kernel-ark/drivers/s390/s390mach.c
Martin Schwidefsky ae6aa2ea89 [PATCH] s390: machine check handler bugs
The new machine check handler still has a few bugs.

1) The system entry time has to be stored in the machine check handler,

2) the machine check return psw may not be stored at the usual place
   because it might overwrite the return psw of the interrupted context,

3) the return address for the call to s390_handle_mcck in the i/o interrupt
   handler is not correct,

4) the system call cleanup has to take the different save area of the
   machine check handler into account,

5) the machine check handler may not call UPDATE_VTIME before
   CREATE_STACK_FRAME, and

6) the io leave path needs a critical section cleanup to make sure that the
   TIF_MCCK_PENDING bit is really checked before switching back to user space.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-05 00:06:25 -07:00

473 lines
11 KiB
C

/*
* drivers/s390/s390mach.c
* S/390 machine check handler
*
* S390 version
* Copyright (C) 2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Ingo Adlung (adlung@de.ibm.com)
* Martin Schwidefsky (schwidefsky@de.ibm.com)
*/
#include <linux/config.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/workqueue.h>
#include <asm/lowcore.h>
#include "s390mach.h"
#define DBG printk
// #define DBG(args,...) do {} while (0);
static struct semaphore m_sem;
extern int css_process_crw(int);
extern int chsc_process_crw(void);
extern int chp_process_crw(int, int);
extern void css_reiterate_subchannels(void);
extern struct workqueue_struct *slow_path_wq;
extern struct work_struct slow_path_work;
static NORET_TYPE void
s390_handle_damage(char *msg)
{
#ifdef CONFIG_SMP
smp_send_stop();
#endif
disabled_wait((unsigned long) __builtin_return_address(0));
for(;;);
}
/*
* Retrieve CRWs and call function to handle event.
*
* Note : we currently process CRWs for io and chsc subchannels only
*/
static int
s390_collect_crw_info(void *param)
{
struct crw crw;
int ccode, ret, slow;
struct semaphore *sem;
sem = (struct semaphore *)param;
/* Set a nice name. */
daemonize("kmcheck");
repeat:
down_interruptible(sem);
slow = 0;
while (1) {
ccode = stcrw(&crw);
if (ccode != 0)
break;
DBG(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
"chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
crw.slct, crw.oflw, crw.chn, crw.rsc, crw.anc,
crw.erc, crw.rsid);
/* Check for overflows. */
if (crw.oflw) {
pr_debug("%s: crw overflow detected!\n", __FUNCTION__);
css_reiterate_subchannels();
slow = 1;
continue;
}
switch (crw.rsc) {
case CRW_RSC_SCH:
pr_debug("source is subchannel %04X\n", crw.rsid);
ret = css_process_crw (crw.rsid);
if (ret == -EAGAIN)
slow = 1;
break;
case CRW_RSC_MONITOR:
pr_debug("source is monitoring facility\n");
break;
case CRW_RSC_CPATH:
pr_debug("source is channel path %02X\n", crw.rsid);
switch (crw.erc) {
case CRW_ERC_IPARM: /* Path has come. */
ret = chp_process_crw(crw.rsid, 1);
break;
case CRW_ERC_PERRI: /* Path has gone. */
case CRW_ERC_PERRN:
ret = chp_process_crw(crw.rsid, 0);
break;
default:
pr_debug("Don't know how to handle erc=%x\n",
crw.erc);
ret = 0;
}
if (ret == -EAGAIN)
slow = 1;
break;
case CRW_RSC_CONFIG:
pr_debug("source is configuration-alert facility\n");
break;
case CRW_RSC_CSS:
pr_debug("source is channel subsystem\n");
ret = chsc_process_crw();
if (ret == -EAGAIN)
slow = 1;
break;
default:
pr_debug("unknown source\n");
break;
}
}
if (slow)
queue_work(slow_path_wq, &slow_path_work);
goto repeat;
return 0;
}
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);
/*
* 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)
up(&m_sem);
#ifdef CONFIG_MACHCHK_WARNING
/*
* The warning may remain for a prolonged period on the bare iron.
* (actually till the machine is powered off, or until the problem is gone)
* So we just stop listening for the WARNING MCH and prevent 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) processor.
*/
if (mcck.warning) { /* WARNING pending ? */
static int mchchk_wng_posted = 0;
/*
* Use single machine clear, as we cannot handle smp right now
*/
__ctl_clear_bit(14, 24); /* Disable WARNING MCH */
if (xchg(&mchchk_wng_posted, 1) == 0)
kill_proc(1, SIGPWR, 1);
}
#endif
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);
}
}
/*
* returns 0 if all registers could be validated
* returns 1 otherwise
*/
static int
s390_revalidate_registers(struct mci *mci)
{
int kill_task;
u64 tmpclock;
u64 zero;
void *fpt_save_area, *fpt_creg_save_area;
kill_task = 0;
zero = 0;
/* General purpose registers */
if (!mci->gr)
/*
* General purpose registers couldn't be restored and have
* unknown contents. Process needs to be terminated.
*/
kill_task = 1;
/* Revalidate floating point registers */
if (!mci->fp)
/*
* Floating point registers can't be restored and
* therefore the process needs to be terminated.
*/
kill_task = 1;
#ifndef __s390x__
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 __s390x__
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
/* Floating point control register */
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 __s390x__
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 __s390x__
/*
* 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 */
asm volatile ("stck 0(%1)\n"
"sckc 0(%1)"
: "=m" (tmpclock) : "a" (&(tmpclock)) : "cc", "memory");
/* 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;
}
/*
* machine check handler.
*/
void
s390_do_machine_check(struct pt_regs *regs)
{
struct mci *mci;
struct mcck_struct *mcck;
int umode;
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 __s390x__
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.");
}
if (!umode)
s390_handle_damage("processing backup machine "
"check in kernel mode.");
mcck->kill_task = 1;
mcck->mcck_code = *(unsigned long long *) mci;
}
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->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);
}
}
/*
* s390_init_machine_check
*
* initialize machine check handling
*/
static int
machine_check_init(void)
{
init_MUTEX_LOCKED(&m_sem);
ctl_clear_bit(14, 25); /* disable external damage MCH */
ctl_set_bit(14, 27); /* enable system recovery MCH */
#ifdef CONFIG_MACHCHK_WARNING
ctl_set_bit(14, 24); /* enable warning MCH */
#endif
return 0;
}
/*
* Initialize the machine check handler really early to be able to
* catch all machine checks that happen during boot
*/
arch_initcall(machine_check_init);
/*
* Machine checks for the channel subsystem must be enabled
* after the channel subsystem is initialized
*/
static int __init
machine_check_crw_init (void)
{
kernel_thread(s390_collect_crw_info, &m_sem, CLONE_FS|CLONE_FILES);
ctl_set_bit(14, 28); /* enable channel report MCH */
return 0;
}
device_initcall (machine_check_crw_init);