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