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Linux/arch/um/kernel/process.c

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  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 static inline void set_current(struct task_struct *task)
 73 {
 74         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
 75                 { external_pid(), task });
 76 }
 77 
 78 extern void arch_switch_to(struct task_struct *to);
 79 
 80 void *__switch_to(struct task_struct *from, struct task_struct *to)
 81 {
 82         to->thread.prev_sched = from;
 83         set_current(to);
 84 
 85         switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
 86         arch_switch_to(current);
 87 
 88         return current->thread.prev_sched;
 89 }
 90 
 91 void interrupt_end(void)
 92 {
 93         if (need_resched())
 94                 schedule();
 95         if (test_thread_flag(TIF_SIGPENDING))
 96                 do_signal();
 97         if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
 98                 tracehook_notify_resume(&current->thread.regs);
 99 }
100 
101 void exit_thread(void)
102 {
103 }
104 
105 int get_current_pid(void)
106 {
107         return task_pid_nr(current);
108 }
109 
110 /*
111  * This is called magically, by its address being stuffed in a jmp_buf
112  * and being longjmp-d to.
113  */
114 void new_thread_handler(void)
115 {
116         int (*fn)(void *), n;
117         void *arg;
118 
119         if (current->thread.prev_sched != NULL)
120                 schedule_tail(current->thread.prev_sched);
121         current->thread.prev_sched = NULL;
122 
123         fn = current->thread.request.u.thread.proc;
124         arg = current->thread.request.u.thread.arg;
125 
126         /*
127          * callback returns only if the kernel thread execs a process
128          */
129         n = fn(arg);
130         userspace(&current->thread.regs.regs);
131 }
132 
133 /* Called magically, see new_thread_handler above */
134 void fork_handler(void)
135 {
136         force_flush_all();
137 
138         schedule_tail(current->thread.prev_sched);
139 
140         /*
141          * XXX: if interrupt_end() calls schedule, this call to
142          * arch_switch_to isn't needed. We could want to apply this to
143          * improve performance. -bb
144          */
145         arch_switch_to(current);
146 
147         current->thread.prev_sched = NULL;
148 
149         userspace(&current->thread.regs.regs);
150 }
151 
152 int copy_thread(unsigned long clone_flags, unsigned long sp,
153                 unsigned long arg, struct task_struct * p)
154 {
155         void (*handler)(void);
156         int kthread = current->flags & PF_KTHREAD;
157         int ret = 0;
158 
159         p->thread = (struct thread_struct) INIT_THREAD;
160 
161         if (!kthread) {
162                 memcpy(&p->thread.regs.regs, current_pt_regs(),
163                        sizeof(p->thread.regs.regs));
164                 PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
165                 if (sp != 0)
166                         REGS_SP(p->thread.regs.regs.gp) = sp;
167 
168                 handler = fork_handler;
169 
170                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
171         } else {
172                 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
173                 p->thread.request.u.thread.proc = (int (*)(void *))sp;
174                 p->thread.request.u.thread.arg = (void *)arg;
175                 handler = new_thread_handler;
176         }
177 
178         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
179 
180         if (!kthread) {
181                 clear_flushed_tls(p);
182 
183                 /*
184                  * Set a new TLS for the child thread?
185                  */
186                 if (clone_flags & CLONE_SETTLS)
187                         ret = arch_copy_tls(p);
188         }
189 
190         return ret;
191 }
192 
193 void initial_thread_cb(void (*proc)(void *), void *arg)
194 {
195         int save_kmalloc_ok = kmalloc_ok;
196 
197         kmalloc_ok = 0;
198         initial_thread_cb_skas(proc, arg);
199         kmalloc_ok = save_kmalloc_ok;
200 }
201 
202 void arch_cpu_idle(void)
203 {
204         unsigned long long nsecs;
205 
206         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
207         nsecs = disable_timer();
208         idle_sleep(nsecs);
209         local_irq_enable();
210 }
211 
212 int __cant_sleep(void) {
213         return in_atomic() || irqs_disabled() || in_interrupt();
214         /* Is in_interrupt() really needed? */
215 }
216 
217 int user_context(unsigned long sp)
218 {
219         unsigned long stack;
220 
221         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
222         return stack != (unsigned long) current_thread_info();
223 }
224 
225 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
226 
227 void do_uml_exitcalls(void)
228 {
229         exitcall_t *call;
230 
231         call = &__uml_exitcall_end;
232         while (--call >= &__uml_exitcall_begin)
233                 (*call)();
234 }
235 
236 char *uml_strdup(const char *string)
237 {
238         return kstrdup(string, GFP_KERNEL);
239 }
240 EXPORT_SYMBOL(uml_strdup);
241 
242 int copy_to_user_proc(void __user *to, void *from, int size)
243 {
244         return copy_to_user(to, from, size);
245 }
246 
247 int copy_from_user_proc(void *to, void __user *from, int size)
248 {
249         return copy_from_user(to, from, size);
250 }
251 
252 int clear_user_proc(void __user *buf, int size)
253 {
254         return clear_user(buf, size);
255 }
256 
257 int strlen_user_proc(char __user *str)
258 {
259         return strlen_user(str);
260 }
261 
262 int smp_sigio_handler(void)
263 {
264 #ifdef CONFIG_SMP
265         int cpu = current_thread_info()->cpu;
266         IPI_handler(cpu);
267         if (cpu != 0)
268                 return 1;
269 #endif
270         return 0;
271 }
272 
273 int cpu(void)
274 {
275         return current_thread_info()->cpu;
276 }
277 
278 static atomic_t using_sysemu = ATOMIC_INIT(0);
279 int sysemu_supported;
280 
281 void set_using_sysemu(int value)
282 {
283         if (value > sysemu_supported)
284                 return;
285         atomic_set(&using_sysemu, value);
286 }
287 
288 int get_using_sysemu(void)
289 {
290         return atomic_read(&using_sysemu);
291 }
292 
293 static int sysemu_proc_show(struct seq_file *m, void *v)
294 {
295         seq_printf(m, "%d\n", get_using_sysemu());
296         return 0;
297 }
298 
299 static int sysemu_proc_open(struct inode *inode, struct file *file)
300 {
301         return single_open(file, sysemu_proc_show, NULL);
302 }
303 
304 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
305                                  size_t count, loff_t *pos)
306 {
307         char tmp[2];
308 
309         if (copy_from_user(tmp, buf, 1))
310                 return -EFAULT;
311 
312         if (tmp[0] >= '' && tmp[0] <= '2')
313                 set_using_sysemu(tmp[0] - '');
314         /* We use the first char, but pretend to write everything */
315         return count;
316 }
317 
318 static const struct file_operations sysemu_proc_fops = {
319         .owner          = THIS_MODULE,
320         .open           = sysemu_proc_open,
321         .read           = seq_read,
322         .llseek         = seq_lseek,
323         .release        = single_release,
324         .write          = sysemu_proc_write,
325 };
326 
327 int __init make_proc_sysemu(void)
328 {
329         struct proc_dir_entry *ent;
330         if (!sysemu_supported)
331                 return 0;
332 
333         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
334 
335         if (ent == NULL)
336         {
337                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
338                 return 0;
339         }
340 
341         return 0;
342 }
343 
344 late_initcall(make_proc_sysemu);
345 
346 int singlestepping(void * t)
347 {
348         struct task_struct *task = t ? t : current;
349 
350         if (!(task->ptrace & PT_DTRACE))
351                 return 0;
352 
353         if (task->thread.singlestep_syscall)
354                 return 1;
355 
356         return 2;
357 }
358 
359 /*
360  * Only x86 and x86_64 have an arch_align_stack().
361  * All other arches have "#define arch_align_stack(x) (x)"
362  * in their asm/exec.h
363  * As this is included in UML from asm-um/system-generic.h,
364  * we can use it to behave as the subarch does.
365  */
366 #ifndef arch_align_stack
367 unsigned long arch_align_stack(unsigned long sp)
368 {
369         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
370                 sp -= get_random_int() % 8192;
371         return sp & ~0xf;
372 }
373 #endif
374 
375 unsigned long get_wchan(struct task_struct *p)
376 {
377         unsigned long stack_page, sp, ip;
378         bool seen_sched = 0;
379 
380         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
381                 return 0;
382 
383         stack_page = (unsigned long) task_stack_page(p);
384         /* Bail if the process has no kernel stack for some reason */
385         if (stack_page == 0)
386                 return 0;
387 
388         sp = p->thread.switch_buf->JB_SP;
389         /*
390          * Bail if the stack pointer is below the bottom of the kernel
391          * stack for some reason
392          */
393         if (sp < stack_page)
394                 return 0;
395 
396         while (sp < stack_page + THREAD_SIZE) {
397                 ip = *((unsigned long *) sp);
398                 if (in_sched_functions(ip))
399                         /* Ignore everything until we're above the scheduler */
400                         seen_sched = 1;
401                 else if (kernel_text_address(ip) && seen_sched)
402                         return ip;
403 
404                 sp += sizeof(unsigned long);
405         }
406 
407         return 0;
408 }
409 
410 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
411 {
412         int cpu = current_thread_info()->cpu;
413 
414         return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
415 }
416 
417 

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