1/*
2 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 */
5
6#include <linux/mm.h>
7#include <linux/sched.h>
8#include <linux/slab.h>
9#include <asm/pgalloc.h>
10#include <asm/pgtable.h>
11#include <as-layout.h>
12#include <os.h>
13#include <skas.h>
14
15extern int __syscall_stub_start;
16
17static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
18			 unsigned long kernel)
19{
20	pgd_t *pgd;
21	pud_t *pud;
22	pmd_t *pmd;
23	pte_t *pte;
24
25	pgd = pgd_offset(mm, proc);
26	pud = pud_alloc(mm, pgd, proc);
27	if (!pud)
28		goto out;
29
30	pmd = pmd_alloc(mm, pud, proc);
31	if (!pmd)
32		goto out_pmd;
33
34	pte = pte_alloc_map(mm, NULL, pmd, proc);
35	if (!pte)
36		goto out_pte;
37
38	*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
39	*pte = pte_mkread(*pte);
40	return 0;
41
42 out_pte:
43	pmd_free(mm, pmd);
44 out_pmd:
45	pud_free(mm, pud);
46 out:
47	return -ENOMEM;
48}
49
50int init_new_context(struct task_struct *task, struct mm_struct *mm)
51{
52 	struct mm_context *from_mm = NULL;
53	struct mm_context *to_mm = &mm->context;
54	unsigned long stack = 0;
55	int ret = -ENOMEM;
56
57	stack = get_zeroed_page(GFP_KERNEL);
58	if (stack == 0)
59		goto out;
60
61	to_mm->id.stack = stack;
62	if (current->mm != NULL && current->mm != &init_mm)
63		from_mm = &current->mm->context;
64
65	if (from_mm)
66		to_mm->id.u.pid = copy_context_skas0(stack,
67						     from_mm->id.u.pid);
68	else to_mm->id.u.pid = start_userspace(stack);
69
70	if (to_mm->id.u.pid < 0) {
71		ret = to_mm->id.u.pid;
72		goto out_free;
73	}
74
75	ret = init_new_ldt(to_mm, from_mm);
76	if (ret < 0) {
77		printk(KERN_ERR "init_new_context_skas - init_ldt"
78		       " failed, errno = %d\n", ret);
79		goto out_free;
80	}
81
82	return 0;
83
84 out_free:
85	if (to_mm->id.stack != 0)
86		free_page(to_mm->id.stack);
87 out:
88	return ret;
89}
90
91void uml_setup_stubs(struct mm_struct *mm)
92{
93	int err, ret;
94
95	ret = init_stub_pte(mm, STUB_CODE,
96			    (unsigned long) &__syscall_stub_start);
97	if (ret)
98		goto out;
99
100	ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
101	if (ret)
102		goto out;
103
104	mm->context.stub_pages[0] = virt_to_page(&__syscall_stub_start);
105	mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
106
107	/* dup_mmap already holds mmap_sem */
108	err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
109				      VM_READ | VM_MAYREAD | VM_EXEC |
110				      VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
111				      mm->context.stub_pages);
112	if (err) {
113		printk(KERN_ERR "install_special_mapping returned %d\n", err);
114		goto out;
115	}
116	return;
117
118out:
119	force_sigsegv(SIGSEGV, current);
120}
121
122void arch_exit_mmap(struct mm_struct *mm)
123{
124	pte_t *pte;
125
126	pte = virt_to_pte(mm, STUB_CODE);
127	if (pte != NULL)
128		pte_clear(mm, STUB_CODE, pte);
129
130	pte = virt_to_pte(mm, STUB_DATA);
131	if (pte == NULL)
132		return;
133
134	pte_clear(mm, STUB_DATA, pte);
135}
136
137void destroy_context(struct mm_struct *mm)
138{
139	struct mm_context *mmu = &mm->context;
140
141	/*
142	 * If init_new_context wasn't called, this will be
143	 * zero, resulting in a kill(0), which will result in the
144	 * whole UML suddenly dying.  Also, cover negative and
145	 * 1 cases, since they shouldn't happen either.
146	 */
147	if (mmu->id.u.pid < 2) {
148		printk(KERN_ERR "corrupt mm_context - pid = %d\n",
149		       mmu->id.u.pid);
150		return;
151	}
152	os_kill_ptraced_process(mmu->id.u.pid, 1);
153
154	free_page(mmu->id.stack);
155	free_ldt(mmu);
156}
157