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