arch/um/kernel/process.c

   1 /*
   2  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
   3  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
   4  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   5  * Copyright 2003 PathScale, Inc.
   6  * Licensed under the GPL
   7  */
   8
   9 #include <linux/stddef.h>
  10 #include <linux/err.h>
  11 #include <linux/hardirq.h>
  12 #include <linux/mm.h>
  13 #include <linux/module.h>
  14 #include <linux/personality.h>
  15 #include <linux/proc_fs.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/random.h>
  18 #include <linux/slab.h>
  19 #include <linux/sched.h>
  20 #include <linux/seq_file.h>
  21 #include <linux/tick.h>
  22 #include <linux/threads.h>
  23 #include <linux/tracehook.h>
  24 #include <asm/current.h>
  25 #include <asm/pgtable.h>
  26 #include <asm/mmu_context.h>
  27 #include <asm/uaccess.h>
  28 #include <as-layout.h>
  29 #include <kern_util.h>
  30 #include <os.h>
  31 #include <skas.h>
  32 #include <timer-internal.h>
  33
  34 /*
  35  * This is a per-cpu array.  A processor only modifies its entry and it only
  36  * cares about its entry, so it's OK if another processor is modifying its
  37  * entry.
  38  */
  39 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
  40
  41 static inline int external_pid(void)
  42 {
  43         /* FIXME: Need to look up userspace_pid by cpu */
  44         return userspace_pid[0];
  45 }
  46
  47 int pid_to_processor_id(int pid)
  48 {
  49         int i;
  50
  51         for (i = 0; i < ncpus; i++) {
  52                 if (cpu_tasks[i].pid == pid)
  53                         return i;
  54         }
  55         return -1;
  56 }
  57
  58 void free_stack(unsigned long stack, int order)
  59 {
  60         free_pages(stack, order);
  61 }
  62
  63 unsigned long alloc_stack(int order, int atomic)
  64 {
  65         unsigned long page;
  66         gfp_t flags = GFP_KERNEL;
  67
  68         if (atomic)
  69                 flags = GFP_ATOMIC;
  70         page = __get_free_pages(flags, order);
  71
  72         return page;
  73 }
  74
  75 static inline void set_current(struct task_struct *task)
  76 {
  77         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
  78                 { external_pid(), task });
  79 }
  80
  81 extern void arch_switch_to(struct task_struct *to);
  82
  83 void *__switch_to(struct task_struct *from, struct task_struct *to)
  84 {
  85         to->thread.prev_sched = from;
  86         set_current(to);
  87
  88         switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
  89         arch_switch_to(current);
  90
  91         return current->thread.prev_sched;
  92 }
  93
  94 void interrupt_end(void)
  95 {
  96         struct pt_regs *regs = &current->thread.regs;
  97
  98         if (need_resched())
  99                 schedule();
 100         if (test_thread_flag(TIF_SIGPENDING))
 101                 do_signal(regs);
 102         if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
 103                 tracehook_notify_resume(regs);
 104 }
 105
 106 int get_current_pid(void)
 107 {
 108         return task_pid_nr(current);
 109 }
 110
 111 /*
 112  * This is called magically, by its address being stuffed in a jmp_buf
 113  * and being longjmp-d to.
 114  */
 115 void new_thread_handler(void)
 116 {
 117         int (*fn)(void *), n;
 118         void *arg;
 119
 120         if (current->thread.prev_sched != NULL)
 121                 schedule_tail(current->thread.prev_sched);
 122         current->thread.prev_sched = NULL;
 123
 124         fn = current->thread.request.u.thread.proc;
 125         arg = current->thread.request.u.thread.arg;
 126
 127         /*
 128          * callback returns only if the kernel thread execs a process
 129          */
 130         n = fn(arg);
 131         userspace(&current->thread.regs.regs);
 132 }
 133
 134 /* Called magically, see new_thread_handler above */
 135 void fork_handler(void)
 136 {
 137         force_flush_all();
 138
 139         schedule_tail(current->thread.prev_sched);
 140
 141         /*
 142          * XXX: if interrupt_end() calls schedule, this call to
 143          * arch_switch_to isn't needed. We could want to apply this to
 144          * improve performance. -bb
 145          */
 146         arch_switch_to(current);
 147
 148         current->thread.prev_sched = NULL;
 149
 150         userspace(&current->thread.regs.regs);
 151 }
 152
 153 int copy_thread(unsigned long clone_flags, unsigned long sp,
 154                 unsigned long arg, struct task_struct * p)
 155 {
 156         void (*handler)(void);
 157         int kthread = current->flags & PF_KTHREAD;
 158         int ret = 0;
 159
 160         p->thread = (struct thread_struct) INIT_THREAD;
 161
 162         if (!kthread) {
 163                 memcpy(&p->thread.regs.regs, current_pt_regs(),
 164                        sizeof(p->thread.regs.regs));
 165                 PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
 166                 if (sp != 0)
 167                         REGS_SP(p->thread.regs.regs.gp) = sp;
 168
 169                 handler = fork_handler;
 170
 171                 arch_copy_thread(&current->thread.arch, &p->thread.arch);
 172         } else {
 173                 get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
 174                 p->thread.request.u.thread.proc = (int (*)(void *))sp;
 175                 p->thread.request.u.thread.arg = (void *)arg;
 176                 handler = new_thread_handler;
 177         }
 178
 179         new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
 180
 181         if (!kthread) {
 182                 clear_flushed_tls(p);
 183
 184                 /*
 185                  * Set a new TLS for the child thread?
 186                  */
 187                 if (clone_flags & CLONE_SETTLS)
 188                         ret = arch_copy_tls(p);
 189         }
 190
 191         return ret;
 192 }
 193
 194 void initial_thread_cb(void (*proc)(void *), void *arg)
 195 {
 196         int save_kmalloc_ok = kmalloc_ok;
 197
 198         kmalloc_ok = 0;
 199         initial_thread_cb_skas(proc, arg);
 200         kmalloc_ok = save_kmalloc_ok;
 201 }
 202
 203 void arch_cpu_idle(void)
 204 {
 205         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 206         os_idle_sleep(UM_NSEC_PER_SEC);
 207         local_irq_enable();
 208 }
 209
 210 int __cant_sleep(void) {
 211         return in_atomic() || irqs_disabled() || in_interrupt();
 212         /* Is in_interrupt() really needed? */
 213 }
 214
 215 int user_context(unsigned long sp)
 216 {
 217         unsigned long stack;
 218
 219         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 220         return stack != (unsigned long) current_thread_info();
 221 }
 222
 223 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 224
 225 void do_uml_exitcalls(void)
 226 {
 227         exitcall_t *call;
 228
 229         call = &__uml_exitcall_end;
 230         while (--call >= &__uml_exitcall_begin)
 231                 (*call)();
 232 }
 233
 234 char *uml_strdup(const char *string)
 235 {
 236         return kstrdup(string, GFP_KERNEL);
 237 }
 238 EXPORT_SYMBOL(uml_strdup);
 239
 240 int copy_to_user_proc(void __user *to, void *from, int size)
 241 {
 242         return copy_to_user(to, from, size);
 243 }
 244
 245 int copy_from_user_proc(void *to, void __user *from, int size)
 246 {
 247         return copy_from_user(to, from, size);
 248 }
 249
 250 int clear_user_proc(void __user *buf, int size)
 251 {
 252         return clear_user(buf, size);
 253 }
 254
 255 int strlen_user_proc(char __user *str)
 256 {
 257         return strlen_user(str);
 258 }
 259
 260 int cpu(void)
 261 {
 262         return current_thread_info()->cpu;
 263 }
 264
 265 static atomic_t using_sysemu = ATOMIC_INIT(0);
 266 int sysemu_supported;
 267
 268 void set_using_sysemu(int value)
 269 {
 270         if (value > sysemu_supported)
 271                 return;
 272         atomic_set(&using_sysemu, value);
 273 }
 274
 275 int get_using_sysemu(void)
 276 {
 277         return atomic_read(&using_sysemu);
 278 }
 279
 280 static int sysemu_proc_show(struct seq_file *m, void *v)
 281 {
 282         seq_printf(m, "%d\n", get_using_sysemu());
 283         return 0;
 284 }
 285
 286 static int sysemu_proc_open(struct inode *inode, struct file *file)
 287 {
 288         return single_open(file, sysemu_proc_show, NULL);
 289 }
 290
 291 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 292                                  size_t count, loff_t *pos)
 293 {
 294         char tmp[2];
 295
 296         if (copy_from_user(tmp, buf, 1))
 297                 return -EFAULT;
 298
 299         if (tmp[0] >= '0' && tmp[0] <= '2')
 300                 set_using_sysemu(tmp[0] - '0');
 301         /* We use the first char, but pretend to write everything */
 302         return count;
 303 }
 304
 305 static const struct file_operations sysemu_proc_fops = {
 306         .owner          = THIS_MODULE,
 307         .open           = sysemu_proc_open,
 308         .read           = seq_read,
 309         .llseek         = seq_lseek,
 310         .release        = single_release,
 311         .write          = sysemu_proc_write,
 312 };
 313
 314 int __init make_proc_sysemu(void)
 315 {
 316         struct proc_dir_entry *ent;
 317         if (!sysemu_supported)
 318                 return 0;
 319
 320         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
 321
 322         if (ent == NULL)
 323         {
 324                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 325                 return 0;
 326         }
 327
 328         return 0;
 329 }
 330
 331 late_initcall(make_proc_sysemu);
 332
 333 int singlestepping(void * t)
 334 {
 335         struct task_struct *task = t ? t : current;
 336
 337         if (!(task->ptrace & PT_DTRACE))
 338                 return 0;
 339
 340         if (task->thread.singlestep_syscall)
 341                 return 1;
 342
 343         return 2;
 344 }
 345
 346 /*
 347  * Only x86 and x86_64 have an arch_align_stack().
 348  * All other arches have "#define arch_align_stack(x) (x)"
 349  * in their asm/exec.h
 350  * As this is included in UML from asm-um/system-generic.h,
 351  * we can use it to behave as the subarch does.
 352  */
 353 #ifndef arch_align_stack
 354 unsigned long arch_align_stack(unsigned long sp)
 355 {
 356         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 357                 sp -= get_random_int() % 8192;
 358         return sp & ~0xf;
 359 }
 360 #endif
 361
 362 unsigned long get_wchan(struct task_struct *p)
 363 {
 364         unsigned long stack_page, sp, ip;
 365         bool seen_sched = 0;
 366
 367         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 368                 return 0;
 369
 370         stack_page = (unsigned long) task_stack_page(p);
 371         /* Bail if the process has no kernel stack for some reason */
 372         if (stack_page == 0)
 373                 return 0;
 374
 375         sp = p->thread.switch_buf->JB_SP;
 376         /*
 377          * Bail if the stack pointer is below the bottom of the kernel
 378          * stack for some reason
 379          */
 380         if (sp < stack_page)
 381                 return 0;
 382
 383         while (sp < stack_page + THREAD_SIZE) {
 384                 ip = *((unsigned long *) sp);
 385                 if (in_sched_functions(ip))
 386                         /* Ignore everything until we're above the scheduler */
 387                         seen_sched = 1;
 388                 else if (kernel_text_address(ip) && seen_sched)
 389                         return ip;
 390
 391                 sp += sizeof(unsigned long);
 392         }
 393
 394         return 0;
 395 }
 396
 397 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 398 {
 399         int cpu = current_thread_info()->cpu;
 400
 401         return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu);
 402 }
 403