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}