/* * linux/arch/arm/kernel/smp.c * * Copyright (C) 2002 ARM Limited, 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 version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * as from 2.5, kernels no longer have an init_tasks structure * so we need some other way of telling a new secondary core * where to place its SVC stack */ struct secondary_data secondary_data; enum ipi_msg_type { IPI_TIMER = 2, IPI_RESCHEDULE, IPI_CALL_FUNC, IPI_CALL_FUNC_SINGLE, IPI_CPU_STOP, }; int __cpuinit __cpu_up(unsigned int cpu) { struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu); struct task_struct *idle = ci->idle; pgd_t *pgd; int ret; /* * Spawn a new process manually, if not already done. * Grab a pointer to its task struct so we can mess with it */ if (!idle) { idle = fork_idle(cpu); if (IS_ERR(idle)) { printk(KERN_ERR "CPU%u: fork() failed\n", cpu); return PTR_ERR(idle); } ci->idle = idle; } else { /* * Since this idle thread is being re-used, call * init_idle() to reinitialize the thread structure. */ init_idle(idle, cpu); } /* * Allocate initial page tables to allow the new CPU to * enable the MMU safely. This essentially means a set * of our "standard" page tables, with the addition of * a 1:1 mapping for the physical address of the kernel. */ pgd = pgd_alloc(&init_mm); if (!pgd) return -ENOMEM; if (PHYS_OFFSET != PAGE_OFFSET) { #ifndef CONFIG_HOTPLUG_CPU identity_mapping_add(pgd, __pa(__init_begin), __pa(__init_end)); #endif identity_mapping_add(pgd, __pa(_stext), __pa(_etext)); identity_mapping_add(pgd, __pa(_sdata), __pa(_edata)); } /* * We need to tell the secondary core where to find * its stack and the page tables. */ secondary_data.stack = task_stack_page(idle) + THREAD_START_SP; secondary_data.pgdir = virt_to_phys(pgd); secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir); __cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data)); outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1)); /* * Now bring the CPU into our world. */ ret = boot_secondary(cpu, idle); if (ret == 0) { unsigned long timeout; /* * CPU was successfully started, wait for it * to come online or time out. */ timeout = jiffies + HZ; while (time_before(jiffies, timeout)) { if (cpu_online(cpu)) break; udelay(10); barrier(); } if (!cpu_online(cpu)) { pr_crit("CPU%u: failed to come online\n", cpu); ret = -EIO; } } else { pr_err("CPU%u: failed to boot: %d\n", cpu, ret); } secondary_data.stack = NULL; secondary_data.pgdir = 0; if (PHYS_OFFSET != PAGE_OFFSET) { #ifndef CONFIG_HOTPLUG_CPU identity_mapping_del(pgd, __pa(__init_begin), __pa(__init_end)); #endif identity_mapping_del(pgd, __pa(_stext), __pa(_etext)); identity_mapping_del(pgd, __pa(_sdata), __pa(_edata)); } pgd_free(&init_mm, pgd); return ret; } #ifdef CONFIG_HOTPLUG_CPU static void percpu_timer_stop(void); /* * __cpu_disable runs on the processor to be shutdown. */ int __cpu_disable(void) { unsigned int cpu = smp_processor_id(); struct task_struct *p; int ret; ret = platform_cpu_disable(cpu); if (ret) return ret; /* * Take this CPU offline. Once we clear this, we can't return, * and we must not schedule until we're ready to give up the cpu. */ set_cpu_online(cpu, false); /* * OK - migrate IRQs away from this CPU */ migrate_irqs(); /* * Stop the local timer for this CPU. */ percpu_timer_stop(); /* * Flush user cache and TLB mappings, and then remove this CPU * from the vm mask set of all processes. */ flush_cache_all(); local_flush_tlb_all(); read_lock(&tasklist_lock); for_each_process(p) { if (p->mm) cpumask_clear_cpu(cpu, mm_cpumask(p->mm)); } read_unlock(&tasklist_lock); return 0; } static DECLARE_COMPLETION(cpu_died); /* * called on the thread which is asking for a CPU to be shutdown - * waits until shutdown has completed, or it is timed out. */ void __cpu_die(unsigned int cpu) { if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) { pr_err("CPU%u: cpu didn't die\n", cpu); return; } printk(KERN_NOTICE "CPU%u: shutdown\n", cpu); if (!platform_cpu_kill(cpu)) printk("CPU%u: unable to kill\n", cpu); } /* * Called from the idle thread for the CPU which has been shutdown. * * Note that we disable IRQs here, but do not re-enable them * before returning to the caller. This is also the behaviour * of the other hotplug-cpu capable cores, so presumably coming * out of idle fixes this. */ void __ref cpu_die(void) { unsigned int cpu = smp_processor_id(); idle_task_exit(); local_irq_disable(); mb(); /* Tell __cpu_die() that this CPU is now safe to dispose of */ complete(&cpu_died); /* * actual CPU shutdown procedure is at least platform (if not * CPU) specific. */ platform_cpu_die(cpu); /* * Do not return to the idle loop - jump back to the secondary * cpu initialisation. There's some initialisation which needs * to be repeated to undo the effects of taking the CPU offline. */ __asm__("mov sp, %0\n" " mov fp, #0\n" " b secondary_start_kernel" : : "r" (task_stack_page(current) + THREAD_SIZE - 8)); } #endif /* CONFIG_HOTPLUG_CPU */ int __cpu_logical_map[NR_CPUS]; void __init smp_setup_processor_id(void) { int i; u32 cpu = is_smp() ? read_cpuid_mpidr() & 0xff : 0; cpu_logical_map(0) = cpu; for (i = 1; i < NR_CPUS; ++i) cpu_logical_map(i) = i == cpu ? 0 : i; printk(KERN_INFO "Booting Linux on physical CPU %d\n", cpu); } /* * Called by both boot and secondaries to move global data into * per-processor storage. */ static void __cpuinit smp_store_cpu_info(unsigned int cpuid) { struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid); cpu_info->loops_per_jiffy = loops_per_jiffy; store_cpu_topology(cpuid); } /* * This is the secondary CPU boot entry. We're using this CPUs * idle thread stack, but a set of temporary page tables. */ asmlinkage void __cpuinit secondary_start_kernel(void) { struct mm_struct *mm = &init_mm; unsigned int cpu; /* * The identity mapping is uncached (strongly ordered), so * switch away from it before attempting any exclusive accesses. */ cpu_switch_mm(mm->pgd, mm); enter_lazy_tlb(mm, current); local_flush_tlb_all(); /* * All kernel threads share the same mm context; grab a * reference and switch to it. */ cpu = smp_processor_id(); atomic_inc(&mm->mm_count); current->active_mm = mm; cpumask_set_cpu(cpu, mm_cpumask(mm)); printk("CPU%u: Booted secondary processor\n", cpu); cpu_init(); preempt_disable(); trace_hardirqs_off(); /* * Give the platform a chance to do its own initialisation. */ platform_secondary_init(cpu); notify_cpu_starting(cpu); calibrate_delay(); smp_store_cpu_info(cpu); /* * OK, now it's safe to let the boot CPU continue. Wait for * the CPU migration code to notice that the CPU is online * before we continue. */ set_cpu_online(cpu, true); /* * Setup the percpu timer for this CPU. */ percpu_timer_setup(); while (!cpu_active(cpu)) cpu_relax(); /* * cpu_active bit is set, so it's safe to enalbe interrupts * now. */ local_irq_enable(); local_fiq_enable(); /* * OK, it's off to the idle thread for us */ cpu_idle(); } void __init smp_cpus_done(unsigned int max_cpus) { int cpu; unsigned long bogosum = 0; for_each_online_cpu(cpu) bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy; printk(KERN_INFO "SMP: Total of %d processors activated " "(%lu.%02lu BogoMIPS).\n", num_online_cpus(), bogosum / (500000/HZ), (bogosum / (5000/HZ)) % 100); } void __init smp_prepare_boot_cpu(void) { unsigned int cpu = smp_processor_id(); per_cpu(cpu_data, cpu).idle = current; } void __init smp_prepare_cpus(unsigned int max_cpus) { unsigned int ncores = num_possible_cpus(); init_cpu_topology(); smp_store_cpu_info(smp_processor_id()); /* * are we trying to boot more cores than exist? */ if (max_cpus > ncores) max_cpus = ncores; if (ncores > 1 && max_cpus) { /* * Enable the local timer or broadcast device for the * boot CPU, but only if we have more than one CPU. */ percpu_timer_setup(); /* * Initialise the present map, which describes the set of CPUs * actually populated at the present time. A platform should * re-initialize the map in platform_smp_prepare_cpus() if * present != possible (e.g. physical hotplug). */ init_cpu_present(&cpu_possible_map); /* * Initialise the SCU if there are more than one CPU * and let them know where to start. */ platform_smp_prepare_cpus(max_cpus); } } static void (*smp_cross_call)(const struct cpumask *, unsigned int); void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int)) { smp_cross_call = fn; } void arch_send_call_function_ipi_mask(const struct cpumask *mask) { smp_cross_call(mask, IPI_CALL_FUNC); } void arch_send_call_function_single_ipi(int cpu) { smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE); } static const char *ipi_types[NR_IPI] = { #define S(x,s) [x - IPI_TIMER] = s S(IPI_TIMER, "Timer broadcast interrupts"), S(IPI_RESCHEDULE, "Rescheduling interrupts"), S(IPI_CALL_FUNC, "Function call interrupts"), S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"), S(IPI_CPU_STOP, "CPU stop interrupts"), }; void show_ipi_list(struct seq_file *p, int prec) { unsigned int cpu, i; for (i = 0; i < NR_IPI; i++) { seq_printf(p, "%*s%u: ", prec - 1, "IPI", i); for_each_present_cpu(cpu) seq_printf(p, "%10u ", __get_irq_stat(cpu, ipi_irqs[i])); seq_printf(p, " %s\n", ipi_types[i]); } } u64 smp_irq_stat_cpu(unsigned int cpu) { u64 sum = 0; int i; for (i = 0; i < NR_IPI; i++) sum += __get_irq_stat(cpu, ipi_irqs[i]); return sum; } /* * Timer (local or broadcast) support */ static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent); static void ipi_timer(void) { struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent); evt->event_handler(evt); } #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST static void smp_timer_broadcast(const struct cpumask *mask) { smp_cross_call(mask, IPI_TIMER); } #else #define smp_timer_broadcast NULL #endif static void broadcast_timer_set_mode(enum clock_event_mode mode, struct clock_event_device *evt) { } static void __cpuinit broadcast_timer_setup(struct clock_event_device *evt) { evt->name = "dummy_timer"; evt->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_DUMMY; evt->rating = 400; evt->mult = 1; evt->set_mode = broadcast_timer_set_mode; clockevents_register_device(evt); } void __cpuinit percpu_timer_setup(void) { unsigned int cpu = smp_processor_id(); struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu); evt->cpumask = cpumask_of(cpu); evt->broadcast = smp_timer_broadcast; if (local_timer_setup(evt)) broadcast_timer_setup(evt); } #ifdef CONFIG_HOTPLUG_CPU /* * The generic clock events code purposely does not stop the local timer * on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it * manually here. */ static void percpu_timer_stop(void) { unsigned int cpu = smp_processor_id(); struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu); local_timer_stop(evt); } #endif static DEFINE_RAW_SPINLOCK(stop_lock); /* * ipi_cpu_stop - handle IPI from smp_send_stop() */ static void ipi_cpu_stop(unsigned int cpu) { if (system_state == SYSTEM_BOOTING || system_state == SYSTEM_RUNNING) { raw_spin_lock(&stop_lock); printk(KERN_CRIT "CPU%u: stopping\n", cpu); dump_stack(); raw_spin_unlock(&stop_lock); } set_cpu_online(cpu, false); local_fiq_disable(); local_irq_disable(); while (1) cpu_relax(); } /* * Main handler for inter-processor interrupts */ asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs) { handle_IPI(ipinr, regs); } void handle_IPI(int ipinr, struct pt_regs *regs) { unsigned int cpu = smp_processor_id(); struct pt_regs *old_regs = set_irq_regs(regs); if (ipinr >= IPI_TIMER && ipinr < IPI_TIMER + NR_IPI) __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_TIMER]); switch (ipinr) { case IPI_TIMER: irq_enter(); ipi_timer(); irq_exit(); break; case IPI_RESCHEDULE: scheduler_ipi(); break; case IPI_CALL_FUNC: irq_enter(); generic_smp_call_function_interrupt(); irq_exit(); break; case IPI_CALL_FUNC_SINGLE: irq_enter(); generic_smp_call_function_single_interrupt(); irq_exit(); break; case IPI_CPU_STOP: irq_enter(); ipi_cpu_stop(cpu); irq_exit(); break; default: printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr); break; } set_irq_regs(old_regs); } void smp_send_reschedule(int cpu) { smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE); } void smp_send_stop(void) { unsigned long timeout; if (num_online_cpus() > 1) { cpumask_t mask = cpu_online_map; cpu_clear(smp_processor_id(), mask); smp_cross_call(&mask, IPI_CPU_STOP); } /* Wait up to one second for other CPUs to stop */ timeout = USEC_PER_SEC; while (num_online_cpus() > 1 && timeout--) udelay(1); if (num_online_cpus() > 1) pr_warning("SMP: failed to stop secondary CPUs\n"); } /* * not supported here */ int setup_profiling_timer(unsigned int multiplier) { return -EINVAL; }