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linux/arch/s390/kernel/nmi.c
Heiko Carstens e8129c6421 [S390] nmi: fix clock comparator revalidation 
On each machine check all registers are revalidated. The save area for
the clock comparator however only contains the upper most seven bytes
of the former contents, if valid.
Therefore the machine check handler uses a store clock instruction to
get the current time and writes that to the clock comparator register
which in turn will generate an immediate timer interrupt.
However within the lowcore the expected time of the next timer
interrupt is stored. If the interrupt happens before that time the
handler won't be called. In turn the clock comparator won't be
reprogrammed and therefore the interrupt condition stays pending which
causes an interrupt loop until the expected time is reached.

On NOHZ machines this can result in unresponsive machines since the
time of the next expected interrupted can be a couple of days in the
future.

To fix this just revalidate the clock comparator register with the
expected value.
In addition the special handling for udelay must be changed as well.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-11-25 09:52:59 +01:00

376 lines
9.7 KiB
C
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/*
* Machine check handler
*
* Copyright IBM Corp. 2000,2009
* Author(s): Ingo Adlung <adlung@de.ibm.com>,
* Martin Schwidefsky <schwidefsky@de.ibm.com>,
* Cornelia Huck <cornelia.huck@de.ibm.com>,
* Heiko Carstens <heiko.carstens@de.ibm.com>,
*/
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/time.h>
#include <linux/module.h>
#include <asm/lowcore.h>
#include <asm/smp.h>
#include <asm/etr.h>
#include <asm/cputime.h>
#include <asm/nmi.h>
#include <asm/crw.h>
struct mcck_struct {
int kill_task;
int channel_report;
int warning;
unsigned long long mcck_code;
};
static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
static NORET_TYPE void s390_handle_damage(char *msg)
{
smp_send_stop();
disabled_wait((unsigned long) __builtin_return_address(0));
while (1);
}
/*
* Main machine check handler function. Will be called with interrupts enabled
* or disabled and machine checks enabled or disabled.
*/
void s390_handle_mcck(void)
{
unsigned long flags;
struct mcck_struct mcck;
/*
* Disable machine checks and get the current state of accumulated
* machine checks. Afterwards delete the old state and enable machine
* checks again.
*/
local_irq_save(flags);
local_mcck_disable();
mcck = __get_cpu_var(cpu_mcck);
memset(&__get_cpu_var(cpu_mcck), 0, sizeof(struct mcck_struct));
clear_thread_flag(TIF_MCCK_PENDING);
local_mcck_enable();
local_irq_restore(flags);
if (mcck.channel_report)
crw_handle_channel_report();
/*
* A warning may remain for a prolonged period on the bare iron.
* (actually until the machine is powered off, or the problem is gone)
* So we just stop listening for the WARNING MCH and avoid continuously
* being interrupted. One caveat is however, that we must do this per
* processor and cannot use the smp version of ctl_clear_bit().
* On VM we only get one interrupt per virtally presented machinecheck.
* Though one suffices, we may get one interrupt per (virtual) cpu.
*/
if (mcck.warning) { /* WARNING pending ? */
static int mchchk_wng_posted = 0;
/* Use single cpu clear, as we cannot handle smp here. */
__ctl_clear_bit(14, 24); /* Disable WARNING MCH */
if (xchg(&mchchk_wng_posted, 1) == 0)
kill_cad_pid(SIGPWR, 1);
}
if (mcck.kill_task) {
local_irq_enable();
printk(KERN_EMERG "mcck: Terminating task because of machine "
"malfunction (code 0x%016llx).\n", mcck.mcck_code);
printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
current->comm, current->pid);
do_exit(SIGSEGV);
}
}
EXPORT_SYMBOL_GPL(s390_handle_mcck);
/*
* returns 0 if all registers could be validated
* returns 1 otherwise
*/
static int notrace s390_revalidate_registers(struct mci *mci)
{
int kill_task;
u64 zero;
void *fpt_save_area, *fpt_creg_save_area;
kill_task = 0;
zero = 0;
if (!mci->gr) {
/*
* General purpose registers couldn't be restored and have
* unknown contents. Process needs to be terminated.
*/
kill_task = 1;
}
if (!mci->fp) {
/*
* Floating point registers can't be restored and
* therefore the process needs to be terminated.
*/
kill_task = 1;
}
#ifndef CONFIG_64BIT
asm volatile(
" ld 0,0(%0)\n"
" ld 2,8(%0)\n"
" ld 4,16(%0)\n"
" ld 6,24(%0)"
: : "a" (&S390_lowcore.floating_pt_save_area));
#endif
if (MACHINE_HAS_IEEE) {
#ifdef CONFIG_64BIT
fpt_save_area = &S390_lowcore.floating_pt_save_area;
fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
#else
fpt_save_area = (void *) S390_lowcore.extended_save_area_addr;
fpt_creg_save_area = fpt_save_area + 128;
#endif
if (!mci->fc) {
/*
* Floating point control register can't be restored.
* Task will be terminated.
*/
asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
kill_task = 1;
} else
asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
asm volatile(
" ld 0,0(%0)\n"
" ld 1,8(%0)\n"
" ld 2,16(%0)\n"
" ld 3,24(%0)\n"
" ld 4,32(%0)\n"
" ld 5,40(%0)\n"
" ld 6,48(%0)\n"
" ld 7,56(%0)\n"
" ld 8,64(%0)\n"
" ld 9,72(%0)\n"
" ld 10,80(%0)\n"
" ld 11,88(%0)\n"
" ld 12,96(%0)\n"
" ld 13,104(%0)\n"
" ld 14,112(%0)\n"
" ld 15,120(%0)\n"
: : "a" (fpt_save_area));
}
/* Revalidate access registers */
asm volatile(
" lam 0,15,0(%0)"
: : "a" (&S390_lowcore.access_regs_save_area));
if (!mci->ar) {
/*
* Access registers have unknown contents.
* Terminating task.
*/
kill_task = 1;
}
/* Revalidate control registers */
if (!mci->cr) {
/*
* Control registers have unknown contents.
* Can't recover and therefore stopping machine.
*/
s390_handle_damage("invalid control registers.");
} else {
#ifdef CONFIG_64BIT
asm volatile(
" lctlg 0,15,0(%0)"
: : "a" (&S390_lowcore.cregs_save_area));
#else
asm volatile(
" lctl 0,15,0(%0)"
: : "a" (&S390_lowcore.cregs_save_area));
#endif
}
/*
* We don't even try to revalidate the TOD register, since we simply
* can't write something sensible into that register.
*/
#ifdef CONFIG_64BIT
/*
* See if we can revalidate the TOD programmable register with its
* old contents (should be zero) otherwise set it to zero.
*/
if (!mci->pr)
asm volatile(
" sr 0,0\n"
" sckpf"
: : : "0", "cc");
else
asm volatile(
" l 0,0(%0)\n"
" sckpf"
: : "a" (&S390_lowcore.tod_progreg_save_area)
: "0", "cc");
#endif
/* Revalidate clock comparator register */
if (S390_lowcore.clock_comparator == -1)
set_clock_comparator(S390_lowcore.mcck_clock);
else
set_clock_comparator(S390_lowcore.clock_comparator);
/* Check if old PSW is valid */
if (!mci->wp)
/*
* Can't tell if we come from user or kernel mode
* -> stopping machine.
*/
s390_handle_damage("old psw invalid.");
if (!mci->ms || !mci->pm || !mci->ia)
kill_task = 1;
return kill_task;
}
#define MAX_IPD_COUNT 29
#define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */
#define ED_STP_ISLAND 6 /* External damage STP island check */
#define ED_STP_SYNC 7 /* External damage STP sync check */
#define ED_ETR_SYNC 12 /* External damage ETR sync check */
#define ED_ETR_SWITCH 13 /* External damage ETR switch to local */
/*
* machine check handler.
*/
void notrace s390_do_machine_check(struct pt_regs *regs)
{
static int ipd_count;
static DEFINE_SPINLOCK(ipd_lock);
static unsigned long long last_ipd;
struct mcck_struct *mcck;
unsigned long long tmp;
struct mci *mci;
int umode;
nmi_enter();
s390_idle_check(regs, S390_lowcore.mcck_clock,
S390_lowcore.mcck_enter_timer);
mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
mcck = &__get_cpu_var(cpu_mcck);
umode = user_mode(regs);
if (mci->sd) {
/* System damage -> stopping machine */
s390_handle_damage("received system damage machine check.");
}
if (mci->pd) {
if (mci->b) {
/* Processing backup -> verify if we can survive this */
u64 z_mcic, o_mcic, t_mcic;
#ifdef CONFIG_64BIT
z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
1ULL<<16);
#else
z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<57 | 1ULL<<50 |
1ULL<<29);
o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
1ULL<<30 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16);
#endif
t_mcic = *(u64 *)mci;
if (((t_mcic & z_mcic) != 0) ||
((t_mcic & o_mcic) != o_mcic)) {
s390_handle_damage("processing backup machine "
"check with damage.");
}
/*
* Nullifying exigent condition, therefore we might
* retry this instruction.
*/
spin_lock(&ipd_lock);
tmp = get_clock();
if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
ipd_count++;
else
ipd_count = 1;
last_ipd = tmp;
if (ipd_count == MAX_IPD_COUNT)
s390_handle_damage("too many ipd retries.");
spin_unlock(&ipd_lock);
} else {
/* Processing damage -> stopping machine */
s390_handle_damage("received instruction processing "
"damage machine check.");
}
}
if (s390_revalidate_registers(mci)) {
if (umode) {
/*
* Couldn't restore all register contents while in
* user mode -> mark task for termination.
*/
mcck->kill_task = 1;
mcck->mcck_code = *(unsigned long long *) mci;
set_thread_flag(TIF_MCCK_PENDING);
} else {
/*
* Couldn't restore all register contents while in
* kernel mode -> stopping machine.
*/
s390_handle_damage("unable to revalidate registers.");
}
}
if (mci->cd) {
/* Timing facility damage */
s390_handle_damage("TOD clock damaged");
}
if (mci->ed && mci->ec) {
/* External damage */
if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
etr_sync_check();
if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
etr_switch_to_local();
if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
stp_sync_check();
if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
stp_island_check();
}
if (mci->se)
/* Storage error uncorrected */
s390_handle_damage("received storage error uncorrected "
"machine check.");
if (mci->ke)
/* Storage key-error uncorrected */
s390_handle_damage("received storage key-error uncorrected "
"machine check.");
if (mci->ds && mci->fa)
/* Storage degradation */
s390_handle_damage("received storage degradation machine "
"check.");
if (mci->cp) {
/* Channel report word pending */
mcck->channel_report = 1;
set_thread_flag(TIF_MCCK_PENDING);
}
if (mci->w) {
/* Warning pending */
mcck->warning = 1;
set_thread_flag(TIF_MCCK_PENDING);
}
nmi_exit();
}
static int __init machine_check_init(void)
{
ctl_set_bit(14, 25); /* enable external damage MCH */
ctl_set_bit(14, 27); /* enable system recovery MCH */
ctl_set_bit(14, 24); /* enable warning MCH */
return 0;
}
arch_initcall(machine_check_init);
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