diff options
Diffstat (limited to 'arch/tile/kernel/smpboot.c')
| -rw-r--r-- | arch/tile/kernel/smpboot.c | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/arch/tile/kernel/smpboot.c b/arch/tile/kernel/smpboot.c new file mode 100644 index 000000000000..aa3aafdb4b93 --- /dev/null +++ b/arch/tile/kernel/smpboot.c @@ -0,0 +1,293 @@ +/* + * 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/smp_lock.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 <asm/mmu_context.h> +#include <asm/tlbflush.h> +#include <asm/sections.h> + +/* + * This assembly function is provided in entry.S. + * When called, it loops on a nap instruction forever. + * FIXME: should be in a header somewhere. + */ +extern void smp_nap(void); + +/* State of each CPU. */ +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) + printk("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) + printk(KERN_WARNING "couldn't reset init affinity (%ld)\n", + rc); + return 0; +} +late_initcall(reset_init_affinity); + +struct cpumask cpu_started __cpuinitdata; + +/* + * 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 __cpuinit 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); + + /* Enable IRQs. */ + init_per_tile_IRQs(); + + /* 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)) { + printk(KERN_WARNING "CPU#%d already started!\n", cpuid); + for (;;) + local_irq_enable(); + } + + smp_nap(); +} + +void setup_mpls(void); /* from kernel/setup.c */ +void store_permanent_mappings(void); + +/* + * Bring a secondary processor online. + */ +void __cpuinit online_secondary() +{ + /* + * 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(); + + /* + * We need to hold call_lock, so there is no inconsistency + * between the time smp_call_function() determines number of + * IPI recipients, and the time when the determination is made + * for which cpus receive the IPI. Holding this + * lock helps us to not include this cpu in a currently in progress + * smp_call_function(). + */ + ipi_call_lock(); + set_cpu_online(smp_processor_id(), 1); + ipi_call_unlock(); + __get_cpu_var(cpu_state) = CPU_ONLINE; + + /* Set up MPLs for this processor */ + setup_mpls(); + + + /* Set up tile-timer clock-event device on this cpu */ + setup_tile_timer(); + + preempt_enable(); + + store_permanent_mappings(); + + cpu_idle(); +} + +int __cpuinit __cpu_up(unsigned int cpu) +{ + /* 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) { + printk(KERN_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) + printk("Couldn't set init affinity to cpu %d (%d)\n", cpu, rc); +} |