s390/kernel/guarded_storage.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright IBM Corp. 2016
0004  * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
0005  */
0006
0007 #include <linux/kernel.h>
0008 #include <linux/syscalls.h>
0009 #include <linux/signal.h>
0010 #include <linux/mm.h>
0011 #include <linux/slab.h>
0012 #include <asm/guarded_storage.h>
0013 #include "entry.h"
0014
0015 void guarded_storage_release(struct task_struct *tsk)
0016 {
0017     kfree(tsk->thread.gs_cb);
0018     kfree(tsk->thread.gs_bc_cb);
0019 }
0020
0021 static int gs_enable(void)
0022 {
0023     struct gs_cb *gs_cb;
0024
0025     if (!current->thread.gs_cb) {
0026         gs_cb = kzalloc(sizeof(*gs_cb), GFP_KERNEL);
0027         if (!gs_cb)
0028             return -ENOMEM;
0029         gs_cb->gsd = 25;
0030         preempt_disable();
0031         __ctl_set_bit(2, 4);
0032         load_gs_cb(gs_cb);
0033         current->thread.gs_cb = gs_cb;
0034         preempt_enable();
0035     }
0036     return 0;
0037 }
0038
0039 static int gs_disable(void)
0040 {
0041     if (current->thread.gs_cb) {
0042         preempt_disable();
0043         kfree(current->thread.gs_cb);
0044         current->thread.gs_cb = NULL;
0045         __ctl_clear_bit(2, 4);
0046         preempt_enable();
0047     }
0048     return 0;
0049 }
0050
0051 static int gs_set_bc_cb(struct gs_cb __user *u_gs_cb)
0052 {
0053     struct gs_cb *gs_cb;
0054
0055     gs_cb = current->thread.gs_bc_cb;
0056     if (!gs_cb) {
0057         gs_cb = kzalloc(sizeof(*gs_cb), GFP_KERNEL);
0058         if (!gs_cb)
0059             return -ENOMEM;
0060         current->thread.gs_bc_cb = gs_cb;
0061     }
0062     if (copy_from_user(gs_cb, u_gs_cb, sizeof(*gs_cb)))
0063         return -EFAULT;
0064     return 0;
0065 }
0066
0067 static int gs_clear_bc_cb(void)
0068 {
0069     struct gs_cb *gs_cb;
0070
0071     gs_cb = current->thread.gs_bc_cb;
0072     current->thread.gs_bc_cb = NULL;
0073     kfree(gs_cb);
0074     return 0;
0075 }
0076
0077 void gs_load_bc_cb(struct pt_regs *regs)
0078 {
0079     struct gs_cb *gs_cb;
0080
0081     preempt_disable();
0082     clear_thread_flag(TIF_GUARDED_STORAGE);
0083     gs_cb = current->thread.gs_bc_cb;
0084     if (gs_cb) {
0085         kfree(current->thread.gs_cb);
0086         current->thread.gs_bc_cb = NULL;
0087         __ctl_set_bit(2, 4);
0088         load_gs_cb(gs_cb);
0089         current->thread.gs_cb = gs_cb;
0090     }
0091     preempt_enable();
0092 }
0093
0094 static int gs_broadcast(void)
0095 {
0096     struct task_struct *sibling;
0097
0098     read_lock(&tasklist_lock);
0099     for_each_thread(current, sibling) {
0100         if (!sibling->thread.gs_bc_cb)
0101             continue;
0102         if (test_and_set_tsk_thread_flag(sibling, TIF_GUARDED_STORAGE))
0103             kick_process(sibling);
0104     }
0105     read_unlock(&tasklist_lock);
0106     return 0;
0107 }
0108
0109 SYSCALL_DEFINE2(s390_guarded_storage, int, command,
0110         struct gs_cb __user *, gs_cb)
0111 {
0112     if (!MACHINE_HAS_GS)
0113         return -EOPNOTSUPP;
0114     switch (command) {
0115     case GS_ENABLE:
0116         return gs_enable();
0117     case GS_DISABLE:
0118         return gs_disable();
0119     case GS_SET_BC_CB:
0120         return gs_set_bc_cb(gs_cb);
0121     case GS_CLEAR_BC_CB:
0122         return gs_clear_bc_cb();
0123     case GS_BROADCAST:
0124         return gs_broadcast();
0125     default:
0126         return -EINVAL;
0127     }
0128 }