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