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