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 }