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Linux/arch/um/kernel/process.c

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  1 /*
  2  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
  3  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  4  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  5  * Copyright 2003 PathScale, Inc.
  6  * Licensed under the GPL
  7  */
  8 
  9 #include <linux/stddef.h>
 10 #include <linux/err.h>
 11 #include <linux/hardirq.h>
 12 #include <linux/mm.h>
 13 #include <linux/module.h>
 14 #include <linux/personality.h>
 15 #include <linux/proc_fs.h>
 16 #include <linux/ptrace.h>
 17 #include <linux/random.h>
 18 #include <linux/slab.h>
 19 #include <linux/sched.h>
 20 #include <linux/seq_file.h>
 21 #include <linux/tick.h>
 22 #include <linux/threads.h>
 23 #include <linux/tracehook.h>
 24 #include <asm/current.h>
 25 #include <asm/pgtable.h>
 26 #include <asm/mmu_context.h>
 27 #include <linux/uaccess.h>
 28 #include <as-layout.h>
 29 #include <kern_util.h>
 30 #include <os.h>
 31 #include <skas.h>
 32 #include <timer-internal.h>
 33 
 34 /*
 35  * This is a per-cpu array.  A processor only modifies its entry and it only
 36  * cares about its entry, so it's OK if another processor is modifying its
 37  * entry.
 38  */
 39 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
 40 
 41 static inline int external_pid(void)
 42 {
 43         /* FIXME: Need to look up userspace_pid by cpu */
 44         return userspace_pid[0];
 45 }
 46 
 47 int pid_to_processor_id(int pid)
 48 {
 49         int i;
 50 
 51         for (i = 0; i < ncpus; i++) {
 52                 if (cpu_tasks[i].pid == pid)
 53                         return i;
 54         }
 55         return -1;
 56 }
 57 
 58 void free_stack(unsigned long stack, int order)
 59 {
 60         free_pages(stack, order);
 61 }
 62 
 63 unsigned long alloc_stack(int order, int atomic)
 64 {
 65         unsigned long page;
 66         gfp_t flags = GFP_KERNEL;
 67 
 68         if (atomic)
 69                 flags = GFP_ATOMIC;
 70         page = __get_free_pages(flags, order);
 71 
 72         return page;
 73 }
 74 
 75 static inline void set_current(struct task_struct *task)
 76 {
 77         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
 78                 { external_pid(), task });
 79 }
 80 
 81 extern void arch_switch_to(struct task_struct *to);
 82 
 83 void *__switch_to(struct task_struct *from, struct task_struct *to)
 84 {
 85         to->thread.prev_sched = from;
 86         set_current(to);
 87 
 88         switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
 89         arch_switch_to(current);
 90 
 91         return current->thread.prev_sched;
 92 }
 93 
 94 void interrupt_end(void)
 95 {
 96         struct pt_regs *regs = &current->thread.regs;
 97 
 98         if (need_resched())
 99                 schedule();
100         if (test_thread_flag(TIF_SIGPENDING))
101                 do_signal(regs);
102         if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
103                 tracehook_notify_resume(regs);
104 }
105 
106 int get_current_pid(void)
107 {
108         return task_pid_nr(current);
109 }
110 
111 /*
112  * This is called magically, by its address being stuffed in a jmp_buf
113  * and being longjmp-d to.
114  */
115 void new_thread_handler(void)
116 {
117         int (*fn)(void *), n;
118         void *arg;
119 
120         if (current->thread.prev_sched != NULL)
121                 schedule_tail(current->thread.prev_sched);
122         current->thread.prev_sched = NULL;
123 
124         fn = current->thread.request.u.thread.proc;
125         arg = current->thread.request.u.thread.arg;
126 
127         /*
128          * callback returns only if the kernel thread execs a process
129          */
130         n = fn(arg);
131         userspace(&current->thread.regs.regs);
132 }
133 
134 /* Called magically, see new_thread_handler above */
135 void fork_handler(void)
136 {
137         force_flush_all();
138 
139         schedule_tail(current->thread.prev_sched);
140 
141         /*
142          * XXX: if interrupt_end() calls schedule, this call to
143          * arch_switch_to isn't needed. We could want to apply this to
144          * improve performance. -bb
145          */
146         arch_switch_to(current);
147 
148         current->thread.prev_sched = NULL;
149 
150         userspace(&current->thread.regs.regs);
151 }
152 
153 int copy_thread(unsigned long clone_flags, unsigned long sp,
154                 unsigned long arg, struct task_struct * p)
155 {
156         void (*handler)(void);
157         int kthread = current->flags & PF_KTHREAD;
158         int ret = 0;
159 
160         p->thread = (struct thread_struct) INIT_THREAD;
161 
162         if (!kthread) {
163                 memcpy(&p->thread.regs.regs, current_pt_regs(),
164                        sizeof(p->thread.regs.regs));
165                 PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
166                 if (sp != 0)
167                         REGS_SP(p->thread.regs.regs.gp) = sp;
168 
169                 handler = fork_handler;
170 
171                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
172         } else {
173                 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
174                 p->thread.request.u.thread.proc = (int (*)(void *))sp;
175                 p->thread.request.u.thread.arg = (void *)arg;
176                 handler = new_thread_handler;
177         }
178 
179         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
180 
181         if (!kthread) {
182                 clear_flushed_tls(p);
183 
184                 /*
185                  * Set a new TLS for the child thread?
186                  */
187                 if (clone_flags & CLONE_SETTLS)
188                         ret = arch_copy_tls(p);
189         }
190 
191         return ret;
192 }
193 
194 void initial_thread_cb(void (*proc)(void *), void *arg)
195 {
196         int save_kmalloc_ok = kmalloc_ok;
197 
198         kmalloc_ok = 0;
199         initial_thread_cb_skas(proc, arg);
200         kmalloc_ok = save_kmalloc_ok;
201 }
202 
203 void arch_cpu_idle(void)
204 {
205         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
206         os_idle_sleep(UM_NSEC_PER_SEC);
207         local_irq_enable();
208 }
209 
210 int __cant_sleep(void) {
211         return in_atomic() || irqs_disabled() || in_interrupt();
212         /* Is in_interrupt() really needed? */
213 }
214 
215 int user_context(unsigned long sp)
216 {
217         unsigned long stack;
218 
219         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
220         return stack != (unsigned long) current_thread_info();
221 }
222 
223 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
224 
225 void do_uml_exitcalls(void)
226 {
227         exitcall_t *call;
228 
229         call = &__uml_exitcall_end;
230         while (--call >= &__uml_exitcall_begin)
231                 (*call)();
232 }
233 
234 char *uml_strdup(const char *string)
235 {
236         return kstrdup(string, GFP_KERNEL);
237 }
238 EXPORT_SYMBOL(uml_strdup);
239 
240 int copy_to_user_proc(void __user *to, void *from, int size)
241 {
242         return copy_to_user(to, from, size);
243 }
244 
245 int copy_from_user_proc(void *to, void __user *from, int size)
246 {
247         return copy_from_user(to, from, size);
248 }
249 
250 int clear_user_proc(void __user *buf, int size)
251 {
252         return clear_user(buf, size);
253 }
254 
255 int strlen_user_proc(char __user *str)
256 {
257         return strlen_user(str);
258 }
259 
260 int cpu(void)
261 {
262         return current_thread_info()->cpu;
263 }
264 
265 static atomic_t using_sysemu = ATOMIC_INIT(0);
266 int sysemu_supported;
267 
268 void set_using_sysemu(int value)
269 {
270         if (value > sysemu_supported)
271                 return;
272         atomic_set(&using_sysemu, value);
273 }
274 
275 int get_using_sysemu(void)
276 {
277         return atomic_read(&using_sysemu);
278 }
279 
280 static int sysemu_proc_show(struct seq_file *m, void *v)
281 {
282         seq_printf(m, "%d\n", get_using_sysemu());
283         return 0;
284 }
285 
286 static int sysemu_proc_open(struct inode *inode, struct file *file)
287 {
288         return single_open(file, sysemu_proc_show, NULL);
289 }
290 
291 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
292                                  size_t count, loff_t *pos)
293 {
294         char tmp[2];
295 
296         if (copy_from_user(tmp, buf, 1))
297                 return -EFAULT;
298 
299         if (tmp[0] >= '' && tmp[0] <= '2')
300                 set_using_sysemu(tmp[0] - '');
301         /* We use the first char, but pretend to write everything */
302         return count;
303 }
304 
305 static const struct file_operations sysemu_proc_fops = {
306         .owner          = THIS_MODULE,
307         .open           = sysemu_proc_open,
308         .read           = seq_read,
309         .llseek         = seq_lseek,
310         .release        = single_release,
311         .write          = sysemu_proc_write,
312 };
313 
314 int __init make_proc_sysemu(void)
315 {
316         struct proc_dir_entry *ent;
317         if (!sysemu_supported)
318                 return 0;
319 
320         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
321 
322         if (ent == NULL)
323         {
324                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
325                 return 0;
326         }
327 
328         return 0;
329 }
330 
331 late_initcall(make_proc_sysemu);
332 
333 int singlestepping(void * t)
334 {
335         struct task_struct *task = t ? t : current;
336 
337         if (!(task->ptrace & PT_DTRACE))
338                 return 0;
339 
340         if (task->thread.singlestep_syscall)
341                 return 1;
342 
343         return 2;
344 }
345 
346 /*
347  * Only x86 and x86_64 have an arch_align_stack().
348  * All other arches have "#define arch_align_stack(x) (x)"
349  * in their asm/exec.h
350  * As this is included in UML from asm-um/system-generic.h,
351  * we can use it to behave as the subarch does.
352  */
353 #ifndef arch_align_stack
354 unsigned long arch_align_stack(unsigned long sp)
355 {
356         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
357                 sp -= get_random_int() % 8192;
358         return sp & ~0xf;
359 }
360 #endif
361 
362 unsigned long get_wchan(struct task_struct *p)
363 {
364         unsigned long stack_page, sp, ip;
365         bool seen_sched = 0;
366 
367         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
368                 return 0;
369 
370         stack_page = (unsigned long) task_stack_page(p);
371         /* Bail if the process has no kernel stack for some reason */
372         if (stack_page == 0)
373                 return 0;
374 
375         sp = p->thread.switch_buf->JB_SP;
376         /*
377          * Bail if the stack pointer is below the bottom of the kernel
378          * stack for some reason
379          */
380         if (sp < stack_page)
381                 return 0;
382 
383         while (sp < stack_page + THREAD_SIZE) {
384                 ip = *((unsigned long *) sp);
385                 if (in_sched_functions(ip))
386                         /* Ignore everything until we're above the scheduler */
387                         seen_sched = 1;
388                 else if (kernel_text_address(ip) && seen_sched)
389                         return ip;
390 
391                 sp += sizeof(unsigned long);
392         }
393 
394         return 0;
395 }
396 
397 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
398 {
399         int cpu = current_thread_info()->cpu;
400 
401         return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu);
402 }
403 
404 

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