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 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         do {
  86                 current->thread.saved_task = NULL;
  87
  88                 switch_threads(&from->thread.switch_buf,
  89                                &to->thread.switch_buf);
  90
  91                 arch_switch_to(current);
  92
  93                 if (current->thread.saved_task)
  94                         show_regs(&(current->thread.regs));
  95                 to = current->thread.saved_task;
  96                 from = current;
  97         } while (current->thread.saved_task);
  98
  99         return current->thread.prev_sched;
 100 }
 101
 102 void interrupt_end(void)
 103 {
 104         if (need_resched())
 105                 schedule();
 106         if (test_thread_flag(TIF_SIGPENDING))
 107                 do_signal();
 108         if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
 109                 tracehook_notify_resume(&current->thread.regs);
 110 }
 111
 112 void exit_thread(void)
 113 {
 114 }
 115
 116 int get_current_pid(void)
 117 {
 118         return task_pid_nr(current);
 119 }
 120
 121 /*
 122  * This is called magically, by its address being stuffed in a jmp_buf
 123  * and being longjmp-d to.
 124  */
 125 void new_thread_handler(void)
 126 {
 127         int (*fn)(void *), n;
 128         void *arg;
 129
 130         if (current->thread.prev_sched != NULL)
 131                 schedule_tail(current->thread.prev_sched);
 132         current->thread.prev_sched = NULL;
 133
 134         fn = current->thread.request.u.thread.proc;
 135         arg = current->thread.request.u.thread.arg;
 136
 137         /*
 138          * callback returns only if the kernel thread execs a process
 139          */
 140         n = fn(arg);
 141         userspace(&current->thread.regs.regs);
 142 }
 143
 144 /* Called magically, see new_thread_handler above */
 145 void fork_handler(void)
 146 {
 147         force_flush_all();
 148
 149         schedule_tail(current->thread.prev_sched);
 150
 151         /*
 152          * XXX: if interrupt_end() calls schedule, this call to
 153          * arch_switch_to isn't needed. We could want to apply this to
 154          * improve performance. -bb
 155          */
 156         arch_switch_to(current);
 157
 158         current->thread.prev_sched = NULL;
 159
 160         userspace(&current->thread.regs.regs);
 161 }
 162
 163 int copy_thread(unsigned long clone_flags, unsigned long sp,
 164                 unsigned long arg, struct task_struct * p)
 165 {
 166         void (*handler)(void);
 167         int kthread = current->flags & PF_KTHREAD;
 168         int ret = 0;
 169
 170         p->thread = (struct thread_struct) INIT_THREAD;
 171
 172         if (!kthread) {
 173                 memcpy(&p->thread.regs.regs, current_pt_regs(),
 174                        sizeof(p->thread.regs.regs));
 175                 PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
 176                 if (sp != 0)
 177                         REGS_SP(p->thread.regs.regs.gp) = sp;
 178
 179                 handler = fork_handler;
 180
 181                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
 182         } else {
 183                 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
 184                 p->thread.request.u.thread.proc = (int (*)(void *))sp;
 185                 p->thread.request.u.thread.arg = (void *)arg;
 186                 handler = new_thread_handler;
 187         }
 188
 189         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
 190
 191         if (!kthread) {
 192                 clear_flushed_tls(p);
 193
 194                 /*
 195                  * Set a new TLS for the child thread?
 196                  */
 197                 if (clone_flags & CLONE_SETTLS)
 198                         ret = arch_copy_tls(p);
 199         }
 200
 201         return ret;
 202 }
 203
 204 void initial_thread_cb(void (*proc)(void *), void *arg)
 205 {
 206         int save_kmalloc_ok = kmalloc_ok;
 207
 208         kmalloc_ok = 0;
 209         initial_thread_cb_skas(proc, arg);
 210         kmalloc_ok = save_kmalloc_ok;
 211 }
 212
 213 void default_idle(void)
 214 {
 215         unsigned long long nsecs;
 216
 217         while (1) {
 218                 /* endless idle loop with no priority at all */
 219
 220                 /*
 221                  * although we are an idle CPU, we do not want to
 222                  * get into the scheduler unnecessarily.
 223                  */
 224                 if (need_resched())
 225                         schedule();
 226
 227                 tick_nohz_idle_enter();
 228                 rcu_idle_enter();
 229                 nsecs = disable_timer();
 230                 idle_sleep(nsecs);
 231                 rcu_idle_exit();
 232                 tick_nohz_idle_exit();
 233         }
 234 }
 235
 236 void cpu_idle(void)
 237 {
 238         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 239         default_idle();
 240 }
 241
 242 int __cant_sleep(void) {
 243         return in_atomic() || irqs_disabled() || in_interrupt();
 244         /* Is in_interrupt() really needed? */
 245 }
 246
 247 int user_context(unsigned long sp)
 248 {
 249         unsigned long stack;
 250
 251         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 252         return stack != (unsigned long) current_thread_info();
 253 }
 254
 255 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 256
 257 void do_uml_exitcalls(void)
 258 {
 259         exitcall_t *call;
 260
 261         call = &__uml_exitcall_end;
 262         while (--call >= &__uml_exitcall_begin)
 263                 (*call)();
 264 }
 265
 266 char *uml_strdup(const char *string)
 267 {
 268         return kstrdup(string, GFP_KERNEL);
 269 }
 270 EXPORT_SYMBOL(uml_strdup);
 271
 272 int copy_to_user_proc(void __user *to, void *from, int size)
 273 {
 274         return copy_to_user(to, from, size);
 275 }
 276
 277 int copy_from_user_proc(void *to, void __user *from, int size)
 278 {
 279         return copy_from_user(to, from, size);
 280 }
 281
 282 int clear_user_proc(void __user *buf, int size)
 283 {
 284         return clear_user(buf, size);
 285 }
 286
 287 int strlen_user_proc(char __user *str)
 288 {
 289         return strlen_user(str);
 290 }
 291
 292 int smp_sigio_handler(void)
 293 {
 294 #ifdef CONFIG_SMP
 295         int cpu = current_thread_info()->cpu;
 296         IPI_handler(cpu);
 297         if (cpu != 0)
 298                 return 1;
 299 #endif
 300         return 0;
 301 }
 302
 303 int cpu(void)
 304 {
 305         return current_thread_info()->cpu;
 306 }
 307
 308 static atomic_t using_sysemu = ATOMIC_INIT(0);
 309 int sysemu_supported;
 310
 311 void set_using_sysemu(int value)
 312 {
 313         if (value > sysemu_supported)
 314                 return;
 315         atomic_set(&using_sysemu, value);
 316 }
 317
 318 int get_using_sysemu(void)
 319 {
 320         return atomic_read(&using_sysemu);
 321 }
 322
 323 static int sysemu_proc_show(struct seq_file *m, void *v)
 324 {
 325         seq_printf(m, "%d\n", get_using_sysemu());
 326         return 0;
 327 }
 328
 329 static int sysemu_proc_open(struct inode *inode, struct file *file)
 330 {
 331         return single_open(file, sysemu_proc_show, NULL);
 332 }
 333
 334 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 335                                  size_t count, loff_t *pos)
 336 {
 337         char tmp[2];
 338
 339         if (copy_from_user(tmp, buf, 1))
 340                 return -EFAULT;
 341
 342         if (tmp[0] >= '0' && tmp[0] <= '2')
 343                 set_using_sysemu(tmp[0] - '0');
 344         /* We use the first char, but pretend to write everything */
 345         return count;
 346 }
 347
 348 static const struct file_operations sysemu_proc_fops = {
 349         .owner          = THIS_MODULE,
 350         .open           = sysemu_proc_open,
 351         .read           = seq_read,
 352         .llseek         = seq_lseek,
 353         .release        = single_release,
 354         .write          = sysemu_proc_write,
 355 };
 356
 357 int __init make_proc_sysemu(void)
 358 {
 359         struct proc_dir_entry *ent;
 360         if (!sysemu_supported)
 361                 return 0;
 362
 363         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
 364
 365         if (ent == NULL)
 366         {
 367                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 368                 return 0;
 369         }
 370
 371         return 0;
 372 }
 373
 374 late_initcall(make_proc_sysemu);
 375
 376 int singlestepping(void * t)
 377 {
 378         struct task_struct *task = t ? t : current;
 379
 380         if (!(task->ptrace & PT_DTRACE))
 381                 return 0;
 382
 383         if (task->thread.singlestep_syscall)
 384                 return 1;
 385
 386         return 2;
 387 }
 388
 389 /*
 390  * Only x86 and x86_64 have an arch_align_stack().
 391  * All other arches have "#define arch_align_stack(x) (x)"
 392  * in their asm/system.h
 393  * As this is included in UML from asm-um/system-generic.h,
 394  * we can use it to behave as the subarch does.
 395  */
 396 #ifndef arch_align_stack
 397 unsigned long arch_align_stack(unsigned long sp)
 398 {
 399         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 400                 sp -= get_random_int() % 8192;
 401         return sp & ~0xf;
 402 }
 403 #endif
 404
 405 unsigned long get_wchan(struct task_struct *p)
 406 {
 407         unsigned long stack_page, sp, ip;
 408         bool seen_sched = 0;
 409
 410         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 411                 return 0;
 412
 413         stack_page = (unsigned long) task_stack_page(p);
 414         /* Bail if the process has no kernel stack for some reason */
 415         if (stack_page == 0)
 416                 return 0;
 417
 418         sp = p->thread.switch_buf->JB_SP;
 419         /*
 420          * Bail if the stack pointer is below the bottom of the kernel
 421          * stack for some reason
 422          */
 423         if (sp < stack_page)
 424                 return 0;
 425
 426         while (sp < stack_page + THREAD_SIZE) {
 427                 ip = *((unsigned long *) sp);
 428                 if (in_sched_functions(ip))
 429                         /* Ignore everything until we're above the scheduler */
 430                         seen_sched = 1;
 431                 else if (kernel_text_address(ip) && seen_sched)
 432                         return ip;
 433
 434                 sp += sizeof(unsigned long);
 435         }
 436
 437         return 0;
 438 }
 439
 440 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 441 {
 442         int cpu = current_thread_info()->cpu;
 443
 444         return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
 445 }
 446