cregit-Linux how code gets into the kernel

Release 4.14 arch/metag/kernel/smp.c

/*
 *  Copyright (C) 2009,2010,2011 Imagination Technologies Ltd.
 *
 *  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 <linux/atomic.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched/mm.h>
#include <linux/sched/hotplug.h>
#include <linux/sched/task_stack.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <linux/bootmem.h>

#include <asm/cacheflush.h>
#include <asm/cachepart.h>
#include <asm/core_reg.h>
#include <asm/cpu.h>
#include <asm/global_lock.h>
#include <asm/metag_mem.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/setup.h>
#include <asm/tlbflush.h>
#include <asm/hwthread.h>
#include <asm/traps.h>


#define SYSC_DCPART(n)	(SYSC_DCPART0 + SYSC_xCPARTn_STRIDE * (n))

#define SYSC_ICPART(n)	(SYSC_ICPART0 + SYSC_xCPARTn_STRIDE * (n))

DECLARE_PER_CPU(PTBI, pTBI);


void *secondary_data_stack;

/*
 * structures for inter-processor calls
 * - A collection of single bit ipi messages.
 */

struct ipi_data {
	
spinlock_t lock;
	
unsigned long ipi_count;
	
unsigned long bits;
};

static DEFINE_PER_CPU(struct ipi_data, ipi_data) = {
	.lock	= __SPIN_LOCK_UNLOCKED(ipi_data.lock),
};

static DEFINE_SPINLOCK(boot_lock);

static DECLARE_COMPLETION(cpu_running);

/*
 * "thread" is assumed to be a valid Meta hardware thread ID.
 */

static int boot_secondary(unsigned int thread, struct task_struct *idle) { u32 val; /* * set synchronisation state between this boot processor * and the secondary one */ spin_lock(&boot_lock); core_reg_write(TXUPC_ID, 0, thread, (unsigned int)secondary_startup); core_reg_write(TXUPC_ID, 1, thread, 0); /* * Give the thread privilege (PSTAT) and clear potentially problematic * bits in the process (namely ISTAT, CBMarker, CBMarkerI, LSM_STEP). */ core_reg_write(TXUCT_ID, TXSTATUS_REGNUM, thread, TXSTATUS_PSTAT_BIT); /* Clear the minim enable bit. */ val = core_reg_read(TXUCT_ID, TXPRIVEXT_REGNUM, thread); core_reg_write(TXUCT_ID, TXPRIVEXT_REGNUM, thread, val & ~0x80); /* * set the ThreadEnable bit (0x1) in the TXENABLE register * for the specified thread - off it goes! */ val = core_reg_read(TXUCT_ID, TXENABLE_REGNUM, thread); core_reg_write(TXUCT_ID, TXENABLE_REGNUM, thread, val | 0x1); /* * now the secondary core is starting up let it run its * calibrations, then wait for it to finish */ spin_unlock(&boot_lock); return 0; }

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/** * describe_cachepart_change: describe a change to cache partitions. * @thread: Hardware thread number. * @label: Label of cache type, e.g. "dcache" or "icache". * @sz: Total size of the cache. * @old: Old cache partition configuration (*CPART* register). * @new: New cache partition configuration (*CPART* register). * * If the cache partition has changed, prints a message to the log describing * those changes. */
static void describe_cachepart_change(unsigned int thread, const char *label, unsigned int sz, unsigned int old, unsigned int new) { unsigned int lor1, land1, gor1, gand1; unsigned int lor2, land2, gor2, gand2; unsigned int diff = old ^ new; if (!diff) return; pr_info("Thread %d: %s partition changed:", thread, label); if (diff & (SYSC_xCPARTL_OR_BITS | SYSC_xCPARTL_AND_BITS)) { lor1 = (old & SYSC_xCPARTL_OR_BITS) >> SYSC_xCPARTL_OR_S; lor2 = (new & SYSC_xCPARTL_OR_BITS) >> SYSC_xCPARTL_OR_S; land1 = (old & SYSC_xCPARTL_AND_BITS) >> SYSC_xCPARTL_AND_S; land2 = (new & SYSC_xCPARTL_AND_BITS) >> SYSC_xCPARTL_AND_S; pr_cont(" L:%#x+%#x->%#x+%#x", (lor1 * sz) >> 4, ((land1 + 1) * sz) >> 4, (lor2 * sz) >> 4, ((land2 + 1) * sz) >> 4); } if (diff & (SYSC_xCPARTG_OR_BITS | SYSC_xCPARTG_AND_BITS)) { gor1 = (old & SYSC_xCPARTG_OR_BITS) >> SYSC_xCPARTG_OR_S; gor2 = (new & SYSC_xCPARTG_OR_BITS) >> SYSC_xCPARTG_OR_S; gand1 = (old & SYSC_xCPARTG_AND_BITS) >> SYSC_xCPARTG_AND_S; gand2 = (new & SYSC_xCPARTG_AND_BITS) >> SYSC_xCPARTG_AND_S; pr_cont(" G:%#x+%#x->%#x+%#x", (gor1 * sz) >> 4, ((gand1 + 1) * sz) >> 4, (gor2 * sz) >> 4, ((gand2 + 1) * sz) >> 4); } if (diff & SYSC_CWRMODE_BIT) pr_cont(" %sWR", (new & SYSC_CWRMODE_BIT) ? "+" : "-"); if (diff & SYSC_DCPART_GCON_BIT) pr_cont(" %sGCOn", (new & SYSC_DCPART_GCON_BIT) ? "+" : "-"); pr_cont("\n"); }

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/** * setup_smp_cache: ensure cache coherency for new SMP thread. * @thread: New hardware thread number. * * Ensures that coherency is enabled and that the threads share the same cache * partitions. */
static void setup_smp_cache(unsigned int thread) { unsigned int this_thread, lflags; unsigned int dcsz, dcpart_this, dcpart_old, dcpart_new; unsigned int icsz, icpart_old, icpart_new; /* * Copy over the current thread's cache partition configuration to the * new thread so that they share cache partitions. */ __global_lock2(lflags); this_thread = hard_processor_id(); /* Share dcache partition */ dcpart_this = metag_in32(SYSC_DCPART(this_thread)); dcpart_old = metag_in32(SYSC_DCPART(thread)); dcpart_new = dcpart_this; #if PAGE_OFFSET < LINGLOBAL_BASE /* * For the local data cache to be coherent the threads must also have * GCOn enabled. */ dcpart_new |= SYSC_DCPART_GCON_BIT; metag_out32(dcpart_new, SYSC_DCPART(this_thread)); #endif metag_out32(dcpart_new, SYSC_DCPART(thread)); /* Share icache partition too */ icpart_new = metag_in32(SYSC_ICPART(this_thread)); icpart_old = metag_in32(SYSC_ICPART(thread)); metag_out32(icpart_new, SYSC_ICPART(thread)); __global_unlock2(lflags); /* * Log if the cache partitions were altered so the user is aware of any * potential unintentional cache wastage. */ dcsz = get_dcache_size(); icsz = get_dcache_size(); describe_cachepart_change(this_thread, "dcache", dcsz, dcpart_this, dcpart_new); describe_cachepart_change(thread, "dcache", dcsz, dcpart_old, dcpart_new); describe_cachepart_change(thread, "icache", icsz, icpart_old, icpart_new); }

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int __cpu_up(unsigned int cpu, struct task_struct *idle) { unsigned int thread = cpu_2_hwthread_id[cpu]; int ret; load_pgd(swapper_pg_dir, thread); flush_tlb_all(); setup_smp_cache(thread); /* * Tell the secondary CPU where to find its idle thread's stack. */ secondary_data_stack = task_stack_page(idle); wmb(); /* * Now bring the CPU into our world. */ ret = boot_secondary(thread, idle); if (ret == 0) { /* * CPU was successfully started, wait for it * to come online or time out. */ wait_for_completion_timeout(&cpu_running, msecs_to_jiffies(1000)); if (!cpu_online(cpu)) ret = -EIO; } secondary_data_stack = NULL; if (ret) { pr_crit("CPU%u: processor failed to boot\n", cpu); /* * FIXME: We need to clean up the new idle thread. --rmk */ } return ret; }

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#ifdef CONFIG_HOTPLUG_CPU /* * __cpu_disable runs on the processor to be shutdown. */
int __cpu_disable(void) { unsigned int cpu = smp_processor_id(); /* * 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(); /* * 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(); clear_tasks_mm_cpumask(cpu); return 0; }

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/* * 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 (!cpu_wait_death(cpu, 1)) pr_err("CPU%u: unable to kill\n", cpu); }

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/* * Called from the idle thread for the CPU which has been shutdown. * * Note that we do not return from this function. If this cpu is * brought online again it will need to run secondary_startup(). */
void cpu_die(void) { local_irq_disable(); idle_task_exit(); irq_ctx_exit(smp_processor_id()); (void)cpu_report_death(); asm ("XOR TXENABLE, D0Re0,D0Re0\n"); }

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#endif /* CONFIG_HOTPLUG_CPU */ /* * Called by both boot and secondaries to move global data into * per-processor storage. */
void smp_store_cpu_info(unsigned int cpuid) { struct cpuinfo_metag *cpu_info = &per_cpu(cpu_data, cpuid); cpu_info->loops_per_jiffy = loops_per_jiffy; }

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/* * This is the secondary CPU boot entry. We're using this CPUs * idle thread stack and the global page tables. */
asmlinkage void secondary_start_kernel(void) { struct mm_struct *mm = &init_mm; unsigned int cpu = smp_processor_id(); /* * All kernel threads share the same mm context; grab a * reference and switch to it. */ mmget(mm); mmgrab(mm); current->active_mm = mm; cpumask_set_cpu(cpu, mm_cpumask(mm)); enter_lazy_tlb(mm, current); local_flush_tlb_all(); /* * TODO: Some day it might be useful for each Linux CPU to * have its own TBI structure. That would allow each Linux CPU * to run different interrupt handlers for the same IRQ * number. * * For now, simply copying the pointer to the boot CPU's TBI * structure is sufficient because we always want to run the * same interrupt handler whatever CPU takes the interrupt. */ per_cpu(pTBI, cpu) = __TBI(TBID_ISTAT_BIT); if (!per_cpu(pTBI, cpu)) panic("No TBI found!"); per_cpu_trap_init(cpu); irq_ctx_init(cpu); preempt_disable(); setup_priv(); notify_cpu_starting(cpu); pr_info("CPU%u (thread %u): Booted secondary processor\n", cpu, cpu_2_hwthread_id[cpu]); calibrate_delay(); smp_store_cpu_info(cpu); /* * OK, now it's safe to let the boot CPU continue */ set_cpu_online(cpu, true); complete(&cpu_running); /* * Enable local interrupts. */ tbi_startup_interrupt(TBID_SIGNUM_TRT); local_irq_enable(); /* * OK, it's off to the idle thread for us */ cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); }

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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; pr_info("SMP: Total of %d processors activated (%lu.%02lu BogoMIPS).\n", num_online_cpus(), bogosum / (500000/HZ), (bogosum / (5000/HZ)) % 100); }

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void __init smp_prepare_cpus(unsigned int max_cpus) { unsigned int cpu = smp_processor_id(); init_new_context(current, &init_mm); current_thread_info()->cpu = cpu; smp_store_cpu_info(cpu); init_cpu_present(cpu_possible_mask); }

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void __init smp_prepare_boot_cpu(void) { unsigned int cpu = smp_processor_id(); per_cpu(pTBI, cpu) = __TBI(TBID_ISTAT_BIT); if (!per_cpu(pTBI, cpu)) panic("No TBI found!"); }

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static void smp_cross_call(cpumask_t callmap, enum ipi_msg_type msg);
static void send_ipi_message(const struct cpumask *mask, enum ipi_msg_type msg) { unsigned long flags; unsigned int cpu; cpumask_t map; cpumask_clear(&map); local_irq_save(flags); for_each_cpu(cpu, mask) { struct ipi_data *ipi = &per_cpu(ipi_data, cpu); spin_lock(&ipi->lock); /* * KICK interrupts are queued in hardware so we'll get * multiple interrupts if we call smp_cross_call() * multiple times for one msg. The problem is that we * only have one bit for each message - we can't queue * them in software. * * The first time through ipi_handler() we'll clear * the msg bit, having done all the work. But when we * return we'll get _another_ interrupt (and another, * and another until we've handled all the queued * KICKs). Running ipi_handler() when there's no work * to do is bad because that's how kick handler * chaining detects who the KICK was intended for. * See arch/metag/kernel/kick.c for more details. * * So only add 'cpu' to 'map' if we haven't already * queued a KICK interrupt for 'msg'. */ if (!(ipi->bits & (1 << msg))) { ipi->bits |= 1 << msg; cpumask_set_cpu(cpu, &map); } spin_unlock(&ipi->lock); } /* * Call the platform specific cross-CPU call function. */ smp_cross_call(map, msg); local_irq_restore(flags); }

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void arch_send_call_function_ipi_mask(const struct cpumask *mask) { send_ipi_message(mask, IPI_CALL_FUNC); }

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void arch_send_call_function_single_ipi(int cpu) { send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC); }

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void show_ipi_list(struct seq_file *p) { unsigned int cpu; seq_puts(p, "IPI:"); for_each_present_cpu(cpu) seq_printf(p, " %10lu", per_cpu(ipi_data, cpu).ipi_count); seq_putc(p, '\n'); }

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static DEFINE_SPINLOCK(stop_lock); /* * Main handler for inter-processor interrupts * * For Meta, the ipimask now only identifies a single * category of IPI (Bit 1 IPIs have been replaced by a * different mechanism): * * Bit 0 - Inter-processor function call */
static int do_IPI(void) { unsigned int cpu = smp_processor_id(); struct ipi_data *ipi = &per_cpu(ipi_data, cpu); unsigned long msgs, nextmsg; int handled = 0; ipi->ipi_count++; spin_lock(&ipi->lock); msgs = ipi->bits; nextmsg = msgs & -msgs; ipi->bits &= ~nextmsg; spin_unlock(&ipi->lock); if (nextmsg) { handled = 1; nextmsg = ffz(~nextmsg); switch (nextmsg) { case IPI_RESCHEDULE: scheduler_ipi(); break; case IPI_CALL_FUNC: generic_smp_call_function_interrupt(); break; default: pr_crit("CPU%u: Unknown IPI message 0x%lx\n", cpu, nextmsg); break; } } return handled; }

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void smp_send_reschedule(int cpu) { send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE); }

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static void stop_this_cpu(void *data) { unsigned int cpu = smp_processor_id(); if (system_state <= SYSTEM_RUNNING) { spin_lock(&stop_lock); pr_crit("CPU%u: stopping\n", cpu); dump_stack(); spin_unlock(&stop_lock); } set_cpu_online(cpu, false); local_irq_disable(); hard_processor_halt(HALT_OK); }

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void smp_send_stop(void) { smp_call_function(stop_this_cpu, NULL, 0); }

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/* * not supported here */
int setup_profiling_timer(unsigned int multiplier) { return -EINVAL; }

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/* * We use KICKs for inter-processor interrupts. * * For every CPU in "callmap" the IPI data must already have been * stored in that CPU's "ipi_data" member prior to calling this * function. */
static void kick_raise_softirq(cpumask_t callmap, unsigned int irq) { int cpu; for_each_cpu(cpu, &callmap) { unsigned int thread; thread = cpu_2_hwthread_id[cpu]; BUG_ON(thread == BAD_HWTHREAD_ID); metag_out32(1, T0KICKI + (thread * TnXKICK_STRIDE)); } }

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static TBIRES ipi_handler(TBIRES State, int SigNum, int Triggers, int Inst, PTBI pTBI, int *handled) { *handled = do_IPI(); return State; }

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static struct kick_irq_handler ipi_irq = { .func = ipi_handler, };
static void smp_cross_call(cpumask_t callmap, enum ipi_msg_type msg) { kick_raise_softirq(callmap, 1); }

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static inline unsigned int get_core_count(void) { int i; unsigned int ret = 0; for (i = 0; i < CONFIG_NR_CPUS; i++) { if (core_reg_read(TXUCT_ID, TXENABLE_REGNUM, i)) ret++; } return ret; }

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/* * Initialise the CPU possible map early - this describes the CPUs * which may be present or become present in the system. */
void __init smp_init_cpus(void) { unsigned int i, ncores = get_core_count(); /* If no hwthread_map early param was set use default mapping */ for (i = 0; i < NR_CPUS; i++) if (cpu_2_hwthread_id[i] == BAD_HWTHREAD_ID) { cpu_2_hwthread_id[i] = i; hwthread_id_2_cpu[i] = i; } for (i = 0; i < ncores; i++) set_cpu_possible(i, true); kick_register_func(&ipi_irq); }

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James Hogan205398.89%842.11%
Paul E. McKenney70.34%15.26%
Ingo Molnar70.34%315.79%
Thomas Gleixner50.24%315.79%
Vegard Nossum20.10%210.53%
Geert Uytterhoeven10.05%15.26%
Jiang Liu10.05%15.26%
Total2076100.00%19100.00%
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