63f21a56f1
The existing code it pretty ugly. How about we clean it up even more like this? From: Anton Blanchard <anton@samba.org> We check for timeout expiry in the outer loop, but we also need to check it in the inner loop or we can lock up forever waiting for a CPU to hit real mode. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@kernel.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
375 lines
9 KiB
C
375 lines
9 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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#undef DEBUG
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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/bootmem.h>
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#include <linux/crash_dump.h>
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#include <linux/delay.h>
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#include <linux/elf.h>
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#include <linux/elfcore.h>
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#include <linux/init.h>
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#include <linux/irq.h>
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#include <linux/types.h>
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#include <linux/memblock.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/firmware.h>
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#include <asm/smp.h>
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#include <asm/system.h>
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#include <asm/setjmp.h>
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#ifdef DEBUG
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#include <asm/udbg.h>
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#define DBG(fmt...) udbg_printf(fmt)
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#else
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#define DBG(fmt...)
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#endif
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/* This keeps a track of which one is crashing cpu. */
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int crashing_cpu = -1;
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static cpumask_t cpus_in_crash = CPU_MASK_NONE;
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cpumask_t cpus_in_sr = CPU_MASK_NONE;
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#define CRASH_HANDLER_MAX 3
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/* NULL terminated list of shutdown handles */
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static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
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static DEFINE_SPINLOCK(crash_handlers_lock);
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#ifdef CONFIG_SMP
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static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);
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void crash_ipi_callback(struct pt_regs *regs)
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{
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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_in_crash))
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crash_save_cpu(regs, cpu);
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cpumask_set_cpu(cpu, &cpus_in_crash);
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/*
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* Entered via soft-reset - could be the kdump
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* process is invoked using soft-reset or user activated
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* it if some CPU did not respond to an IPI.
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* For soft-reset, the secondary CPU can enter this func
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* twice. 1 - using IPI, and 2. soft-reset.
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* Tell the kexec CPU that entered via soft-reset and ready
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* to go down.
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*/
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if (cpumask_test_cpu(cpu, &cpus_in_sr)) {
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cpumask_clear_cpu(cpu, &cpus_in_sr);
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atomic_inc(&enter_on_soft_reset);
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}
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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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* If not, soft-reset will be invoked to bring other CPUs.
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*/
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while (!cpumask_test_cpu(crashing_cpu, &cpus_in_crash))
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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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/*
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* Wait until all CPUs are entered via soft-reset.
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*/
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static void crash_soft_reset_check(int cpu)
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{
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unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
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cpumask_clear_cpu(cpu, &cpus_in_sr);
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while (atomic_read(&enter_on_soft_reset) != ncpus)
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cpu_relax();
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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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crash_send_ipi(crash_ipi_callback);
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smp_wmb();
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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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* Delay of at least 10 seconds.
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*/
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printk(KERN_EMERG "Sending IPI to other cpus...\n");
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msecs = 10000;
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while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {
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cpu_relax();
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mdelay(1);
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}
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/* Would it be better to replace the trap vector here? */
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/*
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* FIXME: In case if we do not get all CPUs, one possibility: ask the
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* user to do soft reset such that we get all.
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* Soft-reset will be used until better mechanism is implemented.
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*/
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if (cpumask_weight(&cpus_in_crash) < ncpus) {
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printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
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ncpus - cpumask_weight(&cpus_in_crash));
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printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
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cpumask_clear(&cpus_in_sr);
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atomic_set(&enter_on_soft_reset, 0);
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while (cpumask_weight(&cpus_in_crash) < ncpus)
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cpu_relax();
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}
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/*
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* Make sure all CPUs are entered via soft-reset if the kdump is
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* invoked using soft-reset.
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*/
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if (cpumask_test_cpu(cpu, &cpus_in_sr))
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crash_soft_reset_check(cpu);
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/* Leave the IPI callback set */
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}
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/*
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* This function will be called by secondary cpus or by kexec cpu
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* if soft-reset is activated to stop some 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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int cpu = smp_processor_id();
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unsigned long flags;
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int msecs = 5;
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local_irq_save(flags);
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/* Wait 5ms if the kexec CPU is not entered yet. */
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while (crashing_cpu < 0) {
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if (--msecs < 0) {
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/*
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* Either kdump image is not loaded or
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* kdump process is not started - Probably xmon
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* exited using 'x'(exit and recover) or
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* kexec_should_crash() failed for all running tasks.
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*/
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cpumask_clear_cpu(cpu, &cpus_in_sr);
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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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cpu_relax();
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}
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if (cpu == crashing_cpu) {
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/*
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* Panic CPU will enter this func only via soft-reset.
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* Wait until all secondary CPUs entered and
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* then start kexec boot.
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*/
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crash_soft_reset_check(cpu);
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cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
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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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machine_kexec(kexec_crash_image);
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/* NOTREACHED */
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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 secondarys 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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cpumask_clear(&cpus_in_sr);
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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_PPC_STD_MMU_64)
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static void 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 = 10000;
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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_PPC_STD_MMU_64 */
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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 (; crash_shutdown_handles[i]; i++)
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crash_shutdown_handles[i] =
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crash_shutdown_handles[i+1];
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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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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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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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crash_save_cpu(regs, crashing_cpu);
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crash_kexec_prepare_cpus(crashing_cpu);
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cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
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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 savely. 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; 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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