uml: stop specially protecting kernel stacks
[linux-2.6.git] / arch / um / kernel / process.c
1 /*
2  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
3  * Copyright 2003 PathScale, Inc.
4  * Licensed under the GPL
5  */
6
7 #include "linux/kernel.h"
8 #include "linux/sched.h"
9 #include "linux/interrupt.h"
10 #include "linux/string.h"
11 #include "linux/mm.h"
12 #include "linux/slab.h"
13 #include "linux/utsname.h"
14 #include "linux/fs.h"
15 #include "linux/utime.h"
16 #include "linux/smp_lock.h"
17 #include "linux/module.h"
18 #include "linux/init.h"
19 #include "linux/capability.h"
20 #include "linux/vmalloc.h"
21 #include "linux/spinlock.h"
22 #include "linux/proc_fs.h"
23 #include "linux/ptrace.h"
24 #include "linux/random.h"
25 #include "linux/personality.h"
26 #include "asm/unistd.h"
27 #include "asm/mman.h"
28 #include "asm/segment.h"
29 #include "asm/stat.h"
30 #include "asm/pgtable.h"
31 #include "asm/processor.h"
32 #include "asm/tlbflush.h"
33 #include "asm/uaccess.h"
34 #include "asm/user.h"
35 #include "kern_util.h"
36 #include "as-layout.h"
37 #include "kern.h"
38 #include "signal_kern.h"
39 #include "init.h"
40 #include "irq_user.h"
41 #include "mem_user.h"
42 #include "tlb.h"
43 #include "frame_kern.h"
44 #include "sigcontext.h"
45 #include "os.h"
46 #include "mode.h"
47 #include "mode_kern.h"
48 #include "choose-mode.h"
49
50 /* This is a per-cpu array.  A processor only modifies its entry and it only
51  * cares about its entry, so it's OK if another processor is modifying its
52  * entry.
53  */
54 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
55
56 static inline int external_pid(struct task_struct *task)
57 {
58         return CHOOSE_MODE_PROC(external_pid_tt, external_pid_skas, task);
59 }
60
61 int pid_to_processor_id(int pid)
62 {
63         int i;
64
65         for(i = 0; i < ncpus; i++){
66                 if(cpu_tasks[i].pid == pid)
67                         return i;
68         }
69         return -1;
70 }
71
72 void free_stack(unsigned long stack, int order)
73 {
74         free_pages(stack, order);
75 }
76
77 unsigned long alloc_stack(int order, int atomic)
78 {
79         unsigned long page;
80         gfp_t flags = GFP_KERNEL;
81
82         if (atomic)
83                 flags = GFP_ATOMIC;
84         page = __get_free_pages(flags, order);
85         if (page == 0)
86                 return 0;
87
88         return page;
89 }
90
91 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
92 {
93         int pid;
94
95         current->thread.request.u.thread.proc = fn;
96         current->thread.request.u.thread.arg = arg;
97         pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
98                       &current->thread.regs, 0, NULL, NULL);
99         return pid;
100 }
101
102 static inline void set_current(struct task_struct *task)
103 {
104         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
105                 { external_pid(task), task });
106 }
107
108 void *_switch_to(void *prev, void *next, void *last)
109 {
110         struct task_struct *from = prev;
111         struct task_struct *to= next;
112
113         to->thread.prev_sched = from;
114         set_current(to);
115
116         do {
117                 current->thread.saved_task = NULL ;
118                 CHOOSE_MODE_PROC(switch_to_tt, switch_to_skas, prev, next);
119                 if(current->thread.saved_task)
120                         show_regs(&(current->thread.regs));
121                 next= current->thread.saved_task;
122                 prev= current;
123         } while(current->thread.saved_task);
124
125         return current->thread.prev_sched;
126
127 }
128
129 void interrupt_end(void)
130 {
131         if(need_resched())
132                 schedule();
133         if(test_tsk_thread_flag(current, TIF_SIGPENDING))
134                 do_signal();
135 }
136
137 void release_thread(struct task_struct *task)
138 {
139         CHOOSE_MODE(release_thread_tt(task), release_thread_skas(task));
140 }
141
142 void exit_thread(void)
143 {
144 }
145
146 void *get_current(void)
147 {
148         return current;
149 }
150
151 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
152                 unsigned long stack_top, struct task_struct * p,
153                 struct pt_regs *regs)
154 {
155         int ret;
156
157         p->thread = (struct thread_struct) INIT_THREAD;
158         ret = CHOOSE_MODE_PROC(copy_thread_tt, copy_thread_skas, nr,
159                                 clone_flags, sp, stack_top, p, regs);
160
161         if (ret || !current->thread.forking)
162                 goto out;
163
164         clear_flushed_tls(p);
165
166         /*
167          * Set a new TLS for the child thread?
168          */
169         if (clone_flags & CLONE_SETTLS)
170                 ret = arch_copy_tls(p);
171
172 out:
173         return ret;
174 }
175
176 void initial_thread_cb(void (*proc)(void *), void *arg)
177 {
178         int save_kmalloc_ok = kmalloc_ok;
179
180         kmalloc_ok = 0;
181         CHOOSE_MODE_PROC(initial_thread_cb_tt, initial_thread_cb_skas, proc,
182                          arg);
183         kmalloc_ok = save_kmalloc_ok;
184 }
185
186 #ifdef CONFIG_MODE_TT
187 unsigned long stack_sp(unsigned long page)
188 {
189         return page + PAGE_SIZE - sizeof(void *);
190 }
191 #endif
192
193 void default_idle(void)
194 {
195         CHOOSE_MODE(uml_idle_timer(), (void) 0);
196
197         while(1){
198                 /* endless idle loop with no priority at all */
199
200                 /*
201                  * although we are an idle CPU, we do not want to
202                  * get into the scheduler unnecessarily.
203                  */
204                 if(need_resched())
205                         schedule();
206
207                 idle_sleep(10);
208         }
209 }
210
211 void cpu_idle(void)
212 {
213         CHOOSE_MODE(init_idle_tt(), init_idle_skas());
214 }
215
216 void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
217                       pte_t *pte_out)
218 {
219         pgd_t *pgd;
220         pud_t *pud;
221         pmd_t *pmd;
222         pte_t *pte;
223         pte_t ptent;
224
225         if(task->mm == NULL)
226                 return ERR_PTR(-EINVAL);
227         pgd = pgd_offset(task->mm, addr);
228         if(!pgd_present(*pgd))
229                 return ERR_PTR(-EINVAL);
230
231         pud = pud_offset(pgd, addr);
232         if(!pud_present(*pud))
233                 return ERR_PTR(-EINVAL);
234
235         pmd = pmd_offset(pud, addr);
236         if(!pmd_present(*pmd))
237                 return ERR_PTR(-EINVAL);
238
239         pte = pte_offset_kernel(pmd, addr);
240         ptent = *pte;
241         if(!pte_present(ptent))
242                 return ERR_PTR(-EINVAL);
243
244         if(pte_out != NULL)
245                 *pte_out = ptent;
246         return (void *) (pte_val(ptent) & PAGE_MASK) + (addr & ~PAGE_MASK);
247 }
248
249 char *current_cmd(void)
250 {
251 #if defined(CONFIG_SMP) || defined(CONFIG_HIGHMEM)
252         return "(Unknown)";
253 #else
254         void *addr = um_virt_to_phys(current, current->mm->arg_start, NULL);
255         return IS_ERR(addr) ? "(Unknown)": __va((unsigned long) addr);
256 #endif
257 }
258
259 void dump_thread(struct pt_regs *regs, struct user *u)
260 {
261 }
262
263 int __cant_sleep(void) {
264         return in_atomic() || irqs_disabled() || in_interrupt();
265         /* Is in_interrupt() really needed? */
266 }
267
268 int user_context(unsigned long sp)
269 {
270         unsigned long stack;
271
272         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
273         return stack != (unsigned long) current_thread;
274 }
275
276 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
277
278 void do_uml_exitcalls(void)
279 {
280         exitcall_t *call;
281
282         call = &__uml_exitcall_end;
283         while (--call >= &__uml_exitcall_begin)
284                 (*call)();
285 }
286
287 char *uml_strdup(char *string)
288 {
289         return kstrdup(string, GFP_KERNEL);
290 }
291
292 int copy_to_user_proc(void __user *to, void *from, int size)
293 {
294         return copy_to_user(to, from, size);
295 }
296
297 int copy_from_user_proc(void *to, void __user *from, int size)
298 {
299         return copy_from_user(to, from, size);
300 }
301
302 int clear_user_proc(void __user *buf, int size)
303 {
304         return clear_user(buf, size);
305 }
306
307 int strlen_user_proc(char __user *str)
308 {
309         return strlen_user(str);
310 }
311
312 int smp_sigio_handler(void)
313 {
314 #ifdef CONFIG_SMP
315         int cpu = current_thread->cpu;
316         IPI_handler(cpu);
317         if(cpu != 0)
318                 return 1;
319 #endif
320         return 0;
321 }
322
323 int cpu(void)
324 {
325         return current_thread->cpu;
326 }
327
328 static atomic_t using_sysemu = ATOMIC_INIT(0);
329 int sysemu_supported;
330
331 void set_using_sysemu(int value)
332 {
333         if (value > sysemu_supported)
334                 return;
335         atomic_set(&using_sysemu, value);
336 }
337
338 int get_using_sysemu(void)
339 {
340         return atomic_read(&using_sysemu);
341 }
342
343 static int proc_read_sysemu(char *buf, char **start, off_t offset, int size,int *eof, void *data)
344 {
345         if (snprintf(buf, size, "%d\n", get_using_sysemu()) < size) /*No overflow*/
346                 *eof = 1;
347
348         return strlen(buf);
349 }
350
351 static int proc_write_sysemu(struct file *file,const char __user *buf, unsigned long count,void *data)
352 {
353         char tmp[2];
354
355         if (copy_from_user(tmp, buf, 1))
356                 return -EFAULT;
357
358         if (tmp[0] >= '0' && tmp[0] <= '2')
359                 set_using_sysemu(tmp[0] - '0');
360         return count; /*We use the first char, but pretend to write everything*/
361 }
362
363 int __init make_proc_sysemu(void)
364 {
365         struct proc_dir_entry *ent;
366         if (!sysemu_supported)
367                 return 0;
368
369         ent = create_proc_entry("sysemu", 0600, &proc_root);
370
371         if (ent == NULL)
372         {
373                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
374                 return 0;
375         }
376
377         ent->read_proc  = proc_read_sysemu;
378         ent->write_proc = proc_write_sysemu;
379
380         return 0;
381 }
382
383 late_initcall(make_proc_sysemu);
384
385 int singlestepping(void * t)
386 {
387         struct task_struct *task = t ? t : current;
388
389         if ( ! (task->ptrace & PT_DTRACE) )
390                 return(0);
391
392         if (task->thread.singlestep_syscall)
393                 return(1);
394
395         return 2;
396 }
397
398 /*
399  * Only x86 and x86_64 have an arch_align_stack().
400  * All other arches have "#define arch_align_stack(x) (x)"
401  * in their asm/system.h
402  * As this is included in UML from asm-um/system-generic.h,
403  * we can use it to behave as the subarch does.
404  */
405 #ifndef arch_align_stack
406 unsigned long arch_align_stack(unsigned long sp)
407 {
408         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
409                 sp -= get_random_int() % 8192;
410         return sp & ~0xf;
411 }
412 #endif