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         /* 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
  82 static inline void set_current(struct task_struct *task)
  83 {
  84         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
  85                 { external_pid(), task });
  86 }
  87
  88 extern void arch_switch_to(struct task_struct *to);
  89
  90 void *_switch_to(void *prev, void *next, void *last)
  91 {
  92         struct task_struct *from = prev;
  93         struct task_struct *to = next;
  94
  95         to->thread.prev_sched = from;
  96         set_current(to);
  97
  98         do {
  99                 current->thread.saved_task = NULL;
 100
 101                 switch_threads(&from->thread.switch_buf,
 102                                &to->thread.switch_buf);
 103
 104                 arch_switch_to(current);
 105
 106                 if (current->thread.saved_task)
 107                         show_regs(&(current->thread.regs));
 108                 to = current->thread.saved_task;
 109                 from = current;
 110         } while (current->thread.saved_task);
 111
 112         return current->thread.prev_sched;
 113
 114 }
 115
 116 void interrupt_end(void)
 117 {
 118         if (need_resched())
 119                 schedule();
 120         if (test_tsk_thread_flag(current, TIF_SIGPENDING))
 121                 do_signal();
 122 }
 123
 124 void exit_thread(void)
 125 {
 126 }
 127
 128 void *get_current(void)
 129 {
 130         return 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                 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(1);
 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 sysemu_proc_show(struct seq_file *m, void *v)
 342 {
 343         seq_printf(m, "%d\n", get_using_sysemu());
 344         return 0;
 345 }
 346
 347 static int sysemu_proc_open(struct inode *inode, struct file *file)
 348 {
 349         return single_open(file, sysemu_proc_show, NULL);
 350 }
 351
 352 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 353                                  size_t count, loff_t *pos)
 354 {
 355         char tmp[2];
 356
 357         if (copy_from_user(tmp, buf, 1))
 358                 return -EFAULT;
 359
 360         if (tmp[0] >= '0' && tmp[0] <= '2')
 361                 set_using_sysemu(tmp[0] - '0');
 362         /* We use the first char, but pretend to write everything */
 363         return count;
 364 }
 365
 366 static const struct file_operations sysemu_proc_fops = {
 367         .owner          = THIS_MODULE,
 368         .open           = sysemu_proc_open,
 369         .read           = seq_read,
 370         .llseek         = seq_lseek,
 371         .release        = single_release,
 372         .write          = sysemu_proc_write,
 373 };
 374
 375 int __init make_proc_sysemu(void)
 376 {
 377         struct proc_dir_entry *ent;
 378         if (!sysemu_supported)
 379                 return 0;
 380
 381         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
 382
 383         if (ent == NULL)
 384         {
 385                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 386                 return 0;
 387         }
 388
 389         return 0;
 390 }
 391
 392 late_initcall(make_proc_sysemu);
 393
 394 int singlestepping(void * t)
 395 {
 396         struct task_struct *task = t ? t : current;
 397
 398         if (!(task->ptrace & PT_DTRACE))
 399                 return 0;
 400
 401         if (task->thread.singlestep_syscall)
 402                 return 1;
 403
 404         return 2;
 405 }
 406
 407 /*
 408  * Only x86 and x86_64 have an arch_align_stack().
 409  * All other arches have "#define arch_align_stack(x) (x)"
 410  * in their asm/system.h
 411  * As this is included in UML from asm-um/system-generic.h,
 412  * we can use it to behave as the subarch does.
 413  */
 414 #ifndef arch_align_stack
 415 unsigned long arch_align_stack(unsigned long sp)
 416 {
 417         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 418                 sp -= get_random_int() % 8192;
 419         return sp & ~0xf;
 420 }
 421 #endif
 422
 423 unsigned long get_wchan(struct task_struct *p)
 424 {
 425         unsigned long stack_page, sp, ip;
 426         bool seen_sched = 0;
 427
 428         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 429                 return 0;
 430
 431         stack_page = (unsigned long) task_stack_page(p);
 432         /* Bail if the process has no kernel stack for some reason */
 433         if (stack_page == 0)
 434                 return 0;
 435
 436         sp = p->thread.switch_buf->JB_SP;
 437         /*
 438          * Bail if the stack pointer is below the bottom of the kernel
 439          * stack for some reason
 440          */
 441         if (sp < stack_page)
 442                 return 0;
 443
 444         while (sp < stack_page + THREAD_SIZE) {
 445                 ip = *((unsigned long *) sp);
 446                 if (in_sched_functions(ip))
 447                         /* Ignore everything until we're above the scheduler */
 448                         seen_sched = 1;
 449                 else if (kernel_text_address(ip) && seen_sched)
 450                         return ip;
 451
 452                 sp += sizeof(unsigned long);
 453         }
 454
 455         return 0;
 456 }
 457
 458 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 459 {
 460         int cpu = current_thread_info()->cpu;
 461
 462         return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
 463 }
 464