2 * Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
3 * Licensed under the GPL
6 #include "linux/config.h"
7 #include "linux/kernel.h"
8 #include "linux/sched.h"
9 #include "linux/slab.h"
10 #include "linux/types.h"
11 #include "asm/uaccess.h"
12 #include "asm/ptrace.h"
13 #include "asm/segment.h"
16 #include "choose-mode.h"
18 #include "kern_util.h"
19 #include "mode_kern.h"
23 #ifdef CONFIG_MODE_SKAS
27 #ifdef CONFIG_MODE_SKAS
28 int do_set_thread_area_skas(struct user_desc *info)
34 ret = os_set_thread_area(info, userspace_pid[cpu]);
39 int do_get_thread_area_skas(struct user_desc *info)
45 ret = os_get_thread_area(info, userspace_pid[cpu]);
52 * sys_get_thread_area: get a yet unused TLS descriptor index.
53 * XXX: Consider leaving one free slot for glibc usage at first place. This must
54 * be done here (and by changing GDT_ENTRY_TLS_* macros) and nowhere else.
56 * Also, this must be tested when compiling in SKAS mode with dinamic linking
57 * and running against NPTL.
59 static int get_free_idx(struct task_struct* task)
61 struct thread_struct *t = &task->thread;
64 if (!t->arch.tls_array)
65 return GDT_ENTRY_TLS_MIN;
67 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
68 if (!t->arch.tls_array[idx].present)
69 return idx + GDT_ENTRY_TLS_MIN;
73 static inline void clear_user_desc(struct user_desc* info)
75 /* Postcondition: LDT_empty(info) returns true. */
76 memset(info, 0, sizeof(*info));
78 /* Check the LDT_empty or the i386 sys_get_thread_area code - we obtain
79 * indeed an empty user_desc.
81 info->read_exec_only = 1;
82 info->seg_not_present = 1;
87 static int load_TLS(int flags, struct task_struct *to)
92 for (idx = GDT_ENTRY_TLS_MIN; idx < GDT_ENTRY_TLS_MAX; idx++) {
93 struct uml_tls_struct* curr = &to->thread.arch.tls_array[idx - GDT_ENTRY_TLS_MIN];
95 /* Actually, now if it wasn't flushed it gets cleared and
96 * flushed to the host, which will clear it.*/
99 clear_user_desc(&curr->tls);
100 curr->tls.entry_number = idx;
102 WARN_ON(!LDT_empty(&curr->tls));
107 if (!(flags & O_FORCE) && curr->flushed)
110 ret = do_set_thread_area(&curr->tls);
120 /* Verify if we need to do a flush for the new process, i.e. if there are any
121 * present desc's, only if they haven't been flushed.
123 static inline int needs_TLS_update(struct task_struct *task)
128 for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
129 struct uml_tls_struct* curr = &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
131 /* Can't test curr->present, we may need to clear a descriptor
132 * which had a value. */
141 /* On a newly forked process, the TLS descriptors haven't yet been flushed. So
142 * we mark them as such and the first switch_to will do the job.
144 void clear_flushed_tls(struct task_struct *task)
148 for (i = GDT_ENTRY_TLS_MIN; i < GDT_ENTRY_TLS_MAX; i++) {
149 struct uml_tls_struct* curr = &task->thread.arch.tls_array[i - GDT_ENTRY_TLS_MIN];
151 /* Still correct to do this, if it wasn't present on the host it
152 * will remain as flushed as it was. */
160 /* This in SKAS0 does not need to be used, since we have different host
161 * processes. Nor will this need to be used when we'll add support to the host
163 int arch_switch_tls_skas(struct task_struct *from, struct task_struct *to)
165 /* We have no need whatsoever to switch TLS for kernel threads; beyond
166 * that, that would also result in us calling os_set_thread_area with
167 * userspace_pid[cpu] == 0, which gives an error. */
169 return load_TLS(O_FORCE, to);
174 int arch_switch_tls_tt(struct task_struct *from, struct task_struct *to)
176 if (needs_TLS_update(to))
177 return load_TLS(0, to);
182 static int set_tls_entry(struct task_struct* task, struct user_desc *info,
183 int idx, int flushed)
185 struct thread_struct *t = &task->thread;
187 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
190 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls = *info;
191 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present = 1;
192 t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed = flushed;
197 int arch_copy_tls(struct task_struct *new)
199 struct user_desc info;
200 int idx, ret = -EFAULT;
202 if (copy_from_user(&info,
203 (void __user *) UPT_ESI(&new->thread.regs.regs),
208 if (LDT_empty(&info))
211 idx = info.entry_number;
213 ret = set_tls_entry(new, &info, idx, 0);
218 /* XXX: use do_get_thread_area to read the host value? I'm not at all sure! */
219 static int get_tls_entry(struct task_struct* task, struct user_desc *info, int idx)
221 struct thread_struct *t = &task->thread;
223 if (!t->arch.tls_array)
226 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
229 if (!t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].present)
232 *info = t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].tls;
235 /* Temporary debugging check, to make sure that things have been
236 * flushed. This could be triggered if load_TLS() failed.
238 if (unlikely(task == current && !t->arch.tls_array[idx - GDT_ENTRY_TLS_MIN].flushed)) {
239 printk(KERN_ERR "get_tls_entry: task with pid %d got here "
240 "without flushed TLS.", current->pid);
245 /* When the TLS entry has not been set, the values read to user in the
246 * tls_array are 0 (because it's cleared at boot, see
247 * arch/i386/kernel/head.S:cpu_gdt_table). Emulate that.
249 clear_user_desc(info);
250 info->entry_number = idx;
254 asmlinkage int sys_set_thread_area(struct user_desc __user *user_desc)
256 struct user_desc info;
259 if (copy_from_user(&info, user_desc, sizeof(info)))
262 idx = info.entry_number;
265 idx = get_free_idx(current);
268 info.entry_number = idx;
269 /* Tell the user which slot we chose for him.*/
270 if (put_user(idx, &user_desc->entry_number))
274 ret = CHOOSE_MODE_PROC(do_set_thread_area_tt, do_set_thread_area_skas, &info);
277 return set_tls_entry(current, &info, idx, 1);
281 * Perform set_thread_area on behalf of the traced child.
282 * Note: error handling is not done on the deferred load, and this differ from
283 * i386. However the only possible error are caused by bugs.
285 int ptrace_set_thread_area(struct task_struct *child, int idx,
286 struct user_desc __user *user_desc)
288 struct user_desc info;
290 if (copy_from_user(&info, user_desc, sizeof(info)))
293 return set_tls_entry(child, &info, idx, 0);
296 asmlinkage int sys_get_thread_area(struct user_desc __user *user_desc)
298 struct user_desc info;
301 if (get_user(idx, &user_desc->entry_number))
304 ret = get_tls_entry(current, &info, idx);
308 if (copy_to_user(user_desc, &info, sizeof(info)))
316 * Perform get_thread_area on behalf of the traced child.
318 int ptrace_get_thread_area(struct task_struct *child, int idx,
319 struct user_desc __user *user_desc)
321 struct user_desc info;
324 ret = get_tls_entry(child, &info, idx);
328 if (copy_to_user(user_desc, &info, sizeof(info)))