/*
* 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.
*
*/
#undef DEBUG
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/bootmem.h>
#include <linux/crash_dump.h>
#include <linux/delay.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/types.h>
#include <linux/memblock.h>
#include <asm/processor.h>
#include <asm/machdep.h>
#include <asm/kexec.h>
#include <asm/kdump.h>
#include <asm/prom.h>
#include <asm/firmware.h>
#include <asm/smp.h>
#include <asm/system.h>
#include <asm/setjmp.h>
#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif
/* This keeps a track of which one is crashing cpu. */
int crashing_cpu = -1;
static cpumask_t cpus_in_crash = CPU_MASK_NONE;
cpumask_t cpus_in_sr = CPU_MASK_NONE;
#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);
#ifdef CONFIG_SMP
static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);
void crash_ipi_callback(struct pt_regs *regs)
{
int cpu = smp_processor_id();
if (!cpu_online(cpu))
return;
hard_irq_disable();
if (!cpu_isset(cpu, cpus_in_crash))
crash_save_cpu(regs, cpu);
cpu_set(cpu, cpus_in_crash);
/*
* Entered via soft-reset - could be the kdump
* process is invoked using soft-reset or user activated
* it if some CPU did not respond to an IPI.
* For soft-reset, the secondary CPU can enter this func
* twice. 1 - using IPI, and 2. soft-reset.
* Tell the kexec CPU that entered via soft-reset and ready
* to go down.
*/
if (cpu_isset(cpu, cpus_in_sr)) {
cpu_clear(cpu, cpus_in_sr);
atomic_inc(&enter_on_soft_reset);
}
/*
* Starting the kdump boot.
* This barrier is needed to make sure that all CPUs are stopped.
* If not, soft-reset will be invoked to bring other CPUs.
*/
while (!cpu_isset(crashing_cpu, cpus_in_crash))
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 */
}
/*
* Wait until all CPUs are entered via soft-reset.
*/
static void crash_soft_reset_check(int cpu)
{
unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
cpu_clear(cpu, cpus_in_sr);
while (atomic_read(&enter_on_soft_reset) != ncpus)
cpu_relax();
}
static void crash_kexec_prepare_cpus(int cpu)
{
unsigned int msecs;
unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
crash_send_ipi(crash_ipi_callback);
smp_wmb();
/*
* 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.
* Delay of at least 10 seconds.
*/
printk(KERN_EMERG "Sending IPI to other cpus...\n");
msecs = 10000;
while ((cpus_weight(cpus_in_crash) < ncpus) && (--msecs > 0)) {
cpu_relax();
mdelay(1);
}
/* Would it be better to replace the trap vector here? */
/*
* FIXME: In case if we do not get all CPUs, one possibility: ask the
* user to do soft reset such that we get all.
* Soft-reset will be used until better mechanism is implemented.
*/
if (cpus_weight(cpus_in_crash) < ncpus) {
printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
ncpus - cpus_weight(cpus_in_crash));
printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
cpus_in_sr = CPU_MASK_NONE;
atomic_set(&enter_on_soft_reset, 0);
while (cpus_weight(cpus_in_crash) < ncpus)
cpu_relax();
}
/*
* Make sure all CPUs are entered via soft-reset if the kdump is
* invoked using soft-reset.
*/
if (cpu_isset(cpu, cpus_in_sr))
crash_soft_reset_check(cpu);
/* Leave the IPI callback set */
}
/* wait for all the CPUs to hit real mode but timeout if they don't come in */
#ifdef CONFIG_PPC_STD_MMU_64
static void crash_kexec_wait_realmode(int cpu)
{
unsigned int msecs;
int i;
msecs = 10000;
for (i=0; i < NR_CPUS && msecs > 0; i++) {
if (i == cpu)
continue;
while (paca[i].kexec_state < KEXEC_STATE_REAL_MODE) {
barrier();
if (!cpu_possible(i)) {
break;
}
if (!cpu_online(i)) {
break;
}
msecs--;
mdelay(1);
}
}
mb();
}
#endif
/*
* This function will be called by secondary cpus or by kexec cpu
* if soft-reset is activated to stop some CPUs.
*/
void crash_kexec_secondary(struct pt_regs *regs)
{
int cpu = smp_processor_id();
unsigned long flags;
int msecs = 5;
local_irq_save(flags);
/* Wait 5ms if the kexec CPU is not entered yet. */
while (crashing_cpu < 0) {
if (--msecs < 0) {
/*
* Either kdump image is not loaded or
* kdump process is not started - Probably xmon
* exited using 'x'(exit and recover) or
* kexec_should_crash() failed for all running tasks.
*/
cpu_clear(cpu, cpus_in_sr);
local_irq_restore(flags);
return;
}
mdelay(1);
cpu_relax();
}
if (cpu == crashing_cpu) {
/*
* Panic CPU will enter this func only via soft-reset.
* Wait until all secondary CPUs entered and
* then start kexec boot.
*/
crash_soft_reset_check(cpu);
cpu_set(crashing_cpu, cpus_in_crash);
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(1, 0);
machine_kexec(kexec_crash_image);
/* NOTREACHED */
}
crash_ipi_callback(regs);
}
#else
static void crash_kexec_prepare_cpus(int cpu)
{
/*
* move the secondarys 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)
{
cpus_in_sr = CPU_MASK_NONE;
}
#endif
/*
* 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);
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;
}
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();
crash_save_cpu(regs, crashing_cpu);
crash_kexec_prepare_cpus(crashing_cpu);
cpu_set(crashing_cpu, cpus_in_crash);
#if defined(CONFIG_PPC_STD_MMU_64) && defined(CONFIG_SMP)
crash_kexec_wait_realmode(crashing_cpu);
#endif
machine_kexec_mask_interrupts();
/*
* Call registered shutdown routines savely. 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);
}
