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