f19ca6152460c61a927794359d6ed7e131e531a0
[linux-3.10.git] / arch / um / kernel / process.c
1 /*
2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3  * Copyright 2003 PathScale, Inc.
4  * Licensed under the GPL
5  */
6
7 #include <linux/stddef.h>
8 #include <linux/err.h>
9 #include <linux/hardirq.h>
10 #include <linux/mm.h>
11 #include <linux/module.h>
12 #include <linux/personality.h>
13 #include <linux/proc_fs.h>
14 #include <linux/ptrace.h>
15 #include <linux/random.h>
16 #include <linux/slab.h>
17 #include <linux/sched.h>
18 #include <linux/seq_file.h>
19 #include <linux/tick.h>
20 #include <linux/threads.h>
21 #include <linux/tracehook.h>
22 #include <asm/current.h>
23 #include <asm/pgtable.h>
24 #include <asm/mmu_context.h>
25 #include <asm/uaccess.h>
26 #include "as-layout.h"
27 #include "kern_util.h"
28 #include "os.h"
29 #include "skas.h"
30
31 /*
32  * This is a per-cpu array.  A processor only modifies its entry and it only
33  * cares about its entry, so it's OK if another processor is modifying its
34  * entry.
35  */
36 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
37
38 static inline int external_pid(void)
39 {
40         /* FIXME: Need to look up userspace_pid by cpu */
41         return userspace_pid[0];
42 }
43
44 int pid_to_processor_id(int pid)
45 {
46         int i;
47
48         for (i = 0; i < ncpus; i++) {
49                 if (cpu_tasks[i].pid == pid)
50                         return i;
51         }
52         return -1;
53 }
54
55 void free_stack(unsigned long stack, int order)
56 {
57         free_pages(stack, order);
58 }
59
60 unsigned long alloc_stack(int order, int atomic)
61 {
62         unsigned long page;
63         gfp_t flags = GFP_KERNEL;
64
65         if (atomic)
66                 flags = GFP_ATOMIC;
67         page = __get_free_pages(flags, order);
68
69         return page;
70 }
71
72 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
73 {
74         int pid;
75
76         current->thread.request.u.thread.proc = fn;
77         current->thread.request.u.thread.arg = arg;
78         pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
79                       &current->thread.regs, 0, NULL, NULL);
80         return pid;
81 }
82 EXPORT_SYMBOL(kernel_thread);
83
84 static inline void set_current(struct task_struct *task)
85 {
86         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
87                 { external_pid(), task });
88 }
89
90 extern void arch_switch_to(struct task_struct *to);
91
92 void *__switch_to(struct task_struct *from, struct task_struct *to)
93 {
94         to->thread.prev_sched = from;
95         set_current(to);
96
97         do {
98                 current->thread.saved_task = NULL;
99
100                 switch_threads(&from->thread.switch_buf,
101                                &to->thread.switch_buf);
102
103                 arch_switch_to(current);
104
105                 if (current->thread.saved_task)
106                         show_regs(&(current->thread.regs));
107                 to = current->thread.saved_task;
108                 from = current;
109         } while (current->thread.saved_task);
110
111         return current->thread.prev_sched;
112 }
113
114 void interrupt_end(void)
115 {
116         if (need_resched())
117                 schedule();
118         if (test_thread_flag(TIF_SIGPENDING))
119                 do_signal();
120         if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
121                 tracehook_notify_resume(&current->thread.regs);
122 }
123
124 void exit_thread(void)
125 {
126 }
127
128 int get_current_pid(void)
129 {
130         return task_pid_nr(current);
131 }
132
133 /*
134  * This is called magically, by its address being stuffed in a jmp_buf
135  * and being longjmp-d to.
136  */
137 void new_thread_handler(void)
138 {
139         int (*fn)(void *), n;
140         void *arg;
141
142         if (current->thread.prev_sched != NULL)
143                 schedule_tail(current->thread.prev_sched);
144         current->thread.prev_sched = NULL;
145
146         fn = current->thread.request.u.thread.proc;
147         arg = current->thread.request.u.thread.arg;
148
149         /*
150          * The return value is 1 if the kernel thread execs a process,
151          * 0 if it just exits
152          */
153         n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
154         if (n == 1) {
155                 /* Handle any immediate reschedules or signals */
156                 interrupt_end();
157                 userspace(&current->thread.regs.regs);
158         }
159         else do_exit(0);
160 }
161
162 /* Called magically, see new_thread_handler above */
163 void fork_handler(void)
164 {
165         force_flush_all();
166
167         schedule_tail(current->thread.prev_sched);
168
169         /*
170          * XXX: if interrupt_end() calls schedule, this call to
171          * arch_switch_to isn't needed. We could want to apply this to
172          * improve performance. -bb
173          */
174         arch_switch_to(current);
175
176         current->thread.prev_sched = NULL;
177
178         /* Handle any immediate reschedules or signals */
179         interrupt_end();
180
181         userspace(&current->thread.regs.regs);
182 }
183
184 int copy_thread(unsigned long clone_flags, unsigned long sp,
185                 unsigned long stack_top, struct task_struct * p,
186                 struct pt_regs *regs)
187 {
188         void (*handler)(void);
189         int ret = 0;
190
191         p->thread = (struct thread_struct) INIT_THREAD;
192
193         if (current->thread.forking) {
194                 memcpy(&p->thread.regs.regs, &regs->regs,
195                        sizeof(p->thread.regs.regs));
196                 PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
197                 if (sp != 0)
198                         REGS_SP(p->thread.regs.regs.gp) = sp;
199
200                 handler = fork_handler;
201
202                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
203         }
204         else {
205                 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
206                 p->thread.request.u.thread = current->thread.request.u.thread;
207                 handler = new_thread_handler;
208         }
209
210         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
211
212         if (current->thread.forking) {
213                 clear_flushed_tls(p);
214
215                 /*
216                  * Set a new TLS for the child thread?
217                  */
218                 if (clone_flags & CLONE_SETTLS)
219                         ret = arch_copy_tls(p);
220         }
221
222         return ret;
223 }
224
225 void initial_thread_cb(void (*proc)(void *), void *arg)
226 {
227         int save_kmalloc_ok = kmalloc_ok;
228
229         kmalloc_ok = 0;
230         initial_thread_cb_skas(proc, arg);
231         kmalloc_ok = save_kmalloc_ok;
232 }
233
234 void default_idle(void)
235 {
236         unsigned long long nsecs;
237
238         while (1) {
239                 /* endless idle loop with no priority at all */
240
241                 /*
242                  * although we are an idle CPU, we do not want to
243                  * get into the scheduler unnecessarily.
244                  */
245                 if (need_resched())
246                         schedule();
247
248                 tick_nohz_idle_enter();
249                 rcu_idle_enter();
250                 nsecs = disable_timer();
251                 idle_sleep(nsecs);
252                 rcu_idle_exit();
253                 tick_nohz_idle_exit();
254         }
255 }
256
257 void cpu_idle(void)
258 {
259         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
260         default_idle();
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_info();
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(const char *string)
288 {
289         return kstrdup(string, GFP_KERNEL);
290 }
291 EXPORT_SYMBOL(uml_strdup);
292
293 int copy_to_user_proc(void __user *to, void *from, int size)
294 {
295         return copy_to_user(to, from, size);
296 }
297
298 int copy_from_user_proc(void *to, void __user *from, int size)
299 {
300         return copy_from_user(to, from, size);
301 }
302
303 int clear_user_proc(void __user *buf, int size)
304 {
305         return clear_user(buf, size);
306 }
307
308 int strlen_user_proc(char __user *str)
309 {
310         return strlen_user(str);
311 }
312
313 int smp_sigio_handler(void)
314 {
315 #ifdef CONFIG_SMP
316         int cpu = current_thread_info()->cpu;
317         IPI_handler(cpu);
318         if (cpu != 0)
319                 return 1;
320 #endif
321         return 0;
322 }
323
324 int cpu(void)
325 {
326         return current_thread_info()->cpu;
327 }
328
329 static atomic_t using_sysemu = ATOMIC_INIT(0);
330 int sysemu_supported;
331
332 void set_using_sysemu(int value)
333 {
334         if (value > sysemu_supported)
335                 return;
336         atomic_set(&using_sysemu, value);
337 }
338
339 int get_using_sysemu(void)
340 {
341         return atomic_read(&using_sysemu);
342 }
343
344 static int sysemu_proc_show(struct seq_file *m, void *v)
345 {
346         seq_printf(m, "%d\n", get_using_sysemu());
347         return 0;
348 }
349
350 static int sysemu_proc_open(struct inode *inode, struct file *file)
351 {
352         return single_open(file, sysemu_proc_show, NULL);
353 }
354
355 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
356                                  size_t count, loff_t *pos)
357 {
358         char tmp[2];
359
360         if (copy_from_user(tmp, buf, 1))
361                 return -EFAULT;
362
363         if (tmp[0] >= '0' && tmp[0] <= '2')
364                 set_using_sysemu(tmp[0] - '0');
365         /* We use the first char, but pretend to write everything */
366         return count;
367 }
368
369 static const struct file_operations sysemu_proc_fops = {
370         .owner          = THIS_MODULE,
371         .open           = sysemu_proc_open,
372         .read           = seq_read,
373         .llseek         = seq_lseek,
374         .release        = single_release,
375         .write          = sysemu_proc_write,
376 };
377
378 int __init make_proc_sysemu(void)
379 {
380         struct proc_dir_entry *ent;
381         if (!sysemu_supported)
382                 return 0;
383
384         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
385
386         if (ent == NULL)
387         {
388                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
389                 return 0;
390         }
391
392         return 0;
393 }
394
395 late_initcall(make_proc_sysemu);
396
397 int singlestepping(void * t)
398 {
399         struct task_struct *task = t ? t : current;
400
401         if (!(task->ptrace & PT_DTRACE))
402                 return 0;
403
404         if (task->thread.singlestep_syscall)
405                 return 1;
406
407         return 2;
408 }
409
410 /*
411  * Only x86 and x86_64 have an arch_align_stack().
412  * All other arches have "#define arch_align_stack(x) (x)"
413  * in their asm/system.h
414  * As this is included in UML from asm-um/system-generic.h,
415  * we can use it to behave as the subarch does.
416  */
417 #ifndef arch_align_stack
418 unsigned long arch_align_stack(unsigned long sp)
419 {
420         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
421                 sp -= get_random_int() % 8192;
422         return sp & ~0xf;
423 }
424 #endif
425
426 unsigned long get_wchan(struct task_struct *p)
427 {
428         unsigned long stack_page, sp, ip;
429         bool seen_sched = 0;
430
431         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
432                 return 0;
433
434         stack_page = (unsigned long) task_stack_page(p);
435         /* Bail if the process has no kernel stack for some reason */
436         if (stack_page == 0)
437                 return 0;
438
439         sp = p->thread.switch_buf->JB_SP;
440         /*
441          * Bail if the stack pointer is below the bottom of the kernel
442          * stack for some reason
443          */
444         if (sp < stack_page)
445                 return 0;
446
447         while (sp < stack_page + THREAD_SIZE) {
448                 ip = *((unsigned long *) sp);
449                 if (in_sched_functions(ip))
450                         /* Ignore everything until we're above the scheduler */
451                         seen_sched = 1;
452                 else if (kernel_text_address(ip) && seen_sched)
453                         return ip;
454
455                 sp += sizeof(unsigned long);
456         }
457
458         return 0;
459 }
460
461 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
462 {
463         int cpu = current_thread_info()->cpu;
464
465         return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
466 }
467