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 <asm/current.h>
  22 #include <asm/pgtable.h>
  23 #include <asm/mmu_context.h>
  24 #include <asm/uaccess.h>
  25 #include "as-layout.h"
  26 #include "kern_util.h"
  27 #include "os.h"
  28 #include "skas.h"
  29
  30 /*
  31  * This is a per-cpu array.  A processor only modifies its entry and it only
  32  * cares about its entry, so it's OK if another processor is modifying its
  33  * entry.
  34  */
  35 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
  36
  37 static inline int external_pid(void)
  38 {
  39         /* FIXME: Need to look up userspace_pid by cpu */
  40         return userspace_pid[0];
  41 }
  42
  43 int pid_to_processor_id(int pid)
  44 {
  45         int i;
  46
  47         for (i = 0; i < ncpus; i++) {
  48                 if (cpu_tasks[i].pid == pid)
  49                         return i;
  50         }
  51         return -1;
  52 }
  53
  54 void free_stack(unsigned long stack, int order)
  55 {
  56         free_pages(stack, order);
  57 }
  58
  59 unsigned long alloc_stack(int order, int atomic)
  60 {
  61         unsigned long page;
  62         gfp_t flags = GFP_KERNEL;
  63
  64         if (atomic)
  65                 flags = GFP_ATOMIC;
  66         page = __get_free_pages(flags, order);
  67
  68         return page;
  69 }
  70
  71 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
  72 {
  73         int pid;
  74
  75         current->thread.request.u.thread.proc = fn;
  76         current->thread.request.u.thread.arg = arg;
  77         pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
  78                       &current->thread.regs, 0, NULL, NULL);
  79         return pid;
  80 }
  81 EXPORT_SYMBOL(kernel_thread);
  82
  83 static inline void set_current(struct task_struct *task)
  84 {
  85         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
  86                 { external_pid(), task });
  87 }
  88
  89 extern void arch_switch_to(struct task_struct *to);
  90
  91 void *_switch_to(void *prev, void *next, void *last)
  92 {
  93         struct task_struct *from = prev;
  94         struct task_struct *to = next;
  95
  96         to->thread.prev_sched = from;
  97         set_current(to);
  98
  99         do {
 100                 current->thread.saved_task = NULL;
 101
 102                 switch_threads(&from->thread.switch_buf,
 103                                &to->thread.switch_buf);
 104
 105                 arch_switch_to(current);
 106
 107                 if (current->thread.saved_task)
 108                         show_regs(&(current->thread.regs));
 109                 to = current->thread.saved_task;
 110                 from = current;
 111         } while (current->thread.saved_task);
 112
 113         return current->thread.prev_sched;
 114
 115 }
 116
 117 void interrupt_end(void)
 118 {
 119         if (need_resched())
 120                 schedule();
 121         if (test_tsk_thread_flag(current, TIF_SIGPENDING))
 122                 do_signal();
 123 }
 124
 125 void exit_thread(void)
 126 {
 127 }
 128
 129 int get_current_pid(void)
 130 {
 131         return task_pid_nr(current);
 132 }
 133
 134 /*
 135  * This is called magically, by its address being stuffed in a jmp_buf
 136  * and being longjmp-d to.
 137  */
 138 void new_thread_handler(void)
 139 {
 140         int (*fn)(void *), n;
 141         void *arg;
 142
 143         if (current->thread.prev_sched != NULL)
 144                 schedule_tail(current->thread.prev_sched);
 145         current->thread.prev_sched = NULL;
 146
 147         fn = current->thread.request.u.thread.proc;
 148         arg = current->thread.request.u.thread.arg;
 149
 150         /*
 151          * The return value is 1 if the kernel thread execs a process,
 152          * 0 if it just exits
 153          */
 154         n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
 155         if (n == 1) {
 156                 /* Handle any immediate reschedules or signals */
 157                 interrupt_end();
 158                 userspace(&current->thread.regs.regs);
 159         }
 160         else do_exit(0);
 161 }
 162
 163 /* Called magically, see new_thread_handler above */
 164 void fork_handler(void)
 165 {
 166         force_flush_all();
 167
 168         schedule_tail(current->thread.prev_sched);
 169
 170         /*
 171          * XXX: if interrupt_end() calls schedule, this call to
 172          * arch_switch_to isn't needed. We could want to apply this to
 173          * improve performance. -bb
 174          */
 175         arch_switch_to(current);
 176
 177         current->thread.prev_sched = NULL;
 178
 179         /* Handle any immediate reschedules or signals */
 180         interrupt_end();
 181
 182         userspace(&current->thread.regs.regs);
 183 }
 184
 185 int copy_thread(unsigned long clone_flags, unsigned long sp,
 186                 unsigned long stack_top, struct task_struct * p,
 187                 struct pt_regs *regs)
 188 {
 189         void (*handler)(void);
 190         int ret = 0;
 191
 192         p->thread = (struct thread_struct) INIT_THREAD;
 193
 194         if (current->thread.forking) {
 195                 memcpy(&p->thread.regs.regs, &regs->regs,
 196                        sizeof(p->thread.regs.regs));
 197                 REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.gp, 0);
 198                 if (sp != 0)
 199                         REGS_SP(p->thread.regs.regs.gp) = sp;
 200
 201                 handler = fork_handler;
 202
 203                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
 204         }
 205         else {
 206                 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
 207                 p->thread.request.u.thread = current->thread.request.u.thread;
 208                 handler = new_thread_handler;
 209         }
 210
 211         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
 212
 213         if (current->thread.forking) {
 214                 clear_flushed_tls(p);
 215
 216                 /*
 217                  * Set a new TLS for the child thread?
 218                  */
 219                 if (clone_flags & CLONE_SETTLS)
 220                         ret = arch_copy_tls(p);
 221         }
 222
 223         return ret;
 224 }
 225
 226 void initial_thread_cb(void (*proc)(void *), void *arg)
 227 {
 228         int save_kmalloc_ok = kmalloc_ok;
 229
 230         kmalloc_ok = 0;
 231         initial_thread_cb_skas(proc, arg);
 232         kmalloc_ok = save_kmalloc_ok;
 233 }
 234
 235 void default_idle(void)
 236 {
 237         unsigned long long nsecs;
 238
 239         while (1) {
 240                 /* endless idle loop with no priority at all */
 241
 242                 /*
 243                  * although we are an idle CPU, we do not want to
 244                  * get into the scheduler unnecessarily.
 245                  */
 246                 if (need_resched())
 247                         schedule();
 248
 249                 tick_nohz_idle_enter();
 250                 rcu_idle_enter();
 251                 nsecs = disable_timer();
 252                 idle_sleep(nsecs);
 253                 rcu_idle_exit();
 254                 tick_nohz_idle_exit();
 255         }
 256 }
 257
 258 void cpu_idle(void)
 259 {
 260         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 261         default_idle();
 262 }
 263
 264 int __cant_sleep(void) {
 265         return in_atomic() || irqs_disabled() || in_interrupt();
 266         /* Is in_interrupt() really needed? */
 267 }
 268
 269 int user_context(unsigned long sp)
 270 {
 271         unsigned long stack;
 272
 273         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 274         return stack != (unsigned long) current_thread_info();
 275 }
 276
 277 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 278
 279 void do_uml_exitcalls(void)
 280 {
 281         exitcall_t *call;
 282
 283         call = &__uml_exitcall_end;
 284         while (--call >= &__uml_exitcall_begin)
 285                 (*call)();
 286 }
 287
 288 char *uml_strdup(const char *string)
 289 {
 290         return kstrdup(string, GFP_KERNEL);
 291 }
 292 EXPORT_SYMBOL(uml_strdup);
 293
 294 int copy_to_user_proc(void __user *to, void *from, int size)
 295 {
 296         return copy_to_user(to, from, size);
 297 }
 298
 299 int copy_from_user_proc(void *to, void __user *from, int size)
 300 {
 301         return copy_from_user(to, from, size);
 302 }
 303
 304 int clear_user_proc(void __user *buf, int size)
 305 {
 306         return clear_user(buf, size);
 307 }
 308
 309 int strlen_user_proc(char __user *str)
 310 {
 311         return strlen_user(str);
 312 }
 313
 314 int smp_sigio_handler(void)
 315 {
 316 #ifdef CONFIG_SMP
 317         int cpu = current_thread_info()->cpu;
 318         IPI_handler(cpu);
 319         if (cpu != 0)
 320                 return 1;
 321 #endif
 322         return 0;
 323 }
 324
 325 int cpu(void)
 326 {
 327         return current_thread_info()->cpu;
 328 }
 329
 330 static atomic_t using_sysemu = ATOMIC_INIT(0);
 331 int sysemu_supported;
 332
 333 void set_using_sysemu(int value)
 334 {
 335         if (value > sysemu_supported)
 336                 return;
 337         atomic_set(&using_sysemu, value);
 338 }
 339
 340 int get_using_sysemu(void)
 341 {
 342         return atomic_read(&using_sysemu);
 343 }
 344
 345 static int sysemu_proc_show(struct seq_file *m, void *v)
 346 {
 347         seq_printf(m, "%d\n", get_using_sysemu());
 348         return 0;
 349 }
 350
 351 static int sysemu_proc_open(struct inode *inode, struct file *file)
 352 {
 353         return single_open(file, sysemu_proc_show, NULL);
 354 }
 355
 356 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 357                                  size_t count, loff_t *pos)
 358 {
 359         char tmp[2];
 360
 361         if (copy_from_user(tmp, buf, 1))
 362                 return -EFAULT;
 363
 364         if (tmp[0] >= '0' && tmp[0] <= '2')
 365                 set_using_sysemu(tmp[0] - '0');
 366         /* We use the first char, but pretend to write everything */
 367         return count;
 368 }
 369
 370 static const struct file_operations sysemu_proc_fops = {
 371         .owner          = THIS_MODULE,
 372         .open           = sysemu_proc_open,
 373         .read           = seq_read,
 374         .llseek         = seq_lseek,
 375         .release        = single_release,
 376         .write          = sysemu_proc_write,
 377 };
 378
 379 int __init make_proc_sysemu(void)
 380 {
 381         struct proc_dir_entry *ent;
 382         if (!sysemu_supported)
 383                 return 0;
 384
 385         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
 386
 387         if (ent == NULL)
 388         {
 389                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 390                 return 0;
 391         }
 392
 393         return 0;
 394 }
 395
 396 late_initcall(make_proc_sysemu);
 397
 398 int singlestepping(void * t)
 399 {
 400         struct task_struct *task = t ? t : current;
 401
 402         if (!(task->ptrace & PT_DTRACE))
 403                 return 0;
 404
 405         if (task->thread.singlestep_syscall)
 406                 return 1;
 407
 408         return 2;
 409 }
 410
 411 /*
 412  * Only x86 and x86_64 have an arch_align_stack().
 413  * All other arches have "#define arch_align_stack(x) (x)"
 414  * in their asm/system.h
 415  * As this is included in UML from asm-um/system-generic.h,
 416  * we can use it to behave as the subarch does.
 417  */
 418 #ifndef arch_align_stack
 419 unsigned long arch_align_stack(unsigned long sp)
 420 {
 421         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 422                 sp -= get_random_int() % 8192;
 423         return sp & ~0xf;
 424 }
 425 #endif
 426
 427 unsigned long get_wchan(struct task_struct *p)
 428 {
 429         unsigned long stack_page, sp, ip;
 430         bool seen_sched = 0;
 431
 432         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 433                 return 0;
 434
 435         stack_page = (unsigned long) task_stack_page(p);
 436         /* Bail if the process has no kernel stack for some reason */
 437         if (stack_page == 0)
 438                 return 0;
 439
 440         sp = p->thread.switch_buf->JB_SP;
 441         /*
 442          * Bail if the stack pointer is below the bottom of the kernel
 443          * stack for some reason
 444          */
 445         if (sp < stack_page)
 446                 return 0;
 447
 448         while (sp < stack_page + THREAD_SIZE) {
 449                 ip = *((unsigned long *) sp);
 450                 if (in_sched_functions(ip))
 451                         /* Ignore everything until we're above the scheduler */
 452                         seen_sched = 1;
 453                 else if (kernel_text_address(ip) && seen_sched)
 454                         return ip;
 455
 456                 sp += sizeof(unsigned long);
 457         }
 458
 459         return 0;
 460 }
 461
 462 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 463 {
 464         int cpu = current_thread_info()->cpu;
 465
 466         return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
 467 }
 468