release/src-rt-6.x.4708/linux/linux-2.6.36/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/uaccess.h>
  24 #include "as-layout.h"
  25 #include "kern_util.h"
  26 #include "os.h"
  27 #include "skas.h"
  28 #include "tlb.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         return userspace_pid[0];
  40 }
  41
  42 int pid_to_processor_id(int pid)
  43 {
  44         int i;
  45
  46         for (i = 0; i < ncpus; i++) {
  47                 if (cpu_tasks[i].pid == pid)
  48                         return i;
  49         }
  50         return -1;
  51 }
  52
  53 void free_stack(unsigned long stack, int order)
  54 {
  55         free_pages(stack, order);
  56 }
  57
  58 unsigned long alloc_stack(int order, int atomic)
  59 {
  60         unsigned long page;
  61         gfp_t flags = GFP_KERNEL;
  62
  63         if (atomic)
  64                 flags = GFP_ATOMIC;
  65         page = __get_free_pages(flags, order);
  66
  67         return page;
  68 }
  69
  70 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
  71 {
  72         int pid;
  73
  74         current->thread.request.u.thread.proc = fn;
  75         current->thread.request.u.thread.arg = arg;
  76         pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
  77                       &current->thread.regs, 0, NULL, NULL);
  78         return pid;
  79 }
  80
  81 static inline void set_current(struct task_struct *task)
  82 {
  83         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
  84                 { external_pid(), task });
  85 }
  86
  87 extern void arch_switch_to(struct task_struct *to);
  88
  89 void *_switch_to(void *prev, void *next, void *last)
  90 {
  91         struct task_struct *from = prev;
  92         struct task_struct *to = next;
  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
 115 void interrupt_end(void)
 116 {
 117         if (need_resched())
 118                 schedule();
 119         if (test_tsk_thread_flag(current, TIF_SIGPENDING))
 120                 do_signal();
 121 }
 122
 123 void exit_thread(void)
 124 {
 125 }
 126
 127 void *get_current(void)
 128 {
 129         return current;
 130 }
 131
 132 /*
 133  * This is called magically, by its address being stuffed in a jmp_buf
 134  * and being longjmp-d to.
 135  */
 136 void new_thread_handler(void)
 137 {
 138         int (*fn)(void *), n;
 139         void *arg;
 140
 141         if (current->thread.prev_sched != NULL)
 142                 schedule_tail(current->thread.prev_sched);
 143         current->thread.prev_sched = NULL;
 144
 145         fn = current->thread.request.u.thread.proc;
 146         arg = current->thread.request.u.thread.arg;
 147
 148         /*
 149          * The return value is 1 if the kernel thread execs a process,
 150          * 0 if it just exits
 151          */
 152         n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
 153         if (n == 1) {
 154                 /* Handle any immediate reschedules or signals */
 155                 interrupt_end();
 156                 userspace(&current->thread.regs.regs);
 157         }
 158         else do_exit(0);
 159 }
 160
 161 /* Called magically, see new_thread_handler above */
 162 void fork_handler(void)
 163 {
 164         force_flush_all();
 165
 166         schedule_tail(current->thread.prev_sched);
 167
 168         arch_switch_to(current);
 169
 170         current->thread.prev_sched = NULL;
 171
 172         /* Handle any immediate reschedules or signals */
 173         interrupt_end();
 174
 175         userspace(&current->thread.regs.regs);
 176 }
 177
 178 int copy_thread(unsigned long clone_flags, unsigned long sp,
 179                 unsigned long stack_top, struct task_struct * p,
 180                 struct pt_regs *regs)
 181 {
 182         void (*handler)(void);
 183         int ret = 0;
 184
 185         p->thread = (struct thread_struct) INIT_THREAD;
 186
 187         if (current->thread.forking) {
 188                 memcpy(&p->thread.regs.regs, &regs->regs,
 189                        sizeof(p->thread.regs.regs));
 190                 REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.gp, 0);
 191                 if (sp != 0)
 192                         REGS_SP(p->thread.regs.regs.gp) = sp;
 193
 194                 handler = fork_handler;
 195
 196                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
 197         }
 198         else {
 199                 get_safe_registers(p->thread.regs.regs.gp);
 200                 p->thread.request.u.thread = current->thread.request.u.thread;
 201                 handler = new_thread_handler;
 202         }
 203
 204         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
 205
 206         if (current->thread.forking) {
 207                 clear_flushed_tls(p);
 208
 209                 /*
 210                  * Set a new TLS for the child thread?
 211                  */
 212                 if (clone_flags & CLONE_SETTLS)
 213                         ret = arch_copy_tls(p);
 214         }
 215
 216         return ret;
 217 }
 218
 219 void initial_thread_cb(void (*proc)(void *), void *arg)
 220 {
 221         int save_kmalloc_ok = kmalloc_ok;
 222
 223         kmalloc_ok = 0;
 224         initial_thread_cb_skas(proc, arg);
 225         kmalloc_ok = save_kmalloc_ok;
 226 }
 227
 228 void default_idle(void)
 229 {
 230         unsigned long long nsecs;
 231
 232         while (1) {
 233                 /* endless idle loop with no priority at all */
 234
 235                 /*
 236                  * although we are an idle CPU, we do not want to
 237                  * get into the scheduler unnecessarily.
 238                  */
 239                 if (need_resched())
 240                         schedule();
 241
 242                 tick_nohz_stop_sched_tick(1);
 243                 nsecs = disable_timer();
 244                 idle_sleep(nsecs);
 245                 tick_nohz_restart_sched_tick();
 246         }
 247 }
 248
 249 void cpu_idle(void)
 250 {
 251         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 252         default_idle();
 253 }
 254
 255 int __cant_sleep(void) {
 256         return in_atomic() || irqs_disabled() || in_interrupt();
 257         /* Is in_interrupt() really needed? */
 258 }
 259
 260 int user_context(unsigned long sp)
 261 {
 262         unsigned long stack;
 263
 264         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 265         return stack != (unsigned long) current_thread_info();
 266 }
 267
 268 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 269
 270 void do_uml_exitcalls(void)
 271 {
 272         exitcall_t *call;
 273
 274         call = &__uml_exitcall_end;
 275         while (--call >= &__uml_exitcall_begin)
 276                 (*call)();
 277 }
 278
 279 char *uml_strdup(const char *string)
 280 {
 281         return kstrdup(string, GFP_KERNEL);
 282 }
 283
 284 int copy_to_user_proc(void __user *to, void *from, int size)
 285 {
 286         return copy_to_user(to, from, size);
 287 }
 288
 289 int copy_from_user_proc(void *to, void __user *from, int size)
 290 {
 291         return copy_from_user(to, from, size);
 292 }
 293
 294 int clear_user_proc(void __user *buf, int size)
 295 {
 296         return clear_user(buf, size);
 297 }
 298
 299 int strlen_user_proc(char __user *str)
 300 {
 301         return strlen_user(str);
 302 }
 303
 304 int smp_sigio_handler(void)
 305 {
 306 #ifdef CONFIG_SMP
 307         int cpu = current_thread_info()->cpu;
 308         IPI_handler(cpu);
 309         if (cpu != 0)
 310                 return 1;
 311 #endif
 312         return 0;
 313 }
 314
 315 int cpu(void)
 316 {
 317         return current_thread_info()->cpu;
 318 }
 319
 320 static atomic_t using_sysemu = ATOMIC_INIT(0);
 321 int sysemu_supported;
 322
 323 void set_using_sysemu(int value)
 324 {
 325         if (value > sysemu_supported)
 326                 return;
 327         atomic_set(&using_sysemu, value);
 328 }
 329
 330 int get_using_sysemu(void)
 331 {
 332         return atomic_read(&using_sysemu);
 333 }
 334
 335 static int sysemu_proc_show(struct seq_file *m, void *v)
 336 {
 337         seq_printf(m, "%d\n", get_using_sysemu());
 338         return 0;
 339 }
 340
 341 static int sysemu_proc_open(struct inode *inode, struct file *file)
 342 {
 343         return single_open(file, sysemu_proc_show, NULL);
 344 }
 345
 346 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 347                                  size_t count, loff_t *pos)
 348 {
 349         char tmp[2];
 350
 351         if (copy_from_user(tmp, buf, 1))
 352                 return -EFAULT;
 353
 354         if (tmp[0] >= '0' && tmp[0] <= '2')
 355                 set_using_sysemu(tmp[0] - '0');
 356         /* We use the first char, but pretend to write everything */
 357         return count;
 358 }
 359
 360 static const struct file_operations sysemu_proc_fops = {
 361         .owner          = THIS_MODULE,
 362         .open           = sysemu_proc_open,
 363         .read           = seq_read,
 364         .llseek         = seq_lseek,
 365         .release        = single_release,
 366         .write          = sysemu_proc_write,
 367 };
 368
 369 int __init make_proc_sysemu(void)
 370 {
 371         struct proc_dir_entry *ent;
 372         if (!sysemu_supported)
 373                 return 0;
 374
 375         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
 376
 377         if (ent == NULL)
 378         {
 379                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 380                 return 0;
 381         }
 382
 383         return 0;
 384 }
 385
 386 late_initcall(make_proc_sysemu);
 387
 388 int singlestepping(void * t)
 389 {
 390         struct task_struct *task = t ? t : current;
 391
 392         if (!(task->ptrace & PT_DTRACE))
 393                 return 0;
 394
 395         if (task->thread.singlestep_syscall)
 396                 return 1;
 397
 398         return 2;
 399 }
 400
 401 /*
 402  * Only x86 and x86_64 have an arch_align_stack().
 403  * All other arches have "#define arch_align_stack(x) (x)"
 404  * in their asm/system.h
 405  * As this is included in UML from asm-um/system-generic.h,
 406  * we can use it to behave as the subarch does.
 407  */
 408 #ifndef arch_align_stack
 409 unsigned long arch_align_stack(unsigned long sp)
 410 {
 411         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 412                 sp -= get_random_int() % 8192;
 413         return sp & ~0xf;
 414 }
 415 #endif
 416
 417 unsigned long get_wchan(struct task_struct *p)
 418 {
 419         unsigned long stack_page, sp, ip;
 420         bool seen_sched = 0;
 421
 422         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 423                 return 0;
 424
 425         stack_page = (unsigned long) task_stack_page(p);
 426         /* Bail if the process has no kernel stack for some reason */
 427         if (stack_page == 0)
 428                 return 0;
 429
 430         sp = p->thread.switch_buf->JB_SP;
 431         /*
 432          * Bail if the stack pointer is below the bottom of the kernel
 433          * stack for some reason
 434          */
 435         if (sp < stack_page)
 436                 return 0;
 437
 438         while (sp < stack_page + THREAD_SIZE) {
 439                 ip = *((unsigned long *) sp);
 440                 if (in_sched_functions(ip))
 441                         /* Ignore everything until we're above the scheduler */
 442                         seen_sched = 1;
 443                 else if (kernel_text_address(ip) && seen_sched)
 444                         return ip;
 445
 446                 sp += sizeof(unsigned long);
 447         }
 448
 449         return 0;
 450 }
 451
 452 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 453 {
 454         int cpu = current_thread_info()->cpu;
 455
 456         return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
 457 }