/* * arch/s390/mm/fault.c * * S390 version * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation * 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 #ifndef CONFIG_64BIT #define __FAIL_ADDR_MASK 0x7ffff000 #define __FIXUP_MASK 0x7fffffff #define __SUBCODE_MASK 0x0200 #define __PF_RES_FIELD 0ULL #else /* CONFIG_64BIT */ #define __FAIL_ADDR_MASK -4096L #define __FIXUP_MASK ~0L #define __SUBCODE_MASK 0x0600 #define __PF_RES_FIELD 0x8000000000000000ULL #endif /* CONFIG_64BIT */ #ifdef CONFIG_SYSCTL extern int sysctl_userprocess_debug; #endif extern void die(const char *,struct pt_regs *,long); extern spinlock_t timerlist_lock; /* * Unlock any spinlocks which will prevent us from getting the * message out (timerlist_lock is acquired through the * console unblank code) */ 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; } } /* * Check which address space is addressed by the access * register in S390_lowcore.exc_access_id. * Returns 1 for user space and 0 for kernel space. */ static int __check_access_register(struct pt_regs *regs, int error_code) { int areg = S390_lowcore.exc_access_id; if (areg == 0) /* Access via access register 0 -> kernel address */ return 0; save_access_regs(current->thread.acrs); if (regs && areg < NUM_ACRS && current->thread.acrs[areg] <= 1) /* * access register contains 0 -> kernel address, * access register contains 1 -> user space address */ return current->thread.acrs[areg]; /* Something unhealthy was done with the access registers... */ die("page fault via unknown access register", regs, error_code); do_exit(SIGKILL); return 0; } /* * Check which address space the address belongs to. * Returns 1 for user space and 0 for kernel space. */ static inline int check_user_space(struct pt_regs *regs, int error_code) { /* * The lowest two bits of S390_lowcore.trans_exc_code indicate * which paging table was used: * 0: Primary Segment Table Descriptor * 1: STD determined via access register * 2: Secondary Segment Table Descriptor * 3: Home Segment Table Descriptor */ int descriptor = S390_lowcore.trans_exc_code & 3; if (unlikely(descriptor == 1)) return __check_access_register(regs, error_code); if (descriptor == 2) return current->thread.mm_segment.ar4; return descriptor != 0; } /* * Send SIGSEGV to task. This is an external routine * to keep the stack usage of do_page_fault small. */ static void do_sigsegv(struct pt_regs *regs, unsigned long error_code, int si_code, unsigned long address) { struct siginfo si; #if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG) #if defined(CONFIG_SYSCTL) if (sysctl_userprocess_debug) #endif { printk("User process fault: interruption code 0x%lX\n", error_code); printk("failing address: %lX\n", address); show_regs(regs); } #endif si.si_signo = SIGSEGV; si.si_code = si_code; si.si_addr = (void *) address; force_sig_info(SIGSEGV, &si, current); } /* * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate * routines. * * error_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 void do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) { struct task_struct *tsk; struct mm_struct *mm; struct vm_area_struct * vma; unsigned long address; int user_address; const struct exception_table_entry *fixup; int si_code = SEGV_MAPERR; tsk = current; mm = tsk->mm; /* * 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 (is_protection && !(S390_lowcore.trans_exc_code & 4)) { /* Low-address protection hit in kernel mode means NULL pointer write access in kernel mode. */ if (!(regs->psw.mask & PSW_MASK_PSTATE)) { address = 0; user_address = 0; goto no_context; } /* Low-address protection hit in user mode 'cannot happen'. */ die ("Low-address protection", regs, error_code); do_exit(SIGKILL); } /* * get the failing address * more specific the segment and page table portion of * the address */ address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK; user_address = check_user_space(regs, error_code); /* * Verify that the fault happened in user space, that * we are not in an interrupt and that there is a * user context. */ if (user_address == 0 || in_atomic() || !mm) goto no_context; /* * When we get here, the fault happened in the current * task's user address space, so we can switch on the * interrupts again and then search the VMAs */ local_irq_enable(); down_read(&mm->mmap_sem); vma = find_vma(mm, address); if (!vma) goto bad_area; if (vma->vm_start <= address) goto good_area; if (!(vma->vm_flags & VM_GROWSDOWN)) goto bad_area; if (expand_stack(vma, address)) goto bad_area; /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ good_area: si_code = SEGV_ACCERR; if (!is_protection) { /* page not present, check vm flags */ if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) goto bad_area; } else { if (!(vma->vm_flags & VM_WRITE)) goto bad_area; } survive: /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo * the fault. */ switch (handle_mm_fault(mm, vma, address, is_protection)) { case VM_FAULT_MINOR: tsk->min_flt++; break; case VM_FAULT_MAJOR: tsk->maj_flt++; break; case VM_FAULT_SIGBUS: goto do_sigbus; case VM_FAULT_OOM: goto out_of_memory; default: BUG(); } up_read(&mm->mmap_sem); /* * The instruction that caused the program check will * be repeated. Don't signal single step via SIGTRAP. */ clear_tsk_thread_flag(current, TIF_SINGLE_STEP); return; /* * Something tried to access memory that isn't in our memory map.. * Fix it, but check if it's kernel or user first.. */ bad_area: up_read(&mm->mmap_sem); /* User mode accesses just cause a SIGSEGV */ if (regs->psw.mask & PSW_MASK_PSTATE) { tsk->thread.prot_addr = address; tsk->thread.trap_no = error_code; do_sigsegv(regs, error_code, si_code, address); return; } no_context: /* Are we prepared to handle this kernel fault? */ fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK); if (fixup) { regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE; return; } /* * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ if (user_address == 0) 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("Oops", regs, error_code); do_exit(SIGKILL); /* * We ran out of memory, or some other thing happened to us that made * us unable to handle the page fault gracefully. */ out_of_memory: up_read(&mm->mmap_sem); if (tsk->pid == 1) { yield(); goto survive; } printk("VM: killing process %s\n", tsk->comm); if (regs->psw.mask & PSW_MASK_PSTATE) do_exit(SIGKILL); goto no_context; do_sigbus: up_read(&mm->mmap_sem); /* * Send a sigbus, regardless of whether we were in kernel * or user mode. */ tsk->thread.prot_addr = address; tsk->thread.trap_no = error_code; force_sig(SIGBUS, tsk); /* Kernel mode? Handle exceptions or die */ if (!(regs->psw.mask & PSW_MASK_PSTATE)) goto no_context; } void do_protection_exception(struct pt_regs *regs, unsigned long error_code) { regs->psw.addr -= (error_code >> 16); do_exception(regs, 4, 1); } void do_dat_exception(struct pt_regs *regs, unsigned long error_code) { do_exception(regs, error_code & 0xff, 0); } #ifdef CONFIG_PFAULT /* * 'pfault' pseudo page faults routines. */ static int pfault_disable = 0; static int __init nopfault(char *str) { pfault_disable = 1; return 1; } __setup("nopfault", nopfault); typedef struct { __u16 refdiagc; __u16 reffcode; __u16 refdwlen; __u16 refversn; __u64 refgaddr; __u64 refselmk; __u64 refcmpmk; __u64 reserved; } __attribute__ ((packed)) pfault_refbk_t; int pfault_init(void) { pfault_refbk_t refbk = { 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48, __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" ".section __ex_table,\"a\"\n" " .align 4\n" #ifndef CONFIG_64BIT " .long 0b,1b\n" #else /* CONFIG_64BIT */ " .quad 0b,1b\n" #endif /* CONFIG_64BIT */ ".previous" : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc" ); __ctl_set_bit(0, 9); return rc; } void pfault_fini(void) { pfault_refbk_t refbk = { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL }; if (pfault_disable) return; __ctl_clear_bit(0,9); __asm__ __volatile__( " diag %0,0,0x258\n" "0:\n" ".section __ex_table,\"a\"\n" " .align 4\n" #ifndef CONFIG_64BIT " .long 0b,0b\n" #else /* CONFIG_64BIT */ " .quad 0b,0b\n" #endif /* CONFIG_64BIT */ ".previous" : : "a" (&refbk), "m" (refbk) : "cc" ); } asmlinkage void pfault_interrupt(struct pt_regs *regs, __u16 error_code) { struct task_struct *tsk; __u16 subcode; /* * Get the external interruption subcode & pfault * initial/completion signal bit. VM stores this * in the 'cpu address' field associated with the * external interrupt. */ subcode = S390_lowcore.cpu_addr; if ((subcode & 0xff00) != __SUBCODE_MASK) return; /* * Get the token (= address of the task structure of the affected task). */ tsk = *(struct task_struct **) __LC_PFAULT_INTPARM; if (subcode & 0x0080) { /* signal bit is set -> a page has been swapped in by VM */ if (xchg(&tsk->thread.pfault_wait, -1) != 0) { /* 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; wake_up_process(tsk); put_task_struct(tsk); } } else { /* signal bit not set -> a real page is missing. */ get_task_struct(tsk); set_task_state(tsk, TASK_UNINTERRUPTIBLE); if (xchg(&tsk->thread.pfault_wait, 1) != 0) { /* Completion interrupt was faster than the initial * interrupt (swapped in a -1 for pfault_wait). Set * pfault_wait back to zero and exit. This can be * done safely because tsk is running in kernel * mode and can't produce new pfaults. */ tsk->thread.pfault_wait = 0; set_task_state(tsk, TASK_RUNNING); put_task_struct(tsk); } else set_tsk_need_resched(tsk); } } #endif