diff options
Diffstat (limited to 'kernel/arch/s390/mm/fault.c')
| -rw-r--r-- | kernel/arch/s390/mm/fault.c | 758 |
1 files changed, 758 insertions, 0 deletions
diff --git a/kernel/arch/s390/mm/fault.c b/kernel/arch/s390/mm/fault.c new file mode 100644 index 000000000..4c8f5d7f9 --- /dev/null +++ b/kernel/arch/s390/mm/fault.c @@ -0,0 +1,758 @@ +/* + * 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 <linux/kernel_stat.h> +#include <linux/perf_event.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/compat.h> +#include <linux/smp.h> +#include <linux/kdebug.h> +#include <linux/init.h> +#include <linux/console.h> +#include <linux/module.h> +#include <linux/hardirq.h> +#include <linux/kprobes.h> +#include <linux/uaccess.h> +#include <linux/hugetlb.h> +#include <asm/asm-offsets.h> +#include <asm/pgtable.h> +#include <asm/irq.h> +#include <asm/mmu_context.h> +#include <asm/facility.h> +#include "../kernel/entry.h" + +#define __FAIL_ADDR_MASK -4096L +#define __SUBCODE_MASK 0x0600 +#define __PF_RES_FIELD 0x8000000000000000ULL + +#define VM_FAULT_BADCONTEXT 0x010000 +#define VM_FAULT_BADMAP 0x020000 +#define VM_FAULT_BADACCESS 0x040000 +#define VM_FAULT_SIGNAL 0x080000 +#define VM_FAULT_PFAULT 0x100000 + +static unsigned long store_indication __read_mostly; + +static int __init fault_init(void) +{ + if (test_facility(75)) + store_indication = 0xc00; + return 0; +} +early_initcall(fault_init); + +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(struct pt_regs *regs) +{ + unsigned long trans_exc_code; + + /* + * The lowest two bits of the translation exception + * identification indicate which paging table was used. + */ + trans_exc_code = regs->int_parm_long & 3; + if (trans_exc_code == 3) /* home space -> kernel */ + return 0; + if (user_mode(regs)) + return 1; + if (trans_exc_code == 2) /* secondary space -> set_fs */ + return current->thread.mm_segment.ar4; + if (current->flags & PF_VCPU) + return 1; + return 0; +} + +static int bad_address(void *p) +{ + unsigned long dummy; + + return probe_kernel_address((unsigned long *)p, dummy); +} + +static void dump_pagetable(unsigned long asce, unsigned long address) +{ + unsigned long *table = __va(asce & PAGE_MASK); + + pr_alert("AS:%016lx ", asce); + switch (asce & _ASCE_TYPE_MASK) { + case _ASCE_TYPE_REGION1: + table = table + ((address >> 53) & 0x7ff); + if (bad_address(table)) + goto bad; + pr_cont("R1:%016lx ", *table); + if (*table & _REGION_ENTRY_INVALID) + goto out; + table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); + /* fallthrough */ + case _ASCE_TYPE_REGION2: + table = table + ((address >> 42) & 0x7ff); + if (bad_address(table)) + goto bad; + pr_cont("R2:%016lx ", *table); + if (*table & _REGION_ENTRY_INVALID) + goto out; + table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); + /* fallthrough */ + case _ASCE_TYPE_REGION3: + table = table + ((address >> 31) & 0x7ff); + if (bad_address(table)) + goto bad; + pr_cont("R3:%016lx ", *table); + if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) + goto out; + table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); + /* fallthrough */ + case _ASCE_TYPE_SEGMENT: + table = table + ((address >> 20) & 0x7ff); + if (bad_address(table)) + goto bad; + pr_cont("S:%016lx ", *table); + if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) + goto out; + table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); + } + table = table + ((address >> 12) & 0xff); + if (bad_address(table)) + goto bad; + pr_cont("P:%016lx ", *table); +out: + pr_cont("\n"); + return; +bad: + pr_cont("BAD\n"); +} + +static void dump_fault_info(struct pt_regs *regs) +{ + unsigned long asce; + + pr_alert("Fault in "); + switch (regs->int_parm_long & 3) { + case 3: + pr_cont("home space "); + break; + case 2: + pr_cont("secondary space "); + break; + case 1: + pr_cont("access register "); + break; + case 0: + pr_cont("primary space "); + break; + } + pr_cont("mode while using "); + if (!user_space_fault(regs)) { + asce = S390_lowcore.kernel_asce; + pr_cont("kernel "); + } +#ifdef CONFIG_PGSTE + else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) { + struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; + asce = gmap->asce; + pr_cont("gmap "); + } +#endif + else { + asce = S390_lowcore.user_asce; + pr_cont("user "); + } + pr_cont("ASCE.\n"); + dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); +} + +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 %04x ilc:%d ", + regs->int_code & 0xffff, regs->int_code >> 17); + print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN); + printk(KERN_CONT "\n"); + printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n", + regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); + dump_fault_info(regs); + 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)) + printk(KERN_ALERT "Unable to handle kernel pointer dereference" + " in virtual kernel address space\n"); + else + printk(KERN_ALERT "Unable to handle kernel paging request" + " in virtual user address space\n"); + printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n", + regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); + dump_fault_info(regs); + 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: + case VM_FAULT_PFAULT: + 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) +{ +#ifdef CONFIG_PGSTE + struct gmap *gmap; +#endif + 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_pt_regs_flag(regs, PIF_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(regs) || faulthandler_disabled() || !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 + gmap = (current->flags & PF_VCPU) ? + (struct gmap *) S390_lowcore.gmap : NULL; + if (gmap) { + current->thread.gmap_addr = address; + address = __gmap_translate(gmap, address); + if (address == -EFAULT) { + fault = VM_FAULT_BADMAP; + goto out_up; + } + if (gmap->pfault_enabled) + flags |= FAULT_FLAG_RETRY_NOWAIT; + } +#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) { +#ifdef CONFIG_PGSTE + if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) { + /* FAULT_FLAG_RETRY_NOWAIT has been set, + * mmap_sem has not been released */ + current->thread.gmap_pfault = 1; + fault = VM_FAULT_PFAULT; + goto out_up; + } +#endif + /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk + * of starvation. */ + flags &= ~(FAULT_FLAG_ALLOW_RETRY | + FAULT_FLAG_RETRY_NOWAIT); + flags |= FAULT_FLAG_TRIED; + down_read(&mm->mmap_sem); + goto retry; + } + } +#ifdef CONFIG_PGSTE + if (gmap) { + address = __gmap_link(gmap, current->thread.gmap_addr, + address); + if (address == -EFAULT) { + fault = VM_FAULT_BADMAP; + goto out_up; + } + if (address == -ENOMEM) { + fault = VM_FAULT_OOM; + goto out_up; + } + } +#endif + fault = 0; +out_up: + up_read(&mm->mmap_sem); +out: + return fault; +} + +void 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); +} +NOKPROBE_SYMBOL(do_protection_exception); + +void 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); +} +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))); + +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_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); + hotcpu_notifier(pfault_cpu_notify, 0); + 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 */ |