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/a.out.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/delay.h>
  35 #include <linux/reboot.h>
  36 #include <linux/init.h>
  37 #include <linux/module.h>
  38 #include <linux/notifier.h>
  39
  40 #include <asm/uaccess.h>
  41 #include <asm/pgtable.h>
  42 #include <asm/system.h>
  43 #include <asm/io.h>
  44 #include <asm/processor.h>
  45 #include <asm/irq.h>
  46 #include <asm/timer.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         /* disable monitor call class 0 */
  95         __ctl_clear_bit(8, 15);
  96
  97         atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
  98                                    (void *)(long) smp_processor_id());
  99 }
 100
 101 extern void s390_handle_mcck(void);
 102 /*
 103  * The idle loop on a S390...
 104  */
 105 static void default_idle(void)
 106 {
 107         int cpu, rc;
 108
 109         /* CPU is going idle. */
 110         cpu = smp_processor_id();
 111
 112         local_irq_disable();
 113         if (need_resched()) {
 114                 local_irq_enable();
 115                 return;
 116         }
 117
 118         rc = atomic_notifier_call_chain(&idle_chain,
 119                                         S390_CPU_IDLE, (void *)(long) cpu);
 120         if (rc != NOTIFY_OK && rc != NOTIFY_DONE)
 121                 BUG();
 122         if (rc != NOTIFY_OK) {
 123                 local_irq_enable();
 124                 return;
 125         }
 126
 127         /* enable monitor call class 0 */
 128         __ctl_set_bit(8, 15);
 129
 130 #ifdef CONFIG_HOTPLUG_CPU
 131         if (cpu_is_offline(cpu)) {
 132                 preempt_enable_no_resched();
 133                 cpu_die();
 134         }
 135 #endif
 136
 137         local_mcck_disable();
 138         if (test_thread_flag(TIF_MCCK_PENDING)) {
 139                 local_mcck_enable();
 140                 local_irq_enable();
 141                 s390_handle_mcck();
 142                 return;
 143         }
 144
 145         trace_hardirqs_on();
 146         /* Wait for external, I/O or machine check interrupt. */
 147         __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
 148                         PSW_MASK_IO | PSW_MASK_EXT);
 149 }
 150
 151 void cpu_idle(void)
 152 {
 153         for (;;) {
 154                 while (!need_resched())
 155                         default_idle();
 156
 157                 preempt_enable_no_resched();
 158                 schedule();
 159                 preempt_disable();
 160         }
 161 }
 162
 163 void show_regs(struct pt_regs *regs)
 164 {
 165         struct task_struct *tsk = current;
 166
 167         printk("CPU:    %d    %s\n", task_thread_info(tsk)->cpu, print_tainted());
 168         printk("Process %s (pid: %d, task: %p, ksp: %p)\n",
 169                current->comm, current->pid, (void *) tsk,
 170                (void *) tsk->thread.ksp);
 171
 172         show_registers(regs);
 173         /* Show stack backtrace if pt_regs is from kernel mode */
 174         if (!(regs->psw.mask & PSW_MASK_PSTATE))
 175                 show_trace(NULL, (unsigned long *) regs->gprs[15]);
 176 }
 177
 178 extern void kernel_thread_starter(void);
 179
 180 asm(
 181         ".align 4\n"
 182         "kernel_thread_starter:\n"
 183         "    la    2,0(10)\n"
 184         "    basr  14,9\n"
 185         "    la    2,0\n"
 186         "    br    11\n");
 187
 188 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 189 {
 190         struct pt_regs regs;
 191
 192         memset(&regs, 0, sizeof(regs));
 193         regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
 194         regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 195         regs.gprs[9] = (unsigned long) fn;
 196         regs.gprs[10] = (unsigned long) arg;
 197         regs.gprs[11] = (unsigned long) do_exit;
 198         regs.orig_gpr2 = -1;
 199
 200         /* Ok, create the new process.. */
 201         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 202                        0, &regs, 0, NULL, NULL);
 203 }
 204
 205 /*
 206  * Free current thread data structures etc..
 207  */
 208 void exit_thread(void)
 209 {
 210 }
 211
 212 void flush_thread(void)
 213 {
 214         clear_used_math();
 215         clear_tsk_thread_flag(current, TIF_USEDFPU);
 216 }
 217
 218 void release_thread(struct task_struct *dead_task)
 219 {
 220 }
 221
 222 int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
 223         unsigned long unused,
 224         struct task_struct * p, struct pt_regs * regs)
 225 {
 226         struct fake_frame
 227           {
 228             struct stack_frame sf;
 229             struct pt_regs childregs;
 230           } *frame;
 231
 232         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 233         p->thread.ksp = (unsigned long) frame;
 234         /* Store access registers to kernel stack of new process. */
 235         frame->childregs = *regs;
 236         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 237         frame->childregs.gprs[15] = new_stackp;
 238         frame->sf.back_chain = 0;
 239
 240         /* new return point is ret_from_fork */
 241         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 242
 243         /* fake return stack for resume(), don't go back to schedule */
 244         frame->sf.gprs[9] = (unsigned long) frame;
 245
 246         /* Save access registers to new thread structure. */
 247         save_access_regs(&p->thread.acrs[0]);
 248
 249 #ifndef CONFIG_64BIT
 250         /*
 251          * save fprs to current->thread.fp_regs to merge them with
 252          * the emulated registers and then copy the result to the child.
 253          */
 254         save_fp_regs(&current->thread.fp_regs);
 255         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 256                sizeof(s390_fp_regs));
 257         p->thread.user_seg = __pa((unsigned long) p->mm->pgd) | _SEGMENT_TABLE;
 258         /* Set a new TLS ?  */
 259         if (clone_flags & CLONE_SETTLS)
 260                 p->thread.acrs[0] = regs->gprs[6];
 261 #else /* CONFIG_64BIT */
 262         /* Save the fpu registers to new thread structure. */
 263         save_fp_regs(&p->thread.fp_regs);
 264         p->thread.user_seg = __pa((unsigned long) p->mm->pgd) | _REGION_TABLE;
 265         /* Set a new TLS ?  */
 266         if (clone_flags & CLONE_SETTLS) {
 267                 if (test_thread_flag(TIF_31BIT)) {
 268                         p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 269                 } else {
 270                         p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 271                         p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 272                 }
 273         }
 274 #endif /* CONFIG_64BIT */
 275         /* start new process with ar4 pointing to the correct address space */
 276         p->thread.mm_segment = get_fs();
 277         /* Don't copy debug registers */
 278         memset(&p->thread.per_info,0,sizeof(p->thread.per_info));
 279
 280         return 0;
 281 }
 282
 283 asmlinkage long sys_fork(void)
 284 {
 285         struct pt_regs *regs = task_pt_regs(current);
 286         return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 287 }
 288
 289 asmlinkage long sys_clone(void)
 290 {
 291         struct pt_regs *regs = task_pt_regs(current);
 292         unsigned long clone_flags;
 293         unsigned long newsp;
 294         int __user *parent_tidptr, *child_tidptr;
 295
 296         clone_flags = regs->gprs[3];
 297         newsp = regs->orig_gpr2;
 298         parent_tidptr = (int __user *) regs->gprs[4];
 299         child_tidptr = (int __user *) regs->gprs[5];
 300         if (!newsp)
 301                 newsp = regs->gprs[15];
 302         return do_fork(clone_flags, newsp, regs, 0,
 303                        parent_tidptr, child_tidptr);
 304 }
 305
 306 /*
 307  * This is trivial, and on the face of it looks like it
 308  * could equally well be done in user mode.
 309  *
 310  * Not so, for quite unobvious reasons - register pressure.
 311  * In user mode vfork() cannot have a stack frame, and if
 312  * done by calling the "clone()" system call directly, you
 313  * do not have enough call-clobbered registers to hold all
 314  * the information you need.
 315  */
 316 asmlinkage long sys_vfork(void)
 317 {
 318         struct pt_regs *regs = task_pt_regs(current);
 319         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 320                        regs->gprs[15], regs, 0, NULL, NULL);
 321 }
 322
 323 asmlinkage void execve_tail(void)
 324 {
 325         task_lock(current);
 326         current->ptrace &= ~PT_DTRACE;
 327         task_unlock(current);
 328         current->thread.fp_regs.fpc = 0;
 329         if (MACHINE_HAS_IEEE)
 330                 asm volatile("sfpc %0,%0" : : "d" (0));
 331 }
 332
 333 /*
 334  * sys_execve() executes a new program.
 335  */
 336 asmlinkage long sys_execve(void)
 337 {
 338         struct pt_regs *regs = task_pt_regs(current);
 339         char *filename;
 340         unsigned long result;
 341         int rc;
 342
 343         filename = getname((char __user *) regs->orig_gpr2);
 344         if (IS_ERR(filename)) {
 345                 result = PTR_ERR(filename);
 346                 goto out;
 347         }
 348         rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
 349                        (char __user * __user *) regs->gprs[4], regs);
 350         if (rc) {
 351                 result = rc;
 352                 goto out_putname;
 353         }
 354         execve_tail();
 355         result = regs->gprs[2];
 356 out_putname:
 357         putname(filename);
 358 out:
 359         return result;
 360 }
 361
 362 /*
 363  * fill in the FPU structure for a core dump.
 364  */
 365 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 366 {
 367 #ifndef CONFIG_64BIT
 368         /*
 369          * save fprs to current->thread.fp_regs to merge them with
 370          * the emulated registers and then copy the result to the dump.
 371          */
 372         save_fp_regs(&current->thread.fp_regs);
 373         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 374 #else /* CONFIG_64BIT */
 375         save_fp_regs(fpregs);
 376 #endif /* CONFIG_64BIT */
 377         return 1;
 378 }
 379
 380 unsigned long get_wchan(struct task_struct *p)
 381 {
 382         struct stack_frame *sf, *low, *high;
 383         unsigned long return_address;
 384         int count;
 385
 386         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 387                 return 0;
 388         low = task_stack_page(p);
 389         high = (struct stack_frame *) task_pt_regs(p);
 390         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 391         if (sf <= low || sf > high)
 392                 return 0;
 393         for (count = 0; count < 16; count++) {
 394                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 395                 if (sf <= low || sf > high)
 396                         return 0;
 397                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 398                 if (!in_sched_functions(return_address))
 399                         return return_address;
 400         }
 401         return 0;
 402 }
 403