diff options
Diffstat (limited to 'arch/s390/mm/fault.c')
-rw-r--r-- | arch/s390/mm/fault.c | 586 |
1 files changed, 586 insertions, 0 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c new file mode 100644 index 00000000000..80306bc8c79 --- /dev/null +++ b/arch/s390/mm/fault.c @@ -0,0 +1,586 @@ +/* + * 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_interrupt() || !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 + |