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 <linux/kernel_stat.h>
  42 #include <linux/syscalls.h>
  43 #include <asm/uaccess.h>
  44 #include <asm/pgtable.h>
  45 #include <asm/system.h>
  46 #include <asm/io.h>
  47 #include <asm/processor.h>
  48 #include <asm/irq.h>
  49 #include <asm/timer.h>
  50 #include "entry.h"
  51
  52 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  53
  54 /*
  55  * Return saved PC of a blocked thread. used in kernel/sched.
  56  * resume in entry.S does not create a new stack frame, it
  57  * just stores the registers %r6-%r15 to the frame given by
  58  * schedule. We want to return the address of the caller of
  59  * schedule, so we have to walk the backchain one time to
  60  * find the frame schedule() store its return address.
  61  */
  62 unsigned long thread_saved_pc(struct task_struct *tsk)
  63 {
  64         struct stack_frame *sf, *low, *high;
  65
  66         if (!tsk || !task_stack_page(tsk))
  67                 return 0;
  68         low = task_stack_page(tsk);
  69         high = (struct stack_frame *) task_pt_regs(tsk);
  70         sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  71         if (sf <= low || sf > high)
  72                 return 0;
  73         sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  74         if (sf <= low || sf > high)
  75                 return 0;
  76         return sf->gprs[8];
  77 }
  78
  79 extern void s390_handle_mcck(void);
  80 /*
  81  * The idle loop on a S390...
  82  */
  83 static void default_idle(void)
  84 {
  85         /* CPU is going idle. */
  86         local_irq_disable();
  87         if (need_resched()) {
  88                 local_irq_enable();
  89                 return;
  90         }
  91 #ifdef CONFIG_HOTPLUG_CPU
  92         if (cpu_is_offline(smp_processor_id())) {
  93                 preempt_enable_no_resched();
  94                 cpu_die();
  95         }
  96 #endif
  97         local_mcck_disable();
  98         if (test_thread_flag(TIF_MCCK_PENDING)) {
  99                 local_mcck_enable();
 100                 local_irq_enable();
 101                 s390_handle_mcck();
 102                 return;
 103         }
 104         trace_hardirqs_on();
 105         /* Don't trace preempt off for idle. */
 106         stop_critical_timings();
 107         /* Stop virtual timer and halt the cpu. */
 108         vtime_stop_cpu();
 109         /* Reenable preemption tracer. */
 110         start_critical_timings();
 111 }
 112
 113 void cpu_idle(void)
 114 {
 115         for (;;) {
 116                 tick_nohz_stop_sched_tick(1);
 117                 while (!need_resched())
 118                         default_idle();
 119                 tick_nohz_restart_sched_tick();
 120                 preempt_enable_no_resched();
 121                 schedule();
 122                 preempt_disable();
 123         }
 124 }
 125
 126 extern void kernel_thread_starter(void);
 127
 128 asm(
 129         ".align 4\n"
 130         "kernel_thread_starter:\n"
 131         "    la    2,0(10)\n"
 132         "    basr  14,9\n"
 133         "    la    2,0\n"
 134         "    br    11\n");
 135
 136 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 137 {
 138         struct pt_regs regs;
 139
 140         memset(&regs, 0, sizeof(regs));
 141         regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
 142         regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 143         regs.gprs[9] = (unsigned long) fn;
 144         regs.gprs[10] = (unsigned long) arg;
 145         regs.gprs[11] = (unsigned long) do_exit;
 146         regs.orig_gpr2 = -1;
 147
 148         /* Ok, create the new process.. */
 149         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 150                        0, &regs, 0, NULL, NULL);
 151 }
 152
 153 /*
 154  * Free current thread data structures etc..
 155  */
 156 void exit_thread(void)
 157 {
 158 }
 159
 160 void flush_thread(void)
 161 {
 162         clear_used_math();
 163         clear_tsk_thread_flag(current, TIF_USEDFPU);
 164 }
 165
 166 void release_thread(struct task_struct *dead_task)
 167 {
 168 }
 169
 170 int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
 171         unsigned long unused,
 172         struct task_struct * p, struct pt_regs * regs)
 173 {
 174         struct fake_frame
 175           {
 176             struct stack_frame sf;
 177             struct pt_regs childregs;
 178           } *frame;
 179
 180         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 181         p->thread.ksp = (unsigned long) frame;
 182         /* Store access registers to kernel stack of new process. */
 183         frame->childregs = *regs;
 184         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 185         frame->childregs.gprs[15] = new_stackp;
 186         frame->sf.back_chain = 0;
 187
 188         /* new return point is ret_from_fork */
 189         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 190
 191         /* fake return stack for resume(), don't go back to schedule */
 192         frame->sf.gprs[9] = (unsigned long) frame;
 193
 194         /* Save access registers to new thread structure. */
 195         save_access_regs(&p->thread.acrs[0]);
 196
 197 #ifndef CONFIG_64BIT
 198         /*
 199          * save fprs to current->thread.fp_regs to merge them with
 200          * the emulated registers and then copy the result to the child.
 201          */
 202         save_fp_regs(&current->thread.fp_regs);
 203         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 204                sizeof(s390_fp_regs));
 205         /* Set a new TLS ?  */
 206         if (clone_flags & CLONE_SETTLS)
 207                 p->thread.acrs[0] = regs->gprs[6];
 208 #else /* CONFIG_64BIT */
 209         /* Save the fpu registers to new thread structure. */
 210         save_fp_regs(&p->thread.fp_regs);
 211         /* Set a new TLS ?  */
 212         if (clone_flags & CLONE_SETTLS) {
 213                 if (test_thread_flag(TIF_31BIT)) {
 214                         p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 215                 } else {
 216                         p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 217                         p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 218                 }
 219         }
 220 #endif /* CONFIG_64BIT */
 221         /* start new process with ar4 pointing to the correct address space */
 222         p->thread.mm_segment = get_fs();
 223         /* Don't copy debug registers */
 224         memset(&p->thread.per_info,0,sizeof(p->thread.per_info));
 225
 226         return 0;
 227 }
 228
 229 SYSCALL_DEFINE0(fork)
 230 {
 231         struct pt_regs *regs = task_pt_regs(current);
 232         return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 233 }
 234
 235 SYSCALL_DEFINE0(clone)
 236 {
 237         struct pt_regs *regs = task_pt_regs(current);
 238         unsigned long clone_flags;
 239         unsigned long newsp;
 240         int __user *parent_tidptr, *child_tidptr;
 241
 242         clone_flags = regs->gprs[3];
 243         newsp = regs->orig_gpr2;
 244         parent_tidptr = (int __user *) regs->gprs[4];
 245         child_tidptr = (int __user *) regs->gprs[5];
 246         if (!newsp)
 247                 newsp = regs->gprs[15];
 248         return do_fork(clone_flags, newsp, regs, 0,
 249                        parent_tidptr, child_tidptr);
 250 }
 251
 252 /*
 253  * This is trivial, and on the face of it looks like it
 254  * could equally well be done in user mode.
 255  *
 256  * Not so, for quite unobvious reasons - register pressure.
 257  * In user mode vfork() cannot have a stack frame, and if
 258  * done by calling the "clone()" system call directly, you
 259  * do not have enough call-clobbered registers to hold all
 260  * the information you need.
 261  */
 262 SYSCALL_DEFINE0(vfork)
 263 {
 264         struct pt_regs *regs = task_pt_regs(current);
 265         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 266                        regs->gprs[15], regs, 0, NULL, NULL);
 267 }
 268
 269 asmlinkage void execve_tail(void)
 270 {
 271         task_lock(current);
 272         current->ptrace &= ~PT_DTRACE;
 273         task_unlock(current);
 274         current->thread.fp_regs.fpc = 0;
 275         if (MACHINE_HAS_IEEE)
 276                 asm volatile("sfpc %0,%0" : : "d" (0));
 277 }
 278
 279 /*
 280  * sys_execve() executes a new program.
 281  */
 282 SYSCALL_DEFINE0(execve)
 283 {
 284         struct pt_regs *regs = task_pt_regs(current);
 285         char *filename;
 286         unsigned long result;
 287         int rc;
 288
 289         filename = getname((char __user *) regs->orig_gpr2);
 290         if (IS_ERR(filename)) {
 291                 result = PTR_ERR(filename);
 292                 goto out;
 293         }
 294         rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
 295                        (char __user * __user *) regs->gprs[4], regs);
 296         if (rc) {
 297                 result = rc;
 298                 goto out_putname;
 299         }
 300         execve_tail();
 301         result = regs->gprs[2];
 302 out_putname:
 303         putname(filename);
 304 out:
 305         return result;
 306 }
 307
 308 /*
 309  * fill in the FPU structure for a core dump.
 310  */
 311 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 312 {
 313 #ifndef CONFIG_64BIT
 314         /*
 315          * save fprs to current->thread.fp_regs to merge them with
 316          * the emulated registers and then copy the result to the dump.
 317          */
 318         save_fp_regs(&current->thread.fp_regs);
 319         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 320 #else /* CONFIG_64BIT */
 321         save_fp_regs(fpregs);
 322 #endif /* CONFIG_64BIT */
 323         return 1;
 324 }
 325
 326 unsigned long get_wchan(struct task_struct *p)
 327 {
 328         struct stack_frame *sf, *low, *high;
 329         unsigned long return_address;
 330         int count;
 331
 332         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 333                 return 0;
 334         low = task_stack_page(p);
 335         high = (struct stack_frame *) task_pt_regs(p);
 336         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 337         if (sf <= low || sf > high)
 338                 return 0;
 339         for (count = 0; count < 16; count++) {
 340                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 341                 if (sf <= low || sf > high)
 342                         return 0;
 343                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 344                 if (!in_sched_functions(return_address))
 345                         return return_address;
 346         }
 347         return 0;
 348 }
 349