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