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

 /*
  * 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 <linux/tracehook.h>
 #include <linux/signal.h>
 #include <linux/delay.h>
 #include <linux/context_tracking.h>
 #include <asm/stack.h>
 #include <asm/switch_to.h>
 #include <asm/homecache.h>
 #include <asm/syscalls.h>
 #include <asm/traps.h>
 #include <asm/setup.h>
 #include <asm/uaccess.h>
 #ifdef CONFIG_HARDWALL
 #include <asm/hardwall.h>
 #endif
 #include <arch/chip.h>
 #include <arch/abi.h>
 #include <arch/sim_def.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 __init idle_setup(char *str)
 {
 	if (!str)
 		return -EINVAL;

 	if (!strcmp(str, "poll")) {
 		pr_info("using polling idle threads\n");
 		cpu_idle_poll_ctrl(true);
 		return 0;
 	} else if (!strcmp(str, "halt")) {
 		return 0;
 	}
 	return -1;
 }
 early_param("idle", idle_setup);

 void arch_cpu_idle(void)
 {
 	__this_cpu_write(irq_stat.idle_timestamp, jiffies);
 	_cpu_idle();
 }

 /*
  * Release a thread_info structure
  */
 void arch_release_thread_info(struct thread_info *info)
 {
 	struct single_step_state *step_state = info->step_state;

 	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);
 	}
 }

 static void save_arch_state(struct thread_struct *t);

 int copy_thread(unsigned long clone_flags, unsigned long sp,
 		unsigned long arg, struct task_struct *p)
 {
 	struct pt_regs *childregs = task_pt_regs(p);
 	unsigned long ksp;
 	unsigned long *callee_regs;

 	/*
 	 * Set up the stack and stack pointer appropriately for the
 	 * new child to find itself woken up in __switch_to().
 	 * The callee-saved registers must be on the stack to be read;
 	 * the new task will then jump to assembly support to handle
 	 * calling schedule_tail(), etc., and (for userspace tasks)
 	 * returning to the context set up in the pt_regs.
 	 */
 	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);
 	callee_regs = (unsigned long *)ksp;
 	ksp -= C_ABI_SAVE_AREA_SIZE;   /* __switch_to() save area */
 	((long *)ksp)[0] = ((long *)ksp)[1] = 0;
 	p->thread.ksp = ksp;

 	/* Record the pid of the task that created this one. */
 	p->thread.creator_pid = current->pid;

 	if (unlikely(p->flags & PF_KTHREAD)) {
 		/* kernel thread */
 		memset(childregs, 0, sizeof(struct pt_regs));
 		memset(&callee_regs[2], 0,
 		       (CALLEE_SAVED_REGS_COUNT - 2) * sizeof(unsigned long));
 		callee_regs[0] = sp;   /* r30 = function */
 		callee_regs[1] = arg;  /* r31 = arg */
 		p->thread.pc = (unsigned long) ret_from_kernel_thread;
 		return 0;
 	}

 	/*
 	 * 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;

 	/*
 	 * Do not clone step state from the parent; each thread
 	 * must make its own lazily.
 	 */
 	task_thread_info(p)->step_state = NULL;

 #ifdef __tilegx__
 	/*
 	 * Do not clone unalign jit fixup from the parent; each thread
 	 * must allocate its own on demand.
 	 */
 	task_thread_info(p)->unalign_jit_base = NULL;
 #endif

 	/*
 	 * Copy the registers onto the kernel stack so the
 	 * return-from-interrupt code will reload it into registers.
 	 */
 	*childregs = *current_pt_regs();
 	childregs->regs[0] = 0;         /* return value is zero */
 	if (sp)
 		childregs->sp = sp;  /* override with new user stack pointer */
 	memcpy(callee_regs, &childregs->regs[CALLEE_SAVED_FIRST_REG],
 	       CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));

 	/* Save user stack top pointer so we can ID the stack vm area later. */
 	p->thread.usp0 = childregs->sp;

 	/*
 	 * If CLONE_SETTLS is set, set "tp" in the new task to "r4",
 	 * which is passed in as arg #5 to sys_clone().
 	 */
 	if (clone_flags & CLONE_SETTLS)
 		childregs->tp = childregs->regs[4];


 #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

 	/* New thread has its miscellaneous processor state bits clear. */
 	p->thread.proc_status = 0;

 #ifdef CONFIG_HARDWALL
 	/* New thread does not own any networks. */
 	memset(&p->thread.hardwall[0], 0,
 	       sizeof(struct hardwall_task) * HARDWALL_TYPES);
 #endif


 	/*
 	 * Start the new thread with the current architecture state
 	 * (user interrupt masks, etc.).
 	 */
 	save_arch_state(&p->thread);

 	return 0;
 }

 int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
 {
 	task_thread_info(tsk)->align_ctl = val;
 	return 0;
 }

 int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
 {
 	return put_user(task_thread_info(tsk)->align_ctl,
 			(unsigned int __user *)adr);
 }

 static struct task_struct corrupt_current = { .comm = "<corrupt>" };

 /*
  * 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)
 {
 	struct task_struct *tsk = current;
 	if (unlikely((unsigned long)tsk < PAGE_OFFSET ||
 		     (high_memory && (void *)tsk > high_memory) ||
 		     ((unsigned long)tsk & (__alignof__(*tsk) - 1)) != 0)) {
 		pr_err("Corrupt 'current' %p (sp %#lx)\n", tsk, stack_pointer);
 		tsk = &corrupt_current;
 	}
 	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)
 {
 #if CONFIG_KERNEL_PL == 2
 	__insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
 	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
 #else
 	__insn_mtspr(SPR_MPL_DMA_CPL_SET_0, 1);
 	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_0, 1);
 #endif
 }

 /* Forbid user processes from accessing the DMA SPRs */
 void restrict_dma_mpls(void)
 {
 #if CONFIG_KERNEL_PL == 2
 	__insn_mtspr(SPR_MPL_DMA_CPL_SET_2, 1);
 	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_2, 1);
 #else
 	__insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
 	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
 #endif
 }

 /* 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);
 	t->proc_status = __insn_mfspr(SPR_PROC_STATUS);
 #if !CHIP_HAS_FIXED_INTVEC_BASE()
 	t->interrupt_vector_base = __insn_mfspr(SPR_INTERRUPT_VECTOR_BASE_0);
 #endif
 	t->tile_rtf_hwm = __insn_mfspr(SPR_TILE_RTF_HWM);
 #if CHIP_HAS_DSTREAM_PF()
 	t->dstream_pf = __insn_mfspr(SPR_DSTREAM_PF);
 #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);
 	__insn_mtspr(SPR_PROC_STATUS, t->proc_status);
 #if !CHIP_HAS_FIXED_INTVEC_BASE()
 	__insn_mtspr(SPR_INTERRUPT_VECTOR_BASE_0, t->interrupt_vector_base);
 #endif
 	__insn_mtspr(SPR_TILE_RTF_HWM, t->tile_rtf_hwm);
 #if CHIP_HAS_DSTREAM_PF()
 	__insn_mtspr(SPR_DSTREAM_PF, t->dstream_pf);
 #endif
 }


 void _prepare_arch_switch(struct task_struct *next)
 {
 #if CHIP_HAS_TILE_DMA()
 	struct tile_dma_state *dma = &current->thread.tile_dma_state;
 	if (dma->enabled)
 		save_tile_dma_state(dma);
 #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);

 #ifdef CONFIG_HARDWALL
 	/* Enable or disable access to the network registers appropriately. */
 	hardwall_switch_tasks(prev, next);
 #endif

 	/* Notify the simulator of task exit. */
 	if (unlikely(prev->state == TASK_DEAD))
 		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |
 			     (prev->pid << _SIM_CONTROL_OPERATOR_BITS));

 	/*
 	 * 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_K_0 when we reset our sp.
 	 */
 	return __switch_to(prev, next, next_current_ksp0(next));
 }

 /*
  * This routine is called on return from interrupt if any of the
  * TIF_WORK_MASK flags are set in thread_info->flags.  It is
  * entered with interrupts disabled so we don't miss an event
  * that modified the thread_info flags.  If any flag is set, we
  * handle it and return, and the calling assembly code will
  * re-disable interrupts, reload the thread flags, and call back
  * if more flags need to be handled.
  *
  * We return whether we need to check the thread_info flags again
  * or not.  Note that we don't clear TIF_SINGLESTEP here, so it's
  * important that it be tested last, and then claim that we don't
  * need to recheck the flags.
  */
 int do_work_pending(struct pt_regs *regs, u32 thread_info_flags)
 {
 	/* If we enter in kernel mode, do nothing and exit the caller loop. */
 	if (!user_mode(regs))
 		return 0;

 	user_exit();

 	/* Enable interrupts; they are disabled again on return to caller. */
 	local_irq_enable();

 	if (thread_info_flags & _TIF_NEED_RESCHED) {
 		schedule();
 		return 1;
 	}
 #if CHIP_HAS_TILE_DMA()
 	if (thread_info_flags & _TIF_ASYNC_TLB) {
 		do_async_page_fault(regs);
 		return 1;
 	}
 #endif
 	if (thread_info_flags & _TIF_SIGPENDING) {
 		do_signal(regs);
 		return 1;
 	}
 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 		clear_thread_flag(TIF_NOTIFY_RESUME);
 		tracehook_notify_resume(regs);
 		return 1;
 	}
 	if (thread_info_flags & _TIF_SINGLESTEP)
 		single_step_once(regs);

 	user_enter();

 	return 0;
 }

 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;
 }

 /* Flush thread state. */
 void flush_thread(void)
 {
 	/* Nothing */
 }

 /*
  * Free current thread data structures etc..
  */
 void exit_thread(void)
 {
 #ifdef CONFIG_HARDWALL
 	/*
 	 * Remove the task from the list of tasks that are associated
 	 * with any live hardwalls.  (If the task that is exiting held
 	 * the last reference to a hardwall fd, it would already have
 	 * been released and deactivated at this point.)
 	 */
 	hardwall_deactivate_all(current);
 #endif
 }

 void tile_show_regs(struct pt_regs *regs)
 {
 	int i;
 #ifdef __tilegx__
 	for (i = 0; i < 17; i++)
 		pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
 		       i, regs->regs[i], i+18, regs->regs[i+18],
 		       i+36, regs->regs[i+36]);
 	pr_err(" r17: "REGFMT" r35: "REGFMT" tp : "REGFMT"\n",
 	       regs->regs[17], regs->regs[35], regs->tp);
 	pr_err(" sp : "REGFMT" lr : "REGFMT"\n", regs->sp, regs->lr);
 #else
 	for (i = 0; i < 13; i++)
 		pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT
 		       " r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
 		       i, regs->regs[i], i+14, regs->regs[i+14],
 		       i+27, regs->regs[i+27], i+40, regs->regs[i+40]);
 	pr_err(" r13: "REGFMT" tp : "REGFMT" sp : "REGFMT" lr : "REGFMT"\n",
 	       regs->regs[13], regs->tp, regs->sp, regs->lr);
 #endif
 	pr_err(" pc : "REGFMT" ex1: %ld     faultnum: %ld flags:%s%s%s%s\n",
 	       regs->pc, regs->ex1, regs->faultnum,
 	       is_compat_task() ? " compat" : "",
 	       (regs->flags & PT_FLAGS_DISABLE_IRQ) ? " noirq" : "",
 	       !(regs->flags & PT_FLAGS_CALLER_SAVES) ? " nocallersave" : "",
 	       (regs->flags & PT_FLAGS_RESTORE_REGS) ? " restoreregs" : "");
 }

 void show_regs(struct pt_regs *regs)
 {
 	struct KBacktraceIterator kbt;

 	show_regs_print_info(KERN_DEFAULT);
 	tile_show_regs(regs);

 	KBacktraceIterator_init(&kbt, NULL, regs);
 	tile_show_stack(&kbt);
 }

 /* To ensure stack dump on tiles occurs one by one. */
 static DEFINE_SPINLOCK(backtrace_lock);
 /* To ensure no backtrace occurs before all of the stack dump are done. */
 static atomic_t backtrace_cpus;
 /* The cpu mask to avoid reentrance. */
 static struct cpumask backtrace_mask;

 void do_nmi_dump_stack(struct pt_regs *regs)
 {
 	int is_idle = is_idle_task(current) && !in_interrupt();
 	int cpu;

 	nmi_enter();
 	cpu = smp_processor_id();
 	if (WARN_ON_ONCE(!cpumask_test_and_clear_cpu(cpu, &backtrace_mask)))
 		goto done;

 	spin_lock(&backtrace_lock);
 	if (is_idle)
 		pr_info("CPU: %d idle\n", cpu);
 	else
 		show_regs(regs);
 	spin_unlock(&backtrace_lock);
 	atomic_dec(&backtrace_cpus);
 done:
 	nmi_exit();
 }

 #ifdef __tilegx__
 void arch_trigger_all_cpu_backtrace(bool self)
 {
 	struct cpumask mask;
 	HV_Coord tile;
 	unsigned int timeout;
 	int cpu;
 	int ongoing;
 	HV_NMI_Info info[NR_CPUS];

 	ongoing = atomic_cmpxchg(&backtrace_cpus, 0, num_online_cpus() - 1);
 	if (ongoing != 0) {
 		pr_err("Trying to do all-cpu backtrace.\n");
 		pr_err("But another all-cpu backtrace is ongoing (%d cpus left)\n",
 		       ongoing);
 		if (self) {
 			pr_err("Reporting the stack on this cpu only.\n");
 			dump_stack();
 		}
 		return;
 	}

 	cpumask_copy(&mask, cpu_online_mask);
 	cpumask_clear_cpu(smp_processor_id(), &mask);
 	cpumask_copy(&backtrace_mask, &mask);

 	/* Backtrace for myself first. */
 	if (self)
 		dump_stack();

 	/* Tentatively dump stack on remote tiles via NMI. */
 	timeout = 100;
 	while (!cpumask_empty(&mask) && timeout) {
 		for_each_cpu(cpu, &mask) {
 			tile.x = cpu_x(cpu);
 			tile.y = cpu_y(cpu);
 			info[cpu] = hv_send_nmi(tile, TILE_NMI_DUMP_STACK, 0);
 			if (info[cpu].result == HV_NMI_RESULT_OK)
 				cpumask_clear_cpu(cpu, &mask);
 		}

 		mdelay(10);
 		timeout--;
 	}

 	/* Warn about cpus stuck in ICS and decrement their counts here. */
 	if (!cpumask_empty(&mask)) {
 		for_each_cpu(cpu, &mask) {
 			switch (info[cpu].result) {
 			case HV_NMI_RESULT_FAIL_ICS:
 				pr_warn("Skipping stack dump of cpu %d in ICS at pc %#llx\n",
 					cpu, info[cpu].pc);
 				break;
 			case HV_NMI_RESULT_FAIL_HV:
 				pr_warn("Skipping stack dump of cpu %d in hypervisor\n",
 					cpu);
 				break;
 			case HV_ENOSYS:
 				pr_warn("Hypervisor too old to allow remote stack dumps.\n");
 				goto skip_for_each;
 			default:  /* should not happen */
 				pr_warn("Skipping stack dump of cpu %d [%d,%#llx]\n",
 					cpu, info[cpu].result, info[cpu].pc);
 				break;
 			}
 		}
 skip_for_each:
 		atomic_sub(cpumask_weight(&mask), &backtrace_cpus);
 	}
 }
 #endif /* __tilegx_ */
	/*
	* 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 <linux/tracehook.h>
	#include <linux/signal.h>
	#include <linux/delay.h>
	#include <linux/context_tracking.h>
	#include <asm/stack.h>
	#include <asm/switch_to.h>
	#include <asm/homecache.h>
	#include <asm/syscalls.h>
	#include <asm/traps.h>
	#include <asm/setup.h>
	#include <asm/uaccess.h>
	#ifdef CONFIG_HARDWALL
	#include <asm/hardwall.h>
	#endif
	#include <arch/chip.h>
	#include <arch/abi.h>
	#include <arch/sim_def.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 __init idle_setup(char *str)
	{
	if (!str)
	return -EINVAL;

	if (!strcmp(str, "poll")) {
	pr_info("using polling idle threads\n");
	cpu_idle_poll_ctrl(true);
	return 0;
	} else if (!strcmp(str, "halt")) {
	return 0;
	}
	return -1;
	}
	early_param("idle", idle_setup);

	void arch_cpu_idle(void)
	{
	__this_cpu_write(irq_stat.idle_timestamp, jiffies);
	_cpu_idle();
	}

	/*
	* Release a thread_info structure
	*/
	void arch_release_thread_info(struct thread_info *info)
	{
	struct single_step_state *step_state = info->step_state;

	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);
	}
	}

	static void save_arch_state(struct thread_struct *t);

	int copy_thread(unsigned long clone_flags, unsigned long sp,
	unsigned long arg, struct task_struct *p)
	{
	struct pt_regs *childregs = task_pt_regs(p);
	unsigned long ksp;
	unsigned long *callee_regs;

	/*
	* Set up the stack and stack pointer appropriately for the
	* new child to find itself woken up in __switch_to().
	* The callee-saved registers must be on the stack to be read;
	* the new task will then jump to assembly support to handle
	* calling schedule_tail(), etc., and (for userspace tasks)
	* returning to the context set up in the pt_regs.
	*/
	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);
	callee_regs = (unsigned long *)ksp;
	ksp -= C_ABI_SAVE_AREA_SIZE; /* __switch_to() save area */
	((long )ksp)[0] = ((long )ksp)[1] = 0;
	p->thread.ksp = ksp;

	/* Record the pid of the task that created this one. */
	p->thread.creator_pid = current->pid;

	if (unlikely(p->flags & PF_KTHREAD)) {
	/* kernel thread */
	memset(childregs, 0, sizeof(struct pt_regs));
	memset(&callee_regs[2], 0,
	(CALLEE_SAVED_REGS_COUNT - 2) * sizeof(unsigned long));
	callee_regs[0] = sp; /* r30 = function */
	callee_regs[1] = arg; /* r31 = arg */
	p->thread.pc = (unsigned long) ret_from_kernel_thread;
	return 0;
	}

	/*
	* 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;

	/*
	* Do not clone step state from the parent; each thread
	* must make its own lazily.
	*/
	task_thread_info(p)->step_state = NULL;

	#ifdef __tilegx__
	/*
	* Do not clone unalign jit fixup from the parent; each thread
	* must allocate its own on demand.
	*/
	task_thread_info(p)->unalign_jit_base = NULL;
	#endif

	/*
	* Copy the registers onto the kernel stack so the
	* return-from-interrupt code will reload it into registers.
	*/
	childregs = current_pt_regs();
	childregs->regs[0] = 0; /* return value is zero */
	if (sp)
	childregs->sp = sp; /* override with new user stack pointer */
	memcpy(callee_regs, &childregs->regs[CALLEE_SAVED_FIRST_REG],
	CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));

	/* Save user stack top pointer so we can ID the stack vm area later. */
	p->thread.usp0 = childregs->sp;

	/*
	* If CLONE_SETTLS is set, set "tp" in the new task to "r4",
	* which is passed in as arg #5 to sys_clone().
	*/
	if (clone_flags & CLONE_SETTLS)
	childregs->tp = childregs->regs[4];


	#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

	/* New thread has its miscellaneous processor state bits clear. */
	p->thread.proc_status = 0;

	#ifdef CONFIG_HARDWALL
	/* New thread does not own any networks. */
	memset(&p->thread.hardwall[0], 0,
	sizeof(struct hardwall_task) * HARDWALL_TYPES);
	#endif


	/*
	* Start the new thread with the current architecture state
	* (user interrupt masks, etc.).
	*/
	save_arch_state(&p->thread);

	return 0;
	}

	int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
	{
	task_thread_info(tsk)->align_ctl = val;
	return 0;
	}

	int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
	{
	return put_user(task_thread_info(tsk)->align_ctl,
	(unsigned int __user *)adr);
	}

	static struct task_struct corrupt_current = { .comm = "<corrupt>" };

	/*
	* 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)
	{
	struct task_struct *tsk = current;
	if (unlikely((unsigned long)tsk < PAGE_OFFSET \|\|
	(high_memory && (void *)tsk > high_memory) \|\|
	((unsigned long)tsk & (__alignof__(*tsk) - 1)) != 0)) {
	pr_err("Corrupt 'current' %p (sp %#lx)\n", tsk, stack_pointer);
	tsk = &corrupt_current;
	}
	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)
	{
	#if CONFIG_KERNEL_PL == 2
	__insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
	#else
	__insn_mtspr(SPR_MPL_DMA_CPL_SET_0, 1);
	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_0, 1);
	#endif
	}

	/* Forbid user processes from accessing the DMA SPRs */
	void restrict_dma_mpls(void)
	{
	#if CONFIG_KERNEL_PL == 2
	__insn_mtspr(SPR_MPL_DMA_CPL_SET_2, 1);
	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_2, 1);
	#else
	__insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
	__insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
	#endif
	}

	/* 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);
	t->proc_status = __insn_mfspr(SPR_PROC_STATUS);
	#if !CHIP_HAS_FIXED_INTVEC_BASE()
	t->interrupt_vector_base = __insn_mfspr(SPR_INTERRUPT_VECTOR_BASE_0);
	#endif
	t->tile_rtf_hwm = __insn_mfspr(SPR_TILE_RTF_HWM);
	#if CHIP_HAS_DSTREAM_PF()
	t->dstream_pf = __insn_mfspr(SPR_DSTREAM_PF);
	#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);
	__insn_mtspr(SPR_PROC_STATUS, t->proc_status);
	#if !CHIP_HAS_FIXED_INTVEC_BASE()
	__insn_mtspr(SPR_INTERRUPT_VECTOR_BASE_0, t->interrupt_vector_base);
	#endif
	__insn_mtspr(SPR_TILE_RTF_HWM, t->tile_rtf_hwm);
	#if CHIP_HAS_DSTREAM_PF()
	__insn_mtspr(SPR_DSTREAM_PF, t->dstream_pf);
	#endif
	}


	void _prepare_arch_switch(struct task_struct *next)
	{
	#if CHIP_HAS_TILE_DMA()
	struct tile_dma_state *dma = &current->thread.tile_dma_state;
	if (dma->enabled)
	save_tile_dma_state(dma);
	#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);

	#ifdef CONFIG_HARDWALL
	/* Enable or disable access to the network registers appropriately. */
	hardwall_switch_tasks(prev, next);
	#endif

	/* Notify the simulator of task exit. */
	if (unlikely(prev->state == TASK_DEAD))
	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT \|
	(prev->pid << _SIM_CONTROL_OPERATOR_BITS));

	/*
	* 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_K_0 when we reset our sp.
	*/
	return __switch_to(prev, next, next_current_ksp0(next));
	}

	/*
	* This routine is called on return from interrupt if any of the
	* TIF_WORK_MASK flags are set in thread_info->flags. It is
	* entered with interrupts disabled so we don't miss an event
	* that modified the thread_info flags. If any flag is set, we
	* handle it and return, and the calling assembly code will
	* re-disable interrupts, reload the thread flags, and call back
	* if more flags need to be handled.
	*
	* We return whether we need to check the thread_info flags again
	* or not. Note that we don't clear TIF_SINGLESTEP here, so it's
	* important that it be tested last, and then claim that we don't
	* need to recheck the flags.
	*/
	int do_work_pending(struct pt_regs *regs, u32 thread_info_flags)
	{
	/* If we enter in kernel mode, do nothing and exit the caller loop. */
	if (!user_mode(regs))
	return 0;

	user_exit();

	/* Enable interrupts; they are disabled again on return to caller. */
	local_irq_enable();

	if (thread_info_flags & _TIF_NEED_RESCHED) {
	schedule();
	return 1;
	}
	#if CHIP_HAS_TILE_DMA()
	if (thread_info_flags & _TIF_ASYNC_TLB) {
	do_async_page_fault(regs);
	return 1;
	}
	#endif
	if (thread_info_flags & _TIF_SIGPENDING) {
	do_signal(regs);
	return 1;
	}
	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
	clear_thread_flag(TIF_NOTIFY_RESUME);
	tracehook_notify_resume(regs);
	return 1;
	}
	if (thread_info_flags & _TIF_SINGLESTEP)
	single_step_once(regs);

	user_enter();

	return 0;
	}

	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;
	}

	/* Flush thread state. */
	void flush_thread(void)
	{
	/* Nothing */
	}

	/*
	* Free current thread data structures etc..
	*/
	void exit_thread(void)
	{
	#ifdef CONFIG_HARDWALL
	/*
	* Remove the task from the list of tasks that are associated
	* with any live hardwalls. (If the task that is exiting held
	* the last reference to a hardwall fd, it would already have
	* been released and deactivated at this point.)
	*/
	hardwall_deactivate_all(current);
	#endif
	}

	void tile_show_regs(struct pt_regs *regs)
	{
	int i;
	#ifdef __tilegx__
	for (i = 0; i < 17; i++)
	pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
	i, regs->regs[i], i+18, regs->regs[i+18],
	i+36, regs->regs[i+36]);
	pr_err(" r17: "REGFMT" r35: "REGFMT" tp : "REGFMT"\n",
	regs->regs[17], regs->regs[35], regs->tp);
	pr_err(" sp : "REGFMT" lr : "REGFMT"\n", regs->sp, regs->lr);
	#else
	for (i = 0; i < 13; i++)
	pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT
	" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
	i, regs->regs[i], i+14, regs->regs[i+14],
	i+27, regs->regs[i+27], i+40, regs->regs[i+40]);
	pr_err(" r13: "REGFMT" tp : "REGFMT" sp : "REGFMT" lr : "REGFMT"\n",
	regs->regs[13], regs->tp, regs->sp, regs->lr);
	#endif
	pr_err(" pc : "REGFMT" ex1: %ld faultnum: %ld flags:%s%s%s%s\n",
	regs->pc, regs->ex1, regs->faultnum,
	is_compat_task() ? " compat" : "",
	(regs->flags & PT_FLAGS_DISABLE_IRQ) ? " noirq" : "",
	!(regs->flags & PT_FLAGS_CALLER_SAVES) ? " nocallersave" : "",
	(regs->flags & PT_FLAGS_RESTORE_REGS) ? " restoreregs" : "");
	}

	void show_regs(struct pt_regs *regs)
	{
	struct KBacktraceIterator kbt;

	show_regs_print_info(KERN_DEFAULT);
	tile_show_regs(regs);

	KBacktraceIterator_init(&kbt, NULL, regs);
	tile_show_stack(&kbt);
	}

	/* To ensure stack dump on tiles occurs one by one. */
	static DEFINE_SPINLOCK(backtrace_lock);
	/* To ensure no backtrace occurs before all of the stack dump are done. */
	static atomic_t backtrace_cpus;
	/* The cpu mask to avoid reentrance. */
	static struct cpumask backtrace_mask;

	void do_nmi_dump_stack(struct pt_regs *regs)
	{
	int is_idle = is_idle_task(current) && !in_interrupt();
	int cpu;

	nmi_enter();
	cpu = smp_processor_id();
	if (WARN_ON_ONCE(!cpumask_test_and_clear_cpu(cpu, &backtrace_mask)))
	goto done;

	spin_lock(&backtrace_lock);
	if (is_idle)
	pr_info("CPU: %d idle\n", cpu);
	else
	show_regs(regs);
	spin_unlock(&backtrace_lock);
	atomic_dec(&backtrace_cpus);
	done:
	nmi_exit();
	}

	#ifdef __tilegx__
	void arch_trigger_all_cpu_backtrace(bool self)
	{
	struct cpumask mask;
	HV_Coord tile;
	unsigned int timeout;
	int cpu;
	int ongoing;
	HV_NMI_Info info[NR_CPUS];

	ongoing = atomic_cmpxchg(&backtrace_cpus, 0, num_online_cpus() - 1);
	if (ongoing != 0) {
	pr_err("Trying to do all-cpu backtrace.\n");
	pr_err("But another all-cpu backtrace is ongoing (%d cpus left)\n",
	ongoing);
	if (self) {
	pr_err("Reporting the stack on this cpu only.\n");
	dump_stack();
	}
	return;
	}

	cpumask_copy(&mask, cpu_online_mask);
	cpumask_clear_cpu(smp_processor_id(), &mask);
	cpumask_copy(&backtrace_mask, &mask);

	/* Backtrace for myself first. */
	if (self)
	dump_stack();

	/* Tentatively dump stack on remote tiles via NMI. */
	timeout = 100;
	while (!cpumask_empty(&mask) && timeout) {
	for_each_cpu(cpu, &mask) {
	tile.x = cpu_x(cpu);
	tile.y = cpu_y(cpu);
	info[cpu] = hv_send_nmi(tile, TILE_NMI_DUMP_STACK, 0);
	if (info[cpu].result == HV_NMI_RESULT_OK)
	cpumask_clear_cpu(cpu, &mask);
	}

	mdelay(10);
	timeout--;
	}

	/* Warn about cpus stuck in ICS and decrement their counts here. */
	if (!cpumask_empty(&mask)) {
	for_each_cpu(cpu, &mask) {
	switch (info[cpu].result) {
	case HV_NMI_RESULT_FAIL_ICS:
	pr_warn("Skipping stack dump of cpu %d in ICS at pc %#llx\n",
	cpu, info[cpu].pc);
	break;
	case HV_NMI_RESULT_FAIL_HV:
	pr_warn("Skipping stack dump of cpu %d in hypervisor\n",
	cpu);
	break;
	case HV_ENOSYS:
	pr_warn("Hypervisor too old to allow remote stack dumps.\n");
	goto skip_for_each;
	default: /* should not happen */
	pr_warn("Skipping stack dump of cpu %d [%d,%#llx]\n",
	cpu, info[cpu].result, info[cpu].pc);
	break;
	}
	}
	skip_for_each:
	atomic_sub(cpumask_weight(&mask), &backtrace_cpus);
	}
	}
	#endif /* __tilegx_ */