sparc: prepare kernel/ for unification

o sparc32 files with identical names to sparc64 renamed to <name>_32.S
o introduced a few Kconfig helpers to simplify Makefile logic
o refactored Makefile to prepare for unification
  - use obj-$(CONFIG_SPARC32) for sparc32 specific files
  - use <name>_$(BITS) for files where sparc64 has a _64 variant
  - sparc64 directly include a few files where sparc32 builds them,
    refer to these files directly (no BITS)
  - sneaked in -Werror as used by sparc64
o modified sparc/Makefile to use the new names for head/init_task

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 709 insertions, 0 deletions

diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
new file mode 100644
index 000000000000..e8c43ffe317e
--- /dev/null
+++ b/arch/sparc/kernel/process_32.c
@@ -0,0 +1,709 @@
+/*  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;
+}
+