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         if (page == 0)
  64                 return 0;
  65
  66         return page;
  67 }
  68
  69 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
  70 {
  71         int pid;
  72
  73         current->thread.request.u.thread.proc = fn;
  74         current->thread.request.u.thread.arg = arg;
  75         pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
  76                       &current->thread.regs, 0, NULL, NULL);
  77         return pid;
  78 }
  79
  80 static inline void set_current(struct task_struct *task)
  81 {
  82         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
  83                 { external_pid(task), task });
  84 }
  85
  86 extern void arch_switch_to(struct task_struct *from, struct task_struct *to);
  87
  88 void *_switch_to(void *prev, void *next, void *last)
  89 {
  90         struct task_struct *from = prev;
  91         struct task_struct *to= next;
  92
  93         to->thread.prev_sched = from;
  94         set_current(to);
  95
  96         do {
  97                 current->thread.saved_task = NULL;
  98
  99                 switch_threads(&from->thread.switch_buf,
 100                                &to->thread.switch_buf);
 101
 102                 arch_switch_to(current->thread.prev_sched, current);
 103
 104                 if (current->thread.saved_task)
 105                         show_regs(&(current->thread.regs));
 106                 next= current->thread.saved_task;
 107                 prev= current;
 108         } while(current->thread.saved_task);
 109
 110         return current->thread.prev_sched;
 111
 112 }
 113
 114 void interrupt_end(void)
 115 {
 116         if (need_resched())
 117                 schedule();
 118         if (test_tsk_thread_flag(current, TIF_SIGPENDING))
 119                 do_signal();
 120 }
 121
 122 void exit_thread(void)
 123 {
 124 }
 125
 126 void *get_current(void)
 127 {
 128         return current;
 129 }
 130
 131 extern void schedule_tail(struct task_struct *prev);
 132
 133 /*
 134  * This is called magically, by its address being stuffed in a jmp_buf
 135  * and being longjmp-d to.
 136  */
 137 void new_thread_handler(void)
 138 {
 139         int (*fn)(void *), n;
 140         void *arg;
 141
 142         if (current->thread.prev_sched != NULL)
 143                 schedule_tail(current->thread.prev_sched);
 144         current->thread.prev_sched = NULL;
 145
 146         fn = current->thread.request.u.thread.proc;
 147         arg = current->thread.request.u.thread.arg;
 148
 149         /*
 150          * The return value is 1 if the kernel thread execs a process,
 151          * 0 if it just exits
 152          */
 153         n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
 154         if (n == 1) {
 155                 /* Handle any immediate reschedules or signals */
 156                 interrupt_end();
 157                 userspace(&current->thread.regs.regs);
 158         }
 159         else do_exit(0);
 160 }
 161
 162 /* Called magically, see new_thread_handler above */
 163 void fork_handler(void)
 164 {
 165         force_flush_all();
 166         if (current->thread.prev_sched == NULL)
 167                 panic("blech");
 168
 169         schedule_tail(current->thread.prev_sched);
 170
 171         /*
 172          * XXX: if interrupt_end() calls schedule, this call to
 173          * arch_switch_to isn't needed. We could want to apply this to
 174          * improve performance. -bb
 175          */
 176         arch_switch_to(current->thread.prev_sched, current);
 177
 178         current->thread.prev_sched = NULL;
 179
 180         /* Handle any immediate reschedules or signals */
 181         interrupt_end();
 182
 183         userspace(&current->thread.regs.regs);
 184 }
 185
 186 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
 187                 unsigned long stack_top, struct task_struct * p,
 188                 struct pt_regs *regs)
 189 {
 190         void (*handler)(void);
 191         int ret = 0;
 192
 193         p->thread = (struct thread_struct) INIT_THREAD;
 194
 195         if (current->thread.forking) {
 196                 memcpy(&p->thread.regs.regs, &regs->regs,
 197                        sizeof(p->thread.regs.regs));
 198                 REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.gp, 0);
 199                 if (sp != 0)
 200                         REGS_SP(p->thread.regs.regs.gp) = sp;
 201
 202                 handler = fork_handler;
 203
 204                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
 205         }
 206         else {
 207                 init_thread_registers(&p->thread.regs.regs);
 208                 p->thread.request.u.thread = current->thread.request.u.thread;
 209                 handler = new_thread_handler;
 210         }
 211
 212         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
 213
 214         if (current->thread.forking) {
 215                 clear_flushed_tls(p);
 216
 217                 /*
 218                  * Set a new TLS for the child thread?
 219                  */
 220                 if (clone_flags & CLONE_SETTLS)
 221                         ret = arch_copy_tls(p);
 222         }
 223
 224         return ret;
 225 }
 226
 227 void initial_thread_cb(void (*proc)(void *), void *arg)
 228 {
 229         int save_kmalloc_ok = kmalloc_ok;
 230
 231         kmalloc_ok = 0;
 232         initial_thread_cb_skas(proc, arg);
 233         kmalloc_ok = save_kmalloc_ok;
 234 }
 235
 236 void default_idle(void)
 237 {
 238         unsigned long long nsecs;
 239
 240         while(1) {
 241                 /* endless idle loop with no priority at all */
 242
 243                 /*
 244                  * although we are an idle CPU, we do not want to
 245                  * get into the scheduler unnecessarily.
 246                  */
 247                 if (need_resched())
 248                         schedule();
 249
 250                 tick_nohz_stop_sched_tick();
 251                 nsecs = disable_timer();
 252                 idle_sleep(nsecs);
 253                 tick_nohz_restart_sched_tick();
 254         }
 255 }
 256
 257 void cpu_idle(void)
 258 {
 259         cpu_tasks[current_thread->cpu].pid = os_getpid();
 260         default_idle();
 261 }
 262
 263 void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
 264                       pte_t *pte_out)
 265 {
 266         pgd_t *pgd;
 267         pud_t *pud;
 268         pmd_t *pmd;
 269         pte_t *pte;
 270         pte_t ptent;
 271
 272         if (task->mm == NULL)
 273                 return ERR_PTR(-EINVAL);
 274         pgd = pgd_offset(task->mm, addr);
 275         if (!pgd_present(*pgd))
 276                 return ERR_PTR(-EINVAL);
 277
 278         pud = pud_offset(pgd, addr);
 279         if (!pud_present(*pud))
 280                 return ERR_PTR(-EINVAL);
 281
 282         pmd = pmd_offset(pud, addr);
 283         if (!pmd_present(*pmd))
 284                 return ERR_PTR(-EINVAL);
 285
 286         pte = pte_offset_kernel(pmd, addr);
 287         ptent = *pte;
 288         if (!pte_present(ptent))
 289                 return ERR_PTR(-EINVAL);
 290
 291         if (pte_out != NULL)
 292                 *pte_out = ptent;
 293         return (void *) (pte_val(ptent) & PAGE_MASK) + (addr & ~PAGE_MASK);
 294 }
 295
 296 char *current_cmd(void)
 297 {
 298 #if defined(CONFIG_SMP) || defined(CONFIG_HIGHMEM)
 299         return "(Unknown)";
 300 #else
 301         void *addr = um_virt_to_phys(current, current->mm->arg_start, NULL);
 302         return IS_ERR(addr) ? "(Unknown)": __va((unsigned long) addr);
 303 #endif
 304 }
 305
 306 void dump_thread(struct pt_regs *regs, struct user *u)
 307 {
 308 }
 309
 310 int __cant_sleep(void) {
 311         return in_atomic() || irqs_disabled() || in_interrupt();
 312         /* Is in_interrupt() really needed? */
 313 }
 314
 315 int user_context(unsigned long sp)
 316 {
 317         unsigned long stack;
 318
 319         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 320         return stack != (unsigned long) current_thread;
 321 }
 322
 323 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 324
 325 void do_uml_exitcalls(void)
 326 {
 327         exitcall_t *call;
 328
 329         call = &__uml_exitcall_end;
 330         while (--call >= &__uml_exitcall_begin)
 331                 (*call)();
 332 }
 333
 334 char *uml_strdup(char *string)
 335 {
 336         return kstrdup(string, GFP_KERNEL);
 337 }
 338
 339 int copy_to_user_proc(void __user *to, void *from, int size)
 340 {
 341         return copy_to_user(to, from, size);
 342 }
 343
 344 int copy_from_user_proc(void *to, void __user *from, int size)
 345 {
 346         return copy_from_user(to, from, size);
 347 }
 348
 349 int clear_user_proc(void __user *buf, int size)
 350 {
 351         return clear_user(buf, size);
 352 }
 353
 354 int strlen_user_proc(char __user *str)
 355 {
 356         return strlen_user(str);
 357 }
 358
 359 int smp_sigio_handler(void)
 360 {
 361 #ifdef CONFIG_SMP
 362         int cpu = current_thread->cpu;
 363         IPI_handler(cpu);
 364         if (cpu != 0)
 365                 return 1;
 366 #endif
 367         return 0;
 368 }
 369
 370 int cpu(void)
 371 {
 372         return current_thread->cpu;
 373 }
 374
 375 static atomic_t using_sysemu = ATOMIC_INIT(0);
 376 int sysemu_supported;
 377
 378 void set_using_sysemu(int value)
 379 {
 380         if (value > sysemu_supported)
 381                 return;
 382         atomic_set(&using_sysemu, value);
 383 }
 384
 385 int get_using_sysemu(void)
 386 {
 387         return atomic_read(&using_sysemu);
 388 }
 389
 390 static int proc_read_sysemu(char *buf, char **start, off_t offset, int size,int *eof, void *data)
 391 {
 392         if (snprintf(buf, size, "%d\n", get_using_sysemu()) < size)
 393                 /* No overflow */
 394                 *eof = 1;
 395
 396         return strlen(buf);
 397 }
 398
 399 static int proc_write_sysemu(struct file *file,const char __user *buf, unsigned long count,void *data)
 400 {
 401         char tmp[2];
 402
 403         if (copy_from_user(tmp, buf, 1))
 404                 return -EFAULT;
 405
 406         if (tmp[0] >= '0' && tmp[0] <= '2')
 407                 set_using_sysemu(tmp[0] - '0');
 408         /* We use the first char, but pretend to write everything */
 409         return count;
 410 }
 411
 412 int __init make_proc_sysemu(void)
 413 {
 414         struct proc_dir_entry *ent;
 415         if (!sysemu_supported)
 416                 return 0;
 417
 418         ent = create_proc_entry("sysemu", 0600, &proc_root);
 419
 420         if (ent == NULL)
 421         {
 422                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 423                 return 0;
 424         }
 425
 426         ent->read_proc  = proc_read_sysemu;
 427         ent->write_proc = proc_write_sysemu;
 428
 429         return 0;
 430 }
 431
 432 late_initcall(make_proc_sysemu);
 433
 434 int singlestepping(void * t)
 435 {
 436         struct task_struct *task = t ? t : current;
 437
 438         if ( ! (task->ptrace & PT_DTRACE) )
 439                 return 0;
 440
 441         if (task->thread.singlestep_syscall)
 442                 return 1;
 443
 444         return 2;
 445 }
 446
 447 /*
 448  * Only x86 and x86_64 have an arch_align_stack().
 449  * All other arches have "#define arch_align_stack(x) (x)"
 450  * in their asm/system.h
 451  * As this is included in UML from asm-um/system-generic.h,
 452  * we can use it to behave as the subarch does.
 453  */
 454 #ifndef arch_align_stack
 455 unsigned long arch_align_stack(unsigned long sp)
 456 {
 457         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 458                 sp -= get_random_int() % 8192;
 459         return sp & ~0xf;
 460 }
 461 #endif