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/gfp.h>
  11 #include <linux/mm.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/sched.h>
  17 #include <linux/tick.h>
  18 #include <linux/threads.h>
  19 #include <asm/current.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/uaccess.h>
  22 #include "as-layout.h"
  23 #include "kern_util.h"
  24 #include "os.h"
  25 #include "skas.h"
  26 #include "tlb.h"
  27
  28 /*
  29  * This is a per-cpu array.  A processor only modifies its entry and it only
  30  * cares about its entry, so it's OK if another processor is modifying its
  31  * entry.
  32  */
  33 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
  34
  35 static inline int external_pid(void)
  36 {
  37         /* FIXME: Need to look up userspace_pid by cpu */
  38         return userspace_pid[0];
  39 }
  40
  41 int pid_to_processor_id(int pid)
  42 {
  43         int i;
  44
  45         for (i = 0; i < ncpus; i++) {
  46                 if (cpu_tasks[i].pid == pid)
  47                         return i;
  48         }
  49         return -1;
  50 }
  51
  52 void free_stack(unsigned long stack, int order)
  53 {
  54         free_pages(stack, order);
  55 }
  56
  57 unsigned long alloc_stack(int order, int atomic)
  58 {
  59         unsigned long page;
  60         gfp_t flags = GFP_KERNEL;
  61
  62         if (atomic)
  63                 flags = GFP_ATOMIC;
  64         page = __get_free_pages(flags, order);
  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 });
  84 }
  85
  86 extern void arch_switch_to(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);
 103
 104                 if (current->thread.saved_task)
 105                         show_regs(&(current->thread.regs));
 106                 to = current->thread.saved_task;
 107                 from = 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
 167         schedule_tail(current->thread.prev_sched);
 168
 169         /*
 170          * XXX: if interrupt_end() calls schedule, this call to
 171          * arch_switch_to isn't needed. We could want to apply this to
 172          * improve performance. -bb
 173          */
 174         arch_switch_to(current);
 175
 176         current->thread.prev_sched = NULL;
 177
 178         /* Handle any immediate reschedules or signals */
 179         interrupt_end();
 180
 181         userspace(&current->thread.regs.regs);
 182 }
 183
 184 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
 185                 unsigned long stack_top, struct task_struct * p,
 186                 struct pt_regs *regs)
 187 {
 188         void (*handler)(void);
 189         int ret = 0;
 190
 191         p->thread = (struct thread_struct) INIT_THREAD;
 192
 193         if (current->thread.forking) {
 194                 memcpy(&p->thread.regs.regs, &regs->regs,
 195                        sizeof(p->thread.regs.regs));
 196                 REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.gp, 0);
 197                 if (sp != 0)
 198                         REGS_SP(p->thread.regs.regs.gp) = sp;
 199
 200                 handler = fork_handler;
 201
 202                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
 203         }
 204         else {
 205                 get_safe_registers(p->thread.regs.regs.gp);
 206                 p->thread.request.u.thread = current->thread.request.u.thread;
 207                 handler = new_thread_handler;
 208         }
 209
 210         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
 211
 212         if (current->thread.forking) {
 213                 clear_flushed_tls(p);
 214
 215                 /*
 216                  * Set a new TLS for the child thread?
 217                  */
 218                 if (clone_flags & CLONE_SETTLS)
 219                         ret = arch_copy_tls(p);
 220         }
 221
 222         return ret;
 223 }
 224
 225 void initial_thread_cb(void (*proc)(void *), void *arg)
 226 {
 227         int save_kmalloc_ok = kmalloc_ok;
 228
 229         kmalloc_ok = 0;
 230         initial_thread_cb_skas(proc, arg);
 231         kmalloc_ok = save_kmalloc_ok;
 232 }
 233
 234 void default_idle(void)
 235 {
 236         unsigned long long nsecs;
 237
 238         while (1) {
 239                 /* endless idle loop with no priority at all */
 240
 241                 /*
 242                  * although we are an idle CPU, we do not want to
 243                  * get into the scheduler unnecessarily.
 244                  */
 245                 if (need_resched())
 246                         schedule();
 247
 248                 tick_nohz_stop_sched_tick();
 249                 nsecs = disable_timer();
 250                 idle_sleep(nsecs);
 251                 tick_nohz_restart_sched_tick();
 252         }
 253 }
 254
 255 void cpu_idle(void)
 256 {
 257         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 258         default_idle();
 259 }
 260
 261 int __cant_sleep(void) {
 262         return in_atomic() || irqs_disabled() || in_interrupt();
 263         /* Is in_interrupt() really needed? */
 264 }
 265
 266 int user_context(unsigned long sp)
 267 {
 268         unsigned long stack;
 269
 270         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 271         return stack != (unsigned long) current_thread_info();
 272 }
 273
 274 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 275
 276 void do_uml_exitcalls(void)
 277 {
 278         exitcall_t *call;
 279
 280         call = &__uml_exitcall_end;
 281         while (--call >= &__uml_exitcall_begin)
 282                 (*call)();
 283 }
 284
 285 char *uml_strdup(const char *string)
 286 {
 287         return kstrdup(string, GFP_KERNEL);
 288 }
 289
 290 int copy_to_user_proc(void __user *to, void *from, int size)
 291 {
 292         return copy_to_user(to, from, size);
 293 }
 294
 295 int copy_from_user_proc(void *to, void __user *from, int size)
 296 {
 297         return copy_from_user(to, from, size);
 298 }
 299
 300 int clear_user_proc(void __user *buf, int size)
 301 {
 302         return clear_user(buf, size);
 303 }
 304
 305 int strlen_user_proc(char __user *str)
 306 {
 307         return strlen_user(str);
 308 }
 309
 310 int smp_sigio_handler(void)
 311 {
 312 #ifdef CONFIG_SMP
 313         int cpu = current_thread_info()->cpu;
 314         IPI_handler(cpu);
 315         if (cpu != 0)
 316                 return 1;
 317 #endif
 318         return 0;
 319 }
 320
 321 int cpu(void)
 322 {
 323         return current_thread_info()->cpu;
 324 }
 325
 326 static atomic_t using_sysemu = ATOMIC_INIT(0);
 327 int sysemu_supported;
 328
 329 void set_using_sysemu(int value)
 330 {
 331         if (value > sysemu_supported)
 332                 return;
 333         atomic_set(&using_sysemu, value);
 334 }
 335
 336 int get_using_sysemu(void)
 337 {
 338         return atomic_read(&using_sysemu);
 339 }
 340
 341 static int proc_read_sysemu(char *buf, char **start, off_t offset, int size,int *eof, void *data)
 342 {
 343         if (snprintf(buf, size, "%d\n", get_using_sysemu()) < size)
 344                 /* No overflow */
 345                 *eof = 1;
 346
 347         return strlen(buf);
 348 }
 349
 350 static int proc_write_sysemu(struct file *file,const char __user *buf, unsigned long count,void *data)
 351 {
 352         char tmp[2];
 353
 354         if (copy_from_user(tmp, buf, 1))
 355                 return -EFAULT;
 356
 357         if (tmp[0] >= '0' && tmp[0] <= '2')
 358                 set_using_sysemu(tmp[0] - '0');
 359         /* We use the first char, but pretend to write everything */
 360         return count;
 361 }
 362
 363 int __init make_proc_sysemu(void)
 364 {
 365         struct proc_dir_entry *ent;
 366         if (!sysemu_supported)
 367                 return 0;
 368
 369         ent = create_proc_entry("sysemu", 0600, &proc_root);
 370
 371         if (ent == NULL)
 372         {
 373                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 374                 return 0;
 375         }
 376
 377         ent->read_proc  = proc_read_sysemu;
 378         ent->write_proc = proc_write_sysemu;
 379
 380         return 0;
 381 }
 382
 383 late_initcall(make_proc_sysemu);
 384
 385 int singlestepping(void * t)
 386 {
 387         struct task_struct *task = t ? t : current;
 388
 389         if (!(task->ptrace & PT_DTRACE))
 390                 return 0;
 391
 392         if (task->thread.singlestep_syscall)
 393                 return 1;
 394
 395         return 2;
 396 }
 397
 398 /*
 399  * Only x86 and x86_64 have an arch_align_stack().
 400  * All other arches have "#define arch_align_stack(x) (x)"
 401  * in their asm/system.h
 402  * As this is included in UML from asm-um/system-generic.h,
 403  * we can use it to behave as the subarch does.
 404  */
 405 #ifndef arch_align_stack
 406 unsigned long arch_align_stack(unsigned long sp)
 407 {
 408         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 409                 sp -= get_random_int() % 8192;
 410         return sp & ~0xf;
 411 }
 412 #endif
 413
 414 unsigned long get_wchan(struct task_struct *p)
 415 {
 416         unsigned long stack_page, sp, ip;
 417         bool seen_sched = 0;
 418
 419         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 420                 return 0;
 421
 422         stack_page = (unsigned long) task_stack_page(p);
 423         /* Bail if the process has no kernel stack for some reason */
 424         if (stack_page == 0)
 425                 return 0;
 426
 427         sp = p->thread.switch_buf->JB_SP;
 428         /*
 429          * Bail if the stack pointer is below the bottom of the kernel
 430          * stack for some reason
 431          */
 432         if (sp < stack_page)
 433                 return 0;
 434
 435         while (sp < stack_page + THREAD_SIZE) {
 436                 ip = *((unsigned long *) sp);
 437                 if (in_sched_functions(ip))
 438                         /* Ignore everything until we're above the scheduler */
 439                         seen_sched = 1;
 440                 else if (kernel_text_address(ip) && seen_sched)
 441                         return ip;
 442
 443                 sp += sizeof(unsigned long);
 444         }
 445
 446         return 0;
 447 }
 448
 449 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 450 {
 451         int cpu = current_thread_info()->cpu;
 452
 453         return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
 454 }
 455