diff options
Diffstat (limited to 'arch/s390/mm/fault.c')
-rw-r--r-- | arch/s390/mm/fault.c | 228 |
1 files changed, 0 insertions, 228 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index a063774ba584..099c4824dd8a 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -43,8 +43,6 @@ #include "../kernel/entry.h" #define __FAIL_ADDR_MASK -4096L -#define __SUBCODE_MASK 0x0600 -#define __PF_RES_FIELD 0x8000000000000000ULL /* * Allocate private vm_fault_reason from top. Please make sure it won't @@ -582,232 +580,6 @@ void do_dat_exception(struct pt_regs *regs) } NOKPROBE_SYMBOL(do_dat_exception); -#ifdef CONFIG_PFAULT -/* - * 'pfault' pseudo page faults routines. - */ -static int pfault_disable; - -static int __init nopfault(char *str) -{ - pfault_disable = 1; - return 1; -} - -__setup("nopfault", nopfault); - -struct pfault_refbk { - u16 refdiagc; - u16 reffcode; - u16 refdwlen; - u16 refversn; - u64 refgaddr; - u64 refselmk; - u64 refcmpmk; - u64 reserved; -} __attribute__ ((packed, aligned(8))); - -static struct pfault_refbk pfault_init_refbk = { - .refdiagc = 0x258, - .reffcode = 0, - .refdwlen = 5, - .refversn = 2, - .refgaddr = __LC_LPP, - .refselmk = 1ULL << 48, - .refcmpmk = 1ULL << 48, - .reserved = __PF_RES_FIELD -}; - -int pfault_init(void) -{ - int rc; - - if (pfault_disable) - return -1; - diag_stat_inc(DIAG_STAT_X258); - asm volatile( - " diag %1,%0,0x258\n" - "0: j 2f\n" - "1: la %0,8\n" - "2:\n" - EX_TABLE(0b,1b) - : "=d" (rc) - : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); - return rc; -} - -static struct pfault_refbk pfault_fini_refbk = { - .refdiagc = 0x258, - .reffcode = 1, - .refdwlen = 5, - .refversn = 2, -}; - -void pfault_fini(void) -{ - - if (pfault_disable) - return; - diag_stat_inc(DIAG_STAT_X258); - asm volatile( - " diag %0,0,0x258\n" - "0: nopr %%r7\n" - EX_TABLE(0b,0b) - : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); -} - -static DEFINE_SPINLOCK(pfault_lock); -static LIST_HEAD(pfault_list); - -#define PF_COMPLETE 0x0080 - -/* - * The mechanism of our pfault code: if Linux is running as guest, runs a user - * space process and the user space process accesses a page that the host has - * paged out we get a pfault interrupt. - * - * This allows us, within the guest, to schedule a different process. Without - * this mechanism the host would have to suspend the whole virtual cpu until - * the page has been paged in. - * - * So when we get such an interrupt then we set the state of the current task - * to uninterruptible and also set the need_resched flag. Both happens within - * interrupt context(!). If we later on want to return to user space we - * recognize the need_resched flag and then call schedule(). It's not very - * obvious how this works... - * - * Of course we have a lot of additional fun with the completion interrupt (-> - * host signals that a page of a process has been paged in and the process can - * continue to run). This interrupt can arrive on any cpu and, since we have - * virtual cpus, actually appear before the interrupt that signals that a page - * is missing. - */ -static void pfault_interrupt(struct ext_code ext_code, - unsigned int param32, unsigned long param64) -{ - struct task_struct *tsk; - __u16 subcode; - pid_t pid; - - /* - * Get the external interruption subcode & pfault initial/completion - * signal bit. VM stores this in the 'cpu address' field associated - * with the external interrupt. - */ - subcode = ext_code.subcode; - if ((subcode & 0xff00) != __SUBCODE_MASK) - return; - inc_irq_stat(IRQEXT_PFL); - /* Get the token (= pid of the affected task). */ - pid = param64 & LPP_PID_MASK; - rcu_read_lock(); - tsk = find_task_by_pid_ns(pid, &init_pid_ns); - if (tsk) - get_task_struct(tsk); - rcu_read_unlock(); - if (!tsk) - return; - spin_lock(&pfault_lock); - if (subcode & PF_COMPLETE) { - /* signal bit is set -> a page has been swapped in by VM */ - if (tsk->thread.pfault_wait == 1) { - /* Initial interrupt was faster than the completion - * interrupt. pfault_wait is valid. Set pfault_wait - * back to zero and wake up the process. This can - * safely be done because the task is still sleeping - * and can't produce new pfaults. */ - tsk->thread.pfault_wait = 0; - list_del(&tsk->thread.list); - wake_up_process(tsk); - put_task_struct(tsk); - } else { - /* Completion interrupt was faster than initial - * interrupt. Set pfault_wait to -1 so the initial - * interrupt doesn't put the task to sleep. - * If the task is not running, ignore the completion - * interrupt since it must be a leftover of a PFAULT - * CANCEL operation which didn't remove all pending - * completion interrupts. */ - if (task_is_running(tsk)) - tsk->thread.pfault_wait = -1; - } - } else { - /* signal bit not set -> a real page is missing. */ - if (WARN_ON_ONCE(tsk != current)) - goto out; - if (tsk->thread.pfault_wait == 1) { - /* Already on the list with a reference: put to sleep */ - goto block; - } else if (tsk->thread.pfault_wait == -1) { - /* Completion interrupt was faster than the initial - * interrupt (pfault_wait == -1). Set pfault_wait - * back to zero and exit. */ - tsk->thread.pfault_wait = 0; - } else { - /* Initial interrupt arrived before completion - * interrupt. Let the task sleep. - * An extra task reference is needed since a different - * cpu may set the task state to TASK_RUNNING again - * before the scheduler is reached. */ - get_task_struct(tsk); - tsk->thread.pfault_wait = 1; - list_add(&tsk->thread.list, &pfault_list); -block: - /* Since this must be a userspace fault, there - * is no kernel task state to trample. Rely on the - * return to userspace schedule() to block. */ - __set_current_state(TASK_UNINTERRUPTIBLE); - set_tsk_need_resched(tsk); - set_preempt_need_resched(); - } - } -out: - spin_unlock(&pfault_lock); - put_task_struct(tsk); -} - -static int pfault_cpu_dead(unsigned int cpu) -{ - struct thread_struct *thread, *next; - struct task_struct *tsk; - - spin_lock_irq(&pfault_lock); - list_for_each_entry_safe(thread, next, &pfault_list, list) { - thread->pfault_wait = 0; - list_del(&thread->list); - tsk = container_of(thread, struct task_struct, thread); - wake_up_process(tsk); - put_task_struct(tsk); - } - spin_unlock_irq(&pfault_lock); - return 0; -} - -static int __init pfault_irq_init(void) -{ - int rc; - - rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); - if (rc) - goto out_extint; - rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; - if (rc) - goto out_pfault; - irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); - cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", - NULL, pfault_cpu_dead); - return 0; - -out_pfault: - unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); -out_extint: - pfault_disable = 1; - return rc; -} -early_initcall(pfault_irq_init); - -#endif /* CONFIG_PFAULT */ - #if IS_ENABLED(CONFIG_PGSTE) void do_secure_storage_access(struct pt_regs *regs) |