1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
4 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
5 */
6
7 #include <linux/mm.h>
8 #include <linux/sched/signal.h>
9 #include <linux/slab.h>
10
11 #include <asm/pgalloc.h>
12 #include <asm/sections.h>
13 #include <as-layout.h>
14 #include <os.h>
15 #include <skas.h>
16
init_new_context(struct task_struct * task,struct mm_struct * mm)17 int init_new_context(struct task_struct *task, struct mm_struct *mm)
18 {
19 struct mm_context *from_mm = NULL;
20 struct mm_context *to_mm = &mm->context;
21 unsigned long stack = 0;
22 int ret = -ENOMEM;
23
24 stack = get_zeroed_page(GFP_KERNEL);
25 if (stack == 0)
26 goto out;
27
28 to_mm->id.stack = stack;
29 if (current->mm != NULL && current->mm != &init_mm)
30 from_mm = ¤t->mm->context;
31
32 block_signals_trace();
33 if (from_mm)
34 to_mm->id.u.pid = copy_context_skas0(stack,
35 from_mm->id.u.pid);
36 else to_mm->id.u.pid = start_userspace(stack);
37 unblock_signals_trace();
38
39 if (to_mm->id.u.pid < 0) {
40 ret = to_mm->id.u.pid;
41 goto out_free;
42 }
43
44 ret = init_new_ldt(to_mm, from_mm);
45 if (ret < 0) {
46 printk(KERN_ERR "init_new_context_skas - init_ldt"
47 " failed, errno = %d\n", ret);
48 goto out_free;
49 }
50
51 return 0;
52
53 out_free:
54 if (to_mm->id.stack != 0)
55 free_page(to_mm->id.stack);
56 out:
57 return ret;
58 }
59
destroy_context(struct mm_struct * mm)60 void destroy_context(struct mm_struct *mm)
61 {
62 struct mm_context *mmu = &mm->context;
63
64 /*
65 * If init_new_context wasn't called, this will be
66 * zero, resulting in a kill(0), which will result in the
67 * whole UML suddenly dying. Also, cover negative and
68 * 1 cases, since they shouldn't happen either.
69 */
70 if (mmu->id.u.pid < 2) {
71 printk(KERN_ERR "corrupt mm_context - pid = %d\n",
72 mmu->id.u.pid);
73 return;
74 }
75 os_kill_ptraced_process(mmu->id.u.pid, 1);
76
77 free_page(mmu->id.stack);
78 free_ldt(mmu);
79 }
80