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-rw-r--r--arch/s390/mm/fault.c664
1 files changed, 664 insertions, 0 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
new file mode 100644
index 00000000..4e668600
--- /dev/null
+++ b/arch/s390/mm/fault.c
@@ -0,0 +1,664 @@
+/*
+ * 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/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"
+
+#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
+
+static unsigned long store_indication;
+
+void fault_init(void)
+{
+ if (test_facility(2) && test_facility(75))
+ store_indication = 0xc00;
+}
+
+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;
+ if (user_mode == HOME_SPACE_MODE)
+ /* User space if the access has been done via home space. */
+ return trans_exc_code == 3;
+ /*
+ * If the user space is not the home space the kernel runs in home
+ * space. Access via secondary space has already been covered,
+ * 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 = 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 (regs->psw.mask & PSW_MASK_PSTATE) {
+ /* 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;
+ default: /* fault & VM_FAULT_ERROR */
+ if (fault & VM_FAULT_OOM) {
+ if (!(regs->psw.mask & PSW_MASK_PSTATE))
+ do_no_context(regs);
+ else
+ pagefault_out_of_memory();
+ } else if (fault & VM_FAULT_SIGBUS) {
+ /* Kernel mode? Handle exceptions or die */
+ if (!(regs->psw.mask & PSW_MASK_PSTATE))
+ 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;
+
+ if (notify_page_fault(regs))
+ return 0;
+
+ tsk = current;
+ 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;
+ if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
+ flags |= FAULT_FLAG_WRITE;
+ down_read(&mm->mmap_sem);
+
+#ifdef CONFIG_PGSTE
+ if (test_tsk_thread_flag(current, TIF_SIE) && 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);
+ 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;
+ down_read(&mm->mmap_sem);
+ goto retry;
+ }
+ }
+ /*
+ * The instruction that caused the program check will
+ * be repeated. Don't signal single step via SIGTRAP.
+ */
+ clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
+ 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 exception is suppressing, decrement psw address. */
+ 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);
+}
+
+#ifdef CONFIG_64BIT
+void __kprobes do_asce_exception(struct pt_regs *regs)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ unsigned long trans_exc_code;
+
+ trans_exc_code = regs->int_parm_long;
+ if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
+ goto no_context;
+
+ down_read(&mm->mmap_sem);
+ vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
+ up_read(&mm->mmap_sem);
+
+ if (vma) {
+ update_mm(mm, current);
+ return;
+ }
+
+ /* User mode accesses just cause a SIGSEGV */
+ if (regs->psw.mask & PSW_MASK_PSTATE) {
+ do_sigsegv(regs, SEGV_MAPERR);
+ return;
+ }
+
+no_context:
+ do_no_context(regs);
+}
+#endif
+
+int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
+{
+ struct pt_regs regs;
+ int access, fault;
+
+ 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(&regs, access);
+ if (unlikely(fault)) {
+ if (fault & VM_FAULT_OOM)
+ return -EFAULT;
+ else if (fault & VM_FAULT_SIGBUS)
+ do_sigbus(&regs);
+ }
+ 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;
+ kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++;
+ if (subcode & 0x0080) {
+ /* 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;
+ } else {
+ tsk = current;
+ }
+ 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;
+ }
+ put_task_struct(tsk);
+ } else {
+ /* signal bit not set -> a real page is missing. */
+ 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);
+ }
+ }
+ spin_unlock(&pfault_lock);
+}
+
+static int __cpuinit pfault_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ struct thread_struct *thread, *next;
+ struct task_struct *tsk;
+
+ switch (action) {
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ 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;
+ service_subclass_irq_register();
+ 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 */
generated by cgit (git 2.34.1) at 2025-01-10 18:08:39 +0000