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-rw-r--r--arch/s390/mm/fault.c907
1 files changed, 907 insertions, 0 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
new file mode 100644
index 000000000..2ab388179
--- /dev/null
+++ b/arch/s390/mm/fault.c
@@ -0,0 +1,907 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/sched/debug.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/extable.h>
+#include <linux/hardirq.h>
+#include <linux/kprobes.h>
+#include <linux/uaccess.h>
+#include <linux/hugetlb.h>
+#include <linux/kfence.h>
+#include <asm/asm-extable.h>
+#include <asm/asm-offsets.h>
+#include <asm/diag.h>
+#include <asm/gmap.h>
+#include <asm/irq.h>
+#include <asm/mmu_context.h>
+#include <asm/facility.h>
+#include <asm/uv.h>
+#include "../kernel/entry.h"
+
+#define __FAIL_ADDR_MASK -4096L
+#define __SUBCODE_MASK 0x0600
+#define __PF_RES_FIELD 0x8000000000000000ULL
+
+#define VM_FAULT_BADCONTEXT ((__force vm_fault_t) 0x010000)
+#define VM_FAULT_BADMAP ((__force vm_fault_t) 0x020000)
+#define VM_FAULT_BADACCESS ((__force vm_fault_t) 0x040000)
+#define VM_FAULT_SIGNAL ((__force vm_fault_t) 0x080000)
+#define VM_FAULT_PFAULT ((__force vm_fault_t) 0x100000)
+
+enum fault_type {
+ KERNEL_FAULT,
+ USER_FAULT,
+ GMAP_FAULT,
+};
+
+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);
+
+/*
+ * Find out which address space caused the exception.
+ */
+static enum fault_type get_fault_type(struct pt_regs *regs)
+{
+ unsigned long trans_exc_code;
+
+ trans_exc_code = regs->int_parm_long & 3;
+ if (likely(trans_exc_code == 0)) {
+ /* primary space exception */
+ if (user_mode(regs))
+ return USER_FAULT;
+ if (!IS_ENABLED(CONFIG_PGSTE))
+ return KERNEL_FAULT;
+ if (test_pt_regs_flag(regs, PIF_GUEST_FAULT))
+ return GMAP_FAULT;
+ return KERNEL_FAULT;
+ }
+ if (trans_exc_code == 2)
+ return USER_FAULT;
+ if (trans_exc_code == 1) {
+ /* access register mode, not used in the kernel */
+ return USER_FAULT;
+ }
+ /* home space exception -> access via kernel ASCE */
+ return KERNEL_FAULT;
+}
+
+static unsigned long get_fault_address(struct pt_regs *regs)
+{
+ unsigned long trans_exc_code = regs->int_parm_long;
+
+ return trans_exc_code & __FAIL_ADDR_MASK;
+}
+
+static bool fault_is_write(struct pt_regs *regs)
+{
+ unsigned long trans_exc_code = regs->int_parm_long;
+
+ return (trans_exc_code & store_indication) == 0x400;
+}
+
+static int bad_address(void *p)
+{
+ unsigned long dummy;
+
+ return get_kernel_nofault(dummy, (unsigned long *)p);
+}
+
+static void dump_pagetable(unsigned long asce, unsigned long address)
+{
+ unsigned long *table = __va(asce & _ASCE_ORIGIN);
+
+ pr_alert("AS:%016lx ", asce);
+ switch (asce & _ASCE_TYPE_MASK) {
+ case _ASCE_TYPE_REGION1:
+ table += (address & _REGION1_INDEX) >> _REGION1_SHIFT;
+ if (bad_address(table))
+ goto bad;
+ pr_cont("R1:%016lx ", *table);
+ if (*table & _REGION_ENTRY_INVALID)
+ goto out;
+ table = __va(*table & _REGION_ENTRY_ORIGIN);
+ fallthrough;
+ case _ASCE_TYPE_REGION2:
+ table += (address & _REGION2_INDEX) >> _REGION2_SHIFT;
+ if (bad_address(table))
+ goto bad;
+ pr_cont("R2:%016lx ", *table);
+ if (*table & _REGION_ENTRY_INVALID)
+ goto out;
+ table = __va(*table & _REGION_ENTRY_ORIGIN);
+ fallthrough;
+ case _ASCE_TYPE_REGION3:
+ table += (address & _REGION3_INDEX) >> _REGION3_SHIFT;
+ if (bad_address(table))
+ goto bad;
+ pr_cont("R3:%016lx ", *table);
+ if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
+ goto out;
+ table = __va(*table & _REGION_ENTRY_ORIGIN);
+ fallthrough;
+ case _ASCE_TYPE_SEGMENT:
+ table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
+ if (bad_address(table))
+ goto bad;
+ pr_cont("S:%016lx ", *table);
+ if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
+ goto out;
+ table = __va(*table & _SEGMENT_ENTRY_ORIGIN);
+ }
+ table += (address & _PAGE_INDEX) >> _PAGE_SHIFT;
+ 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("Failing address: %016lx TEID: %016lx\n",
+ regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
+ 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 ");
+ switch (get_fault_type(regs)) {
+ case USER_FAULT:
+ asce = S390_lowcore.user_asce;
+ pr_cont("user ");
+ break;
+ case GMAP_FAULT:
+ asce = ((struct gmap *) S390_lowcore.gmap)->asce;
+ pr_cont("gmap ");
+ break;
+ case KERNEL_FAULT:
+ asce = S390_lowcore.kernel_asce;
+ pr_cont("kernel ");
+ break;
+ default:
+ unreachable();
+ }
+ pr_cont("ASCE.\n");
+ dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
+}
+
+int show_unhandled_signals = 1;
+
+void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault)
+{
+ 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);
+ printk(KERN_CONT "\n");
+ if (is_mm_fault)
+ 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)
+{
+ report_user_fault(regs, SIGSEGV, 1);
+ force_sig_fault(SIGSEGV, si_code,
+ (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
+}
+
+static noinline void do_no_context(struct pt_regs *regs, vm_fault_t fault)
+{
+ enum fault_type fault_type;
+ unsigned long address;
+ bool is_write;
+
+ if (fixup_exception(regs))
+ return;
+ fault_type = get_fault_type(regs);
+ if ((fault_type == KERNEL_FAULT) && (fault == VM_FAULT_BADCONTEXT)) {
+ address = get_fault_address(regs);
+ is_write = fault_is_write(regs);
+ if (kfence_handle_page_fault(address, is_write, regs))
+ return;
+ }
+ /*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+ if (fault_type == KERNEL_FAULT)
+ 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");
+ dump_fault_info(regs);
+ die(regs, "Oops");
+}
+
+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_no_context(regs, VM_FAULT_BADACCESS);
+}
+
+static noinline void do_sigbus(struct pt_regs *regs)
+{
+ /*
+ * Send a sigbus, regardless of whether we were in kernel
+ * or user mode.
+ */
+ force_sig_fault(SIGBUS, BUS_ADRERR,
+ (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
+}
+
+static noinline void do_fault_error(struct pt_regs *regs, vm_fault_t 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);
+ break;
+ }
+ fallthrough;
+ case VM_FAULT_BADCONTEXT:
+ case VM_FAULT_PFAULT:
+ do_no_context(regs, fault);
+ break;
+ case VM_FAULT_SIGNAL:
+ if (!user_mode(regs))
+ do_no_context(regs, fault);
+ break;
+ default: /* fault & VM_FAULT_ERROR */
+ if (fault & VM_FAULT_OOM) {
+ if (!user_mode(regs))
+ do_no_context(regs, fault);
+ 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, fault);
+ 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, fault);
+ 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 (suppression)
+ * 10 Segment translation -> Not present (nullification)
+ * 11 Page translation -> Not present (nullification)
+ * 3b Region third trans. -> Not present (nullification)
+ */
+static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
+{
+ struct gmap *gmap;
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ struct vm_area_struct *vma;
+ enum fault_type type;
+ unsigned long address;
+ unsigned int flags;
+ vm_fault_t fault;
+ bool is_write;
+
+ tsk = current;
+ /*
+ * The instruction that caused the program check has
+ * been nullified. Don't signal single step via SIGTRAP.
+ */
+ clear_thread_flag(TIF_PER_TRAP);
+
+ if (kprobe_page_fault(regs, 14))
+ return 0;
+
+ mm = tsk->mm;
+ address = get_fault_address(regs);
+ is_write = fault_is_write(regs);
+
+ /*
+ * 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;
+ type = get_fault_type(regs);
+ switch (type) {
+ case KERNEL_FAULT:
+ goto out;
+ case USER_FAULT:
+ case GMAP_FAULT:
+ if (faulthandler_disabled() || !mm)
+ goto out;
+ break;
+ }
+
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+ flags = FAULT_FLAG_DEFAULT;
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+ if (is_write)
+ access = VM_WRITE;
+ if (access == VM_WRITE)
+ flags |= FAULT_FLAG_WRITE;
+ mmap_read_lock(mm);
+
+ gmap = NULL;
+ if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) {
+ gmap = (struct gmap *) S390_lowcore.gmap;
+ current->thread.gmap_addr = address;
+ current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE);
+ current->thread.gmap_int_code = regs->int_code & 0xffff;
+ address = __gmap_translate(gmap, address);
+ if (address == -EFAULT) {
+ fault = VM_FAULT_BADMAP;
+ goto out_up;
+ }
+ if (gmap->pfault_enabled)
+ flags |= FAULT_FLAG_RETRY_NOWAIT;
+ }
+
+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;
+ vma = expand_stack(mm, address);
+ if (!vma)
+ goto out;
+ }
+
+ /*
+ * 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 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(vma, address, flags, regs);
+ if (fault_signal_pending(fault, regs)) {
+ fault = VM_FAULT_SIGNAL;
+ if (flags & FAULT_FLAG_RETRY_NOWAIT)
+ goto out_up;
+ goto out;
+ }
+
+ /* The fault is fully completed (including releasing mmap lock) */
+ if (fault & VM_FAULT_COMPLETED) {
+ if (gmap) {
+ mmap_read_lock(mm);
+ goto out_gmap;
+ }
+ fault = 0;
+ goto out;
+ }
+
+ if (unlikely(fault & VM_FAULT_ERROR))
+ goto out_up;
+
+ if (fault & VM_FAULT_RETRY) {
+ if (IS_ENABLED(CONFIG_PGSTE) && gmap &&
+ (flags & FAULT_FLAG_RETRY_NOWAIT)) {
+ /*
+ * FAULT_FLAG_RETRY_NOWAIT has been set, mmap_lock has
+ * not been released
+ */
+ current->thread.gmap_pfault = 1;
+ fault = VM_FAULT_PFAULT;
+ goto out_up;
+ }
+ flags &= ~FAULT_FLAG_RETRY_NOWAIT;
+ flags |= FAULT_FLAG_TRIED;
+ mmap_read_lock(mm);
+ goto retry;
+ }
+out_gmap:
+ if (IS_ENABLED(CONFIG_PGSTE) && 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;
+ }
+ }
+ fault = 0;
+out_up:
+ mmap_read_unlock(mm);
+out:
+ return fault;
+}
+
+void do_protection_exception(struct pt_regs *regs)
+{
+ unsigned long trans_exc_code;
+ int access;
+ vm_fault_t 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;
+ }
+ if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) {
+ regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) |
+ (regs->psw.addr & PAGE_MASK);
+ access = VM_EXEC;
+ fault = VM_FAULT_BADACCESS;
+ } else {
+ access = VM_WRITE;
+ fault = do_exception(regs, access);
+ }
+ if (unlikely(fault))
+ do_fault_error(regs, fault);
+}
+NOKPROBE_SYMBOL(do_protection_exception);
+
+void do_dat_exception(struct pt_regs *regs)
+{
+ int access;
+ vm_fault_t fault;
+
+ access = VM_ACCESS_FLAGS;
+ 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)));
+
+static struct pfault_refbk pfault_init_refbk = {
+ .refdiagc = 0x258,
+ .reffcode = 0,
+ .refdwlen = 5,
+ .refversn = 2,
+ .refgaddr = __LC_LPP,
+ .refselmk = 1ULL << 48,
+ .refcmpmk = 1ULL << 48,
+ .reserved = __PF_RES_FIELD
+};
+
+int pfault_init(void)
+{
+ int rc;
+
+ if (pfault_disable)
+ return -1;
+ diag_stat_inc(DIAG_STAT_X258);
+ 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" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc");
+ return rc;
+}
+
+static struct pfault_refbk pfault_fini_refbk = {
+ .refdiagc = 0x258,
+ .reffcode = 1,
+ .refdwlen = 5,
+ .refversn = 2,
+};
+
+void pfault_fini(void)
+{
+
+ if (pfault_disable)
+ return;
+ diag_stat_inc(DIAG_STAT_X258);
+ asm volatile(
+ " diag %0,0,0x258\n"
+ "0: nopr %%r7\n"
+ EX_TABLE(0b,0b)
+ : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc");
+}
+
+static DEFINE_SPINLOCK(pfault_lock);
+static LIST_HEAD(pfault_list);
+
+#define PF_COMPLETE 0x0080
+
+/*
+ * The mechanism of our pfault code: if Linux is running as guest, runs a user
+ * space process and the user space process accesses a page that the host has
+ * paged out we get a pfault interrupt.
+ *
+ * This allows us, within the guest, to schedule a different process. Without
+ * this mechanism the host would have to suspend the whole virtual cpu until
+ * the page has been paged in.
+ *
+ * So when we get such an interrupt then we set the state of the current task
+ * to uninterruptible and also set the need_resched flag. Both happens within
+ * interrupt context(!). If we later on want to return to user space we
+ * recognize the need_resched flag and then call schedule(). It's not very
+ * obvious how this works...
+ *
+ * Of course we have a lot of additional fun with the completion interrupt (->
+ * host signals that a page of a process has been paged in and the process can
+ * continue to run). This interrupt can arrive on any cpu and, since we have
+ * virtual cpus, actually appear before the interrupt that signals that a page
+ * is missing.
+ */
+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 = param64 & LPP_PID_MASK;
+ 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 & PF_COMPLETE) {
+ /* 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 (task_is_running(tsk))
+ 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 */
+ goto block;
+ } 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);
+block:
+ /* Since this must be a userspace fault, there
+ * is no kernel task state to trample. Rely on the
+ * return to userspace schedule() to block. */
+ __set_current_state(TASK_UNINTERRUPTIBLE);
+ set_tsk_need_resched(tsk);
+ set_preempt_need_resched();
+ }
+ }
+out:
+ spin_unlock(&pfault_lock);
+ put_task_struct(tsk);
+}
+
+static int pfault_cpu_dead(unsigned int cpu)
+{
+ struct thread_struct *thread, *next;
+ struct task_struct *tsk;
+
+ 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);
+ return 0;
+}
+
+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);
+ cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead",
+ NULL, pfault_cpu_dead);
+ 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 */
+
+#if IS_ENABLED(CONFIG_PGSTE)
+
+void do_secure_storage_access(struct pt_regs *regs)
+{
+ unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK;
+ struct vm_area_struct *vma;
+ struct mm_struct *mm;
+ struct page *page;
+ struct gmap *gmap;
+ int rc;
+
+ /*
+ * bit 61 tells us if the address is valid, if it's not we
+ * have a major problem and should stop the kernel or send a
+ * SIGSEGV to the process. Unfortunately bit 61 is not
+ * reliable without the misc UV feature so we need to check
+ * for that as well.
+ */
+ if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
+ !test_bit_inv(61, &regs->int_parm_long)) {
+ /*
+ * When this happens, userspace did something that it
+ * was not supposed to do, e.g. branching into secure
+ * memory. Trigger a segmentation fault.
+ */
+ if (user_mode(regs)) {
+ send_sig(SIGSEGV, current, 0);
+ return;
+ }
+
+ /*
+ * The kernel should never run into this case and we
+ * have no way out of this situation.
+ */
+ panic("Unexpected PGM 0x3d with TEID bit 61=0");
+ }
+
+ switch (get_fault_type(regs)) {
+ case GMAP_FAULT:
+ mm = current->mm;
+ gmap = (struct gmap *)S390_lowcore.gmap;
+ mmap_read_lock(mm);
+ addr = __gmap_translate(gmap, addr);
+ mmap_read_unlock(mm);
+ if (IS_ERR_VALUE(addr)) {
+ do_fault_error(regs, VM_FAULT_BADMAP);
+ break;
+ }
+ fallthrough;
+ case USER_FAULT:
+ mm = current->mm;
+ mmap_read_lock(mm);
+ vma = find_vma(mm, addr);
+ if (!vma) {
+ mmap_read_unlock(mm);
+ do_fault_error(regs, VM_FAULT_BADMAP);
+ break;
+ }
+ page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET);
+ if (IS_ERR_OR_NULL(page)) {
+ mmap_read_unlock(mm);
+ break;
+ }
+ if (arch_make_page_accessible(page))
+ send_sig(SIGSEGV, current, 0);
+ put_page(page);
+ mmap_read_unlock(mm);
+ break;
+ case KERNEL_FAULT:
+ page = phys_to_page(addr);
+ if (unlikely(!try_get_page(page)))
+ break;
+ rc = arch_make_page_accessible(page);
+ put_page(page);
+ if (rc)
+ BUG();
+ break;
+ default:
+ do_fault_error(regs, VM_FAULT_BADMAP);
+ WARN_ON_ONCE(1);
+ }
+}
+NOKPROBE_SYMBOL(do_secure_storage_access);
+
+void do_non_secure_storage_access(struct pt_regs *regs)
+{
+ unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK;
+ struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
+
+ if (get_fault_type(regs) != GMAP_FAULT) {
+ do_fault_error(regs, VM_FAULT_BADMAP);
+ WARN_ON_ONCE(1);
+ return;
+ }
+
+ if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL)
+ send_sig(SIGSEGV, current, 0);
+}
+NOKPROBE_SYMBOL(do_non_secure_storage_access);
+
+void do_secure_storage_violation(struct pt_regs *regs)
+{
+ unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK;
+ struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
+
+ /*
+ * If the VM has been rebooted, its address space might still contain
+ * secure pages from the previous boot.
+ * Clear the page so it can be reused.
+ */
+ if (!gmap_destroy_page(gmap, gaddr))
+ return;
+ /*
+ * Either KVM messed up the secure guest mapping or the same
+ * page is mapped into multiple secure guests.
+ *
+ * This exception is only triggered when a guest 2 is running
+ * and can therefore never occur in kernel context.
+ */
+ printk_ratelimited(KERN_WARNING
+ "Secure storage violation in task: %s, pid %d\n",
+ current->comm, current->pid);
+ send_sig(SIGSEGV, current, 0);
+}
+
+#endif /* CONFIG_PGSTE */
generated by cgit v1.2.3 (git 2.39.1) at 2024-08-03 20:51:56 +0000