ia64/linux-2.6.18-xen.hg

view kernel/exec_domain.c @ 562:66faefe721eb

pvSCSI backend driver

Signed-off-by: Tomonari Horikoshi <t.horikoshi@jp.fujitsu.com>
Signed-off-by: Jun Kamada <kama@jp.fujitsu.com>
author Keir Fraser <keir.fraser@citrix.com>
date Mon Jun 02 09:58:27 2008 +0100 (2008-06-02)
parents 831230e53067
children
line source
1 /*
2 * Handling of different ABIs (personalities).
3 *
4 * We group personalities into execution domains which have their
5 * own handlers for kernel entry points, signal mapping, etc...
6 *
7 * 2001-05-06 Complete rewrite, Christoph Hellwig (hch@infradead.org)
8 */
10 #include <linux/init.h>
11 #include <linux/kernel.h>
12 #include <linux/kmod.h>
13 #include <linux/module.h>
14 #include <linux/personality.h>
15 #include <linux/sched.h>
16 #include <linux/syscalls.h>
17 #include <linux/sysctl.h>
18 #include <linux/types.h>
21 static void default_handler(int, struct pt_regs *);
23 static struct exec_domain *exec_domains = &default_exec_domain;
24 static DEFINE_RWLOCK(exec_domains_lock);
27 static u_long ident_map[32] = {
28 0, 1, 2, 3, 4, 5, 6, 7,
29 8, 9, 10, 11, 12, 13, 14, 15,
30 16, 17, 18, 19, 20, 21, 22, 23,
31 24, 25, 26, 27, 28, 29, 30, 31
32 };
34 struct exec_domain default_exec_domain = {
35 .name = "Linux", /* name */
36 .handler = default_handler, /* lcall7 causes a seg fault. */
37 .pers_low = 0, /* PER_LINUX personality. */
38 .pers_high = 0, /* PER_LINUX personality. */
39 .signal_map = ident_map, /* Identity map signals. */
40 .signal_invmap = ident_map, /* - both ways. */
41 };
44 static void
45 default_handler(int segment, struct pt_regs *regp)
46 {
47 set_personality(0);
49 if (current_thread_info()->exec_domain->handler != default_handler)
50 current_thread_info()->exec_domain->handler(segment, regp);
51 else
52 send_sig(SIGSEGV, current, 1);
53 }
55 static struct exec_domain *
56 lookup_exec_domain(u_long personality)
57 {
58 struct exec_domain * ep;
59 u_long pers = personality(personality);
61 read_lock(&exec_domains_lock);
62 for (ep = exec_domains; ep; ep = ep->next) {
63 if (pers >= ep->pers_low && pers <= ep->pers_high)
64 if (try_module_get(ep->module))
65 goto out;
66 }
68 #ifdef CONFIG_KMOD
69 read_unlock(&exec_domains_lock);
70 request_module("personality-%ld", pers);
71 read_lock(&exec_domains_lock);
73 for (ep = exec_domains; ep; ep = ep->next) {
74 if (pers >= ep->pers_low && pers <= ep->pers_high)
75 if (try_module_get(ep->module))
76 goto out;
77 }
78 #endif
80 ep = &default_exec_domain;
81 out:
82 read_unlock(&exec_domains_lock);
83 return (ep);
84 }
86 int
87 register_exec_domain(struct exec_domain *ep)
88 {
89 struct exec_domain *tmp;
90 int err = -EBUSY;
92 if (ep == NULL)
93 return -EINVAL;
95 if (ep->next != NULL)
96 return -EBUSY;
98 write_lock(&exec_domains_lock);
99 for (tmp = exec_domains; tmp; tmp = tmp->next) {
100 if (tmp == ep)
101 goto out;
102 }
104 ep->next = exec_domains;
105 exec_domains = ep;
106 err = 0;
108 out:
109 write_unlock(&exec_domains_lock);
110 return (err);
111 }
113 int
114 unregister_exec_domain(struct exec_domain *ep)
115 {
116 struct exec_domain **epp;
118 epp = &exec_domains;
119 write_lock(&exec_domains_lock);
120 for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
121 if (ep == *epp)
122 goto unregister;
123 }
124 write_unlock(&exec_domains_lock);
125 return -EINVAL;
127 unregister:
128 *epp = ep->next;
129 ep->next = NULL;
130 write_unlock(&exec_domains_lock);
131 return 0;
132 }
134 int
135 __set_personality(u_long personality)
136 {
137 struct exec_domain *ep, *oep;
139 ep = lookup_exec_domain(personality);
140 if (ep == current_thread_info()->exec_domain) {
141 current->personality = personality;
142 module_put(ep->module);
143 return 0;
144 }
146 if (atomic_read(&current->fs->count) != 1) {
147 struct fs_struct *fsp, *ofsp;
149 fsp = copy_fs_struct(current->fs);
150 if (fsp == NULL) {
151 module_put(ep->module);
152 return -ENOMEM;
153 }
155 task_lock(current);
156 ofsp = current->fs;
157 current->fs = fsp;
158 task_unlock(current);
160 put_fs_struct(ofsp);
161 }
163 /*
164 * At that point we are guaranteed to be the sole owner of
165 * current->fs.
166 */
168 current->personality = personality;
169 oep = current_thread_info()->exec_domain;
170 current_thread_info()->exec_domain = ep;
171 set_fs_altroot();
173 module_put(oep->module);
174 return 0;
175 }
177 int
178 get_exec_domain_list(char *page)
179 {
180 struct exec_domain *ep;
181 int len = 0;
183 read_lock(&exec_domains_lock);
184 for (ep = exec_domains; ep && len < PAGE_SIZE - 80; ep = ep->next)
185 len += sprintf(page + len, "%d-%d\t%-16s\t[%s]\n",
186 ep->pers_low, ep->pers_high, ep->name,
187 module_name(ep->module));
188 read_unlock(&exec_domains_lock);
189 return (len);
190 }
192 asmlinkage long
193 sys_personality(u_long personality)
194 {
195 u_long old = current->personality;
197 if (personality != 0xffffffff) {
198 set_personality(personality);
199 if (current->personality != personality)
200 return -EINVAL;
201 }
203 return (long)old;
204 }
207 EXPORT_SYMBOL(register_exec_domain);
208 EXPORT_SYMBOL(unregister_exec_domain);
209 EXPORT_SYMBOL(__set_personality);