LXR linux/arch/s390/kernel/guarded

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright IBM Corp. 2016
   4 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
   5 */
   6
   7#include <linux/kernel.h>
   8#include <linux/syscalls.h>
   9#include <linux/signal.h>
  10#include <linux/mm.h>
  11#include <linux/slab.h>
  12#include <asm/guarded_storage.h>
  13#include "entry.h"
  14
  15void guarded_storage_release(struct task_struct *tsk)
  16{
  17        kfree(tsk->thread.gs_cb);
  18        kfree(tsk->thread.gs_bc_cb);
  19}
  20
  21static int gs_enable(void)
  22{
  23        struct gs_cb *gs_cb;
  24
  25        if (!current->thread.gs_cb) {
  26                gs_cb = kzalloc(sizeof(*gs_cb), GFP_KERNEL);
  27                if (!gs_cb)
  28                        return -ENOMEM;
  29                gs_cb->gsd = 25;
  30                preempt_disable();
  31                __ctl_set_bit(2, 4);
  32                load_gs_cb(gs_cb);
  33                current->thread.gs_cb = gs_cb;
  34                preempt_enable();
  35        }
  36        return 0;
  37}
  38
  39static int gs_disable(void)
  40{
  41        if (current->thread.gs_cb) {
  42                preempt_disable();
  43                kfree(current->thread.gs_cb);
  44                current->thread.gs_cb = NULL;
  45                __ctl_clear_bit(2, 4);
  46                preempt_enable();
  47        }
  48        return 0;
  49}
  50
  51static int gs_set_bc_cb(struct gs_cb __user *u_gs_cb)
  52{
  53        struct gs_cb *gs_cb;
  54
  55        gs_cb = current->thread.gs_bc_cb;
  56        if (!gs_cb) {
  57                gs_cb = kzalloc(sizeof(*gs_cb), GFP_KERNEL);
  58                if (!gs_cb)
  59                        return -ENOMEM;
  60                current->thread.gs_bc_cb = gs_cb;
  61        }
  62        if (copy_from_user(gs_cb, u_gs_cb, sizeof(*gs_cb)))
  63                return -EFAULT;
  64        return 0;
  65}
  66
  67static int gs_clear_bc_cb(void)
  68{
  69        struct gs_cb *gs_cb;
  70
  71        gs_cb = current->thread.gs_bc_cb;
  72        current->thread.gs_bc_cb = NULL;
  73        kfree(gs_cb);
  74        return 0;
  75}
  76
  77void gs_load_bc_cb(struct pt_regs *regs)
  78{
  79        struct gs_cb *gs_cb;
  80
  81        preempt_disable();
  82        clear_thread_flag(TIF_GUARDED_STORAGE);
  83        gs_cb = current->thread.gs_bc_cb;
  84        if (gs_cb) {
  85                kfree(current->thread.gs_cb);
  86                current->thread.gs_bc_cb = NULL;
  87                __ctl_set_bit(2, 4);
  88                load_gs_cb(gs_cb);
  89                current->thread.gs_cb = gs_cb;
  90        }
  91        preempt_enable();
  92}
  93
  94static int gs_broadcast(void)
  95{
  96        struct task_struct *sibling;
  97
  98        read_lock(&tasklist_lock);
  99        for_each_thread(current, sibling) {
 100                if (!sibling->thread.gs_bc_cb)
 101                        continue;
 102                if (test_and_set_tsk_thread_flag(sibling, TIF_GUARDED_STORAGE))
 103                        kick_process(sibling);
 104        }
 105        read_unlock(&tasklist_lock);
 106        return 0;
 107}
 108
 109SYSCALL_DEFINE2(s390_guarded_storage, int, command,
 110                struct gs_cb __user *, gs_cb)
 111{
 112        if (!MACHINE_HAS_GS)
 113                return -EOPNOTSUPP;
 114        switch (command) {
 115        case GS_ENABLE:
 116                return gs_enable();
 117        case GS_DISABLE:
 118                return gs_disable();
 119        case GS_SET_BC_CB:
 120                return gs_set_bc_cb(gs_cb);
 121        case GS_CLEAR_BC_CB:
 122                return gs_clear_bc_cb();
 123        case GS_BROADCAST:
 124                return gs_broadcast();
 125        default:
 126                return -EINVAL;
 127        }
 128}
 129