linux/arch/ia64/kernel/crash.c
Simon Horman 6672f76a5a kdump/kexec: calculate note size at compile time
Currently the size of the per-cpu region reserved to save crash notes is
set by the per-architecture value MAX_NOTE_BYTES.  Which in turn is
currently set to 1024 on all supported architectures.

While testing ia64 I recently discovered that this value is in fact too
small.  The particular setup I was using actually needs 1172 bytes.  This
lead to very tedious failure mode where the tail of one elf note would
overwrite the head of another if they ended up being alocated sequentially
by kmalloc, which was often the case.

It seems to me that a far better approach is to caclculate the size that
the area needs to be.  This patch does just that.

If a simpler stop-gap patch for ia64 to be squeezed into 2.6.21(.X) is
needed then this should be as easy as making MAX_NOTE_BYTES larger in
arch/asm-ia64/kexec.h.  Perhaps 2048 would be a good choice.  However, I
think that the approach in this patch is a much more robust idea.

Acked-by:  Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:07 -07:00

232 lines
5.1 KiB
C

/*
* arch/ia64/kernel/crash.c
*
* Architecture specific (ia64) functions for kexec based crash dumps.
*
* Created by: Khalid Aziz <khalid.aziz@hp.com>
* Copyright (C) 2005 Hewlett-Packard Development Company, L.P.
* Copyright (C) 2005 Intel Corp Zou Nan hai <nanhai.zou@intel.com>
*
*/
#include <linux/smp.h>
#include <linux/delay.h>
#include <linux/crash_dump.h>
#include <linux/bootmem.h>
#include <linux/kexec.h>
#include <linux/elfcore.h>
#include <linux/sysctl.h>
#include <linux/init.h>
#include <linux/kdebug.h>
#include <asm/mca.h>
int kdump_status[NR_CPUS];
static atomic_t kdump_cpu_frozen;
atomic_t kdump_in_progress;
static int kdump_on_init = 1;
static inline Elf64_Word
*append_elf_note(Elf64_Word *buf, char *name, unsigned type, void *data,
size_t data_len)
{
struct elf_note *note = (struct elf_note *)buf;
note->n_namesz = strlen(name) + 1;
note->n_descsz = data_len;
note->n_type = type;
buf += (sizeof(*note) + 3)/4;
memcpy(buf, name, note->n_namesz);
buf += (note->n_namesz + 3)/4;
memcpy(buf, data, data_len);
buf += (data_len + 3)/4;
return buf;
}
static void
final_note(void *buf)
{
memset(buf, 0, sizeof(struct elf_note));
}
extern void ia64_dump_cpu_regs(void *);
static DEFINE_PER_CPU(struct elf_prstatus, elf_prstatus);
void
crash_save_this_cpu(void)
{
void *buf;
unsigned long cfm, sof, sol;
int cpu = smp_processor_id();
struct elf_prstatus *prstatus = &per_cpu(elf_prstatus, cpu);
elf_greg_t *dst = (elf_greg_t *)&(prstatus->pr_reg);
memset(prstatus, 0, sizeof(*prstatus));
prstatus->pr_pid = current->pid;
ia64_dump_cpu_regs(dst);
cfm = dst[43];
sol = (cfm >> 7) & 0x7f;
sof = cfm & 0x7f;
dst[46] = (unsigned long)ia64_rse_skip_regs((unsigned long *)dst[46],
sof - sol);
buf = (u64 *) per_cpu_ptr(crash_notes, cpu);
if (!buf)
return;
buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, prstatus,
sizeof(*prstatus));
final_note(buf);
}
#ifdef CONFIG_SMP
static int
kdump_wait_cpu_freeze(void)
{
int cpu_num = num_online_cpus() - 1;
int timeout = 1000;
while(timeout-- > 0) {
if (atomic_read(&kdump_cpu_frozen) == cpu_num)
return 0;
udelay(1000);
}
return 1;
}
#endif
void
machine_crash_shutdown(struct pt_regs *pt)
{
/* 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 shooting down the other cpus in
* an SMP system.
*/
kexec_disable_iosapic();
#ifdef CONFIG_SMP
kdump_smp_send_stop();
/* not all cpu response to IPI, send INIT to freeze them */
if (kdump_wait_cpu_freeze() && kdump_on_init) {
kdump_smp_send_init();
}
#endif
}
static void
machine_kdump_on_init(void)
{
if (!ia64_kimage) {
printk(KERN_NOTICE "machine_kdump_on_init(): "
"kdump not configured\n");
return;
}
local_irq_disable();
kexec_disable_iosapic();
machine_kexec(ia64_kimage);
}
void
kdump_cpu_freeze(struct unw_frame_info *info, void *arg)
{
int cpuid;
local_irq_disable();
cpuid = smp_processor_id();
crash_save_this_cpu();
current->thread.ksp = (__u64)info->sw - 16;
atomic_inc(&kdump_cpu_frozen);
kdump_status[cpuid] = 1;
mb();
#ifdef CONFIG_HOTPLUG_CPU
if (cpuid != 0)
ia64_jump_to_sal(&sal_boot_rendez_state[cpuid]);
#endif
for (;;)
cpu_relax();
}
static int
kdump_init_notifier(struct notifier_block *self, unsigned long val, void *data)
{
struct ia64_mca_notify_die *nd;
struct die_args *args = data;
if (!kdump_on_init)
return NOTIFY_DONE;
if (val != DIE_INIT_MONARCH_ENTER &&
val != DIE_INIT_SLAVE_ENTER &&
val != DIE_MCA_RENDZVOUS_LEAVE &&
val != DIE_MCA_MONARCH_LEAVE)
return NOTIFY_DONE;
nd = (struct ia64_mca_notify_die *)args->err;
/* Reason code 1 means machine check rendezous*/
if ((val == DIE_INIT_MONARCH_ENTER || val == DIE_INIT_SLAVE_ENTER) &&
nd->sos->rv_rc == 1)
return NOTIFY_DONE;
switch (val) {
case DIE_INIT_MONARCH_ENTER:
machine_kdump_on_init();
break;
case DIE_INIT_SLAVE_ENTER:
unw_init_running(kdump_cpu_freeze, NULL);
break;
case DIE_MCA_RENDZVOUS_LEAVE:
if (atomic_read(&kdump_in_progress))
unw_init_running(kdump_cpu_freeze, NULL);
break;
case DIE_MCA_MONARCH_LEAVE:
/* die_register->signr indicate if MCA is recoverable */
if (!args->signr)
machine_kdump_on_init();
break;
}
return NOTIFY_DONE;
}
#ifdef CONFIG_SYSCTL
static ctl_table kdump_on_init_table[] = {
{
.ctl_name = CTL_UNNUMBERED,
.procname = "kdump_on_init",
.data = &kdump_on_init,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{ .ctl_name = 0 }
};
static ctl_table sys_table[] = {
{
.ctl_name = CTL_KERN,
.procname = "kernel",
.mode = 0555,
.child = kdump_on_init_table,
},
{ .ctl_name = 0 }
};
#endif
static int
machine_crash_setup(void)
{
static struct notifier_block kdump_init_notifier_nb = {
.notifier_call = kdump_init_notifier,
};
int ret;
if((ret = register_die_notifier(&kdump_init_notifier_nb)) != 0)
return ret;
#ifdef CONFIG_SYSCTL
register_sysctl_table(sys_table);
#endif
return 0;
}
__initcall(machine_crash_setup);