arch/s390/kernel/process.c

   1 /*
   2  *  arch/s390/kernel/process.c
   3  *
   4  *  S390 version
   5  *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
   6  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
   7  *               Hartmut Penner (hp@de.ibm.com),
   8  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
   9  *
  10  *  Derived from "arch/i386/kernel/process.c"
  11  *    Copyright (C) 1995, Linus Torvalds
  12  */
  13
  14 /*
  15  * This file handles the architecture-dependent parts of process handling..
  16  */
  17
  18 #include <linux/compiler.h>
  19 #include <linux/cpu.h>
  20 #include <linux/errno.h>
  21 #include <linux/sched.h>
  22 #include <linux/kernel.h>
  23 #include <linux/mm.h>
  24 #include <linux/fs.h>
  25 #include <linux/smp.h>
  26 #include <linux/stddef.h>
  27 #include <linux/unistd.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/slab.h>
  30 #include <linux/vmalloc.h>
  31 #include <linux/user.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/delay.h>
  34 #include <linux/reboot.h>
  35 #include <linux/init.h>
  36 #include <linux/module.h>
  37 #include <linux/notifier.h>
  38 #include <linux/utsname.h>
  39 #include <asm/uaccess.h>
  40 #include <asm/pgtable.h>
  41 #include <asm/system.h>
  42 #include <asm/io.h>
  43 #include <asm/processor.h>
  44 #include <asm/irq.h>
  45 #include <asm/timer.h>
  46 #include <asm/cpu.h>
  47
  48 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  49
  50 /*
  51  * Return saved PC of a blocked thread. used in kernel/sched.
  52  * resume in entry.S does not create a new stack frame, it
  53  * just stores the registers %r6-%r15 to the frame given by
  54  * schedule. We want to return the address of the caller of
  55  * schedule, so we have to walk the backchain one time to
  56  * find the frame schedule() store its return address.
  57  */
  58 unsigned long thread_saved_pc(struct task_struct *tsk)
  59 {
  60         struct stack_frame *sf, *low, *high;
  61
  62         if (!tsk || !task_stack_page(tsk))
  63                 return 0;
  64         low = task_stack_page(tsk);
  65         high = (struct stack_frame *) task_pt_regs(tsk);
  66         sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  67         if (sf <= low || sf > high)
  68                 return 0;
  69         sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  70         if (sf <= low || sf > high)
  71                 return 0;
  72         return sf->gprs[8];
  73 }
  74
  75 /*
  76  * Need to know about CPUs going idle?
  77  */
  78 static ATOMIC_NOTIFIER_HEAD(idle_chain);
  79
  80 int register_idle_notifier(struct notifier_block *nb)
  81 {
  82         return atomic_notifier_chain_register(&idle_chain, nb);
  83 }
  84 EXPORT_SYMBOL(register_idle_notifier);
  85
  86 int unregister_idle_notifier(struct notifier_block *nb)
  87 {
  88         return atomic_notifier_chain_unregister(&idle_chain, nb);
  89 }
  90 EXPORT_SYMBOL(unregister_idle_notifier);
  91
  92 void do_monitor_call(struct pt_regs *regs, long interruption_code)
  93 {
  94 #ifdef CONFIG_SMP
  95         struct s390_idle_data *idle;
  96
  97         idle = &__get_cpu_var(s390_idle);
  98         spin_lock(&idle->lock);
  99         idle->idle_time += get_clock() - idle->idle_enter;
 100         idle->in_idle = 0;
 101         spin_unlock(&idle->lock);
 102 #endif
 103         /* disable monitor call class 0 */
 104         __ctl_clear_bit(8, 15);
 105
 106         atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
 107                                    (void *)(long) smp_processor_id());
 108 }
 109
 110 extern void s390_handle_mcck(void);
 111 /*
 112  * The idle loop on a S390...
 113  */
 114 static void default_idle(void)
 115 {
 116         int cpu, rc;
 117         int nr_calls = 0;
 118         void *hcpu;
 119 #ifdef CONFIG_SMP
 120         struct s390_idle_data *idle;
 121 #endif
 122
 123         /* CPU is going idle. */
 124         cpu = smp_processor_id();
 125         hcpu = (void *)(long)cpu;
 126         local_irq_disable();
 127         if (need_resched()) {
 128                 local_irq_enable();
 129                 return;
 130         }
 131
 132         rc = __atomic_notifier_call_chain(&idle_chain, S390_CPU_IDLE, hcpu, -1,
 133                                           &nr_calls);
 134         if (rc == NOTIFY_BAD) {
 135                 nr_calls--;
 136                 __atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
 137                                              hcpu, nr_calls, NULL);
 138                 local_irq_enable();
 139                 return;
 140         }
 141
 142         /* enable monitor call class 0 */
 143         __ctl_set_bit(8, 15);
 144
 145 #ifdef CONFIG_HOTPLUG_CPU
 146         if (cpu_is_offline(cpu)) {
 147                 preempt_enable_no_resched();
 148                 cpu_die();
 149         }
 150 #endif
 151
 152         local_mcck_disable();
 153         if (test_thread_flag(TIF_MCCK_PENDING)) {
 154                 local_mcck_enable();
 155                 /* disable monitor call class 0 */
 156                 __ctl_clear_bit(8, 15);
 157                 atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
 158                                            hcpu);
 159                 local_irq_enable();
 160                 s390_handle_mcck();
 161                 return;
 162         }
 163 #ifdef CONFIG_SMP
 164         idle = &__get_cpu_var(s390_idle);
 165         spin_lock(&idle->lock);
 166         idle->idle_count++;
 167         idle->in_idle = 1;
 168         idle->idle_enter = get_clock();
 169         spin_unlock(&idle->lock);
 170 #endif
 171         trace_hardirqs_on();
 172         /* Wait for external, I/O or machine check interrupt. */
 173         __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
 174                         PSW_MASK_IO | PSW_MASK_EXT);
 175 }
 176
 177 void cpu_idle(void)
 178 {
 179         for (;;) {
 180                 while (!need_resched())
 181                         default_idle();
 182
 183                 preempt_enable_no_resched();
 184                 schedule();
 185                 preempt_disable();
 186         }
 187 }
 188
 189 void show_regs(struct pt_regs *regs)
 190 {
 191         print_modules();
 192         printk("CPU: %d %s %s %.*s\n",
 193                task_thread_info(current)->cpu, print_tainted(),
 194                init_utsname()->release,
 195                (int)strcspn(init_utsname()->version, " "),
 196                init_utsname()->version);
 197         printk("Process %s (pid: %d, task: %p, ksp: %p)\n",
 198                current->comm, current->pid, current,
 199                (void *) current->thread.ksp);
 200         show_registers(regs);
 201         /* Show stack backtrace if pt_regs is from kernel mode */
 202         if (!(regs->psw.mask & PSW_MASK_PSTATE))
 203                 show_trace(NULL, (unsigned long *) regs->gprs[15]);
 204 }
 205
 206 extern void kernel_thread_starter(void);
 207
 208 asm(
 209         ".align 4\n"
 210         "kernel_thread_starter:\n"
 211         "    la    2,0(10)\n"
 212         "    basr  14,9\n"
 213         "    la    2,0\n"
 214         "    br    11\n");
 215
 216 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 217 {
 218         struct pt_regs regs;
 219
 220         memset(&regs, 0, sizeof(regs));
 221         regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
 222         regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 223         regs.gprs[9] = (unsigned long) fn;
 224         regs.gprs[10] = (unsigned long) arg;
 225         regs.gprs[11] = (unsigned long) do_exit;
 226         regs.orig_gpr2 = -1;
 227
 228         /* Ok, create the new process.. */
 229         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 230                        0, &regs, 0, NULL, NULL);
 231 }
 232
 233 /*
 234  * Free current thread data structures etc..
 235  */
 236 void exit_thread(void)
 237 {
 238 }
 239
 240 void flush_thread(void)
 241 {
 242         clear_used_math();
 243         clear_tsk_thread_flag(current, TIF_USEDFPU);
 244 }
 245
 246 void release_thread(struct task_struct *dead_task)
 247 {
 248 }
 249
 250 int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
 251         unsigned long unused,
 252         struct task_struct * p, struct pt_regs * regs)
 253 {
 254         struct fake_frame
 255           {
 256             struct stack_frame sf;
 257             struct pt_regs childregs;
 258           } *frame;
 259
 260         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 261         p->thread.ksp = (unsigned long) frame;
 262         /* Store access registers to kernel stack of new process. */
 263         frame->childregs = *regs;
 264         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 265         frame->childregs.gprs[15] = new_stackp;
 266         frame->sf.back_chain = 0;
 267
 268         /* new return point is ret_from_fork */
 269         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 270
 271         /* fake return stack for resume(), don't go back to schedule */
 272         frame->sf.gprs[9] = (unsigned long) frame;
 273
 274         /* Save access registers to new thread structure. */
 275         save_access_regs(&p->thread.acrs[0]);
 276
 277 #ifndef CONFIG_64BIT
 278         /*
 279          * save fprs to current->thread.fp_regs to merge them with
 280          * the emulated registers and then copy the result to the child.
 281          */
 282         save_fp_regs(&current->thread.fp_regs);
 283         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 284                sizeof(s390_fp_regs));
 285         /* Set a new TLS ?  */
 286         if (clone_flags & CLONE_SETTLS)
 287                 p->thread.acrs[0] = regs->gprs[6];
 288 #else /* CONFIG_64BIT */
 289         /* Save the fpu registers to new thread structure. */
 290         save_fp_regs(&p->thread.fp_regs);
 291         /* Set a new TLS ?  */
 292         if (clone_flags & CLONE_SETTLS) {
 293                 if (test_thread_flag(TIF_31BIT)) {
 294                         p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 295                 } else {
 296                         p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 297                         p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 298                 }
 299         }
 300 #endif /* CONFIG_64BIT */
 301         /* start new process with ar4 pointing to the correct address space */
 302         p->thread.mm_segment = get_fs();
 303         /* Don't copy debug registers */
 304         memset(&p->thread.per_info,0,sizeof(p->thread.per_info));
 305
 306         return 0;
 307 }
 308
 309 asmlinkage long sys_fork(void)
 310 {
 311         struct pt_regs *regs = task_pt_regs(current);
 312         return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 313 }
 314
 315 asmlinkage long sys_clone(void)
 316 {
 317         struct pt_regs *regs = task_pt_regs(current);
 318         unsigned long clone_flags;
 319         unsigned long newsp;
 320         int __user *parent_tidptr, *child_tidptr;
 321
 322         clone_flags = regs->gprs[3];
 323         newsp = regs->orig_gpr2;
 324         parent_tidptr = (int __user *) regs->gprs[4];
 325         child_tidptr = (int __user *) regs->gprs[5];
 326         if (!newsp)
 327                 newsp = regs->gprs[15];
 328         return do_fork(clone_flags, newsp, regs, 0,
 329                        parent_tidptr, child_tidptr);
 330 }
 331
 332 /*
 333  * This is trivial, and on the face of it looks like it
 334  * could equally well be done in user mode.
 335  *
 336  * Not so, for quite unobvious reasons - register pressure.
 337  * In user mode vfork() cannot have a stack frame, and if
 338  * done by calling the "clone()" system call directly, you
 339  * do not have enough call-clobbered registers to hold all
 340  * the information you need.
 341  */
 342 asmlinkage long sys_vfork(void)
 343 {
 344         struct pt_regs *regs = task_pt_regs(current);
 345         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 346                        regs->gprs[15], regs, 0, NULL, NULL);
 347 }
 348
 349 asmlinkage void execve_tail(void)
 350 {
 351         task_lock(current);
 352         current->ptrace &= ~PT_DTRACE;
 353         task_unlock(current);
 354         current->thread.fp_regs.fpc = 0;
 355         if (MACHINE_HAS_IEEE)
 356                 asm volatile("sfpc %0,%0" : : "d" (0));
 357 }
 358
 359 /*
 360  * sys_execve() executes a new program.
 361  */
 362 asmlinkage long sys_execve(void)
 363 {
 364         struct pt_regs *regs = task_pt_regs(current);
 365         char *filename;
 366         unsigned long result;
 367         int rc;
 368
 369         filename = getname((char __user *) regs->orig_gpr2);
 370         if (IS_ERR(filename)) {
 371                 result = PTR_ERR(filename);
 372                 goto out;
 373         }
 374         rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
 375                        (char __user * __user *) regs->gprs[4], regs);
 376         if (rc) {
 377                 result = rc;
 378                 goto out_putname;
 379         }
 380         execve_tail();
 381         result = regs->gprs[2];
 382 out_putname:
 383         putname(filename);
 384 out:
 385         return result;
 386 }
 387
 388 /*
 389  * fill in the FPU structure for a core dump.
 390  */
 391 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 392 {
 393 #ifndef CONFIG_64BIT
 394         /*
 395          * save fprs to current->thread.fp_regs to merge them with
 396          * the emulated registers and then copy the result to the dump.
 397          */
 398         save_fp_regs(&current->thread.fp_regs);
 399         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 400 #else /* CONFIG_64BIT */
 401         save_fp_regs(fpregs);
 402 #endif /* CONFIG_64BIT */
 403         return 1;
 404 }
 405
 406 unsigned long get_wchan(struct task_struct *p)
 407 {
 408         struct stack_frame *sf, *low, *high;
 409         unsigned long return_address;
 410         int count;
 411
 412         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 413                 return 0;
 414         low = task_stack_page(p);
 415         high = (struct stack_frame *) task_pt_regs(p);
 416         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 417         if (sf <= low || sf > high)
 418                 return 0;
 419         for (count = 0; count < 16; count++) {
 420                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 421                 if (sf <= low || sf > high)
 422                         return 0;
 423                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 424                 if (!in_sched_functions(return_address))
 425                         return return_address;
 426         }
 427         return 0;
 428 }
 429