uml: remove unused variables in the context switcher
[linux-2.6.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/personality.h"
12 #include "linux/proc_fs.h"
13 #include "linux/ptrace.h"
14 #include "linux/random.h"
15 #include "linux/sched.h"
16 #include "linux/tick.h"
17 #include "linux/threads.h"
18 #include "asm/pgtable.h"
19 #include "asm/uaccess.h"
20 #include "as-layout.h"
21 #include "kern_util.h"
22 #include "os.h"
23 #include "skas.h"
24 #include "tlb.h"
25
26 /*
27  * This is a per-cpu array.  A processor only modifies its entry and it only
28  * cares about its entry, so it's OK if another processor is modifying its
29  * entry.
30  */
31 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
32
33 static inline int external_pid(struct task_struct *task)
34 {
35         /* FIXME: Need to look up userspace_pid by cpu */
36         return userspace_pid[0];
37 }
38
39 int pid_to_processor_id(int pid)
40 {
41         int i;
42
43         for(i = 0; i < ncpus; i++) {
44                 if (cpu_tasks[i].pid == pid)
45                         return i;
46         }
47         return -1;
48 }
49
50 void free_stack(unsigned long stack, int order)
51 {
52         free_pages(stack, order);
53 }
54
55 unsigned long alloc_stack(int order, int atomic)
56 {
57         unsigned long page;
58         gfp_t flags = GFP_KERNEL;
59
60         if (atomic)
61                 flags = GFP_ATOMIC;
62         page = __get_free_pages(flags, order);
63
64         return page;
65 }
66
67 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
68 {
69         int pid;
70
71         current->thread.request.u.thread.proc = fn;
72         current->thread.request.u.thread.arg = arg;
73         pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
74                       &current->thread.regs, 0, NULL, NULL);
75         return pid;
76 }
77
78 static inline void set_current(struct task_struct *task)
79 {
80         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
81                 { external_pid(task), task });
82 }
83
84 extern void arch_switch_to(struct task_struct *to);
85
86 void *_switch_to(void *prev, void *next, void *last)
87 {
88         struct task_struct *from = prev;
89         struct task_struct *to = next;
90
91         to->thread.prev_sched = from;
92         set_current(to);
93
94         do {
95                 current->thread.saved_task = NULL;
96
97                 switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
98
99                 arch_switch_to(current);
100
101                 if (current->thread.saved_task)
102                         show_regs(&(current->thread.regs));
103                 next = current->thread.saved_task;
104                 prev = current;
105         } while (current->thread.saved_task);
106
107         return current->thread.prev_sched;
108
109 }
110
111 void interrupt_end(void)
112 {
113         if (need_resched())
114                 schedule();
115         if (test_tsk_thread_flag(current, TIF_SIGPENDING))
116                 do_signal();
117 }
118
119 void exit_thread(void)
120 {
121 }
122
123 void *get_current(void)
124 {
125         return current;
126 }
127
128 extern void schedule_tail(struct task_struct *prev);
129
130 /*
131  * This is called magically, by its address being stuffed in a jmp_buf
132  * and being longjmp-d to.
133  */
134 void new_thread_handler(void)
135 {
136         int (*fn)(void *), n;
137         void *arg;
138
139         if (current->thread.prev_sched != NULL)
140                 schedule_tail(current->thread.prev_sched);
141         current->thread.prev_sched = NULL;
142
143         fn = current->thread.request.u.thread.proc;
144         arg = current->thread.request.u.thread.arg;
145
146         /*
147          * The return value is 1 if the kernel thread execs a process,
148          * 0 if it just exits
149          */
150         n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
151         if (n == 1) {
152                 /* Handle any immediate reschedules or signals */
153                 interrupt_end();
154                 userspace(&current->thread.regs.regs);
155         }
156         else do_exit(0);
157 }
158
159 /* Called magically, see new_thread_handler above */
160 void fork_handler(void)
161 {
162         force_flush_all();
163
164         schedule_tail(current->thread.prev_sched);
165
166         /*
167          * XXX: if interrupt_end() calls schedule, this call to
168          * arch_switch_to isn't needed. We could want to apply this to
169          * improve performance. -bb
170          */
171         arch_switch_to(current);
172
173         current->thread.prev_sched = NULL;
174
175         /* Handle any immediate reschedules or signals */
176         interrupt_end();
177
178         userspace(&current->thread.regs.regs);
179 }
180
181 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
182                 unsigned long stack_top, struct task_struct * p,
183                 struct pt_regs *regs)
184 {
185         void (*handler)(void);
186         int ret = 0;
187
188         p->thread = (struct thread_struct) INIT_THREAD;
189
190         if (current->thread.forking) {
191                 memcpy(&p->thread.regs.regs, &regs->regs,
192                        sizeof(p->thread.regs.regs));
193                 REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.gp, 0);
194                 if (sp != 0)
195                         REGS_SP(p->thread.regs.regs.gp) = sp;
196
197                 handler = fork_handler;
198
199                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
200         }
201         else {
202                 init_thread_registers(&p->thread.regs.regs);
203                 p->thread.request.u.thread = current->thread.request.u.thread;
204                 handler = new_thread_handler;
205         }
206
207         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
208
209         if (current->thread.forking) {
210                 clear_flushed_tls(p);
211
212                 /*
213                  * Set a new TLS for the child thread?
214                  */
215                 if (clone_flags & CLONE_SETTLS)
216                         ret = arch_copy_tls(p);
217         }
218
219         return ret;
220 }
221
222 void initial_thread_cb(void (*proc)(void *), void *arg)
223 {
224         int save_kmalloc_ok = kmalloc_ok;
225
226         kmalloc_ok = 0;
227         initial_thread_cb_skas(proc, arg);
228         kmalloc_ok = save_kmalloc_ok;
229 }
230
231 void default_idle(void)
232 {
233         unsigned long long nsecs;
234
235         while(1) {
236                 /* endless idle loop with no priority at all */
237
238                 /*
239                  * although we are an idle CPU, we do not want to
240                  * get into the scheduler unnecessarily.
241                  */
242                 if (need_resched())
243                         schedule();
244
245                 tick_nohz_stop_sched_tick();
246                 nsecs = disable_timer();
247                 idle_sleep(nsecs);
248                 tick_nohz_restart_sched_tick();
249         }
250 }
251
252 void cpu_idle(void)
253 {
254         cpu_tasks[current_thread->cpu].pid = os_getpid();
255         default_idle();
256 }
257
258 void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
259                       pte_t *pte_out)
260 {
261         pgd_t *pgd;
262         pud_t *pud;
263         pmd_t *pmd;
264         pte_t *pte;
265         pte_t ptent;
266
267         if (task->mm == NULL)
268                 return ERR_PTR(-EINVAL);
269         pgd = pgd_offset(task->mm, addr);
270         if (!pgd_present(*pgd))
271                 return ERR_PTR(-EINVAL);
272
273         pud = pud_offset(pgd, addr);
274         if (!pud_present(*pud))
275                 return ERR_PTR(-EINVAL);
276
277         pmd = pmd_offset(pud, addr);
278         if (!pmd_present(*pmd))
279                 return ERR_PTR(-EINVAL);
280
281         pte = pte_offset_kernel(pmd, addr);
282         ptent = *pte;
283         if (!pte_present(ptent))
284                 return ERR_PTR(-EINVAL);
285
286         if (pte_out != NULL)
287                 *pte_out = ptent;
288         return (void *) (pte_val(ptent) & PAGE_MASK) + (addr & ~PAGE_MASK);
289 }
290
291 char *current_cmd(void)
292 {
293 #if defined(CONFIG_SMP) || defined(CONFIG_HIGHMEM)
294         return "(Unknown)";
295 #else
296         void *addr = um_virt_to_phys(current, current->mm->arg_start, NULL);
297         return IS_ERR(addr) ? "(Unknown)": __va((unsigned long) addr);
298 #endif
299 }
300
301 void dump_thread(struct pt_regs *regs, struct user *u)
302 {
303 }
304
305 int __cant_sleep(void) {
306         return in_atomic() || irqs_disabled() || in_interrupt();
307         /* Is in_interrupt() really needed? */
308 }
309
310 int user_context(unsigned long sp)
311 {
312         unsigned long stack;
313
314         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
315         return stack != (unsigned long) current_thread;
316 }
317
318 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
319
320 void do_uml_exitcalls(void)
321 {
322         exitcall_t *call;
323
324         call = &__uml_exitcall_end;
325         while (--call >= &__uml_exitcall_begin)
326                 (*call)();
327 }
328
329 char *uml_strdup(const char *string)
330 {
331         return kstrdup(string, GFP_KERNEL);
332 }
333
334 int copy_to_user_proc(void __user *to, void *from, int size)
335 {
336         return copy_to_user(to, from, size);
337 }
338
339 int copy_from_user_proc(void *to, void __user *from, int size)
340 {
341         return copy_from_user(to, from, size);
342 }
343
344 int clear_user_proc(void __user *buf, int size)
345 {
346         return clear_user(buf, size);
347 }
348
349 int strlen_user_proc(char __user *str)
350 {
351         return strlen_user(str);
352 }
353
354 int smp_sigio_handler(void)
355 {
356 #ifdef CONFIG_SMP
357         int cpu = current_thread->cpu;
358         IPI_handler(cpu);
359         if (cpu != 0)
360                 return 1;
361 #endif
362         return 0;
363 }
364
365 int cpu(void)
366 {
367         return current_thread->cpu;
368 }
369
370 static atomic_t using_sysemu = ATOMIC_INIT(0);
371 int sysemu_supported;
372
373 void set_using_sysemu(int value)
374 {
375         if (value > sysemu_supported)
376                 return;
377         atomic_set(&using_sysemu, value);
378 }
379
380 int get_using_sysemu(void)
381 {
382         return atomic_read(&using_sysemu);
383 }
384
385 static int proc_read_sysemu(char *buf, char **start, off_t offset, int size,int *eof, void *data)
386 {
387         if (snprintf(buf, size, "%d\n", get_using_sysemu()) < size)
388                 /* No overflow */
389                 *eof = 1;
390
391         return strlen(buf);
392 }
393
394 static int proc_write_sysemu(struct file *file,const char __user *buf, unsigned long count,void *data)
395 {
396         char tmp[2];
397
398         if (copy_from_user(tmp, buf, 1))
399                 return -EFAULT;
400
401         if (tmp[0] >= '0' && tmp[0] <= '2')
402                 set_using_sysemu(tmp[0] - '0');
403         /* We use the first char, but pretend to write everything */
404         return count;
405 }
406
407 int __init make_proc_sysemu(void)
408 {
409         struct proc_dir_entry *ent;
410         if (!sysemu_supported)
411                 return 0;
412
413         ent = create_proc_entry("sysemu", 0600, &proc_root);
414
415         if (ent == NULL)
416         {
417                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
418                 return 0;
419         }
420
421         ent->read_proc  = proc_read_sysemu;
422         ent->write_proc = proc_write_sysemu;
423
424         return 0;
425 }
426
427 late_initcall(make_proc_sysemu);
428
429 int singlestepping(void * t)
430 {
431         struct task_struct *task = t ? t : current;
432
433         if ( ! (task->ptrace & PT_DTRACE) )
434                 return 0;
435
436         if (task->thread.singlestep_syscall)
437                 return 1;
438
439         return 2;
440 }
441
442 /*
443  * Only x86 and x86_64 have an arch_align_stack().
444  * All other arches have "#define arch_align_stack(x) (x)"
445  * in their asm/system.h
446  * As this is included in UML from asm-um/system-generic.h,
447  * we can use it to behave as the subarch does.
448  */
449 #ifndef arch_align_stack
450 unsigned long arch_align_stack(unsigned long sp)
451 {
452         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
453                 sp -= get_random_int() % 8192;
454         return sp & ~0xf;
455 }
456 #endif
457
458 unsigned long get_wchan(struct task_struct *p)
459 {
460         unsigned long stack_page, sp, ip;
461         bool seen_sched = 0;
462
463         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
464                 return 0;
465
466         stack_page = (unsigned long) task_stack_page(p);
467         /* Bail if the process has no kernel stack for some reason */
468         if (stack_page == 0)
469                 return 0;
470
471         sp = p->thread.switch_buf->JB_SP;
472         /*
473          * Bail if the stack pointer is below the bottom of the kernel
474          * stack for some reason
475          */
476         if (sp < stack_page)
477                 return 0;
478
479         while (sp < stack_page + THREAD_SIZE) {
480                 ip = *((unsigned long *) sp);
481                 if (in_sched_functions(ip))
482                         /* Ignore everything until we're above the scheduler */
483                         seen_sched = 1;
484                 else if (kernel_text_address(ip) && seen_sched)
485                         return ip;
486
487                 sp += sizeof(unsigned long);
488         }
489
490         return 0;
491 }