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 <linux/tick.h>
  40 #include <linux/elfcore.h>
  41 #include <asm/uaccess.h>
  42 #include <asm/pgtable.h>
  43 #include <asm/system.h>
  44 #include <asm/io.h>
  45 #include <asm/processor.h>
  46 #include <asm/irq.h>
  47 #include <asm/timer.h>
  48 #include <asm/cpu.h>
  49 #include "entry.h"
  50
  51 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  52
  53 /*
  54  * Return saved PC of a blocked thread. used in kernel/sched.
  55  * resume in entry.S does not create a new stack frame, it
  56  * just stores the registers %r6-%r15 to the frame given by
  57  * schedule. We want to return the address of the caller of
  58  * schedule, so we have to walk the backchain one time to
  59  * find the frame schedule() store its return address.
  60  */
  61 unsigned long thread_saved_pc(struct task_struct *tsk)
  62 {
  63         struct stack_frame *sf, *low, *high;
  64
  65         if (!tsk || !task_stack_page(tsk))
  66                 return 0;
  67         low = task_stack_page(tsk);
  68         high = (struct stack_frame *) task_pt_regs(tsk);
  69         sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  70         if (sf <= low || sf > high)
  71                 return 0;
  72         sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  73         if (sf <= low || sf > high)
  74                 return 0;
  75         return sf->gprs[8];
  76 }
  77
  78 /*
  79  * Need to know about CPUs going idle?
  80  */
  81 static ATOMIC_NOTIFIER_HEAD(idle_chain);
  82 DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
  83
  84 int register_idle_notifier(struct notifier_block *nb)
  85 {
  86         return atomic_notifier_chain_register(&idle_chain, nb);
  87 }
  88 EXPORT_SYMBOL(register_idle_notifier);
  89
  90 int unregister_idle_notifier(struct notifier_block *nb)
  91 {
  92         return atomic_notifier_chain_unregister(&idle_chain, nb);
  93 }
  94 EXPORT_SYMBOL(unregister_idle_notifier);
  95
  96 static int s390_idle_enter(void)
  97 {
  98         struct s390_idle_data *idle;
  99         int nr_calls = 0;
 100         void *hcpu;
 101         int rc;
 102
 103         hcpu = (void *)(long)smp_processor_id();
 104         rc = __atomic_notifier_call_chain(&idle_chain, S390_CPU_IDLE, hcpu, -1,
 105                                           &nr_calls);
 106         if (rc == NOTIFY_BAD) {
 107                 nr_calls--;
 108                 __atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
 109                                              hcpu, nr_calls, NULL);
 110                 return rc;
 111         }
 112         idle = &__get_cpu_var(s390_idle);
 113         spin_lock(&idle->lock);
 114         idle->idle_count++;
 115         idle->in_idle = 1;
 116         idle->idle_enter = get_clock();
 117         spin_unlock(&idle->lock);
 118         return NOTIFY_OK;
 119 }
 120
 121 void s390_idle_leave(void)
 122 {
 123         struct s390_idle_data *idle;
 124
 125         idle = &__get_cpu_var(s390_idle);
 126         spin_lock(&idle->lock);
 127         idle->idle_time += get_clock() - idle->idle_enter;
 128         idle->in_idle = 0;
 129         spin_unlock(&idle->lock);
 130         atomic_notifier_call_chain(&idle_chain, S390_CPU_NOT_IDLE,
 131                                    (void *)(long) smp_processor_id());
 132 }
 133
 134 extern void s390_handle_mcck(void);
 135 /*
 136  * The idle loop on a S390...
 137  */
 138 static void default_idle(void)
 139 {
 140         /* CPU is going idle. */
 141         local_irq_disable();
 142         if (need_resched()) {
 143                 local_irq_enable();
 144                 return;
 145         }
 146         if (s390_idle_enter() == NOTIFY_BAD) {
 147                 local_irq_enable();
 148                 return;
 149         }
 150 #ifdef CONFIG_HOTPLUG_CPU
 151         if (cpu_is_offline(smp_processor_id())) {
 152                 preempt_enable_no_resched();
 153                 cpu_die();
 154         }
 155 #endif
 156         local_mcck_disable();
 157         if (test_thread_flag(TIF_MCCK_PENDING)) {
 158                 local_mcck_enable();
 159                 s390_idle_leave();
 160                 local_irq_enable();
 161                 s390_handle_mcck();
 162                 return;
 163         }
 164         trace_hardirqs_on();
 165         /* Wait for external, I/O or machine check interrupt. */
 166         __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
 167                         PSW_MASK_IO | PSW_MASK_EXT);
 168 }
 169
 170 void cpu_idle(void)
 171 {
 172         for (;;) {
 173                 tick_nohz_stop_sched_tick();
 174                 while (!need_resched())
 175                         default_idle();
 176                 tick_nohz_restart_sched_tick();
 177                 preempt_enable_no_resched();
 178                 schedule();
 179                 preempt_disable();
 180         }
 181 }
 182
 183 extern void kernel_thread_starter(void);
 184
 185 asm(
 186         ".align 4\n"
 187         "kernel_thread_starter:\n"
 188         "    la    2,0(10)\n"
 189         "    basr  14,9\n"
 190         "    la    2,0\n"
 191         "    br    11\n");
 192
 193 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 194 {
 195         struct pt_regs regs;
 196
 197         memset(&regs, 0, sizeof(regs));
 198         regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
 199         regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 200         regs.gprs[9] = (unsigned long) fn;
 201         regs.gprs[10] = (unsigned long) arg;
 202         regs.gprs[11] = (unsigned long) do_exit;
 203         regs.orig_gpr2 = -1;
 204
 205         /* Ok, create the new process.. */
 206         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 207                        0, &regs, 0, NULL, NULL);
 208 }
 209
 210 /*
 211  * Free current thread data structures etc..
 212  */
 213 void exit_thread(void)
 214 {
 215 }
 216
 217 void flush_thread(void)
 218 {
 219         clear_used_math();
 220         clear_tsk_thread_flag(current, TIF_USEDFPU);
 221 }
 222
 223 void release_thread(struct task_struct *dead_task)
 224 {
 225 }
 226
 227 int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
 228         unsigned long unused,
 229         struct task_struct * p, struct pt_regs * regs)
 230 {
 231         struct fake_frame
 232           {
 233             struct stack_frame sf;
 234             struct pt_regs childregs;
 235           } *frame;
 236
 237         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 238         p->thread.ksp = (unsigned long) frame;
 239         /* Store access registers to kernel stack of new process. */
 240         frame->childregs = *regs;
 241         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 242         frame->childregs.gprs[15] = new_stackp;
 243         frame->sf.back_chain = 0;
 244
 245         /* new return point is ret_from_fork */
 246         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 247
 248         /* fake return stack for resume(), don't go back to schedule */
 249         frame->sf.gprs[9] = (unsigned long) frame;
 250
 251         /* Save access registers to new thread structure. */
 252         save_access_regs(&p->thread.acrs[0]);
 253
 254 #ifndef CONFIG_64BIT
 255         /*
 256          * save fprs to current->thread.fp_regs to merge them with
 257          * the emulated registers and then copy the result to the child.
 258          */
 259         save_fp_regs(&current->thread.fp_regs);
 260         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 261                sizeof(s390_fp_regs));
 262         /* Set a new TLS ?  */
 263         if (clone_flags & CLONE_SETTLS)
 264                 p->thread.acrs[0] = regs->gprs[6];
 265 #else /* CONFIG_64BIT */
 266         /* Save the fpu registers to new thread structure. */
 267         save_fp_regs(&p->thread.fp_regs);
 268         /* Set a new TLS ?  */
 269         if (clone_flags & CLONE_SETTLS) {
 270                 if (test_thread_flag(TIF_31BIT)) {
 271                         p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 272                 } else {
 273                         p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 274                         p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 275                 }
 276         }
 277 #endif /* CONFIG_64BIT */
 278         /* start new process with ar4 pointing to the correct address space */
 279         p->thread.mm_segment = get_fs();
 280         /* Don't copy debug registers */
 281         memset(&p->thread.per_info,0,sizeof(p->thread.per_info));
 282
 283         return 0;
 284 }
 285
 286 asmlinkage long sys_fork(void)
 287 {
 288         struct pt_regs *regs = task_pt_regs(current);
 289         return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 290 }
 291
 292 asmlinkage long sys_clone(void)
 293 {
 294         struct pt_regs *regs = task_pt_regs(current);
 295         unsigned long clone_flags;
 296         unsigned long newsp;
 297         int __user *parent_tidptr, *child_tidptr;
 298
 299         clone_flags = regs->gprs[3];
 300         newsp = regs->orig_gpr2;
 301         parent_tidptr = (int __user *) regs->gprs[4];
 302         child_tidptr = (int __user *) regs->gprs[5];
 303         if (!newsp)
 304                 newsp = regs->gprs[15];
 305         return do_fork(clone_flags, newsp, regs, 0,
 306                        parent_tidptr, child_tidptr);
 307 }
 308
 309 /*
 310  * This is trivial, and on the face of it looks like it
 311  * could equally well be done in user mode.
 312  *
 313  * Not so, for quite unobvious reasons - register pressure.
 314  * In user mode vfork() cannot have a stack frame, and if
 315  * done by calling the "clone()" system call directly, you
 316  * do not have enough call-clobbered registers to hold all
 317  * the information you need.
 318  */
 319 asmlinkage long sys_vfork(void)
 320 {
 321         struct pt_regs *regs = task_pt_regs(current);
 322         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 323                        regs->gprs[15], regs, 0, NULL, NULL);
 324 }
 325
 326 asmlinkage void execve_tail(void)
 327 {
 328         task_lock(current);
 329         current->ptrace &= ~PT_DTRACE;
 330         task_unlock(current);
 331         current->thread.fp_regs.fpc = 0;
 332         if (MACHINE_HAS_IEEE)
 333                 asm volatile("sfpc %0,%0" : : "d" (0));
 334 }
 335
 336 /*
 337  * sys_execve() executes a new program.
 338  */
 339 asmlinkage long sys_execve(void)
 340 {
 341         struct pt_regs *regs = task_pt_regs(current);
 342         char *filename;
 343         unsigned long result;
 344         int rc;
 345
 346         filename = getname((char __user *) regs->orig_gpr2);
 347         if (IS_ERR(filename)) {
 348                 result = PTR_ERR(filename);
 349                 goto out;
 350         }
 351         rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
 352                        (char __user * __user *) regs->gprs[4], regs);
 353         if (rc) {
 354                 result = rc;
 355                 goto out_putname;
 356         }
 357         execve_tail();
 358         result = regs->gprs[2];
 359 out_putname:
 360         putname(filename);
 361 out:
 362         return result;
 363 }
 364
 365 /*
 366  * fill in the FPU structure for a core dump.
 367  */
 368 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 369 {
 370 #ifndef CONFIG_64BIT
 371         /*
 372          * save fprs to current->thread.fp_regs to merge them with
 373          * the emulated registers and then copy the result to the dump.
 374          */
 375         save_fp_regs(&current->thread.fp_regs);
 376         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 377 #else /* CONFIG_64BIT */
 378         save_fp_regs(fpregs);
 379 #endif /* CONFIG_64BIT */
 380         return 1;
 381 }
 382
 383 unsigned long get_wchan(struct task_struct *p)
 384 {
 385         struct stack_frame *sf, *low, *high;
 386         unsigned long return_address;
 387         int count;
 388
 389         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 390                 return 0;
 391         low = task_stack_page(p);
 392         high = (struct stack_frame *) task_pt_regs(p);
 393         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 394         if (sf <= low || sf > high)
 395                 return 0;
 396         for (count = 0; count < 16; count++) {
 397                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 398                 if (sf <= low || sf > high)
 399                         return 0;
 400                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 401                 if (!in_sched_functions(return_address))
 402                         return return_address;
 403         }
 404         return 0;
 405 }
 406