");
	panic("Reboot failed!");
	}

	void machine_power_off(void)
	{
	#ifdef CONFIG_SUN_AUXIO
	if (auxio_power_register &&
	(strcmp(of_console_device->type, "serial") \|\| scons_pwroff))
	*auxio_power_register \|= AUXIO_POWER_OFF;
	#endif
	machine_halt();
	}

	#if 0

	static DEFINE_SPINLOCK(sparc_backtrace_lock);

	void __show_backtrace(unsigned long fp)
	{
	struct reg_window *rw;
	unsigned long flags;
	int cpu = smp_processor_id();

	spin_lock_irqsave(&sparc_backtrace_lock, flags);

	rw = (struct reg_window *)fp;
	while(rw && (((unsigned long) rw) >= PAGE_OFFSET) &&
	!(((unsigned long) rw) & 0x7)) {
	printk("CPU[%d]: ARGS[%08lx,%08lx,%08lx,%08lx,%08lx,%08lx] "
	"FP[%08lx] CALLER[%08lx]: ", cpu,
	rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
	rw->ins[4], rw->ins[5],
	rw->ins[6],
	rw->ins[7]);
	printk("%pS\n", (void *) rw->ins[7]);
	rw = (struct reg_window *) rw->ins[6];
	}
	spin_unlock_irqrestore(&sparc_backtrace_lock, flags);
	}

	#define __SAVE __asm__ __volatile__("save %sp, -0x40, %sp\n\t")
	#define __RESTORE __asm__ __volatile__("restore %g0, %g0, %g0\n\t")
	#define __GET_FP(fp) __asm__ __volatile__("mov %%i6, %0" : "=r" (fp))

	void show_backtrace(void)
	{
	unsigned long fp;

	__SAVE; __SAVE; __SAVE; __SAVE;
	__SAVE; __SAVE; __SAVE; __SAVE;
	__RESTORE; __RESTORE; __RESTORE; __RESTORE;
	__RESTORE; __RESTORE; __RESTORE; __RESTORE;

	__GET_FP(fp);

	__show_backtrace(fp);
	}

	#ifdef CONFIG_SMP
	void smp_show_backtrace_all_cpus(void)
	{
	xc0((smpfunc_t) show_backtrace);
	show_backtrace();
	}
	#endif

	void show_stackframe(struct sparc_stackf *sf)
	{
	unsigned long size;
	unsigned long *stk;
	int i;

	printk("l0: %08lx l1: %08lx l2: %08lx l3: %08lx "
	"l4: %08lx l5: %08lx l6: %08lx l7: %08lx\n",
	sf->locals[0], sf->locals[1], sf->locals[2], sf->locals[3],
	sf->locals[4], sf->locals[5], sf->locals[6], sf->locals[7]);
	printk("i0: %08lx i1: %08lx i2: %08lx i3: %08lx "
	"i4: %08lx i5: %08lx fp: %08lx i7: %08lx\n",
	sf->ins[0], sf->ins[1], sf->ins[2], sf->ins[3],
	sf->ins[4], sf->ins[5], (unsigned long)sf->fp, sf->callers_pc);
	printk("sp: %08lx x0: %08lx x1: %08lx x2: %08lx "
	"x3: %08lx x4: %08lx x5: %08lx xx: %08lx\n",
	(unsigned long)sf->structptr, sf->xargs[0], sf->xargs[1],
	sf->xargs[2], sf->xargs[3], sf->xargs[4], sf->xargs[5],
	sf->xxargs[0]);
	size = ((unsigned long)sf->fp) - ((unsigned long)sf);
	size -= STACKFRAME_SZ;
	stk = (unsigned long *)((unsigned long)sf + STACKFRAME_SZ);
	i = 0;
	do {
	printk("s%d: %08lx\n", i++, *stk++);
	} while ((size -= sizeof(unsigned long)));
	}
	#endif

	void show_regs(struct pt_regs *r)
	{
	struct reg_window rw = (struct reg_window ) r->u_regs[14];

	printk("PSR: %08lx PC: %08lx NPC: %08lx Y: %08lx %s\n",
	r->psr, r->pc, r->npc, r->y, print_tainted());
	printk("PC: <%pS>\n", (void *) r->pc);
	printk("%%G: %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
	r->u_regs[0], r->u_regs[1], r->u_regs[2], r->u_regs[3],
	r->u_regs[4], r->u_regs[5], r->u_regs[6], r->u_regs[7]);
	printk("%%O: %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
	r->u_regs[8], r->u_regs[9], r->u_regs[10], r->u_regs[11],
	r->u_regs[12], r->u_regs[13], r->u_regs[14], r->u_regs[15]);
	printk("RPC: <%pS>\n", (void *) r->u_regs[15]);

	printk("%%L: %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
	rw->locals[0], rw->locals[1], rw->locals[2], rw->locals[3],
	rw->locals[4], rw->locals[5], rw->locals[6], rw->locals[7]);
	printk("%%I: %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
	rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
	rw->ins[4], rw->ins[5], rw->ins[6], rw->ins[7]);
	}

	/*
	* The show_stack is an external API which we do not use ourselves.
	* The oops is printed in die_if_kernel.
	*/
	void show_stack(struct task_struct tsk, unsigned long _ksp)
	{
	unsigned long pc, fp;
	unsigned long task_base;
	struct reg_window *rw;
	int count = 0;

	if (tsk != NULL)
	task_base = (unsigned long) task_stack_page(tsk);
	else
	task_base = (unsigned long) current_thread_info();

	fp = (unsigned long) _ksp;
	do {
	/* Bogus frame pointer? */
	if (fp < (task_base + sizeof(struct thread_info)) \|\|
	fp >= (task_base + (PAGE_SIZE << 1)))
	break;
	rw = (struct reg_window *) fp;
	pc = rw->ins[7];
	printk("[%08lx : ", pc);
	printk("%pS ] ", (void *) pc);
	fp = rw->ins[6];
	} while (++count < 16);
	printk("\n");
	}

	void dump_stack(void)
	{
	unsigned long *ksp;

	__asm__ __volatile__("mov %%fp, %0"
	: "=r" (ksp));
	show_stack(current, ksp);
	}

	EXPORT_SYMBOL(dump_stack);

	/*
	* Note: sparc64 has a pretty intricated thread_saved_pc, check it out.
	*/
	unsigned long thread_saved_pc(struct task_struct *tsk)
	{
	return task_thread_info(tsk)->kpc;
	}

	/*
	* Free current thread data structures etc..
	*/
	void exit_thread(void)
	{
	#ifndef CONFIG_SMP
	if(last_task_used_math == current) {
	#else
	if (test_thread_flag(TIF_USEDFPU)) {
	#endif
	/* Keep process from leaving FPU in a bogon state. */
	put_psr(get_psr() \| PSR_EF);
	fpsave(&current->thread.float_regs[0], &current->thread.fsr,
	&current->thread.fpqueue[0], &current->thread.fpqdepth);
	#ifndef CONFIG_SMP
	last_task_used_math = NULL;
	#else
	clear_thread_flag(TIF_USEDFPU);
	#endif
	}
	}

	void flush_thread(void)
	{
	current_thread_info()->w_saved = 0;

	#ifndef CONFIG_SMP
	if(last_task_used_math == current) {
	#else
	if (test_thread_flag(TIF_USEDFPU)) {
	#endif
	/* Clean the fpu. */
	put_psr(get_psr() \| PSR_EF);
	fpsave(&current->thread.float_regs[0], &current->thread.fsr,
	&current->thread.fpqueue[0], &current->thread.fpqdepth);
	#ifndef CONFIG_SMP
	last_task_used_math = NULL;
	#else
	clear_thread_flag(TIF_USEDFPU);
	#endif
	}

	/* Now, this task is no longer a kernel thread. */
	current->thread.current_ds = USER_DS;
	if (current->thread.flags & SPARC_FLAG_KTHREAD) {
	current->thread.flags &= ~SPARC_FLAG_KTHREAD;

	/* We must fixup kregs as well. */
	/* XXX This was not fixed for ti for a while, worked. Unused? */
	current->thread.kregs = (struct pt_regs *)
	(task_stack_page(current) + (THREAD_SIZE - TRACEREG_SZ));
	}
	}

	static inline struct sparc_stackf __user *
	clone_stackframe(struct sparc_stackf __user *dst,
	struct sparc_stackf __user *src)
	{
	unsigned long size, fp;
	struct sparc_stackf *tmp;
	struct sparc_stackf __user *sp;

	if (get_user(tmp, &src->fp))
	return NULL;

	fp = (unsigned long) tmp;
	size = (fp - ((unsigned long) src));
	fp = (unsigned long) dst;
	sp = (struct sparc_stackf __user *)(fp - size);

	/* do_fork() grabs the parent semaphore, we must release it
	* temporarily so we can build the child clone stack frame
	* without deadlocking.
	*/
	if (__copy_user(sp, src, size))
	sp = NULL;
	else if (put_user(fp, &sp->fp))
	sp = NULL;

	return sp;
	}

	asmlinkage int sparc_do_fork(unsigned long clone_flags,
	unsigned long stack_start,
	struct pt_regs *regs,
	unsigned long stack_size)
	{
	unsigned long parent_tid_ptr, child_tid_ptr;
	unsigned long orig_i1 = regs->u_regs[UREG_I1];
	long ret;

	parent_tid_ptr = regs->u_regs[UREG_I2];
	child_tid_ptr = regs->u_regs[UREG_I4];

	ret = do_fork(clone_flags, stack_start,
	regs, stack_size,
	(int __user *) parent_tid_ptr,
	(int __user *) child_tid_ptr);

	/* If we get an error and potentially restart the system
	* call, we're screwed because copy_thread() clobbered
	* the parent's %o1. So detect that case and restore it
	* here.
	*/
	if ((unsigned long)ret >= -ERESTART_RESTARTBLOCK)
	regs->u_regs[UREG_I1] = orig_i1;

	return ret;
	}

	/* Copy a Sparc thread. The fork() return value conventions
	* under SunOS are nothing short of bletcherous:
	* Parent --> %o0 == childs pid, %o1 == 0
	* Child --> %o0 == parents pid, %o1 == 1
	*
	* NOTE: We have a separate fork kpsr/kwim because
	* the parent could change these values between
	* sys_fork invocation and when we reach here
	* if the parent should sleep while trying to
	* allocate the task_struct and kernel stack in
	* do_fork().
	* XXX See comment above sys_vfork in sparc64. todo.
	*/
	extern void ret_from_fork(void);

	int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
	unsigned long unused,
	struct task_struct p, struct pt_regs regs)
	{
	struct thread_info *ti = task_thread_info(p);
	struct pt_regs *childregs;
	char *new_stack;

	#ifndef CONFIG_SMP
	if(last_task_used_math == current) {
	#else
	if (test_thread_flag(TIF_USEDFPU)) {
	#endif
	put_psr(get_psr() \| PSR_EF);
	fpsave(&p->thread.float_regs[0], &p->thread.fsr,
	&p->thread.fpqueue[0], &p->thread.fpqdepth);
	#ifdef CONFIG_SMP
	clear_thread_flag(TIF_USEDFPU);
	#endif
	}

	/*
	* p->thread_info new_stack childregs
	* ! ! ! {if(PSR_PS) }
	* V V (stk.fr.) V (pt_regs) { (stk.fr.) }
	* +----- - - - - - ------+===========+============={+==========}+
	*/
	new_stack = task_stack_page(p) + THREAD_SIZE;
	if (regs->psr & PSR_PS)
	new_stack -= STACKFRAME_SZ;
	new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
	memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
	childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);

	/*
	* A new process must start with interrupts closed in 2.5,
	* because this is how Mingo's scheduler works (see schedule_tail
	* and finish_arch_switch). If we do not do it, a timer interrupt hits
	* before we unlock, attempts to re-take the rq->lock, and then we die.
	* Thus, kpsr\|=PSR_PIL.
	*/
	ti->ksp = (unsigned long) new_stack;
	ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
	ti->kpsr = current->thread.fork_kpsr \| PSR_PIL;
	ti->kwim = current->thread.fork_kwim;

	if(regs->psr & PSR_PS) {
	extern struct pt_regs fake_swapper_regs;

	p->thread.kregs = &fake_swapper_regs;
	new_stack += STACKFRAME_SZ + TRACEREG_SZ;
	childregs->u_regs[UREG_FP] = (unsigned long) new_stack;
	p->thread.flags \|= SPARC_FLAG_KTHREAD;
	p->thread.current_ds = KERNEL_DS;
	memcpy(new_stack, (void *)regs->u_regs[UREG_FP], STACKFRAME_SZ);
	childregs->u_regs[UREG_G6] = (unsigned long) ti;
	} else {
	p->thread.kregs = childregs;
	childregs->u_regs[UREG_FP] = sp;
	p->thread.flags &= ~SPARC_FLAG_KTHREAD;
	p->thread.current_ds = USER_DS;

	if (sp != regs->u_regs[UREG_FP]) {
	struct sparc_stackf __user *childstack;
	struct sparc_stackf __user *parentstack;

	/*
	* This is a clone() call with supplied user stack.
	* Set some valid stack frames to give to the child.
	*/
	childstack = (struct sparc_stackf __user *)
	(sp & ~0x7UL);
	parentstack = (struct sparc_stackf __user *)
	regs->u_regs[UREG_FP];

	#if 0
	printk("clone: parent stack:\n");
	show_stackframe(parentstack);
	#endif

	childstack = clone_stackframe(childstack, parentstack);
	if (!childstack)
	return -EFAULT;

	#if 0
	printk("clone: child stack:\n");
	show_stackframe(childstack);
	#endif

	childregs->u_regs[UREG_FP] = (unsigned long)childstack;
	}
	}

	#ifdef CONFIG_SMP
	/* FPU must be disabled on SMP. */
	childregs->psr &= ~PSR_EF;
	#endif

	/* Set the return value for the child. */
	childregs->u_regs[UREG_I0] = current->pid;
	childregs->u_regs[UREG_I1] = 1;

	/* Set the return value for the parent. */
	regs->u_regs[UREG_I1] = 0;

	if (clone_flags & CLONE_SETTLS)
	childregs->u_regs[UREG_G7] = regs->u_regs[UREG_I3];

	return 0;
	}

	/*
	* fill in the fpu structure for a core dump.
	*/
	int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
	{
	if (used_math()) {
	memset(fpregs, 0, sizeof(*fpregs));
	fpregs->pr_q_entrysize = 8;
	return 1;
	}
	#ifdef CONFIG_SMP
	if (test_thread_flag(TIF_USEDFPU)) {
	put_psr(get_psr() \| PSR_EF);
	fpsave(&current->thread.float_regs[0], &current->thread.fsr,
	&current->thread.fpqueue[0], &current->thread.fpqdepth);
	if (regs != NULL) {
	regs->psr &= ~(PSR_EF);
	clear_thread_flag(TIF_USEDFPU);
	}
	}
	#else
	if (current == last_task_used_math) {
	put_psr(get_psr() \| PSR_EF);
	fpsave(&current->thread.float_regs[0], &current->thread.fsr,
	&current->thread.fpqueue[0], &current->thread.fpqdepth);
	if (regs != NULL) {
	regs->psr &= ~(PSR_EF);
	last_task_used_math = NULL;
	}
	}
	#endif
	memcpy(&fpregs->pr_fr.pr_regs[0],
	&current->thread.float_regs[0],
	(sizeof(unsigned long) * 32));
	fpregs->pr_fsr = current->thread.fsr;
	fpregs->pr_qcnt = current->thread.fpqdepth;
	fpregs->pr_q_entrysize = 8;
	fpregs->pr_en = 1;
	if(fpregs->pr_qcnt != 0) {
	memcpy(&fpregs->pr_q[0],
	&current->thread.fpqueue[0],
	sizeof(struct fpq) * fpregs->pr_qcnt);
	}
	/* Zero out the rest. */
	memset(&fpregs->pr_q[fpregs->pr_qcnt], 0,
	sizeof(struct fpq) * (32 - fpregs->pr_qcnt));
	return 1;
	}

	/*
	* sparc_execve() executes a new program after the asm stub has set
	* things up for us. This should basically do what I want it to.
	*/
	asmlinkage int sparc_execve(struct pt_regs *regs)
	{
	int error, base = 0;
	char *filename;

	/* Check for indirect call. */
	if(regs->u_regs[UREG_G1] == 0)
	base = 1;

	filename = getname((char __user *)regs->u_regs[base + UREG_I0]);
	error = PTR_ERR(filename);
	if(IS_ERR(filename))
	goto out;
	error = do_execve(filename,
	(char __user * __user *)regs->u_regs[base + UREG_I1],
	(char __user * __user *)regs->u_regs[base + UREG_I2],
	regs);
	putname(filename);
	out:
	return error;
	}

	/*
	* This is the mechanism for creating a new kernel thread.
	*
	* NOTE! Only a kernel-only process(ie the swapper or direct descendants
	* who haven't done an "execve()") should use this: it will work within
	* a system call from a "real" process, but the process memory space will
	* not be freed until both the parent and the child have exited.
	*/
	pid_t kernel_thread(int (fn)(void ), void * arg, unsigned long flags)
	{
	long retval;

	__asm__ __volatile__("mov %4, %%g2\n\t" /* Set aside fn ptr... */
	"mov %5, %%g3\n\t" /* and arg. */
	"mov %1, %%g1\n\t"
	"mov %2, %%o0\n\t" /* Clone flags. */
	"mov 0, %%o1\n\t" /* usp arg == 0 */
	"t 0x10\n\t" /* Linux/Sparc clone(). */
	"cmp %%o1, 0\n\t"
	"be 1f\n\t" /* The parent, just return. */
	" nop\n\t" /* Delay slot. */
	"jmpl %%g2, %%o7\n\t" /* Call the function. */
	" mov %%g3, %%o0\n\t" /* Get back the arg in delay. */
	"mov %3, %%g1\n\t"
	"t 0x10\n\t" /* Linux/Sparc exit(). */
	/* Notreached by child. */
	"1: mov %%o0, %0\n\t" :
	"=r" (retval) :
	"i" (__NR_clone), "r" (flags \| CLONE_VM \| CLONE_UNTRACED),
	"i" (__NR_exit), "r" (fn), "r" (arg) :
	"g1", "g2", "g3", "o0", "o1", "memory", "cc");
	return retval;
	}

	unsigned long get_wchan(struct task_struct *task)
	{
	unsigned long pc, fp, bias = 0;
	unsigned long task_base = (unsigned long) task;
	unsigned long ret = 0;
	struct reg_window *rw;
	int count = 0;

	if (!task \|\| task == current \|\|
	task->state == TASK_RUNNING)
	goto out;

	fp = task_thread_info(task)->ksp + bias;
	do {
	/* Bogus frame pointer? */
	if (fp < (task_base + sizeof(struct thread_info)) \|\|
	fp >= (task_base + (2 * PAGE_SIZE)))
	break;
	rw = (struct reg_window *) fp;
	pc = rw->ins[7];
	if (!in_sched_functions(pc)) {
	ret = pc;
	goto out;
	}
	fp = rw->ins[6] + bias;
	} while (++count < 16);

	out:
	return ret;
	}