um: pull interrupt_end() into userspace()
[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                 userspace(&current->thread.regs.regs);
156         else
157                 do_exit(0);
158 }
159
160 /* Called magically, see new_thread_handler above */
161 void fork_handler(void)
162 {
163         force_flush_all();
164
165         schedule_tail(current->thread.prev_sched);
166
167         /*
168          * XXX: if interrupt_end() calls schedule, this call to
169          * arch_switch_to isn't needed. We could want to apply this to
170          * improve performance. -bb
171          */
172         arch_switch_to(current);
173
174         current->thread.prev_sched = NULL;
175
176         userspace(&current->thread.regs.regs);
177 }
178
179 int copy_thread(unsigned long clone_flags, unsigned long sp,
180                 unsigned long stack_top, struct task_struct * p,
181                 struct pt_regs *regs)
182 {
183         void (*handler)(void);
184         int ret = 0;
185
186         p->thread = (struct thread_struct) INIT_THREAD;
187
188         if (current->thread.forking) {
189                 memcpy(&p->thread.regs.regs, &regs->regs,
190                        sizeof(p->thread.regs.regs));
191                 PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
192                 if (sp != 0)
193                         REGS_SP(p->thread.regs.regs.gp) = sp;
194
195                 handler = fork_handler;
196
197                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
198         }
199         else {
200                 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
201                 p->thread.request.u.thread = current->thread.request.u.thread;
202                 handler = new_thread_handler;
203         }
204
205         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
206
207         if (current->thread.forking) {
208                 clear_flushed_tls(p);
209
210                 /*
211                  * Set a new TLS for the child thread?
212                  */
213                 if (clone_flags & CLONE_SETTLS)
214                         ret = arch_copy_tls(p);
215         }
216
217         return ret;
218 }
219
220 void initial_thread_cb(void (*proc)(void *), void *arg)
221 {
222         int save_kmalloc_ok = kmalloc_ok;
223
224         kmalloc_ok = 0;
225         initial_thread_cb_skas(proc, arg);
226         kmalloc_ok = save_kmalloc_ok;
227 }
228
229 void default_idle(void)
230 {
231         unsigned long long nsecs;
232
233         while (1) {
234                 /* endless idle loop with no priority at all */
235
236                 /*
237                  * although we are an idle CPU, we do not want to
238                  * get into the scheduler unnecessarily.
239                  */
240                 if (need_resched())
241                         schedule();
242
243                 tick_nohz_idle_enter();
244                 rcu_idle_enter();
245                 nsecs = disable_timer();
246                 idle_sleep(nsecs);
247                 rcu_idle_exit();
248                 tick_nohz_idle_exit();
249         }
250 }
251
252 void cpu_idle(void)
253 {
254         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
255         default_idle();
256 }
257
258 int __cant_sleep(void) {
259         return in_atomic() || irqs_disabled() || in_interrupt();
260         /* Is in_interrupt() really needed? */
261 }
262
263 int user_context(unsigned long sp)
264 {
265         unsigned long stack;
266
267         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
268         return stack != (unsigned long) current_thread_info();
269 }
270
271 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
272
273 void do_uml_exitcalls(void)
274 {
275         exitcall_t *call;
276
277         call = &__uml_exitcall_end;
278         while (--call >= &__uml_exitcall_begin)
279                 (*call)();
280 }
281
282 char *uml_strdup(const char *string)
283 {
284         return kstrdup(string, GFP_KERNEL);
285 }
286 EXPORT_SYMBOL(uml_strdup);
287
288 int copy_to_user_proc(void __user *to, void *from, int size)
289 {
290         return copy_to_user(to, from, size);
291 }
292
293 int copy_from_user_proc(void *to, void __user *from, int size)
294 {
295         return copy_from_user(to, from, size);
296 }
297
298 int clear_user_proc(void __user *buf, int size)
299 {
300         return clear_user(buf, size);
301 }
302
303 int strlen_user_proc(char __user *str)
304 {
305         return strlen_user(str);
306 }
307
308 int smp_sigio_handler(void)
309 {
310 #ifdef CONFIG_SMP
311         int cpu = current_thread_info()->cpu;
312         IPI_handler(cpu);
313         if (cpu != 0)
314                 return 1;
315 #endif
316         return 0;
317 }
318
319 int cpu(void)
320 {
321         return current_thread_info()->cpu;
322 }
323
324 static atomic_t using_sysemu = ATOMIC_INIT(0);
325 int sysemu_supported;
326
327 void set_using_sysemu(int value)
328 {
329         if (value > sysemu_supported)
330                 return;
331         atomic_set(&using_sysemu, value);
332 }
333
334 int get_using_sysemu(void)
335 {
336         return atomic_read(&using_sysemu);
337 }
338
339 static int sysemu_proc_show(struct seq_file *m, void *v)
340 {
341         seq_printf(m, "%d\n", get_using_sysemu());
342         return 0;
343 }
344
345 static int sysemu_proc_open(struct inode *inode, struct file *file)
346 {
347         return single_open(file, sysemu_proc_show, NULL);
348 }
349
350 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
351                                  size_t count, loff_t *pos)
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         /* We use the first char, but pretend to write everything */
361         return count;
362 }
363
364 static const struct file_operations sysemu_proc_fops = {
365         .owner          = THIS_MODULE,
366         .open           = sysemu_proc_open,
367         .read           = seq_read,
368         .llseek         = seq_lseek,
369         .release        = single_release,
370         .write          = sysemu_proc_write,
371 };
372
373 int __init make_proc_sysemu(void)
374 {
375         struct proc_dir_entry *ent;
376         if (!sysemu_supported)
377                 return 0;
378
379         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
380
381         if (ent == NULL)
382         {
383                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
384                 return 0;
385         }
386
387         return 0;
388 }
389
390 late_initcall(make_proc_sysemu);
391
392 int singlestepping(void * t)
393 {
394         struct task_struct *task = t ? t : current;
395
396         if (!(task->ptrace & PT_DTRACE))
397                 return 0;
398
399         if (task->thread.singlestep_syscall)
400                 return 1;
401
402         return 2;
403 }
404
405 /*
406  * Only x86 and x86_64 have an arch_align_stack().
407  * All other arches have "#define arch_align_stack(x) (x)"
408  * in their asm/system.h
409  * As this is included in UML from asm-um/system-generic.h,
410  * we can use it to behave as the subarch does.
411  */
412 #ifndef arch_align_stack
413 unsigned long arch_align_stack(unsigned long sp)
414 {
415         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
416                 sp -= get_random_int() % 8192;
417         return sp & ~0xf;
418 }
419 #endif
420
421 unsigned long get_wchan(struct task_struct *p)
422 {
423         unsigned long stack_page, sp, ip;
424         bool seen_sched = 0;
425
426         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
427                 return 0;
428
429         stack_page = (unsigned long) task_stack_page(p);
430         /* Bail if the process has no kernel stack for some reason */
431         if (stack_page == 0)
432                 return 0;
433
434         sp = p->thread.switch_buf->JB_SP;
435         /*
436          * Bail if the stack pointer is below the bottom of the kernel
437          * stack for some reason
438          */
439         if (sp < stack_page)
440                 return 0;
441
442         while (sp < stack_page + THREAD_SIZE) {
443                 ip = *((unsigned long *) sp);
444                 if (in_sched_functions(ip))
445                         /* Ignore everything until we're above the scheduler */
446                         seen_sched = 1;
447                 else if (kernel_text_address(ip) && seen_sched)
448                         return ip;
449
450                 sp += sizeof(unsigned long);
451         }
452
453         return 0;
454 }
455
456 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
457 {
458         int cpu = current_thread_info()->cpu;
459
460         return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
461 }
462