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 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
  73 {
  74         int pid;
  75
  76         current->thread.request.u.thread.proc = fn;
  77         current->thread.request.u.thread.arg = arg;
  78         pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
  79                       &current->thread.regs, 0, NULL, NULL);
  80         return pid;
  81 }
  82 EXPORT_SYMBOL(kernel_thread);
  83
  84 static inline void set_current(struct task_struct *task)
  85 {
  86         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
  87                 { external_pid(), task });
  88 }
  89
  90 extern void arch_switch_to(struct task_struct *to);
  91
  92 void *__switch_to(struct task_struct *from, struct task_struct *to)
  93 {
  94         to->thread.prev_sched = from;
  95         set_current(to);
  96
  97         do {
  98                 current->thread.saved_task = NULL;
  99
 100                 switch_threads(&from->thread.switch_buf,
 101                                &to->thread.switch_buf);
 102
 103                 arch_switch_to(current);
 104
 105                 if (current->thread.saved_task)
 106                         show_regs(&(current->thread.regs));
 107                 to = current->thread.saved_task;
 108                 from = current;
 109         } while (current->thread.saved_task);
 110
 111         return current->thread.prev_sched;
 112 }
 113
 114 void interrupt_end(void)
 115 {
 116         if (need_resched())
 117                 schedule();
 118         if (test_thread_flag(TIF_SIGPENDING))
 119                 do_signal();
 120         if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
 121                 tracehook_notify_resume(&current->thread.regs);
 122 }
 123
 124 void exit_thread(void)
 125 {
 126 }
 127
 128 int get_current_pid(void)
 129 {
 130         return task_pid_nr(current);
 131 }
 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(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                 UPT_SET_SYSCALL_RETURN(&p->thread.regs.regs, 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, p->thread.regs.regs.fp);
 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_idle_enter();
 249                 rcu_idle_enter();
 250                 nsecs = disable_timer();
 251                 idle_sleep(nsecs);
 252                 rcu_idle_exit();
 253                 tick_nohz_idle_exit();
 254         }
 255 }
 256
 257 void cpu_idle(void)
 258 {
 259         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 260         default_idle();
 261 }
 262
 263 int __cant_sleep(void) {
 264         return in_atomic() || irqs_disabled() || in_interrupt();
 265         /* Is in_interrupt() really needed? */
 266 }
 267
 268 int user_context(unsigned long sp)
 269 {
 270         unsigned long stack;
 271
 272         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 273         return stack != (unsigned long) current_thread_info();
 274 }
 275
 276 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 277
 278 void do_uml_exitcalls(void)
 279 {
 280         exitcall_t *call;
 281
 282         call = &__uml_exitcall_end;
 283         while (--call >= &__uml_exitcall_begin)
 284                 (*call)();
 285 }
 286
 287 char *uml_strdup(const char *string)
 288 {
 289         return kstrdup(string, GFP_KERNEL);
 290 }
 291 EXPORT_SYMBOL(uml_strdup);
 292
 293 int copy_to_user_proc(void __user *to, void *from, int size)
 294 {
 295         return copy_to_user(to, from, size);
 296 }
 297
 298 int copy_from_user_proc(void *to, void __user *from, int size)
 299 {
 300         return copy_from_user(to, from, size);
 301 }
 302
 303 int clear_user_proc(void __user *buf, int size)
 304 {
 305         return clear_user(buf, size);
 306 }
 307
 308 int strlen_user_proc(char __user *str)
 309 {
 310         return strlen_user(str);
 311 }
 312
 313 int smp_sigio_handler(void)
 314 {
 315 #ifdef CONFIG_SMP
 316         int cpu = current_thread_info()->cpu;
 317         IPI_handler(cpu);
 318         if (cpu != 0)
 319                 return 1;
 320 #endif
 321         return 0;
 322 }
 323
 324 int cpu(void)
 325 {
 326         return current_thread_info()->cpu;
 327 }
 328
 329 static atomic_t using_sysemu = ATOMIC_INIT(0);
 330 int sysemu_supported;
 331
 332 void set_using_sysemu(int value)
 333 {
 334         if (value > sysemu_supported)
 335                 return;
 336         atomic_set(&using_sysemu, value);
 337 }
 338
 339 int get_using_sysemu(void)
 340 {
 341         return atomic_read(&using_sysemu);
 342 }
 343
 344 static int sysemu_proc_show(struct seq_file *m, void *v)
 345 {
 346         seq_printf(m, "%d\n", get_using_sysemu());
 347         return 0;
 348 }
 349
 350 static int sysemu_proc_open(struct inode *inode, struct file *file)
 351 {
 352         return single_open(file, sysemu_proc_show, NULL);
 353 }
 354
 355 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 356                                  size_t count, loff_t *pos)
 357 {
 358         char tmp[2];
 359
 360         if (copy_from_user(tmp, buf, 1))
 361                 return -EFAULT;
 362
 363         if (tmp[0] >= '0' && tmp[0] <= '2')
 364                 set_using_sysemu(tmp[0] - '0');
 365         /* We use the first char, but pretend to write everything */
 366         return count;
 367 }
 368
 369 static const struct file_operations sysemu_proc_fops = {
 370         .owner          = THIS_MODULE,
 371         .open           = sysemu_proc_open,
 372         .read           = seq_read,
 373         .llseek         = seq_lseek,
 374         .release        = single_release,
 375         .write          = sysemu_proc_write,
 376 };
 377
 378 int __init make_proc_sysemu(void)
 379 {
 380         struct proc_dir_entry *ent;
 381         if (!sysemu_supported)
 382                 return 0;
 383
 384         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
 385
 386         if (ent == NULL)
 387         {
 388                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 389                 return 0;
 390         }
 391
 392         return 0;
 393 }
 394
 395 late_initcall(make_proc_sysemu);
 396
 397 int singlestepping(void * t)
 398 {
 399         struct task_struct *task = t ? t : current;
 400
 401         if (!(task->ptrace & PT_DTRACE))
 402                 return 0;
 403
 404         if (task->thread.singlestep_syscall)
 405                 return 1;
 406
 407         return 2;
 408 }
 409
 410 /*
 411  * Only x86 and x86_64 have an arch_align_stack().
 412  * All other arches have "#define arch_align_stack(x) (x)"
 413  * in their asm/system.h
 414  * As this is included in UML from asm-um/system-generic.h,
 415  * we can use it to behave as the subarch does.
 416  */
 417 #ifndef arch_align_stack
 418 unsigned long arch_align_stack(unsigned long sp)
 419 {
 420         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 421                 sp -= get_random_int() % 8192;
 422         return sp & ~0xf;
 423 }
 424 #endif
 425
 426 unsigned long get_wchan(struct task_struct *p)
 427 {
 428         unsigned long stack_page, sp, ip;
 429         bool seen_sched = 0;
 430
 431         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 432                 return 0;
 433
 434         stack_page = (unsigned long) task_stack_page(p);
 435         /* Bail if the process has no kernel stack for some reason */
 436         if (stack_page == 0)
 437                 return 0;
 438
 439         sp = p->thread.switch_buf->JB_SP;
 440         /*
 441          * Bail if the stack pointer is below the bottom of the kernel
 442          * stack for some reason
 443          */
 444         if (sp < stack_page)
 445                 return 0;
 446
 447         while (sp < stack_page + THREAD_SIZE) {
 448                 ip = *((unsigned long *) sp);
 449                 if (in_sched_functions(ip))
 450                         /* Ignore everything until we're above the scheduler */
 451                         seen_sched = 1;
 452                 else if (kernel_text_address(ip) && seen_sched)
 453                         return ip;
 454
 455                 sp += sizeof(unsigned long);
 456         }
 457
 458         return 0;
 459 }
 460
 461 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 462 {
 463         int cpu = current_thread_info()->cpu;
 464
 465         return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
 466 }
 467