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/*
* Architecture specific (x86_64) functions for kexec based crash dumps.
*
* Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
*
* Copyright (C) IBM Corporation, 2004. All rights reserved.
*
*/
#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/irq.h>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <asm/processor.h>
#include <asm/hardirq.h>
#include <asm/nmi.h>
#include <asm/hw_irq.h>
#include <asm/mach_apic.h>
#include <asm/kdebug.h>
/* This keeps a track of which one is crashing cpu. */
static int crashing_cpu;
static u32 *append_elf_note(u32 *buf, char *name, unsigned type,
void *data, size_t data_len)
{
struct elf_note note;
note.n_namesz = strlen(name) + 1;
note.n_descsz = data_len;
note.n_type = type;
memcpy(buf, ¬e, sizeof(note));
buf += (sizeof(note) +3)/4;
memcpy(buf, name, note.n_namesz);
buf += (note.n_namesz + 3)/4;
memcpy(buf, data, note.n_descsz);
buf += (note.n_descsz + 3)/4;
return buf;
}
static void final_note(u32 *buf)
{
struct elf_note note;
note.n_namesz = 0;
note.n_descsz = 0;
note.n_type = 0;
memcpy(buf, ¬e, sizeof(note));
}
static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
{
struct elf_prstatus prstatus;
u32 *buf;
if ((cpu < 0) || (cpu >= NR_CPUS))
return;
/* Using ELF notes here is opportunistic.
* I need a well defined structure format
* for the data I pass, and I need tags
* on the data to indicate what information I have
* squirrelled away. ELF notes happen to provide
* all of that, no need to invent something new.
*/
buf = (u32*)per_cpu_ptr(crash_notes, cpu);
if (!buf)
return;
memset(&prstatus, 0, sizeof(prstatus));
prstatus.pr_pid = current->pid;
elf_core_copy_regs(&prstatus.pr_reg, regs);
buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
sizeof(prstatus));
final_note(buf);
}
static void crash_save_self(struct pt_regs *regs)
{
int cpu;
cpu = smp_processor_id();
crash_save_this_cpu(regs, cpu);
}
#ifdef CONFIG_SMP
static atomic_t waiting_for_crash_ipi;
static int crash_nmi_callback(struct notifier_block *self,
unsigned long val, void *data)
{
struct pt_regs *regs;
int cpu;
if (val != DIE_NMI_IPI)
return NOTIFY_OK;
regs = ((struct die_args *)data)->regs;
cpu = raw_smp_processor_id();
/*
* Don't do anything if this handler is invoked on crashing cpu.
* Otherwise, system will completely hang. Crashing cpu can get
* an NMI if system was initially booted with nmi_watchdog parameter.
*/
if (cpu == crashing_cpu)
return NOTIFY_STOP;
local_irq_disable();
crash_save_this_cpu(regs, cpu);
disable_local_APIC();
atomic_dec(&waiting_for_crash_ipi);
/* Assume hlt works */
for(;;)
halt();
return 1;
}
static void smp_send_nmi_allbutself(void)
{
send_IPI_allbutself(NMI_VECTOR);
}
/*
* This code is a best effort heuristic to get the
* other cpus to stop executing. So races with
* cpu hotplug shouldn't matter.
*/
static struct notifier_block crash_nmi_nb = {
.notifier_call = crash_nmi_callback,
};
static void nmi_shootdown_cpus(void)
{
unsigned long msecs;
atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
if (register_die_notifier(&crash_nmi_nb))
return; /* return what? */
/*
* Ensure the new callback function is set before sending
* out the NMI
*/
wmb();
smp_send_nmi_allbutself();
msecs = 1000; /* Wait at most a second for the other cpus to stop */
while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
mdelay(1);
msecs--;
}
/* Leave the nmi callback set */
disable_local_APIC();
}
#else
static void nmi_shootdown_cpus(void)
{
/* There are no cpus to shootdown */
}
#endif
void machine_crash_shutdown(struct pt_regs *regs)
{
/*
* This function is only called after the system
* has panicked or is otherwise in a critical state.
* The minimum amount of code to allow a kexec'd kernel
* to run successfully needs to happen here.
*
* In practice this means shooting down the other cpus in
* an SMP system.
*/
/* The kernel is broken so disable interrupts */
local_irq_disable();
/* Make a note of crashing cpu. Will be used in NMI callback.*/
crashing_cpu = smp_processor_id();
nmi_shootdown_cpus();
if(cpu_has_apic)
disable_local_APIC();
disable_IO_APIC();
crash_save_self(regs);
}
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