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