arch/tile/kernel/smpboot.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/module.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/sched.h>
 #include <linux/kernel_stat.h>
 #include <linux/bootmem.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
 #include <linux/percpu.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/irq.h>
 #include <asm/mmu_context.h>
 #include <asm/tlbflush.h>
 #include <asm/sections.h>

 /* State of each CPU. */
 static DEFINE_PER_CPU(int, cpu_state) = { 0 };

 /* The messaging code jumps to this pointer during boot-up */
 unsigned long start_cpu_function_addr;

 /* Called very early during startup to mark boot cpu as online */
 void __init smp_prepare_boot_cpu(void)
 {
 	int cpu = smp_processor_id();
 	set_cpu_online(cpu, 1);
 	set_cpu_present(cpu, 1);
 	__get_cpu_var(cpu_state) = CPU_ONLINE;

 	init_messaging();
 }

 static void start_secondary(void);

 /*
  * Called at the top of init() to launch all the other CPUs.
  * They run free to complete their initialization and then wait
  * until they get an IPI from the boot cpu to come online.
  */
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 	long rc;
 	int cpu, cpu_count;
 	int boot_cpu = smp_processor_id();

 	current_thread_info()->cpu = boot_cpu;

 	/*
 	 * Pin this task to the boot CPU while we bring up the others,
 	 * just to make sure we don't uselessly migrate as they come up.
 	 */
 	rc = sched_setaffinity(current->pid, cpumask_of(boot_cpu));
 	if (rc != 0)
 		pr_err("Couldn't set init affinity to boot cpu (%ld)\n", rc);

 	/* Print information about disabled and dataplane cpus. */
 	print_disabled_cpus();

 	/*
 	 * Tell the messaging subsystem how to respond to the
 	 * startup message.  We use a level of indirection to avoid
 	 * confusing the linker with the fact that the messaging
 	 * subsystem is calling __init code.
 	 */
 	start_cpu_function_addr = (unsigned long) &online_secondary;

 	/* Set up thread context for all new processors. */
 	cpu_count = 1;
 	for (cpu = 0; cpu < NR_CPUS; ++cpu)	{
 		struct task_struct *idle;

 		if (cpu == boot_cpu)
 			continue;

 		if (!cpu_possible(cpu)) {
 			/*
 			 * Make this processor do nothing on boot.
 			 * Note that we don't give the boot_pc function
 			 * a stack, so it has to be assembly code.
 			 */
 			per_cpu(boot_sp, cpu) = 0;
 			per_cpu(boot_pc, cpu) = (unsigned long) smp_nap;
 			continue;
 		}

 		/* Create a new idle thread to run start_secondary() */
 		idle = fork_idle(cpu);
 		if (IS_ERR(idle))
 			panic("failed fork for CPU %d", cpu);
 		idle->thread.pc = (unsigned long) start_secondary;

 		/* Make this thread the boot thread for this processor */
 		per_cpu(boot_sp, cpu) = task_ksp0(idle);
 		per_cpu(boot_pc, cpu) = idle->thread.pc;

 		++cpu_count;
 	}
 	BUG_ON(cpu_count > (max_cpus ? max_cpus : 1));

 	/* Fire up the other tiles, if any */
 	init_cpu_present(cpu_possible_mask);
 	if (cpumask_weight(cpu_present_mask) > 1) {
 		mb();  /* make sure all data is visible to new processors */
 		hv_start_all_tiles();
 	}
 }

 static __initdata struct cpumask init_affinity;

 static __init int reset_init_affinity(void)
 {
 	long rc = sched_setaffinity(current->pid, &init_affinity);
 	if (rc != 0)
 		pr_warning("couldn't reset init affinity (%ld)\n",
 		       rc);
 	return 0;
 }
 late_initcall(reset_init_affinity);

 static struct cpumask cpu_started;

 /*
  * Activate a secondary processor.  Very minimal; don't add anything
  * to this path without knowing what you're doing, since SMP booting
  * is pretty fragile.
  */
 static void start_secondary(void)
 {
 	int cpuid = smp_processor_id();

 	/* Set our thread pointer appropriately. */
 	set_my_cpu_offset(__per_cpu_offset[cpuid]);

 	preempt_disable();

 	/*
 	 * In large machines even this will slow us down, since we
 	 * will be contending for for the printk spinlock.
 	 */
 	/* printk(KERN_DEBUG "Initializing CPU#%d\n", cpuid); */

 	/* Initialize the current asid for our first page table. */
 	__get_cpu_var(current_asid) = min_asid;

 	/* Set up this thread as another owner of the init_mm */
 	atomic_inc(&init_mm.mm_count);
 	current->active_mm = &init_mm;
 	if (current->mm)
 		BUG();
 	enter_lazy_tlb(&init_mm, current);

 	/* Allow hypervisor messages to be received */
 	init_messaging();
 	local_irq_enable();

 	/* Indicate that we're ready to come up. */
 	/* Must not do this before we're ready to receive messages */
 	if (cpumask_test_and_set_cpu(cpuid, &cpu_started)) {
 		pr_warning("CPU#%d already started!\n", cpuid);
 		for (;;)
 			local_irq_enable();
 	}

 	smp_nap();
 }

 /*
  * Bring a secondary processor online.
  */
 void online_secondary(void)
 {
 	/*
 	 * low-memory mappings have been cleared, flush them from
 	 * the local TLBs too.
 	 */
 	local_flush_tlb();

 	BUG_ON(in_interrupt());

 	/* This must be done before setting cpu_online_mask */
 	wmb();

 	notify_cpu_starting(smp_processor_id());

 	set_cpu_online(smp_processor_id(), 1);
 	__get_cpu_var(cpu_state) = CPU_ONLINE;

 	/* Set up tile-specific state for this cpu. */
 	setup_cpu(0);

 	/* Set up tile-timer clock-event device on this cpu */
 	setup_tile_timer();

 	cpu_startup_entry(CPUHP_ONLINE);
 }

 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 {
 	/* Wait 5s total for all CPUs for them to come online */
 	static int timeout;
 	for (; !cpumask_test_cpu(cpu, &cpu_started); timeout++) {
 		if (timeout >= 50000) {
 			pr_info("skipping unresponsive cpu%d\n", cpu);
 			local_irq_enable();
 			return -EIO;
 		}
 		udelay(100);
 	}

 	local_irq_enable();
 	per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;

 	/* Unleash the CPU! */
 	send_IPI_single(cpu, MSG_TAG_START_CPU);
 	while (!cpumask_test_cpu(cpu, cpu_online_mask))
 		cpu_relax();
 	return 0;
 }

 static void panic_start_cpu(void)
 {
 	panic("Received a MSG_START_CPU IPI after boot finished.");
 }

 void __init smp_cpus_done(unsigned int max_cpus)
 {
 	int cpu, next, rc;

 	/* Reset the response to a (now illegal) MSG_START_CPU IPI. */
 	start_cpu_function_addr = (unsigned long) &panic_start_cpu;

 	cpumask_copy(&init_affinity, cpu_online_mask);

 	/*
 	 * Pin ourselves to a single cpu in the initial affinity set
 	 * so that kernel mappings for the rootfs are not in the dataplane,
 	 * if set, and to avoid unnecessary migrating during bringup.
 	 * Use the last cpu just in case the whole chip has been
 	 * isolated from the scheduler, to keep init away from likely
 	 * more useful user code.  This also ensures that work scheduled
 	 * via schedule_delayed_work() in the init routines will land
 	 * on this cpu.
 	 */
 	for (cpu = cpumask_first(&init_affinity);
 	     (next = cpumask_next(cpu, &init_affinity)) < nr_cpu_ids;
 	     cpu = next)
 		;
 	rc = sched_setaffinity(current->pid, cpumask_of(cpu));
 	if (rc != 0)
 		pr_err("Couldn't set init affinity to cpu %d (%d)\n", cpu, rc);
 }
	/*
	* 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/module.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/sched.h>
	#include <linux/kernel_stat.h>
	#include <linux/bootmem.h>
	#include <linux/notifier.h>
	#include <linux/cpu.h>
	#include <linux/percpu.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/irq.h>
	#include <asm/mmu_context.h>
	#include <asm/tlbflush.h>
	#include <asm/sections.h>

	/* State of each CPU. */
	static DEFINE_PER_CPU(int, cpu_state) = { 0 };

	/* The messaging code jumps to this pointer during boot-up */
	unsigned long start_cpu_function_addr;

	/* Called very early during startup to mark boot cpu as online */
	void __init smp_prepare_boot_cpu(void)
	{
	int cpu = smp_processor_id();
	set_cpu_online(cpu, 1);
	set_cpu_present(cpu, 1);
	__get_cpu_var(cpu_state) = CPU_ONLINE;

	init_messaging();
	}

	static void start_secondary(void);

	/*
	* Called at the top of init() to launch all the other CPUs.
	* They run free to complete their initialization and then wait
	* until they get an IPI from the boot cpu to come online.
	*/
	void __init smp_prepare_cpus(unsigned int max_cpus)
	{
	long rc;
	int cpu, cpu_count;
	int boot_cpu = smp_processor_id();

	current_thread_info()->cpu = boot_cpu;

	/*
	* Pin this task to the boot CPU while we bring up the others,
	* just to make sure we don't uselessly migrate as they come up.
	*/
	rc = sched_setaffinity(current->pid, cpumask_of(boot_cpu));
	if (rc != 0)
	pr_err("Couldn't set init affinity to boot cpu (%ld)\n", rc);

	/* Print information about disabled and dataplane cpus. */
	print_disabled_cpus();

	/*
	* Tell the messaging subsystem how to respond to the
	* startup message. We use a level of indirection to avoid
	* confusing the linker with the fact that the messaging
	* subsystem is calling __init code.
	*/
	start_cpu_function_addr = (unsigned long) &online_secondary;

	/* Set up thread context for all new processors. */
	cpu_count = 1;
	for (cpu = 0; cpu < NR_CPUS; ++cpu) {
	struct task_struct *idle;

	if (cpu == boot_cpu)
	continue;

	if (!cpu_possible(cpu)) {
	/*
	* Make this processor do nothing on boot.
	* Note that we don't give the boot_pc function
	* a stack, so it has to be assembly code.
	*/
	per_cpu(boot_sp, cpu) = 0;
	per_cpu(boot_pc, cpu) = (unsigned long) smp_nap;
	continue;
	}

	/* Create a new idle thread to run start_secondary() */
	idle = fork_idle(cpu);
	if (IS_ERR(idle))
	panic("failed fork for CPU %d", cpu);
	idle->thread.pc = (unsigned long) start_secondary;

	/* Make this thread the boot thread for this processor */
	per_cpu(boot_sp, cpu) = task_ksp0(idle);
	per_cpu(boot_pc, cpu) = idle->thread.pc;

	++cpu_count;
	}
	BUG_ON(cpu_count > (max_cpus ? max_cpus : 1));

	/* Fire up the other tiles, if any */
	init_cpu_present(cpu_possible_mask);
	if (cpumask_weight(cpu_present_mask) > 1) {
	mb(); /* make sure all data is visible to new processors */
	hv_start_all_tiles();
	}
	}

	static __initdata struct cpumask init_affinity;

	static __init int reset_init_affinity(void)
	{
	long rc = sched_setaffinity(current->pid, &init_affinity);
	if (rc != 0)
	pr_warning("couldn't reset init affinity (%ld)\n",
	rc);
	return 0;
	}
	late_initcall(reset_init_affinity);

	static struct cpumask cpu_started;

	/*
	* Activate a secondary processor. Very minimal; don't add anything
	* to this path without knowing what you're doing, since SMP booting
	* is pretty fragile.
	*/
	static void start_secondary(void)
	{
	int cpuid = smp_processor_id();

	/* Set our thread pointer appropriately. */
	set_my_cpu_offset(__per_cpu_offset[cpuid]);

	preempt_disable();

	/*
	* In large machines even this will slow us down, since we
	* will be contending for for the printk spinlock.
	*/
	/* printk(KERN_DEBUG "Initializing CPU#%d\n", cpuid); */

	/* Initialize the current asid for our first page table. */
	__get_cpu_var(current_asid) = min_asid;

	/* Set up this thread as another owner of the init_mm */
	atomic_inc(&init_mm.mm_count);
	current->active_mm = &init_mm;
	if (current->mm)
	BUG();
	enter_lazy_tlb(&init_mm, current);

	/* Allow hypervisor messages to be received */
	init_messaging();
	local_irq_enable();

	/* Indicate that we're ready to come up. */
	/* Must not do this before we're ready to receive messages */
	if (cpumask_test_and_set_cpu(cpuid, &cpu_started)) {
	pr_warning("CPU#%d already started!\n", cpuid);
	for (;;)
	local_irq_enable();
	}

	smp_nap();
	}

	/*
	* Bring a secondary processor online.
	*/
	void online_secondary(void)
	{
	/*
	* low-memory mappings have been cleared, flush them from
	* the local TLBs too.
	*/
	local_flush_tlb();

	BUG_ON(in_interrupt());

	/* This must be done before setting cpu_online_mask */
	wmb();

	notify_cpu_starting(smp_processor_id());

	set_cpu_online(smp_processor_id(), 1);
	__get_cpu_var(cpu_state) = CPU_ONLINE;

	/* Set up tile-specific state for this cpu. */
	setup_cpu(0);

	/* Set up tile-timer clock-event device on this cpu */
	setup_tile_timer();

	cpu_startup_entry(CPUHP_ONLINE);
	}

	int __cpu_up(unsigned int cpu, struct task_struct *tidle)
	{
	/* Wait 5s total for all CPUs for them to come online */
	static int timeout;
	for (; !cpumask_test_cpu(cpu, &cpu_started); timeout++) {
	if (timeout >= 50000) {
	pr_info("skipping unresponsive cpu%d\n", cpu);
	local_irq_enable();
	return -EIO;
	}
	udelay(100);
	}

	local_irq_enable();
	per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;

	/* Unleash the CPU! */
	send_IPI_single(cpu, MSG_TAG_START_CPU);
	while (!cpumask_test_cpu(cpu, cpu_online_mask))
	cpu_relax();
	return 0;
	}

	static void panic_start_cpu(void)
	{
	panic("Received a MSG_START_CPU IPI after boot finished.");
	}

	void __init smp_cpus_done(unsigned int max_cpus)
	{
	int cpu, next, rc;

	/* Reset the response to a (now illegal) MSG_START_CPU IPI. */
	start_cpu_function_addr = (unsigned long) &panic_start_cpu;

	cpumask_copy(&init_affinity, cpu_online_mask);

	/*
	* Pin ourselves to a single cpu in the initial affinity set
	* so that kernel mappings for the rootfs are not in the dataplane,
	* if set, and to avoid unnecessary migrating during bringup.
	* Use the last cpu just in case the whole chip has been
	* isolated from the scheduler, to keep init away from likely
	* more useful user code. This also ensures that work scheduled
	* via schedule_delayed_work() in the init routines will land
	* on this cpu.
	*/
	for (cpu = cpumask_first(&init_affinity);
	(next = cpumask_next(cpu, &init_affinity)) < nr_cpu_ids;
	cpu = next)
	;
	rc = sched_setaffinity(current->pid, cpumask_of(cpu));
	if (rc != 0)
	pr_err("Couldn't set init affinity to cpu %d (%d)\n", cpu, rc);
	}