android_kernel_motorola_sm6225/arch/powerpc/kernel/crash.c
Michael Ellerman d6c1a90810 [PATCH] powerpc: Disable and EOI interrupts in machine_crash_shutdown()
We've seen several bugs caused by interrupt weirdness in the kdump kernel.
Panicking from an interrupt handler means we fail to EOI the interrupt, and
so the second kernel never gets that interrupt ever again. We also see hangs
on JS20 where we take interrupts in the second kernel early during boot.

This patch fixes both those problems, and although it adds more code to the
crash path I think it is the best solution.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-04-22 18:44:25 +10:00

212 lines
4.9 KiB
C

/*
* 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 <asm/processor.h>
#include <asm/machdep.h>
#include <asm/kdump.h>
#include <asm/lmb.h>
#include <asm/firmware.h>
#include <asm/smp.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 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, &note, 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, &note, 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 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);
}
#ifdef CONFIG_SMP
static atomic_t waiting_for_crash_ipi;
void crash_ipi_callback(struct pt_regs *regs)
{
int cpu = smp_processor_id();
if (cpu == crashing_cpu)
return;
if (!cpu_online(cpu))
return;
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(1, 1);
local_irq_disable();
crash_save_this_cpu(regs, cpu);
atomic_dec(&waiting_for_crash_ipi);
kexec_smp_wait();
/* NOTREACHED */
}
static void crash_kexec_prepare_cpus(void)
{
unsigned int msecs;
atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
crash_send_ipi(crash_ipi_callback);
smp_wmb();
/*
* FIXME: Until we will have the way to stop other CPUSs reliabally,
* the crash CPU will send an IPI and wait for other CPUs to
* respond. If not, proceed the kexec boot even though we failed to
* capture other CPU states.
* Delay of at least 10 seconds.
*/
printk(KERN_ALERT "Sending IPI to other cpus...\n");
msecs = 10000;
while ((atomic_read(&waiting_for_crash_ipi) > 0) && (--msecs > 0)) {
barrier();
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.
* IPI handler is already set by the panic cpu initially. Therefore,
* all cpus could invoke this handler from die() and the panic CPU
* will call machine_kexec() directly from this handler to do
* kexec boot.
*/
if (atomic_read(&waiting_for_crash_ipi))
printk(KERN_ALERT "done waiting: %d cpus not responding\n",
atomic_read(&waiting_for_crash_ipi));
/* Leave the IPI callback set */
}
#else
static void crash_kexec_prepare_cpus(void)
{
/*
* move the secondarys to us so that we can copy
* the new kernel 0-0x100 safely
*
* do this if kexec in setup.c ?
*/
smp_release_cpus();
}
#endif
void default_machine_crash_shutdown(struct pt_regs *regs)
{
unsigned int irq;
/*
* This function is only called after the system
* has paniced 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.
*/
local_irq_disable();
for_each_irq(irq) {
struct irq_desc *desc = irq_descp(irq);
if (desc->status & IRQ_INPROGRESS)
desc->handler->end(irq);
if (!(desc->status & IRQ_DISABLED))
desc->handler->disable(irq);
}
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(1, 0);
/*
* 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_kexec_prepare_cpus();
crash_save_this_cpu(regs, crashing_cpu);
}