/* * S390 version * Copyright IBM Corp. 1999 * Author(s): Hartmut Penner (hp@de.ibm.com) * Ulrich Weigand (uweigand@de.ibm.com) * * Derived from "arch/i386/mm/fault.c" * Copyright (C) 1995 Linus Torvalds */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "../kernel/entry.h" #ifndef CONFIG_64BIT #define __FAIL_ADDR_MASK 0x7ffff000 #define __SUBCODE_MASK 0x0200 #define __PF_RES_FIELD 0ULL #else /* CONFIG_64BIT */ #define __FAIL_ADDR_MASK -4096L #define __SUBCODE_MASK 0x0600 #define __PF_RES_FIELD 0x8000000000000000ULL #endif /* CONFIG_64BIT */ #define VM_FAULT_BADCONTEXT 0x010000 #define VM_FAULT_BADMAP 0x020000 #define VM_FAULT_BADACCESS 0x040000 #define VM_FAULT_SIGNAL 0x080000 static unsigned long store_indication __read_mostly; #ifdef CONFIG_64BIT static int __init fault_init(void) { if (test_facility(75)) store_indication = 0xc00; return 0; } early_initcall(fault_init); #endif static inline int notify_page_fault(struct pt_regs *regs) { int ret = 0; /* kprobe_running() needs smp_processor_id() */ if (kprobes_built_in() && !user_mode(regs)) { preempt_disable(); if (kprobe_running() && kprobe_fault_handler(regs, 14)) ret = 1; preempt_enable(); } return ret; } /* * Unlock any spinlocks which will prevent us from getting the * message out. */ void bust_spinlocks(int yes) { if (yes) { oops_in_progress = 1; } else { int loglevel_save = console_loglevel; console_unblank(); oops_in_progress = 0; /* * OK, the message is on the console. Now we call printk() * without oops_in_progress set so that printk will give klogd * a poke. Hold onto your hats... */ console_loglevel = 15; printk(" "); console_loglevel = loglevel_save; } } /* * Returns the address space associated with the fault. * Returns 0 for kernel space and 1 for user space. */ static inline int user_space_fault(unsigned long trans_exc_code) { /* * The lowest two bits of the translation exception * identification indicate which paging table was used. */ trans_exc_code &= 3; if (trans_exc_code == 2) /* Access via secondary space, set_fs setting decides */ return current->thread.mm_segment.ar4; /* * Access via primary space or access register is from user space * and access via home space is from the kernel. */ return trans_exc_code != 3; } static inline void report_user_fault(struct pt_regs *regs, long signr) { if ((task_pid_nr(current) > 1) && !show_unhandled_signals) return; if (!unhandled_signal(current, signr)) return; if (!printk_ratelimit()) return; printk(KERN_ALERT "User process fault: interruption code 0x%X ", regs->int_code); print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN); printk(KERN_CONT "\n"); printk(KERN_ALERT "failing address: %lX\n", regs->int_parm_long & __FAIL_ADDR_MASK); show_regs(regs); } /* * Send SIGSEGV to task. This is an external routine * to keep the stack usage of do_page_fault small. */ static noinline void do_sigsegv(struct pt_regs *regs, int si_code) { struct siginfo si; report_user_fault(regs, SIGSEGV); si.si_signo = SIGSEGV; si.si_code = si_code; si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); force_sig_info(SIGSEGV, &si, current); } static noinline void do_no_context(struct pt_regs *regs) { const struct exception_table_entry *fixup; unsigned long address; /* Are we prepared to handle this kernel fault? */ fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN); if (fixup) { regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE; return; } /* * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ address = regs->int_parm_long & __FAIL_ADDR_MASK; if (!user_space_fault(regs->int_parm_long)) printk(KERN_ALERT "Unable to handle kernel pointer dereference" " at virtual kernel address %p\n", (void *)address); else printk(KERN_ALERT "Unable to handle kernel paging request" " at virtual user address %p\n", (void *)address); die(regs, "Oops"); do_exit(SIGKILL); } static noinline void do_low_address(struct pt_regs *regs) { /* Low-address protection hit in kernel mode means NULL pointer write access in kernel mode. */ if (regs->psw.mask & PSW_MASK_PSTATE) { /* Low-address protection hit in user mode 'cannot happen'. */ die (regs, "Low-address protection"); do_exit(SIGKILL); } do_no_context(regs); } static noinline void do_sigbus(struct pt_regs *regs) { struct task_struct *tsk = current; struct siginfo si; /* * Send a sigbus, regardless of whether we were in kernel * or user mode. */ si.si_signo = SIGBUS; si.si_errno = 0; si.si_code = BUS_ADRERR; si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); force_sig_info(SIGBUS, &si, tsk); } static noinline void do_fault_error(struct pt_regs *regs, int fault) { int si_code; switch (fault) { case VM_FAULT_BADACCESS: case VM_FAULT_BADMAP: /* Bad memory access. Check if it is kernel or user space. */ if (user_mode(regs)) { /* User mode accesses just cause a SIGSEGV */ si_code = (fault == VM_FAULT_BADMAP) ? SEGV_MAPERR : SEGV_ACCERR; do_sigsegv(regs, si_code); return; } case VM_FAULT_BADCONTEXT: do_no_context(regs); break; case VM_FAULT_SIGNAL: if (!user_mode(regs)) do_no_context(regs); break; default: /* fault & VM_FAULT_ERROR */ if (fault & VM_FAULT_OOM) { if (!user_mode(regs)) do_no_context(regs); else pagefault_out_of_memory(); } else if (fault & VM_FAULT_SIGSEGV) { /* Kernel mode? Handle exceptions or die */ if (!user_mode(regs)) do_no_context(regs); else do_sigsegv(regs, SEGV_MAPERR); } else if (fault & VM_FAULT_SIGBUS) { /* Kernel mode? Handle exceptions or die */ if (!user_mode(regs)) do_no_context(regs); else do_sigbus(regs); } else BUG(); break; } } /* * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate * routines. * * interruption code (int_code): * 04 Protection -> Write-Protection (suprression) * 10 Segment translation -> Not present (nullification) * 11 Page translation -> Not present (nullification) * 3b Region third trans. -> Not present (nullification) */ static inline int do_exception(struct pt_regs *regs, int access) { struct task_struct *tsk; struct mm_struct *mm; struct vm_area_struct *vma; unsigned long trans_exc_code; unsigned long address; unsigned int flags; int fault; tsk = current; /* * The instruction that caused the program check has * been nullified. Don't signal single step via SIGTRAP. */ clear_tsk_thread_flag(tsk, TIF_PER_TRAP); if (notify_page_fault(regs)) return 0; mm = tsk->mm; trans_exc_code = regs->int_parm_long; /* * Verify that the fault happened in user space, that * we are not in an interrupt and that there is a * user context. */ fault = VM_FAULT_BADCONTEXT; if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm)) goto out; address = trans_exc_code & __FAIL_ADDR_MASK; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; if (user_mode(regs)) flags |= FAULT_FLAG_USER; if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) flags |= FAULT_FLAG_WRITE; down_read(&mm->mmap_sem); #ifdef CONFIG_PGSTE if ((current->flags & PF_VCPU) && S390_lowcore.gmap) { address = __gmap_fault(address, (struct gmap *) S390_lowcore.gmap); if (address == -EFAULT) { fault = VM_FAULT_BADMAP; goto out_up; } if (address == -ENOMEM) { fault = VM_FAULT_OOM; goto out_up; } } #endif retry: fault = VM_FAULT_BADMAP; vma = find_vma(mm, address); if (!vma) goto out_up; if (unlikely(vma->vm_start > address)) { if (!(vma->vm_flags & VM_GROWSDOWN)) goto out_up; if (expand_stack(vma, address)) goto out_up; } /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ fault = VM_FAULT_BADACCESS; if (unlikely(!(vma->vm_flags & access))) goto out_up; if (is_vm_hugetlb_page(vma)) address &= HPAGE_MASK; /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo * the fault. */ fault = handle_mm_fault(mm, vma, address, flags); /* No reason to continue if interrupted by SIGKILL. */ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { fault = VM_FAULT_SIGNAL; goto out; } if (unlikely(fault & VM_FAULT_ERROR)) goto out_up; /* * Major/minor page fault accounting is only done on the * initial attempt. If we go through a retry, it is extremely * likely that the page will be found in page cache at that point. */ if (flags & FAULT_FLAG_ALLOW_RETRY) { if (fault & VM_FAULT_MAJOR) { tsk->maj_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address); } else { tsk->min_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address); } if (fault & VM_FAULT_RETRY) { /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk * of starvation. */ flags &= ~FAULT_FLAG_ALLOW_RETRY; flags |= FAULT_FLAG_TRIED; down_read(&mm->mmap_sem); goto retry; } } fault = 0; out_up: up_read(&mm->mmap_sem); out: return fault; } void __kprobes do_protection_exception(struct pt_regs *regs) { unsigned long trans_exc_code; int fault; trans_exc_code = regs->int_parm_long; /* * Protection exceptions are suppressing, decrement psw address. * The exception to this rule are aborted transactions, for these * the PSW already points to the correct location. */ if (!(regs->int_code & 0x200)) regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); /* * Check for low-address protection. This needs to be treated * as a special case because the translation exception code * field is not guaranteed to contain valid data in this case. */ if (unlikely(!(trans_exc_code & 4))) { do_low_address(regs); return; } fault = do_exception(regs, VM_WRITE); if (unlikely(fault)) do_fault_error(regs, fault); } void __kprobes do_dat_exception(struct pt_regs *regs) { int access, fault; access = VM_READ | VM_EXEC | VM_WRITE; fault = do_exception(regs, access); if (unlikely(fault)) do_fault_error(regs, fault); } int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write) { struct pt_regs regs; int access, fault; /* Emulate a uaccess fault from kernel mode. */ regs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT | PSW_MASK_MCHECK; if (!irqs_disabled()) regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT; regs.psw.addr = (unsigned long) __builtin_return_address(0); regs.psw.addr |= PSW_ADDR_AMODE; regs.int_code = pgm_int_code; regs.int_parm_long = (uaddr & PAGE_MASK) | 2; access = write ? VM_WRITE : VM_READ; fault = do_exception(®s, access); /* * Since the fault happened in kernel mode while performing a uaccess * all we need to do now is emulating a fixup in case "fault" is not * zero. * For the calling uaccess functions this results always in -EFAULT. */ return fault ? -EFAULT : 0; } #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))); int pfault_init(void) { struct pfault_refbk refbk = { .refdiagc = 0x258, .reffcode = 0, .refdwlen = 5, .refversn = 2, .refgaddr = __LC_CURRENT_PID, .refselmk = 1ULL << 48, .refcmpmk = 1ULL << 48, .reserved = __PF_RES_FIELD }; int rc; if (pfault_disable) return -1; 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" (&refbk), "m" (refbk) : "cc"); return rc; } void pfault_fini(void) { struct pfault_refbk refbk = { .refdiagc = 0x258, .reffcode = 1, .refdwlen = 5, .refversn = 2, }; if (pfault_disable) return; asm volatile( " diag %0,0,0x258\n" "0:\n" EX_TABLE(0b,0b) : : "a" (&refbk), "m" (refbk) : "cc"); } static DEFINE_SPINLOCK(pfault_lock); static LIST_HEAD(pfault_list); 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 = sizeof(void *) == 4 ? param32 : param64; 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 & 0x0080) { /* 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 (tsk->state == TASK_RUNNING) 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 */ __set_task_state(tsk, TASK_UNINTERRUPTIBLE); set_tsk_need_resched(tsk); } 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); __set_task_state(tsk, TASK_UNINTERRUPTIBLE); set_tsk_need_resched(tsk); } } out: spin_unlock(&pfault_lock); put_task_struct(tsk); } static int pfault_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { struct thread_struct *thread, *next; struct task_struct *tsk; switch (action & ~CPU_TASKS_FROZEN) { case CPU_DEAD: 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); break; default: break; } return NOTIFY_OK; } static int __init pfault_irq_init(void) { int rc; rc = register_external_interrupt(0x2603, 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); hotcpu_notifier(pfault_cpu_notify, 0); return 0; out_pfault: unregister_external_interrupt(0x2603, pfault_interrupt); out_extint: pfault_disable = 1; return rc; } early_initcall(pfault_irq_init); #endif /* CONFIG_PFAULT */