linux/arch/s390/kernel/process.c
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   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
  51asmlinkage 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 */
  61unsigned 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
  78DEFINE_PER_CPU(struct s390_idle_data, s390_idle) = {
  79        .lock = __SPIN_LOCK_UNLOCKED(s390_idle.lock)
  80};
  81
  82static 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
  96void 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
 108extern void s390_handle_mcck(void);
 109/*
 110 * The idle loop on a S390...
 111 */
 112static 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        /* Don't trace preempt off for idle. */
 140        stop_critical_timings();
 141        /* Wait for external, I/O or machine check interrupt. */
 142        __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
 143                        PSW_MASK_IO | PSW_MASK_EXT);
 144        start_critical_timings();
 145}
 146
 147void cpu_idle(void)
 148{
 149        for (;;) {
 150                tick_nohz_stop_sched_tick(1);
 151                while (!need_resched())
 152                        default_idle();
 153                tick_nohz_restart_sched_tick();
 154                preempt_enable_no_resched();
 155                schedule();
 156                preempt_disable();
 157        }
 158}
 159
 160extern void kernel_thread_starter(void);
 161
 162asm(
 163        ".align 4\n"
 164        "kernel_thread_starter:\n"
 165        "    la    2,0(10)\n"
 166        "    basr  14,9\n"
 167        "    la    2,0\n"
 168        "    br    11\n");
 169
 170int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 171{
 172        struct pt_regs regs;
 173
 174        memset(&regs, 0, sizeof(regs));
 175        regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
 176        regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 177        regs.gprs[9] = (unsigned long) fn;
 178        regs.gprs[10] = (unsigned long) arg;
 179        regs.gprs[11] = (unsigned long) do_exit;
 180        regs.orig_gpr2 = -1;
 181
 182        /* Ok, create the new process.. */
 183        return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 184                       0, &regs, 0, NULL, NULL);
 185}
 186
 187/*
 188 * Free current thread data structures etc..
 189 */
 190void exit_thread(void)
 191{
 192}
 193
 194void flush_thread(void)
 195{
 196        clear_used_math();
 197        clear_tsk_thread_flag(current, TIF_USEDFPU);
 198}
 199
 200void release_thread(struct task_struct *dead_task)
 201{
 202}
 203
 204int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
 205        unsigned long unused,
 206        struct task_struct * p, struct pt_regs * regs)
 207{
 208        struct fake_frame
 209          {
 210            struct stack_frame sf;
 211            struct pt_regs childregs;
 212          } *frame;
 213
 214        frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 215        p->thread.ksp = (unsigned long) frame;
 216        /* Store access registers to kernel stack of new process. */
 217        frame->childregs = *regs;
 218        frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 219        frame->childregs.gprs[15] = new_stackp;
 220        frame->sf.back_chain = 0;
 221
 222        /* new return point is ret_from_fork */
 223        frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 224
 225        /* fake return stack for resume(), don't go back to schedule */
 226        frame->sf.gprs[9] = (unsigned long) frame;
 227
 228        /* Save access registers to new thread structure. */
 229        save_access_regs(&p->thread.acrs[0]);
 230
 231#ifndef CONFIG_64BIT
 232        /*
 233         * save fprs to current->thread.fp_regs to merge them with
 234         * the emulated registers and then copy the result to the child.
 235         */
 236        save_fp_regs(&current->thread.fp_regs);
 237        memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 238               sizeof(s390_fp_regs));
 239        /* Set a new TLS ?  */
 240        if (clone_flags & CLONE_SETTLS)
 241                p->thread.acrs[0] = regs->gprs[6];
 242#else /* CONFIG_64BIT */
 243        /* Save the fpu registers to new thread structure. */
 244        save_fp_regs(&p->thread.fp_regs);
 245        /* Set a new TLS ?  */
 246        if (clone_flags & CLONE_SETTLS) {
 247                if (test_thread_flag(TIF_31BIT)) {
 248                        p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 249                } else {
 250                        p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 251                        p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 252                }
 253        }
 254#endif /* CONFIG_64BIT */
 255        /* start new process with ar4 pointing to the correct address space */
 256        p->thread.mm_segment = get_fs();
 257        /* Don't copy debug registers */
 258        memset(&p->thread.per_info,0,sizeof(p->thread.per_info));
 259
 260        return 0;
 261}
 262
 263asmlinkage long sys_fork(void)
 264{
 265        struct pt_regs *regs = task_pt_regs(current);
 266        return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 267}
 268
 269asmlinkage long sys_clone(void)
 270{
 271        struct pt_regs *regs = task_pt_regs(current);
 272        unsigned long clone_flags;
 273        unsigned long newsp;
 274        int __user *parent_tidptr, *child_tidptr;
 275
 276        clone_flags = regs->gprs[3];
 277        newsp = regs->orig_gpr2;
 278        parent_tidptr = (int __user *) regs->gprs[4];
 279        child_tidptr = (int __user *) regs->gprs[5];
 280        if (!newsp)
 281                newsp = regs->gprs[15];
 282        return do_fork(clone_flags, newsp, regs, 0,
 283                       parent_tidptr, child_tidptr);
 284}
 285
 286/*
 287 * This is trivial, and on the face of it looks like it
 288 * could equally well be done in user mode.
 289 *
 290 * Not so, for quite unobvious reasons - register pressure.
 291 * In user mode vfork() cannot have a stack frame, and if
 292 * done by calling the "clone()" system call directly, you
 293 * do not have enough call-clobbered registers to hold all
 294 * the information you need.
 295 */
 296asmlinkage long sys_vfork(void)
 297{
 298        struct pt_regs *regs = task_pt_regs(current);
 299        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 300                       regs->gprs[15], regs, 0, NULL, NULL);
 301}
 302
 303asmlinkage void execve_tail(void)
 304{
 305        task_lock(current);
 306        current->ptrace &= ~PT_DTRACE;
 307        task_unlock(current);
 308        current->thread.fp_regs.fpc = 0;
 309        if (MACHINE_HAS_IEEE)
 310                asm volatile("sfpc %0,%0" : : "d" (0));
 311}
 312
 313/*
 314 * sys_execve() executes a new program.
 315 */
 316asmlinkage long sys_execve(void)
 317{
 318        struct pt_regs *regs = task_pt_regs(current);
 319        char *filename;
 320        unsigned long result;
 321        int rc;
 322
 323        filename = getname((char __user *) regs->orig_gpr2);
 324        if (IS_ERR(filename)) {
 325                result = PTR_ERR(filename);
 326                goto out;
 327        }
 328        rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
 329                       (char __user * __user *) regs->gprs[4], regs);
 330        if (rc) {
 331                result = rc;
 332                goto out_putname;
 333        }
 334        execve_tail();
 335        result = regs->gprs[2];
 336out_putname:
 337        putname(filename);
 338out:
 339        return result;
 340}
 341
 342/*
 343 * fill in the FPU structure for a core dump.
 344 */
 345int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 346{
 347#ifndef CONFIG_64BIT
 348        /*
 349         * save fprs to current->thread.fp_regs to merge them with
 350         * the emulated registers and then copy the result to the dump.
 351         */
 352        save_fp_regs(&current->thread.fp_regs);
 353        memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 354#else /* CONFIG_64BIT */
 355        save_fp_regs(fpregs);
 356#endif /* CONFIG_64BIT */
 357        return 1;
 358}
 359
 360unsigned long get_wchan(struct task_struct *p)
 361{
 362        struct stack_frame *sf, *low, *high;
 363        unsigned long return_address;
 364        int count;
 365
 366        if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 367                return 0;
 368        low = task_stack_page(p);
 369        high = (struct stack_frame *) task_pt_regs(p);
 370        sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 371        if (sf <= low || sf > high)
 372                return 0;
 373        for (count = 0; count < 16; count++) {
 374                sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 375                if (sf <= low || sf > high)
 376                        return 0;
 377                return_address = sf->gprs[8] & PSW_ADDR_INSN;
 378                if (!in_sched_functions(return_address))
 379                        return return_address;
 380        }
 381        return 0;
 382}
 383
 384