| /* |
| * 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 <linux/config.h> |
| #include <linux/signal.h> |
| #include <linux/sched.h> |
| #include <linux/kernel.h> |
| #include <linux/errno.h> |
| #include <linux/string.h> |
| #include <linux/types.h> |
| #include <linux/ptrace.h> |
| #include <linux/mman.h> |
| #include <linux/mm.h> |
| #include <linux/smp.h> |
| #include <linux/smp_lock.h> |
| #include <linux/init.h> |
| #include <linux/console.h> |
| #include <linux/module.h> |
| #include <linux/hardirq.h> |
| |
| #include <asm/system.h> |
| #include <asm/uaccess.h> |
| #include <asm/pgtable.h> |
| |
| #ifndef CONFIG_ARCH_S390X |
| #define __FAIL_ADDR_MASK 0x7ffff000 |
| #define __FIXUP_MASK 0x7fffffff |
| #define __SUBCODE_MASK 0x0200 |
| #define __PF_RES_FIELD 0ULL |
| #else /* CONFIG_ARCH_S390X */ |
| #define __FAIL_ADDR_MASK -4096L |
| #define __FIXUP_MASK ~0L |
| #define __SUBCODE_MASK 0x0600 |
| #define __PF_RES_FIELD 0x8000000000000000ULL |
| #endif /* CONFIG_ARCH_S390X */ |
| |
| #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) |
| */ |
| extern 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); |
| } |
| |
| #ifndef CONFIG_ARCH_S390X |
| |
| typedef struct _pseudo_wait_t { |
| struct _pseudo_wait_t *next; |
| wait_queue_head_t queue; |
| unsigned long address; |
| int resolved; |
| } pseudo_wait_t; |
| |
| static pseudo_wait_t *pseudo_lock_queue = NULL; |
| static spinlock_t pseudo_wait_spinlock; /* spinlock to protect lock queue */ |
| |
| /* |
| * This routine handles 'pagex' pseudo page faults. |
| */ |
| asmlinkage void |
| do_pseudo_page_fault(struct pt_regs *regs, unsigned long error_code) |
| { |
| pseudo_wait_t wait_struct; |
| pseudo_wait_t *ptr, *last, *next; |
| unsigned long address; |
| |
| /* |
| * get the failing address |
| * more specific the segment and page table portion of |
| * the address |
| */ |
| address = S390_lowcore.trans_exc_code & 0xfffff000; |
| |
| if (address & 0x80000000) { |
| /* high bit set -> a page has been swapped in by VM */ |
| address &= 0x7fffffff; |
| spin_lock(&pseudo_wait_spinlock); |
| last = NULL; |
| ptr = pseudo_lock_queue; |
| while (ptr != NULL) { |
| next = ptr->next; |
| if (address == ptr->address) { |
| /* |
| * This is one of the processes waiting |
| * for the page. Unchain from the queue. |
| * There can be more than one process |
| * waiting for the same page. VM presents |
| * an initial and a completion interrupt for |
| * every process that tries to access a |
| * page swapped out by VM. |
| */ |
| if (last == NULL) |
| pseudo_lock_queue = next; |
| else |
| last->next = next; |
| /* now wake up the process */ |
| ptr->resolved = 1; |
| wake_up(&ptr->queue); |
| } else |
| last = ptr; |
| ptr = next; |
| } |
| spin_unlock(&pseudo_wait_spinlock); |
| } else { |
| /* Pseudo page faults in kernel mode is a bad idea */ |
| if (!(regs->psw.mask & PSW_MASK_PSTATE)) { |
| /* |
| * VM presents pseudo page faults if the interrupted |
| * state was not disabled for interrupts. So we can |
| * get pseudo page fault interrupts while running |
| * in kernel mode. We simply access the page here |
| * while we are running disabled. VM will then swap |
| * in the page synchronously. |
| */ |
| if (check_user_space(regs, error_code) == 0) |
| /* dereference a virtual kernel address */ |
| __asm__ __volatile__ ( |
| " ic 0,0(%0)" |
| : : "a" (address) : "0"); |
| else |
| /* dereference a virtual user address */ |
| __asm__ __volatile__ ( |
| " la 2,0(%0)\n" |
| " sacf 512\n" |
| " ic 2,0(2)\n" |
| "0:sacf 0\n" |
| ".section __ex_table,\"a\"\n" |
| " .align 4\n" |
| " .long 0b,0b\n" |
| ".previous" |
| : : "a" (address) : "2" ); |
| |
| return; |
| } |
| /* initialize and add element to pseudo_lock_queue */ |
| init_waitqueue_head (&wait_struct.queue); |
| wait_struct.address = address; |
| wait_struct.resolved = 0; |
| spin_lock(&pseudo_wait_spinlock); |
| wait_struct.next = pseudo_lock_queue; |
| pseudo_lock_queue = &wait_struct; |
| spin_unlock(&pseudo_wait_spinlock); |
| /* |
| * 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); |
| /* go to sleep */ |
| wait_event(wait_struct.queue, wait_struct.resolved); |
| } |
| } |
| #endif /* CONFIG_ARCH_S390X */ |
| |
| #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_ARCH_S390X |
| " .long 0b,1b\n" |
| #else /* CONFIG_ARCH_S390X */ |
| " .quad 0b,1b\n" |
| #endif /* CONFIG_ARCH_S390X */ |
| ".previous" |
| : "=d" (rc) : "a" (&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_ARCH_S390X |
| " .long 0b,0b\n" |
| #else /* CONFIG_ARCH_S390X */ |
| " .quad 0b,0b\n" |
| #endif /* CONFIG_ARCH_S390X */ |
| ".previous" |
| : : "a" (&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 procude new pfaults. */ |
| tsk->thread.pfault_wait = 0; |
| wake_up_process(tsk); |
| } |
| } else { |
| /* signal bit not set -> a real page is missing. */ |
| 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); |
| } else |
| set_tsk_need_resched(tsk); |
| } |
| } |
| #endif |
| |
