![Nick Piggin](/assets/img/avatar_default.png)
Run idle threads with preempt disabled. Also corrected a bugs in arm26's cpu_idle (make it actually call schedule()). How did it ever work before? Might fix the CPU hotplugging hang which Nigel Cunningham noted. We think the bug hits if the idle thread is preempted after checking need_resched() and before going to sleep, then the CPU offlined. After calling stop_machine_run, the CPU eventually returns from preemption and into the idle thread and goes to sleep. The CPU will continue executing previous idle and have no chance to call play_dead. By disabling preemption until we are ready to explicitly schedule, this bug is fixed and the idle threads generally become more robust. From: alexs <ashepard@u.washington.edu> PPC build fix From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> MIPS build fix Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
413 lines
9.4 KiB
C
413 lines
9.4 KiB
C
/*
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* Smp support for ppc.
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*
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* Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great
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* deal of code from the sparc and intel versions.
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*
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* Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
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*
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*/
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#include <linux/config.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/smp.h>
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#include <linux/smp_lock.h>
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#include <linux/interrupt.h>
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#include <linux/kernel_stat.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/cache.h>
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#include <asm/ptrace.h>
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#include <asm/atomic.h>
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#include <asm/irq.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <asm/io.h>
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#include <asm/prom.h>
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#include <asm/smp.h>
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#include <asm/residual.h>
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#include <asm/time.h>
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#include <asm/thread_info.h>
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#include <asm/tlbflush.h>
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#include <asm/xmon.h>
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#include <asm/machdep.h>
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volatile int smp_commenced;
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int smp_tb_synchronized;
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struct cpuinfo_PPC cpu_data[NR_CPUS];
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atomic_t ipi_recv;
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atomic_t ipi_sent;
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cpumask_t cpu_online_map;
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cpumask_t cpu_possible_map;
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int smp_hw_index[NR_CPUS];
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struct thread_info *secondary_ti;
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static struct task_struct *idle_tasks[NR_CPUS];
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EXPORT_SYMBOL(cpu_online_map);
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EXPORT_SYMBOL(cpu_possible_map);
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/* SMP operations for this machine */
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struct smp_ops_t *smp_ops;
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/* all cpu mappings are 1-1 -- Cort */
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volatile unsigned long cpu_callin_map[NR_CPUS];
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int start_secondary(void *);
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void smp_call_function_interrupt(void);
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static int __smp_call_function(void (*func) (void *info), void *info,
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int wait, int target);
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/* Low level assembly function used to backup CPU 0 state */
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extern void __save_cpu_setup(void);
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/* Since OpenPIC has only 4 IPIs, we use slightly different message numbers.
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*
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* Make sure this matches openpic_request_IPIs in open_pic.c, or what shows up
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* in /proc/interrupts will be wrong!!! --Troy */
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#define PPC_MSG_CALL_FUNCTION 0
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#define PPC_MSG_RESCHEDULE 1
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#define PPC_MSG_INVALIDATE_TLB 2
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#define PPC_MSG_XMON_BREAK 3
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static inline void
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smp_message_pass(int target, int msg)
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{
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if (smp_ops) {
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atomic_inc(&ipi_sent);
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smp_ops->message_pass(target, msg);
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}
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}
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/*
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* Common functions
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*/
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void smp_message_recv(int msg, struct pt_regs *regs)
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{
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atomic_inc(&ipi_recv);
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switch( msg ) {
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case PPC_MSG_CALL_FUNCTION:
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smp_call_function_interrupt();
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break;
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case PPC_MSG_RESCHEDULE:
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set_need_resched();
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break;
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case PPC_MSG_INVALIDATE_TLB:
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_tlbia();
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break;
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#ifdef CONFIG_XMON
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case PPC_MSG_XMON_BREAK:
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xmon(regs);
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break;
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#endif /* CONFIG_XMON */
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default:
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printk("SMP %d: smp_message_recv(): unknown msg %d\n",
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smp_processor_id(), msg);
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break;
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}
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}
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/*
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* 750's don't broadcast tlb invalidates so
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* we have to emulate that behavior.
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* -- Cort
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*/
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void smp_send_tlb_invalidate(int cpu)
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{
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if ( PVR_VER(mfspr(SPRN_PVR)) == 8 )
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smp_message_pass(MSG_ALL_BUT_SELF, PPC_MSG_INVALIDATE_TLB);
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}
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void smp_send_reschedule(int cpu)
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{
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/*
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* This is only used if `cpu' is running an idle task,
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* so it will reschedule itself anyway...
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*
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* This isn't the case anymore since the other CPU could be
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* sleeping and won't reschedule until the next interrupt (such
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* as the timer).
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* -- Cort
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*/
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/* This is only used if `cpu' is running an idle task,
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so it will reschedule itself anyway... */
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smp_message_pass(cpu, PPC_MSG_RESCHEDULE);
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}
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#ifdef CONFIG_XMON
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void smp_send_xmon_break(int cpu)
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{
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smp_message_pass(cpu, PPC_MSG_XMON_BREAK);
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}
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#endif /* CONFIG_XMON */
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static void stop_this_cpu(void *dummy)
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{
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local_irq_disable();
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while (1)
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;
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}
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void smp_send_stop(void)
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{
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smp_call_function(stop_this_cpu, NULL, 1, 0);
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}
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/*
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* Structure and data for smp_call_function(). This is designed to minimise
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* static memory requirements. It also looks cleaner.
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* Stolen from the i386 version.
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*/
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static DEFINE_SPINLOCK(call_lock);
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static struct call_data_struct {
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void (*func) (void *info);
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void *info;
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atomic_t started;
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atomic_t finished;
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int wait;
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} *call_data;
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/*
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* this function sends a 'generic call function' IPI to all other CPUs
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* in the system.
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*/
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int smp_call_function(void (*func) (void *info), void *info, int nonatomic,
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int wait)
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/*
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* [SUMMARY] Run a function on all other CPUs.
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* <func> The function to run. This must be fast and non-blocking.
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* <info> An arbitrary pointer to pass to the function.
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* <nonatomic> currently unused.
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* <wait> If true, wait (atomically) until function has completed on other CPUs.
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* [RETURNS] 0 on success, else a negative status code. Does not return until
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* remote CPUs are nearly ready to execute <<func>> or are or have executed.
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*
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* You must not call this function with disabled interrupts or from a
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* hardware interrupt handler or from a bottom half handler.
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*/
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{
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/* FIXME: get cpu lock with hotplug cpus, or change this to
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bitmask. --RR */
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if (num_online_cpus() <= 1)
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return 0;
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/* Can deadlock when called with interrupts disabled */
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WARN_ON(irqs_disabled());
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return __smp_call_function(func, info, wait, MSG_ALL_BUT_SELF);
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}
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static int __smp_call_function(void (*func) (void *info), void *info,
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int wait, int target)
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{
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struct call_data_struct data;
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int ret = -1;
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int timeout;
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int ncpus = 1;
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if (target == MSG_ALL_BUT_SELF)
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ncpus = num_online_cpus() - 1;
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else if (target == MSG_ALL)
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ncpus = num_online_cpus();
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data.func = func;
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data.info = info;
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atomic_set(&data.started, 0);
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data.wait = wait;
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if (wait)
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atomic_set(&data.finished, 0);
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spin_lock(&call_lock);
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call_data = &data;
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/* Send a message to all other CPUs and wait for them to respond */
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smp_message_pass(target, PPC_MSG_CALL_FUNCTION);
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/* Wait for response */
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timeout = 1000000;
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while (atomic_read(&data.started) != ncpus) {
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if (--timeout == 0) {
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printk("smp_call_function on cpu %d: other cpus not responding (%d)\n",
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smp_processor_id(), atomic_read(&data.started));
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goto out;
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}
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barrier();
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udelay(1);
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}
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if (wait) {
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timeout = 1000000;
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while (atomic_read(&data.finished) != ncpus) {
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if (--timeout == 0) {
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printk("smp_call_function on cpu %d: other cpus not finishing (%d/%d)\n",
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smp_processor_id(), atomic_read(&data.finished), atomic_read(&data.started));
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goto out;
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}
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barrier();
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udelay(1);
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}
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}
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ret = 0;
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out:
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spin_unlock(&call_lock);
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return ret;
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}
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void smp_call_function_interrupt(void)
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{
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void (*func) (void *info) = call_data->func;
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void *info = call_data->info;
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int wait = call_data->wait;
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/*
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* Notify initiating CPU that I've grabbed the data and am
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* about to execute the function
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*/
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atomic_inc(&call_data->started);
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/*
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* At this point the info structure may be out of scope unless wait==1
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*/
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(*func)(info);
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if (wait)
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atomic_inc(&call_data->finished);
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}
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static void __devinit smp_store_cpu_info(int id)
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{
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struct cpuinfo_PPC *c = &cpu_data[id];
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/* assume bogomips are same for everything */
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c->loops_per_jiffy = loops_per_jiffy;
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c->pvr = mfspr(SPRN_PVR);
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}
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void __init smp_prepare_cpus(unsigned int max_cpus)
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{
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int num_cpus, i, cpu;
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struct task_struct *p;
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/* Fixup boot cpu */
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smp_store_cpu_info(smp_processor_id());
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cpu_callin_map[smp_processor_id()] = 1;
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if (smp_ops == NULL) {
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printk("SMP not supported on this machine.\n");
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return;
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}
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/* Probe platform for CPUs: always linear. */
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num_cpus = smp_ops->probe();
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for (i = 0; i < num_cpus; ++i)
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cpu_set(i, cpu_possible_map);
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/* Backup CPU 0 state */
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__save_cpu_setup();
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for_each_cpu(cpu) {
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if (cpu == smp_processor_id())
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continue;
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/* create a process for the processor */
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p = fork_idle(cpu);
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if (IS_ERR(p))
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panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
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p->thread_info->cpu = cpu;
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idle_tasks[cpu] = p;
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}
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}
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void __devinit smp_prepare_boot_cpu(void)
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{
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cpu_set(smp_processor_id(), cpu_online_map);
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cpu_set(smp_processor_id(), cpu_possible_map);
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}
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int __init setup_profiling_timer(unsigned int multiplier)
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{
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return 0;
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}
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/* Processor coming up starts here */
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int __devinit start_secondary(void *unused)
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{
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int cpu;
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atomic_inc(&init_mm.mm_count);
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current->active_mm = &init_mm;
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cpu = smp_processor_id();
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smp_store_cpu_info(cpu);
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set_dec(tb_ticks_per_jiffy);
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preempt_disable();
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cpu_callin_map[cpu] = 1;
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printk("CPU %d done callin...\n", cpu);
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smp_ops->setup_cpu(cpu);
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printk("CPU %d done setup...\n", cpu);
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smp_ops->take_timebase();
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printk("CPU %d done timebase take...\n", cpu);
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spin_lock(&call_lock);
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cpu_set(cpu, cpu_online_map);
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spin_unlock(&call_lock);
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local_irq_enable();
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cpu_idle();
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return 0;
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}
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int __cpu_up(unsigned int cpu)
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{
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char buf[32];
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int c;
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secondary_ti = idle_tasks[cpu]->thread_info;
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mb();
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/*
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* There was a cache flush loop here to flush the cache
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* to memory for the first 8MB of RAM. The cache flush
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* has been pushed into the kick_cpu function for those
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* platforms that need it.
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*/
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/* wake up cpu */
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smp_ops->kick_cpu(cpu);
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/*
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* wait to see if the cpu made a callin (is actually up).
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* use this value that I found through experimentation.
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* -- Cort
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*/
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for (c = 1000; c && !cpu_callin_map[cpu]; c--)
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udelay(100);
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if (!cpu_callin_map[cpu]) {
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sprintf(buf, "didn't find cpu %u", cpu);
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if (ppc_md.progress) ppc_md.progress(buf, 0x360+cpu);
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printk("Processor %u is stuck.\n", cpu);
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return -ENOENT;
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}
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sprintf(buf, "found cpu %u", cpu);
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if (ppc_md.progress) ppc_md.progress(buf, 0x350+cpu);
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printk("Processor %d found.\n", cpu);
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smp_ops->give_timebase();
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/* Wait until cpu puts itself in the online map */
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while (!cpu_online(cpu))
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cpu_relax();
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return 0;
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}
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void smp_cpus_done(unsigned int max_cpus)
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{
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smp_ops->setup_cpu(0);
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}
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