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

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