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