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/sched/debug.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/tick.h>
  23 #include <linux/threads.h>
  24 #include <linux/tracehook.h>
  25 #include <asm/current.h>
  26 #include <asm/pgtable.h>
  27 #include <asm/mmu_context.h>
  28 #include <linux/uaccess.h>
  29 #include <as-layout.h>
  30 #include <kern_util.h>
  31 #include <os.h>
  32 #include <skas.h>
  33 #include <timer-internal.h>
  34
  35 /*
  36  * This is a per-cpu array.  A processor only modifies its entry and it only
  37  * cares about its entry, so it's OK if another processor is modifying its
  38  * entry.
  39  */
  40 struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
  41
  42 static inline int external_pid(void)
  43 {
  44         /* FIXME: Need to look up userspace_pid by cpu */
  45         return userspace_pid[0];
  46 }
  47
  48 int pid_to_processor_id(int pid)
  49 {
  50         int i;
  51
  52         for (i = 0; i < ncpus; i++) {
  53                 if (cpu_tasks[i].pid == pid)
  54                         return i;
  55         }
  56         return -1;
  57 }
  58
  59 void free_stack(unsigned long stack, int order)
  60 {
  61         free_pages(stack, order);
  62 }
  63
  64 unsigned long alloc_stack(int order, int atomic)
  65 {
  66         unsigned long page;
  67         gfp_t flags = GFP_KERNEL;
  68
  69         if (atomic)
  70                 flags = GFP_ATOMIC;
  71         page = __get_free_pages(flags, order);
  72
  73         return page;
  74 }
  75
  76 static inline void set_current(struct task_struct *task)
  77 {
  78         cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
  79                 { external_pid(), task });
  80 }
  81
  82 extern void arch_switch_to(struct task_struct *to);
  83
  84 void *__switch_to(struct task_struct *from, struct task_struct *to)
  85 {
  86         to->thread.prev_sched = from;
  87         set_current(to);
  88
  89         switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
  90         arch_switch_to(current);
  91
  92         return current->thread.prev_sched;
  93 }
  94
  95 void interrupt_end(void)
  96 {
  97         struct pt_regs *regs = &current->thread.regs;
  98
  99         if (need_resched())
 100                 schedule();
 101         if (test_thread_flag(TIF_SIGPENDING))
 102                 do_signal(regs);
 103         if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
 104                 tracehook_notify_resume(regs);
 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         cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 207         os_idle_sleep(UM_NSEC_PER_SEC);
 208         local_irq_enable();
 209 }
 210
 211 int __cant_sleep(void) {
 212         return in_atomic() || irqs_disabled() || in_interrupt();
 213         /* Is in_interrupt() really needed? */
 214 }
 215
 216 int user_context(unsigned long sp)
 217 {
 218         unsigned long stack;
 219
 220         stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 221         return stack != (unsigned long) current_thread_info();
 222 }
 223
 224 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 225
 226 void do_uml_exitcalls(void)
 227 {
 228         exitcall_t *call;
 229
 230         call = &__uml_exitcall_end;
 231         while (--call >= &__uml_exitcall_begin)
 232                 (*call)();
 233 }
 234
 235 char *uml_strdup(const char *string)
 236 {
 237         return kstrdup(string, GFP_KERNEL);
 238 }
 239 EXPORT_SYMBOL(uml_strdup);
 240
 241 int copy_to_user_proc(void __user *to, void *from, int size)
 242 {
 243         return copy_to_user(to, from, size);
 244 }
 245
 246 int copy_from_user_proc(void *to, void __user *from, int size)
 247 {
 248         return copy_from_user(to, from, size);
 249 }
 250
 251 int clear_user_proc(void __user *buf, int size)
 252 {
 253         return clear_user(buf, size);
 254 }
 255
 256 int strlen_user_proc(char __user *str)
 257 {
 258         return strlen_user(str);
 259 }
 260
 261 int cpu(void)
 262 {
 263         return current_thread_info()->cpu;
 264 }
 265
 266 static atomic_t using_sysemu = ATOMIC_INIT(0);
 267 int sysemu_supported;
 268
 269 void set_using_sysemu(int value)
 270 {
 271         if (value > sysemu_supported)
 272                 return;
 273         atomic_set(&using_sysemu, value);
 274 }
 275
 276 int get_using_sysemu(void)
 277 {
 278         return atomic_read(&using_sysemu);
 279 }
 280
 281 static int sysemu_proc_show(struct seq_file *m, void *v)
 282 {
 283         seq_printf(m, "%d\n", get_using_sysemu());
 284         return 0;
 285 }
 286
 287 static int sysemu_proc_open(struct inode *inode, struct file *file)
 288 {
 289         return single_open(file, sysemu_proc_show, NULL);
 290 }
 291
 292 static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 293                                  size_t count, loff_t *pos)
 294 {
 295         char tmp[2];
 296
 297         if (copy_from_user(tmp, buf, 1))
 298                 return -EFAULT;
 299
 300         if (tmp[0] >= '0' && tmp[0] <= '2')
 301                 set_using_sysemu(tmp[0] - '0');
 302         /* We use the first char, but pretend to write everything */
 303         return count;
 304 }
 305
 306 static const struct file_operations sysemu_proc_fops = {
 307         .owner          = THIS_MODULE,
 308         .open           = sysemu_proc_open,
 309         .read           = seq_read,
 310         .llseek         = seq_lseek,
 311         .release        = single_release,
 312         .write          = sysemu_proc_write,
 313 };
 314
 315 int __init make_proc_sysemu(void)
 316 {
 317         struct proc_dir_entry *ent;
 318         if (!sysemu_supported)
 319                 return 0;
 320
 321         ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
 322
 323         if (ent == NULL)
 324         {
 325                 printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 326                 return 0;
 327         }
 328
 329         return 0;
 330 }
 331
 332 late_initcall(make_proc_sysemu);
 333
 334 int singlestepping(void * t)
 335 {
 336         struct task_struct *task = t ? t : current;
 337
 338         if (!(task->ptrace & PT_DTRACE))
 339                 return 0;
 340
 341         if (task->thread.singlestep_syscall)
 342                 return 1;
 343
 344         return 2;
 345 }
 346
 347 /*
 348  * Only x86 and x86_64 have an arch_align_stack().
 349  * All other arches have "#define arch_align_stack(x) (x)"
 350  * in their asm/exec.h
 351  * As this is included in UML from asm-um/system-generic.h,
 352  * we can use it to behave as the subarch does.
 353  */
 354 #ifndef arch_align_stack
 355 unsigned long arch_align_stack(unsigned long sp)
 356 {
 357         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 358                 sp -= get_random_int() % 8192;
 359         return sp & ~0xf;
 360 }
 361 #endif
 362
 363 unsigned long get_wchan(struct task_struct *p)
 364 {
 365         unsigned long stack_page, sp, ip;
 366         bool seen_sched = 0;
 367
 368         if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 369                 return 0;
 370
 371         stack_page = (unsigned long) task_stack_page(p);
 372         /* Bail if the process has no kernel stack for some reason */
 373         if (stack_page == 0)
 374                 return 0;
 375
 376         sp = p->thread.switch_buf->JB_SP;
 377         /*
 378          * Bail if the stack pointer is below the bottom of the kernel
 379          * stack for some reason
 380          */
 381         if (sp < stack_page)
 382                 return 0;
 383
 384         while (sp < stack_page + THREAD_SIZE) {
 385                 ip = *((unsigned long *) sp);
 386                 if (in_sched_functions(ip))
 387                         /* Ignore everything until we're above the scheduler */
 388                         seen_sched = 1;
 389                 else if (kernel_text_address(ip) && seen_sched)
 390                         return ip;
 391
 392                 sp += sizeof(unsigned long);
 393         }
 394
 395         return 0;
 396 }
 397
 398 int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 399 {
 400         int cpu = current_thread_info()->cpu;
 401
 402         return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu);
 403 }
 404