373 lines
8.5 KiB
C
373 lines
8.5 KiB
C
/*
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* Architecture specific (PPC64) functions for kexec based crash dumps.
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*
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* Copyright (C) 2005, IBM Corp.
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*
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* Created by: Haren Myneni
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/smp.h>
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#include <linux/reboot.h>
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#include <linux/kexec.h>
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#include <linux/export.h>
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#include <linux/crash_dump.h>
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#include <linux/delay.h>
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#include <linux/irq.h>
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#include <linux/types.h>
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#include <asm/processor.h>
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#include <asm/machdep.h>
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#include <asm/kexec.h>
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#include <asm/kdump.h>
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#include <asm/prom.h>
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#include <asm/smp.h>
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#include <asm/setjmp.h>
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#include <asm/debug.h>
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/*
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* The primary CPU waits a while for all secondary CPUs to enter. This is to
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* avoid sending an IPI if the secondary CPUs are entering
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* crash_kexec_secondary on their own (eg via a system reset).
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*
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* The secondary timeout has to be longer than the primary. Both timeouts are
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* in milliseconds.
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*/
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#define PRIMARY_TIMEOUT 500
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#define SECONDARY_TIMEOUT 1000
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#define IPI_TIMEOUT 10000
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#define REAL_MODE_TIMEOUT 10000
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/* This keeps a track of which one is the crashing cpu. */
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int crashing_cpu = -1;
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static int time_to_dump;
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#define CRASH_HANDLER_MAX 3
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/* List of shutdown handles */
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static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX];
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static DEFINE_SPINLOCK(crash_handlers_lock);
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static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
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static int crash_shutdown_cpu = -1;
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static int handle_fault(struct pt_regs *regs)
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{
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if (crash_shutdown_cpu == smp_processor_id())
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longjmp(crash_shutdown_buf, 1);
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return 0;
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}
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#ifdef CONFIG_SMP
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static atomic_t cpus_in_crash;
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static void crash_ipi_callback(struct pt_regs *regs)
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{
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static cpumask_t cpus_state_saved = CPU_MASK_NONE;
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int cpu = smp_processor_id();
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if (!cpu_online(cpu))
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return;
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hard_irq_disable();
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if (!cpumask_test_cpu(cpu, &cpus_state_saved)) {
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crash_save_cpu(regs, cpu);
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cpumask_set_cpu(cpu, &cpus_state_saved);
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}
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atomic_inc(&cpus_in_crash);
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smp_mb__after_atomic();
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/*
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* Starting the kdump boot.
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* This barrier is needed to make sure that all CPUs are stopped.
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*/
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while (!time_to_dump)
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cpu_relax();
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if (ppc_md.kexec_cpu_down)
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ppc_md.kexec_cpu_down(1, 1);
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#ifdef CONFIG_PPC64
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kexec_smp_wait();
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#else
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for (;;); /* FIXME */
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#endif
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/* NOTREACHED */
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}
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static void crash_kexec_prepare_cpus(int cpu)
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{
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unsigned int msecs;
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unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
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int tries = 0;
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int (*old_handler)(struct pt_regs *regs);
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printk(KERN_EMERG "Sending IPI to other CPUs\n");
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crash_send_ipi(crash_ipi_callback);
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smp_wmb();
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again:
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/*
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* FIXME: Until we will have the way to stop other CPUs reliably,
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* the crash CPU will send an IPI and wait for other CPUs to
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* respond.
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*/
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msecs = IPI_TIMEOUT;
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while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0))
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mdelay(1);
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/* Would it be better to replace the trap vector here? */
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if (atomic_read(&cpus_in_crash) >= ncpus) {
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printk(KERN_EMERG "IPI complete\n");
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return;
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}
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printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",
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ncpus - atomic_read(&cpus_in_crash));
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/*
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* If we have a panic timeout set then we can't wait indefinitely
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* for someone to activate system reset. We also give up on the
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* second time through if system reset fail to work.
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*/
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if ((panic_timeout > 0) || (tries > 0))
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return;
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/*
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* A system reset will cause all CPUs to take an 0x100 exception.
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* The primary CPU returns here via setjmp, and the secondary
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* CPUs reexecute the crash_kexec_secondary path.
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*/
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old_handler = __debugger;
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__debugger = handle_fault;
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crash_shutdown_cpu = smp_processor_id();
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if (setjmp(crash_shutdown_buf) == 0) {
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printk(KERN_EMERG "Activate system reset (dumprestart) "
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"to stop other cpu(s)\n");
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/*
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* A system reset will force all CPUs to execute the
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* crash code again. We need to reset cpus_in_crash so we
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* wait for everyone to do this.
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*/
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atomic_set(&cpus_in_crash, 0);
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smp_mb();
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while (atomic_read(&cpus_in_crash) < ncpus)
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cpu_relax();
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}
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crash_shutdown_cpu = -1;
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__debugger = old_handler;
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tries++;
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goto again;
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}
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/*
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* This function will be called by secondary cpus.
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*/
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void crash_kexec_secondary(struct pt_regs *regs)
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{
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unsigned long flags;
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int msecs = SECONDARY_TIMEOUT;
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local_irq_save(flags);
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/* Wait for the primary crash CPU to signal its progress */
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while (crashing_cpu < 0) {
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if (--msecs < 0) {
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/* No response, kdump image may not have been loaded */
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local_irq_restore(flags);
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return;
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}
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mdelay(1);
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}
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crash_ipi_callback(regs);
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}
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#else /* ! CONFIG_SMP */
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static void crash_kexec_prepare_cpus(int cpu)
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{
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/*
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* move the secondaries to us so that we can copy
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* the new kernel 0-0x100 safely
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*
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* do this if kexec in setup.c ?
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*/
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#ifdef CONFIG_PPC64
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smp_release_cpus();
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#else
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/* FIXME */
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#endif
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}
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void crash_kexec_secondary(struct pt_regs *regs)
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{
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}
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#endif /* CONFIG_SMP */
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/* wait for all the CPUs to hit real mode but timeout if they don't come in */
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#if defined(CONFIG_SMP) && defined(CONFIG_PPC64)
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static void __maybe_unused crash_kexec_wait_realmode(int cpu)
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{
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unsigned int msecs;
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int i;
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msecs = REAL_MODE_TIMEOUT;
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for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
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if (i == cpu)
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continue;
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while (paca[i].kexec_state < KEXEC_STATE_REAL_MODE) {
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barrier();
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if (!cpu_possible(i) || !cpu_online(i) || (msecs <= 0))
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break;
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msecs--;
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mdelay(1);
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}
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}
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mb();
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}
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#else
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static inline void crash_kexec_wait_realmode(int cpu) {}
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#endif /* CONFIG_SMP && CONFIG_PPC64 */
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/*
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* Register a function to be called on shutdown. Only use this if you
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* can't reset your device in the second kernel.
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*/
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int crash_shutdown_register(crash_shutdown_t handler)
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{
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unsigned int i, rc;
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spin_lock(&crash_handlers_lock);
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for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
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if (!crash_shutdown_handles[i]) {
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/* Insert handle at first empty entry */
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crash_shutdown_handles[i] = handler;
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rc = 0;
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break;
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}
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if (i == CRASH_HANDLER_MAX) {
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printk(KERN_ERR "Crash shutdown handles full, "
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"not registered.\n");
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rc = 1;
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}
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spin_unlock(&crash_handlers_lock);
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return rc;
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}
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EXPORT_SYMBOL(crash_shutdown_register);
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int crash_shutdown_unregister(crash_shutdown_t handler)
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{
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unsigned int i, rc;
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spin_lock(&crash_handlers_lock);
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for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
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if (crash_shutdown_handles[i] == handler)
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break;
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if (i == CRASH_HANDLER_MAX) {
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printk(KERN_ERR "Crash shutdown handle not found\n");
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rc = 1;
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} else {
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/* Shift handles down */
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for (; i < (CRASH_HANDLER_MAX - 1); i++)
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crash_shutdown_handles[i] =
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crash_shutdown_handles[i+1];
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/*
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* Reset last entry to NULL now that it has been shifted down,
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* this will allow new handles to be added here.
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*/
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crash_shutdown_handles[i] = NULL;
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rc = 0;
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}
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spin_unlock(&crash_handlers_lock);
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return rc;
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}
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EXPORT_SYMBOL(crash_shutdown_unregister);
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void default_machine_crash_shutdown(struct pt_regs *regs)
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{
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unsigned int i;
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int (*old_handler)(struct pt_regs *regs);
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/*
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* This function is only called after the system
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* has panicked or is otherwise in a critical state.
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* The minimum amount of code to allow a kexec'd kernel
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* to run successfully needs to happen here.
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*
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* In practice this means stopping other cpus in
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* an SMP system.
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* The kernel is broken so disable interrupts.
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*/
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hard_irq_disable();
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/*
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* Make a note of crashing cpu. Will be used in machine_kexec
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* such that another IPI will not be sent.
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*/
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crashing_cpu = smp_processor_id();
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/*
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* If we came in via system reset, wait a while for the secondary
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* CPUs to enter.
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*/
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if (TRAP(regs) == 0x100)
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mdelay(PRIMARY_TIMEOUT);
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crash_kexec_prepare_cpus(crashing_cpu);
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crash_save_cpu(regs, crashing_cpu);
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time_to_dump = 1;
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crash_kexec_wait_realmode(crashing_cpu);
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machine_kexec_mask_interrupts();
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/*
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* Call registered shutdown routines safely. Swap out
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* __debugger_fault_handler, and replace on exit.
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*/
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old_handler = __debugger_fault_handler;
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__debugger_fault_handler = handle_fault;
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crash_shutdown_cpu = smp_processor_id();
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for (i = 0; i < CRASH_HANDLER_MAX && crash_shutdown_handles[i]; i++) {
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if (setjmp(crash_shutdown_buf) == 0) {
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/*
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* Insert syncs and delay to ensure
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* instructions in the dangerous region don't
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* leak away from this protected region.
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*/
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asm volatile("sync; isync");
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/* dangerous region */
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crash_shutdown_handles[i]();
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asm volatile("sync; isync");
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}
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}
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crash_shutdown_cpu = -1;
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__debugger_fault_handler = old_handler;
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if (ppc_md.kexec_cpu_down)
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ppc_md.kexec_cpu_down(1, 0);
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}
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