Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile

* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile:
  arch/tile: check kmalloc() result
  arch/tile: catch up on various minor cleanups.
  arch/tile: avoid erroneous error return for PTRACE_POKEUSR.
  tile: set ARCH_KMALLOC_MINALIGN
  tile: remove homegrown L1_CACHE_ALIGN macro
  arch/tile: Miscellaneous cleanup changes.
  arch/tile: Split the icache flush code off to a generic <arch> header.
  arch/tile: Fix bug in support for atomic64_xx() ops.
  arch/tile: Shrink the tile-opcode files considerably.
  arch/tile: Add driver to enable access to the user dynamic network.
  arch/tile: Enable more sophisticated IRQ model for 32-bit chips.
  Move list types from <linux/list.h> to <linux/types.h>.
  Add wait4() back to the set of <asm-generic/unistd.h> syscalls.
  Revert adding some arch-specific signal syscalls to <linux/syscalls.h>.
  arch/tile: Do not use GFP_KERNEL for dma_alloc_coherent(). Feedback from fujita.tomonori@lab.ntt.co.jp.
  arch/tile: core support for Tilera 32-bit chips.
  Fix up the "generic" unistd.h ABI to be more useful.

1 files changed, 671 insertions, 0 deletions

diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
new file mode 100644
index 000000000000..ed590ad0acdc
--- /dev/null
+++ b/arch/tile/kernel/process.c
@@ -0,0 +1,671 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#include <linux/sched.h>
+#include <linux/preempt.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/kprobes.h>
+#include <linux/elfcore.h>
+#include <linux/tick.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/compat.h>
+#include <linux/hardirq.h>
+#include <linux/syscalls.h>
+#include <linux/kernel.h>
+#include <asm/system.h>
+#include <asm/stack.h>
+#include <asm/homecache.h>
+#include <asm/syscalls.h>
+#ifdef CONFIG_HARDWALL
+#include <asm/hardwall.h>
+#endif
+#include <arch/chip.h>
+#include <arch/abi.h>
+
+
+/*
+ * Use the (x86) "idle=poll" option to prefer low latency when leaving the
+ * idle loop over low power while in the idle loop, e.g. if we have
+ * one thread per core and we want to get threads out of futex waits fast.
+ */
+static int no_idle_nap;
+static int __init idle_setup(char *str)
+{
+	if (!str)
+		return -EINVAL;
+
+	if (!strcmp(str, "poll")) {
+		pr_info("using polling idle threads.\n");
+		no_idle_nap = 1;
+	} else if (!strcmp(str, "halt"))
+		no_idle_nap = 0;
+	else
+		return -1;
+
+	return 0;
+}
+early_param("idle", idle_setup);
+
+/*
+ * The idle thread. There's no useful work to be
+ * done, so just try to conserve power and have a
+ * low exit latency (ie sit in a loop waiting for
+ * somebody to say that they'd like to reschedule)
+ */
+void cpu_idle(void)
+{
+	int cpu = smp_processor_id();
+
+
+	current_thread_info()->status |= TS_POLLING;
+
+	if (no_idle_nap) {
+		while (1) {
+			while (!need_resched())
+				cpu_relax();
+			schedule();
+		}
+	}
+
+	/* endless idle loop with no priority at all */
+	while (1) {
+		tick_nohz_stop_sched_tick(1);
+		while (!need_resched()) {
+			if (cpu_is_offline(cpu))
+				BUG();  /* no HOTPLUG_CPU */
+
+			local_irq_disable();
+			__get_cpu_var(irq_stat).idle_timestamp = jiffies;
+			current_thread_info()->status &= ~TS_POLLING;
+			/*
+			 * TS_POLLING-cleared state must be visible before we
+			 * test NEED_RESCHED:
+			 */
+			smp_mb();
+
+			if (!need_resched())
+				_cpu_idle();
+			else
+				local_irq_enable();
+			current_thread_info()->status |= TS_POLLING;
+		}
+		tick_nohz_restart_sched_tick();
+		preempt_enable_no_resched();
+		schedule();
+		preempt_disable();
+	}
+}
+
+struct thread_info *alloc_thread_info(struct task_struct *task)
+{
+	struct page *page;
+	gfp_t flags = GFP_KERNEL;
+
+#ifdef CONFIG_DEBUG_STACK_USAGE
+	flags |= __GFP_ZERO;
+#endif
+
+	page = alloc_pages(flags, THREAD_SIZE_ORDER);
+	if (!page)
+		return NULL;
+
+	return (struct thread_info *)page_address(page);
+}
+
+/*
+ * Free a thread_info node, and all of its derivative
+ * data structures.
+ */
+void free_thread_info(struct thread_info *info)
+{
+	struct single_step_state *step_state = info->step_state;
+
+#ifdef CONFIG_HARDWALL
+	/*
+	 * We free a thread_info from the context of the task that has
+	 * been scheduled next, so the original task is already dead.
+	 * Calling deactivate here just frees up the data structures.
+	 * If the task we're freeing held the last reference to a
+	 * hardwall fd, it would have been released prior to this point
+	 * anyway via exit_files(), and "hardwall" would be NULL by now.
+	 */
+	if (info->task->thread.hardwall)
+		hardwall_deactivate(info->task);
+#endif
+
+	if (step_state) {
+
+		/*
+		 * FIXME: we don't munmap step_state->buffer
+		 * because the mm_struct for this process (info->task->mm)
+		 * has already been zeroed in exit_mm().  Keeping a
+		 * reference to it here seems like a bad move, so this
+		 * means we can't munmap() the buffer, and therefore if we
+		 * ptrace multiple threads in a process, we will slowly
+		 * leak user memory.  (Note that as soon as the last
+		 * thread in a process dies, we will reclaim all user
+		 * memory including single-step buffers in the usual way.)
+		 * We should either assign a kernel VA to this buffer
+		 * somehow, or we should associate the buffer(s) with the
+		 * mm itself so we can clean them up that way.
+		 */
+		kfree(step_state);
+	}
+
+	free_page((unsigned long)info);
+}
+
+static void save_arch_state(struct thread_struct *t);
+
+int copy_thread(unsigned long clone_flags, unsigned long sp,
+		unsigned long stack_size,
+		struct task_struct *p, struct pt_regs *regs)
+{
+	struct pt_regs *childregs;
+	unsigned long ksp;
+
+	/*
+	 * When creating a new kernel thread we pass sp as zero.
+	 * Assign it to a reasonable value now that we have the stack.
+	 */
+	if (sp == 0 && regs->ex1 == PL_ICS_EX1(KERNEL_PL, 0))
+		sp = KSTK_TOP(p);
+
+	/*
+	 * Do not clone step state from the parent; each thread
+	 * must make its own lazily.
+	 */
+	task_thread_info(p)->step_state = NULL;
+
+	/*
+	 * Start new thread in ret_from_fork so it schedules properly
+	 * and then return from interrupt like the parent.
+	 */
+	p->thread.pc = (unsigned long) ret_from_fork;
+
+	/* Save user stack top pointer so we can ID the stack vm area later. */
+	p->thread.usp0 = sp;
+
+	/* Record the pid of the process that created this one. */
+	p->thread.creator_pid = current->pid;
+
+	/*
+	 * Copy the registers onto the kernel stack so the
+	 * return-from-interrupt code will reload it into registers.
+	 */
+	childregs = task_pt_regs(p);
+	*childregs = *regs;
+	childregs->regs[0] = 0;         /* return value is zero */
+	childregs->sp = sp;  /* override with new user stack pointer */
+
+	/*
+	 * Copy the callee-saved registers from the passed pt_regs struct
+	 * into the context-switch callee-saved registers area.
+	 * We have to restore the callee-saved registers since we may
+	 * be cloning a userspace task with userspace register state,
+	 * and we won't be unwinding the same kernel frames to restore them.
+	 * Zero out the C ABI save area to mark the top of the stack.
+	 */
+	ksp = (unsigned long) childregs;
+	ksp -= C_ABI_SAVE_AREA_SIZE;   /* interrupt-entry save area */
+	((long *)ksp)[0] = ((long *)ksp)[1] = 0;
+	ksp -= CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long);
+	memcpy((void *)ksp, &regs->regs[CALLEE_SAVED_FIRST_REG],
+	       CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));
+	ksp -= C_ABI_SAVE_AREA_SIZE;   /* __switch_to() save area */
+	((long *)ksp)[0] = ((long *)ksp)[1] = 0;
+	p->thread.ksp = ksp;
+
+#if CHIP_HAS_TILE_DMA()
+	/*
+	 * No DMA in the new thread.  We model this on the fact that
+	 * fork() clears the pending signals, alarms, and aio for the child.
+	 */
+	memset(&p->thread.tile_dma_state, 0, sizeof(struct tile_dma_state));
+	memset(&p->thread.dma_async_tlb, 0, sizeof(struct async_tlb));
+#endif
+
+#if CHIP_HAS_SN_PROC()
+	/* Likewise, the new thread is not running static processor code. */
+	p->thread.sn_proc_running = 0;
+	memset(&p->thread.sn_async_tlb, 0, sizeof(struct async_tlb));
+#endif
+
+#if CHIP_HAS_PROC_STATUS_SPR()
+	/* New thread has its miscellaneous processor state bits clear. */
+	p->thread.proc_status = 0;
+#endif
+
+#ifdef CONFIG_HARDWALL
+	/* New thread does not own any networks. */
+	p->thread.hardwall = NULL;
+#endif
+
+
+	/*
+	 * Start the new thread with the current architecture state
+	 * (user interrupt masks, etc.).
+	 */
+	save_arch_state(&p->thread);
+
+	return 0;
+}
+
+/*
+ * Return "current" if it looks plausible, or else a pointer to a dummy.
+ * This can be helpful if we are just trying to emit a clean panic.
+ */
+struct task_struct *validate_current(void)
+{
+	static struct task_struct corrupt = { .comm = "<corrupt>" };
+	struct task_struct *tsk = current;
+	if (unlikely((unsigned long)tsk < PAGE_OFFSET ||
+		     (void *)tsk > high_memory ||
+		     ((unsigned long)tsk & (__alignof__(*tsk) - 1)) != 0)) {
+		pr_err("Corrupt 'current' %p (sp %#lx)\n", tsk, stack_pointer);
+		tsk = &corrupt;
+	}
+	return tsk;
+}
+
+/* Take and return the pointer to the previous task, for schedule_tail(). */
+struct task_struct *sim_notify_fork(struct task_struct *prev)
+{
+	struct task_struct *tsk = current;
+	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_FORK_PARENT |
+		     (tsk->thread.creator_pid << _SIM_CONTROL_OPERATOR_BITS));
+	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_FORK |
+		     (tsk->pid << _SIM_CONTROL_OPERATOR_BITS));
+	return prev;
+}
+
+int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
+{
+	struct pt_regs *ptregs = task_pt_regs(tsk);
+	elf_core_copy_regs(regs, ptregs);
+	return 1;
+}
+
+#if CHIP_HAS_TILE_DMA()
+
+/* Allow user processes to access the DMA SPRs */
+void grant_dma_mpls(void)
+{
+	__insn_mtspr(SPR_MPL_DMA_CPL_SET_0, 1);
+	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_0, 1);
+}
+
+/* Forbid user processes from accessing the DMA SPRs */
+void restrict_dma_mpls(void)
+{
+	__insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
+	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
+}
+
+/* Pause the DMA engine, then save off its state registers. */
+static void save_tile_dma_state(struct tile_dma_state *dma)
+{
+	unsigned long state = __insn_mfspr(SPR_DMA_USER_STATUS);
+	unsigned long post_suspend_state;
+
+	/* If we're running, suspend the engine. */
+	if ((state & DMA_STATUS_MASK) == SPR_DMA_STATUS__RUNNING_MASK)
+		__insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__SUSPEND_MASK);
+
+	/*
+	 * Wait for the engine to idle, then save regs.  Note that we
+	 * want to record the "running" bit from before suspension,
+	 * and the "done" bit from after, so that we can properly
+	 * distinguish a case where the user suspended the engine from
+	 * the case where the kernel suspended as part of the context
+	 * swap.
+	 */
+	do {
+		post_suspend_state = __insn_mfspr(SPR_DMA_USER_STATUS);
+	} while (post_suspend_state & SPR_DMA_STATUS__BUSY_MASK);
+
+	dma->src = __insn_mfspr(SPR_DMA_SRC_ADDR);
+	dma->src_chunk = __insn_mfspr(SPR_DMA_SRC_CHUNK_ADDR);
+	dma->dest = __insn_mfspr(SPR_DMA_DST_ADDR);
+	dma->dest_chunk = __insn_mfspr(SPR_DMA_DST_CHUNK_ADDR);
+	dma->strides = __insn_mfspr(SPR_DMA_STRIDE);
+	dma->chunk_size = __insn_mfspr(SPR_DMA_CHUNK_SIZE);
+	dma->byte = __insn_mfspr(SPR_DMA_BYTE);
+	dma->status = (state & SPR_DMA_STATUS__RUNNING_MASK) |
+		(post_suspend_state & SPR_DMA_STATUS__DONE_MASK);
+}
+
+/* Restart a DMA that was running before we were context-switched out. */
+static void restore_tile_dma_state(struct thread_struct *t)
+{
+	const struct tile_dma_state *dma = &t->tile_dma_state;
+
+	/*
+	 * The only way to restore the done bit is to run a zero
+	 * length transaction.
+	 */
+	if ((dma->status & SPR_DMA_STATUS__DONE_MASK) &&
+	    !(__insn_mfspr(SPR_DMA_USER_STATUS) & SPR_DMA_STATUS__DONE_MASK)) {
+		__insn_mtspr(SPR_DMA_BYTE, 0);
+		__insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK);
+		while (__insn_mfspr(SPR_DMA_USER_STATUS) &
+		       SPR_DMA_STATUS__BUSY_MASK)
+			;
+	}
+
+	__insn_mtspr(SPR_DMA_SRC_ADDR, dma->src);
+	__insn_mtspr(SPR_DMA_SRC_CHUNK_ADDR, dma->src_chunk);
+	__insn_mtspr(SPR_DMA_DST_ADDR, dma->dest);
+	__insn_mtspr(SPR_DMA_DST_CHUNK_ADDR, dma->dest_chunk);
+	__insn_mtspr(SPR_DMA_STRIDE, dma->strides);
+	__insn_mtspr(SPR_DMA_CHUNK_SIZE, dma->chunk_size);
+	__insn_mtspr(SPR_DMA_BYTE, dma->byte);
+
+	/*
+	 * Restart the engine if we were running and not done.
+	 * Clear a pending async DMA fault that we were waiting on return
+	 * to user space to execute, since we expect the DMA engine
+	 * to regenerate those faults for us now.  Note that we don't
+	 * try to clear the TIF_ASYNC_TLB flag, since it's relatively
+	 * harmless if set, and it covers both DMA and the SN processor.
+	 */
+	if ((dma->status & DMA_STATUS_MASK) == SPR_DMA_STATUS__RUNNING_MASK) {
+		t->dma_async_tlb.fault_num = 0;
+		__insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK);
+	}
+}
+
+#endif
+
+static void save_arch_state(struct thread_struct *t)
+{
+#if CHIP_HAS_SPLIT_INTR_MASK()
+	t->interrupt_mask = __insn_mfspr(SPR_INTERRUPT_MASK_0_0) |
+		((u64)__insn_mfspr(SPR_INTERRUPT_MASK_0_1) << 32);
+#else
+	t->interrupt_mask = __insn_mfspr(SPR_INTERRUPT_MASK_0);
+#endif
+	t->ex_context[0] = __insn_mfspr(SPR_EX_CONTEXT_0_0);
+	t->ex_context[1] = __insn_mfspr(SPR_EX_CONTEXT_0_1);
+	t->system_save[0] = __insn_mfspr(SPR_SYSTEM_SAVE_0_0);
+	t->system_save[1] = __insn_mfspr(SPR_SYSTEM_SAVE_0_1);
+	t->system_save[2] = __insn_mfspr(SPR_SYSTEM_SAVE_0_2);
+	t->system_save[3] = __insn_mfspr(SPR_SYSTEM_SAVE_0_3);
+	t->intctrl_0 = __insn_mfspr(SPR_INTCTRL_0_STATUS);
+#if CHIP_HAS_PROC_STATUS_SPR()
+	t->proc_status = __insn_mfspr(SPR_PROC_STATUS);
+#endif
+}
+
+static void restore_arch_state(const struct thread_struct *t)
+{
+#if CHIP_HAS_SPLIT_INTR_MASK()
+	__insn_mtspr(SPR_INTERRUPT_MASK_0_0, (u32) t->interrupt_mask);
+	__insn_mtspr(SPR_INTERRUPT_MASK_0_1, t->interrupt_mask >> 32);
+#else
+	__insn_mtspr(SPR_INTERRUPT_MASK_0, t->interrupt_mask);
+#endif
+	__insn_mtspr(SPR_EX_CONTEXT_0_0, t->ex_context[0]);
+	__insn_mtspr(SPR_EX_CONTEXT_0_1, t->ex_context[1]);
+	__insn_mtspr(SPR_SYSTEM_SAVE_0_0, t->system_save[0]);
+	__insn_mtspr(SPR_SYSTEM_SAVE_0_1, t->system_save[1]);
+	__insn_mtspr(SPR_SYSTEM_SAVE_0_2, t->system_save[2]);
+	__insn_mtspr(SPR_SYSTEM_SAVE_0_3, t->system_save[3]);
+	__insn_mtspr(SPR_INTCTRL_0_STATUS, t->intctrl_0);
+#if CHIP_HAS_PROC_STATUS_SPR()
+	__insn_mtspr(SPR_PROC_STATUS, t->proc_status);
+#endif
+#if CHIP_HAS_TILE_RTF_HWM()
+	/*
+	 * Clear this whenever we switch back to a process in case
+	 * the previous process was monkeying with it.  Even if enabled
+	 * in CBOX_MSR1 via TILE_RTF_HWM_MIN, it's still just a
+	 * performance hint, so isn't worth a full save/restore.
+	 */
+	__insn_mtspr(SPR_TILE_RTF_HWM, 0);
+#endif
+}
+
+
+void _prepare_arch_switch(struct task_struct *next)
+{
+#if CHIP_HAS_SN_PROC()
+	int snctl;
+#endif
+#if CHIP_HAS_TILE_DMA()
+	struct tile_dma_state *dma = &current->thread.tile_dma_state;
+	if (dma->enabled)
+		save_tile_dma_state(dma);
+#endif
+#if CHIP_HAS_SN_PROC()
+	/*
+	 * Suspend the static network processor if it was running.
+	 * We do not suspend the fabric itself, just like we don't
+	 * try to suspend the UDN.
+	 */
+	snctl = __insn_mfspr(SPR_SNCTL);
+	current->thread.sn_proc_running =
+		(snctl & SPR_SNCTL__FRZPROC_MASK) == 0;
+	if (current->thread.sn_proc_running)
+		__insn_mtspr(SPR_SNCTL, snctl | SPR_SNCTL__FRZPROC_MASK);
+#endif
+}
+
+
+struct task_struct *__sched _switch_to(struct task_struct *prev,
+				       struct task_struct *next)
+{
+	/* DMA state is already saved; save off other arch state. */
+	save_arch_state(&prev->thread);
+
+#if CHIP_HAS_TILE_DMA()
+	/*
+	 * Restore DMA in new task if desired.
+	 * Note that it is only safe to restart here since interrupts
+	 * are disabled, so we can't take any DMATLB miss or access
+	 * interrupts before we have finished switching stacks.
+	 */
+	if (next->thread.tile_dma_state.enabled) {
+		restore_tile_dma_state(&next->thread);
+		grant_dma_mpls();
+	} else {
+		restrict_dma_mpls();
+	}
+#endif
+
+	/* Restore other arch state. */
+	restore_arch_state(&next->thread);
+
+#if CHIP_HAS_SN_PROC()
+	/*
+	 * Restart static network processor in the new process
+	 * if it was running before.
+	 */
+	if (next->thread.sn_proc_running) {
+		int snctl = __insn_mfspr(SPR_SNCTL);
+		__insn_mtspr(SPR_SNCTL, snctl & ~SPR_SNCTL__FRZPROC_MASK);
+	}
+#endif
+
+#ifdef CONFIG_HARDWALL
+	/* Enable or disable access to the network registers appropriately. */
+	if (prev->thread.hardwall != NULL) {
+		if (next->thread.hardwall == NULL)
+			restrict_network_mpls();
+	} else if (next->thread.hardwall != NULL) {
+		grant_network_mpls();
+	}
+#endif
+
+	/*
+	 * Switch kernel SP, PC, and callee-saved registers.
+	 * In the context of the new task, return the old task pointer
+	 * (i.e. the task that actually called __switch_to).
+	 * Pass the value to use for SYSTEM_SAVE_1_0 when we reset our sp.
+	 */
+	return __switch_to(prev, next, next_current_ksp0(next));
+}
+
+long _sys_fork(struct pt_regs *regs)
+{
+	return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
+}
+
+long _sys_clone(unsigned long clone_flags, unsigned long newsp,
+		void __user *parent_tidptr, void __user *child_tidptr,
+		struct pt_regs *regs)
+{
+	if (!newsp)
+		newsp = regs->sp;
+	return do_fork(clone_flags, newsp, regs, 0,
+		       parent_tidptr, child_tidptr);
+}
+
+long _sys_vfork(struct pt_regs *regs)
+{
+	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp,
+		       regs, 0, NULL, NULL);
+}
+
+/*
+ * sys_execve() executes a new program.
+ */
+long _sys_execve(char __user *path, char __user *__user *argv,
+		 char __user *__user *envp, struct pt_regs *regs)
+{
+	long error;
+	char *filename;
+
+	filename = getname(path);
+	error = PTR_ERR(filename);
+	if (IS_ERR(filename))
+		goto out;
+	error = do_execve(filename, argv, envp, regs);
+	putname(filename);
+out:
+	return error;
+}
+
+#ifdef CONFIG_COMPAT
+long _compat_sys_execve(char __user *path, compat_uptr_t __user *argv,
+			compat_uptr_t __user *envp, struct pt_regs *regs)
+{
+	long error;
+	char *filename;
+
+	filename = getname(path);
+	error = PTR_ERR(filename);
+	if (IS_ERR(filename))
+		goto out;
+	error = compat_do_execve(filename, argv, envp, regs);
+	putname(filename);
+out:
+	return error;
+}
+#endif
+
+unsigned long get_wchan(struct task_struct *p)
+{
+	struct KBacktraceIterator kbt;
+
+	if (!p || p == current || p->state == TASK_RUNNING)
+		return 0;
+
+	for (KBacktraceIterator_init(&kbt, p, NULL);
+	     !KBacktraceIterator_end(&kbt);
+	     KBacktraceIterator_next(&kbt)) {
+		if (!in_sched_functions(kbt.it.pc))
+			return kbt.it.pc;
+	}
+
+	return 0;
+}
+
+/*
+ * We pass in lr as zero (cleared in kernel_thread) and the caller
+ * part of the backtrace ABI on the stack also zeroed (in copy_thread)
+ * so that backtraces will stop with this function.
+ * Note that we don't use r0, since copy_thread() clears it.
+ */
+static void start_kernel_thread(int dummy, int (*fn)(int), int arg)
+{
+	do_exit(fn(arg));
+}
+
+/*
+ * Create a kernel thread
+ */
+int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+{
+	struct pt_regs regs;
+
+	memset(&regs, 0, sizeof(regs));
+	regs.ex1 = PL_ICS_EX1(KERNEL_PL, 0);  /* run at kernel PL, no ICS */
+	regs.pc = (long) start_kernel_thread;
+	regs.flags = PT_FLAGS_CALLER_SAVES;   /* need to restore r1 and r2 */
+	regs.regs[1] = (long) fn;             /* function pointer */
+	regs.regs[2] = (long) arg;            /* parameter register */
+
+	/* Ok, create the new process.. */
+	return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs,
+		       0, NULL, NULL);
+}
+EXPORT_SYMBOL(kernel_thread);
+
+/* Flush thread state. */
+void flush_thread(void)
+{
+	/* Nothing */
+}
+
+/*
+ * Free current thread data structures etc..
+ */
+void exit_thread(void)
+{
+	/* Nothing */
+}
+
+void show_regs(struct pt_regs *regs)
+{
+	struct task_struct *tsk = validate_current();
+	int i;
+
+	pr_err("\n");
+	pr_err(" Pid: %d, comm: %20s, CPU: %d\n",
+	       tsk->pid, tsk->comm, smp_processor_id());
+#ifdef __tilegx__
+	for (i = 0; i < 51; i += 3)
+		pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
+		       i, regs->regs[i], i+1, regs->regs[i+1],
+		       i+2, regs->regs[i+2]);
+	pr_err(" r51: "REGFMT" r52: "REGFMT" tp : "REGFMT"\n",
+	       regs->regs[51], regs->regs[52], regs->tp);
+	pr_err(" sp : "REGFMT" lr : "REGFMT"\n", regs->sp, regs->lr);
+#else
+	for (i = 0; i < 52; i += 3)
+		pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT
+		       " r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
+		       i, regs->regs[i], i+1, regs->regs[i+1],
+		       i+2, regs->regs[i+2], i+3, regs->regs[i+3]);
+	pr_err(" r52: "REGFMT" tp : "REGFMT" sp : "REGFMT" lr : "REGFMT"\n",
+	       regs->regs[52], regs->tp, regs->sp, regs->lr);
+#endif
+	pr_err(" pc : "REGFMT" ex1: %ld     faultnum: %ld\n",
+	       regs->pc, regs->ex1, regs->faultnum);
+
+	dump_stack_regs(regs);
+}