/*
* Architecture specific (PPC64) functions for kexec based crash dumps.
*
* Copyright (C) 2005, IBM Corp.
*
* Created by: Haren Myneni
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*
*/
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/export.h>
#include <linux/crash_dump.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/types.h>
#include <asm/processor.h>
#include <asm/machdep.h>
#include <asm/kexec.h>
#include <asm/kdump.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/setjmp.h>
#include <asm/debug.h>
/*
* The primary CPU waits a while for all secondary CPUs to enter. This is to
* avoid sending an IPI if the secondary CPUs are entering
* crash_kexec_secondary on their own (eg via a system reset).
*
* The secondary timeout has to be longer than the primary. Both timeouts are
* in milliseconds.
*/
#define PRIMARY_TIMEOUT 500
#define SECONDARY_TIMEOUT 1000
#define IPI_TIMEOUT 10000
#define REAL_MODE_TIMEOUT 10000
/* This keeps a track of which one is the crashing cpu. */
int crashing_cpu = -1;
static int time_to_dump;
#define CRASH_HANDLER_MAX 3
/* NULL terminated list of shutdown handles */
static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
static DEFINE_SPINLOCK(crash_handlers_lock);
static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
static int crash_shutdown_cpu = -1;
static int handle_fault(struct pt_regs *regs)
{
if (crash_shutdown_cpu == smp_processor_id())
longjmp(crash_shutdown_buf, 1);
return 0;
}
#ifdef CONFIG_SMP
static atomic_t cpus_in_crash;
void crash_ipi_callback(struct pt_regs *regs)
{
static cpumask_t cpus_state_saved = CPU_MASK_NONE;
int cpu = smp_processor_id();
if (!cpu_online(cpu))
return;
hard_irq_disable();
if (!cpumask_test_cpu(cpu, &cpus_state_saved)) {
crash_save_cpu(regs, cpu);
cpumask_set_cpu(cpu, &cpus_state_saved);
}
atomic_inc(&cpus_in_crash);
smp_mb__after_atomic();
/*
* Starting the kdump boot.
* This barrier is needed to make sure that all CPUs are stopped.
*/
while (!time_to_dump)
cpu_relax();
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(1, 1);
#ifdef CONFIG_PPC64
kexec_smp_wait();
#else
for (;;); /* FIXME */
#endif
/* NOTREACHED */
}
static void crash_kexec_prepare_cpus(int cpu)
{
unsigned int msecs;
unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
int tries = 0;
int (*old_handler)(struct pt_regs *regs);
printk(KERN_EMERG "Sending IPI to other CPUs\n");
crash_send_ipi(crash_ipi_callback);
smp_wmb();
again:
/*
* FIXME: Until we will have the way to stop other CPUs reliably,
* the crash CPU will send an IPI and wait for other CPUs to
* respond.
*/
msecs = IPI_TIMEOUT;
while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0))
mdelay(1);
/* Would it be better to replace the trap vector here? */
if (atomic_read(&cpus_in_crash) >= ncpus) {
printk(KERN_EMERG "IPI complete\n");
return;
}
printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",
ncpus - atomic_read(&cpus_in_crash));
/*
* If we have a panic timeout set then we can't wait indefinitely
* for someone to activate system reset. We also give up on the
* second time through if system reset fail to work.
*/
if ((panic_timeout > 0) || (tries > 0))
return;
/*
* A system reset will cause all CPUs to take an 0x100 exception.
* The primary CPU returns here via setjmp, and the secondary
* CPUs reexecute the crash_kexec_secondary path.
*/
old_handler = __debugger;
__debugger = handle_fault;
crash_shutdown_cpu = smp_processor_id();
if (setjmp(crash_shutdown_buf) == 0) {
printk(KERN_EMERG "Activate system reset (dumprestart) "
"to stop other cpu(s)\n");
/*
* A system reset will force all CPUs to execute the
* crash code again. We need to reset cpus_in_crash so we
* wait for everyone to do this.
*/
atomic_set(&cpus_in_crash, 0);
smp_mb();
while (atomic_read(&cpus_in_crash) < ncpus)
cpu_relax();
}
crash_shutdown_cpu = -1;
__debugger = old_handler;
tries++;
goto again;
}
/*
* This function will be called by secondary cpus.
*/
void crash_kexec_secondary(struct pt_regs *regs)
{
unsigned long flags;
int msecs = SECONDARY_TIMEOUT;
local_irq_save(flags);
/* Wait for the primary crash CPU to signal its progress */
while (crashing_cpu < 0) {
if (--msecs < 0) {
/* No response, kdump image may not have been loaded */
local_irq_restore(flags);
return;
}
mdelay(1);
}
crash_ipi_callback(regs);
}
#else /* ! CONFIG_SMP */
static void crash_kexec_prepare_cpus(int cpu)
{
/*
* move the secondaries to us so that we can copy
* the new kernel 0-0x100 safely
*
* do this if kexec in setup.c ?
*/
#ifdef CONFIG_PPC64
smp_release_cpus();
#else
/* FIXME */
#endif
}
void crash_kexec_secondary(struct pt_regs *regs)
{
}
#endif /* CONFIG_SMP */
/* wait for all the CPUs to hit real mode but timeout if they don't come in */
#if defined(CONFIG_SMP) && defined(CONFIG_PPC_STD_MMU_64)
static void crash_kexec_wait_realmode(int cpu)
{
unsigned int msecs;
int i;
msecs = REAL_MODE_TIMEOUT;
for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
if (i == cpu)
continue;
while (paca[i].kexec_state < KEXEC_STATE_REAL_MODE) {
barrier();
if (!cpu_possible(i) || !cpu_online(i) || (msecs <= 0))
break;
msecs--;
mdelay(1);
}
}
mb();
}
#else
static inline void crash_kexec_wait_realmode(int cpu) {}
#endif /* CONFIG_SMP && CONFIG_PPC_STD_MMU_64 */
/*
* Register a function to be called on shutdown. Only use this if you
* can't reset your device in the second kernel.
*/
int crash_shutdown_register(crash_shutdown_t handler)
{
unsigned int i, rc;
spin_lock(&crash_handlers_lock);
for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
if (!crash_shutdown_handles[i]) {
/* Insert handle at first empty entry */
crash_shutdown_handles[i] = handler;
rc = 0;
break;
}
if (i == CRASH_HANDLER_MAX) {
printk(KERN_ERR "Crash shutdown handles full, "
"not registered.\n");
rc = 1;
}
spin_unlock(&crash_handlers_lock);
return rc;
}
EXPORT_SYMBOL(crash_shutdown_register);
int crash_shutdown_unregister(crash_shutdown_t handler)
{
unsigned int i, rc;
spin_lock(&crash_handlers_lock);
for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
if (crash_shutdown_handles[i] == handler)
break;
if (i == CRASH_HANDLER_MAX) {
printk(KERN_ERR "Crash shutdown handle not found\n");
rc = 1;
} else {
/* Shift handles down */
for (; crash_shutdown_handles[i]; i++)
crash_shutdown_handles[i] =
crash_shutdown_handles[i+1];
rc = 0;
}
spin_unlock(&crash_handlers_lock);
return rc;
}
EXPORT_SYMBOL(crash_shutdown_unregister);
void default_machine_crash_shutdown(struct pt_regs *regs)
{
unsigned int i;
int (*old_handler)(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 stopping other cpus in
* an SMP system.
* The kernel is broken so disable interrupts.
*/
hard_irq_disable();
/*
* Make a note of crashing cpu. Will be used in machine_kexec
* such that another IPI will not be sent.
*/
crashing_cpu = smp_processor_id();
/*
* If we came in via system reset, wait a while for the secondary
* CPUs to enter.
*/
if (TRAP(regs) == 0x100)
mdelay(PRIMARY_TIMEOUT);
crash_kexec_prepare_cpus(crashing_cpu);
crash_save_cpu(regs, crashing_cpu);
time_to_dump = 1;
crash_kexec_wait_realmode(crashing_cpu);
machine_kexec_mask_interrupts();
/*
* Call registered shutdown routines safely. Swap out
* __debugger_fault_handler, and replace on exit.
*/
old_handler = __debugger_fault_handler;
__debugger_fault_handler = handle_fault;
crash_shutdown_cpu = smp_processor_id();
for (i = 0; crash_shutdown_handles[i]; i++) {
if (setjmp(crash_shutdown_buf) == 0) {
/*
* Insert syncs and delay to ensure
* instructions in the dangerous region don't
* leak away from this protected region.
*/
asm volatile("sync; isync");
/* dangerous region */
crash_shutdown_handles[i]();
asm volatile("sync; isync");
}
}
crash_shutdown_cpu = -1;
__debugger_fault_handler = old_handler;
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(1, 0);
}