arch/s390/kernel/process.c

   1 /*
   2  * This file handles the architecture dependent parts of process handling.
   3  *
   4  *    Copyright IBM Corp. 1999,2009
   5  *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
   6  *               Hartmut Penner <hp@de.ibm.com>,
   7  *               Denis Joseph Barrow,
   8  */
   9
  10 #include <linux/compiler.h>
  11 #include <linux/cpu.h>
  12 #include <linux/errno.h>
  13 #include <linux/sched.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mm.h>
  16 #include <linux/fs.h>
  17 #include <linux/smp.h>
  18 #include <linux/stddef.h>
  19 #include <linux/unistd.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/slab.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/user.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/delay.h>
  26 #include <linux/reboot.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/notifier.h>
  30 #include <linux/utsname.h>
  31 #include <linux/tick.h>
  32 #include <linux/elfcore.h>
  33 #include <linux/kernel_stat.h>
  34 #include <linux/syscalls.h>
  35 #include <asm/compat.h>
  36 #include <asm/uaccess.h>
  37 #include <asm/pgtable.h>
  38 #include <asm/system.h>
  39 #include <asm/io.h>
  40 #include <asm/processor.h>
  41 #include <asm/irq.h>
  42 #include <asm/timer.h>
  43 #include <asm/nmi.h>
  44 #include "entry.h"
  45
  46 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  47
  48 /*
  49  * Return saved PC of a blocked thread. used in kernel/sched.
  50  * resume in entry.S does not create a new stack frame, it
  51  * just stores the registers %r6-%r15 to the frame given by
  52  * schedule. We want to return the address of the caller of
  53  * schedule, so we have to walk the backchain one time to
  54  * find the frame schedule() store its return address.
  55  */
  56 unsigned long thread_saved_pc(struct task_struct *tsk)
  57 {
  58         struct stack_frame *sf, *low, *high;
  59
  60         if (!tsk || !task_stack_page(tsk))
  61                 return 0;
  62         low = task_stack_page(tsk);
  63         high = (struct stack_frame *) task_pt_regs(tsk);
  64         sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  65         if (sf <= low || sf > high)
  66                 return 0;
  67         sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  68         if (sf <= low || sf > high)
  69                 return 0;
  70         return sf->gprs[8];
  71 }
  72
  73 /*
  74  * The idle loop on a S390...
  75  */
  76 static void default_idle(void)
  77 {
  78         /* CPU is going idle. */
  79         local_irq_disable();
  80         if (need_resched()) {
  81                 local_irq_enable();
  82                 return;
  83         }
  84 #ifdef CONFIG_HOTPLUG_CPU
  85         if (cpu_is_offline(smp_processor_id())) {
  86                 preempt_enable_no_resched();
  87                 cpu_die();
  88         }
  89 #endif
  90         local_mcck_disable();
  91         if (test_thread_flag(TIF_MCCK_PENDING)) {
  92                 local_mcck_enable();
  93                 local_irq_enable();
  94                 s390_handle_mcck();
  95                 return;
  96         }
  97         trace_hardirqs_on();
  98         /* Don't trace preempt off for idle. */
  99         stop_critical_timings();
 100         /* Stop virtual timer and halt the cpu. */
 101         vtime_stop_cpu();
 102         /* Reenable preemption tracer. */
 103         start_critical_timings();
 104 }
 105
 106 void cpu_idle(void)
 107 {
 108         for (;;) {
 109                 tick_nohz_stop_sched_tick(1);
 110                 while (!need_resched())
 111                         default_idle();
 112                 tick_nohz_restart_sched_tick();
 113                 preempt_enable_no_resched();
 114                 schedule();
 115                 preempt_disable();
 116         }
 117 }
 118
 119 extern void kernel_thread_starter(void);
 120
 121 asm(
 122         ".align 4\n"
 123         "kernel_thread_starter:\n"
 124         "    la    2,0(10)\n"
 125         "    basr  14,9\n"
 126         "    la    2,0\n"
 127         "    br    11\n");
 128
 129 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 130 {
 131         struct pt_regs regs;
 132
 133         memset(&regs, 0, sizeof(regs));
 134         regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
 135         regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 136         regs.gprs[9] = (unsigned long) fn;
 137         regs.gprs[10] = (unsigned long) arg;
 138         regs.gprs[11] = (unsigned long) do_exit;
 139         regs.orig_gpr2 = -1;
 140
 141         /* Ok, create the new process.. */
 142         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 143                        0, &regs, 0, NULL, NULL);
 144 }
 145 EXPORT_SYMBOL(kernel_thread);
 146
 147 /*
 148  * Free current thread data structures etc..
 149  */
 150 void exit_thread(void)
 151 {
 152 }
 153
 154 void flush_thread(void)
 155 {
 156         clear_used_math();
 157         clear_tsk_thread_flag(current, TIF_USEDFPU);
 158 }
 159
 160 void release_thread(struct task_struct *dead_task)
 161 {
 162 }
 163
 164 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 165                 unsigned long unused,
 166                 struct task_struct *p, struct pt_regs *regs)
 167 {
 168         struct thread_info *ti;
 169         struct fake_frame
 170         {
 171                 struct stack_frame sf;
 172                 struct pt_regs childregs;
 173         } *frame;
 174
 175         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 176         p->thread.ksp = (unsigned long) frame;
 177         /* Store access registers to kernel stack of new process. */
 178         frame->childregs = *regs;
 179         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 180         frame->childregs.gprs[15] = new_stackp;
 181         frame->sf.back_chain = 0;
 182
 183         /* new return point is ret_from_fork */
 184         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 185
 186         /* fake return stack for resume(), don't go back to schedule */
 187         frame->sf.gprs[9] = (unsigned long) frame;
 188
 189         /* Save access registers to new thread structure. */
 190         save_access_regs(&p->thread.acrs[0]);
 191
 192 #ifndef CONFIG_64BIT
 193         /*
 194          * save fprs to current->thread.fp_regs to merge them with
 195          * the emulated registers and then copy the result to the child.
 196          */
 197         save_fp_regs(&current->thread.fp_regs);
 198         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 199                sizeof(s390_fp_regs));
 200         /* Set a new TLS ?  */
 201         if (clone_flags & CLONE_SETTLS)
 202                 p->thread.acrs[0] = regs->gprs[6];
 203 #else /* CONFIG_64BIT */
 204         /* Save the fpu registers to new thread structure. */
 205         save_fp_regs(&p->thread.fp_regs);
 206         /* Set a new TLS ?  */
 207         if (clone_flags & CLONE_SETTLS) {
 208                 if (is_compat_task()) {
 209                         p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 210                 } else {
 211                         p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 212                         p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 213                 }
 214         }
 215 #endif /* CONFIG_64BIT */
 216         /* start new process with ar4 pointing to the correct address space */
 217         p->thread.mm_segment = get_fs();
 218         /* Don't copy debug registers */
 219         memset(&p->thread.per_info, 0, sizeof(p->thread.per_info));
 220         /* Initialize per thread user and system timer values */
 221         ti = task_thread_info(p);
 222         ti->user_timer = 0;
 223         ti->system_timer = 0;
 224         return 0;
 225 }
 226
 227 SYSCALL_DEFINE0(fork)
 228 {
 229         struct pt_regs *regs = task_pt_regs(current);
 230         return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 231 }
 232
 233 SYSCALL_DEFINE0(clone)
 234 {
 235         struct pt_regs *regs = task_pt_regs(current);
 236         unsigned long clone_flags;
 237         unsigned long newsp;
 238         int __user *parent_tidptr, *child_tidptr;
 239
 240         clone_flags = regs->gprs[3];
 241         newsp = regs->orig_gpr2;
 242         parent_tidptr = (int __user *) regs->gprs[4];
 243         child_tidptr = (int __user *) regs->gprs[5];
 244         if (!newsp)
 245                 newsp = regs->gprs[15];
 246         return do_fork(clone_flags, newsp, regs, 0,
 247                        parent_tidptr, child_tidptr);
 248 }
 249
 250 /*
 251  * This is trivial, and on the face of it looks like it
 252  * could equally well be done in user mode.
 253  *
 254  * Not so, for quite unobvious reasons - register pressure.
 255  * In user mode vfork() cannot have a stack frame, and if
 256  * done by calling the "clone()" system call directly, you
 257  * do not have enough call-clobbered registers to hold all
 258  * the information you need.
 259  */
 260 SYSCALL_DEFINE0(vfork)
 261 {
 262         struct pt_regs *regs = task_pt_regs(current);
 263         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 264                        regs->gprs[15], regs, 0, NULL, NULL);
 265 }
 266
 267 asmlinkage void execve_tail(void)
 268 {
 269         current->thread.fp_regs.fpc = 0;
 270         if (MACHINE_HAS_IEEE)
 271                 asm volatile("sfpc %0,%0" : : "d" (0));
 272 }
 273
 274 /*
 275  * sys_execve() executes a new program.
 276  */
 277 SYSCALL_DEFINE0(execve)
 278 {
 279         struct pt_regs *regs = task_pt_regs(current);
 280         char *filename;
 281         unsigned long result;
 282         int rc;
 283
 284         filename = getname((char __user *) regs->orig_gpr2);
 285         if (IS_ERR(filename)) {
 286                 result = PTR_ERR(filename);
 287                 goto out;
 288         }
 289         rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
 290                        (char __user * __user *) regs->gprs[4], regs);
 291         if (rc) {
 292                 result = rc;
 293                 goto out_putname;
 294         }
 295         execve_tail();
 296         result = regs->gprs[2];
 297 out_putname:
 298         putname(filename);
 299 out:
 300         return result;
 301 }
 302
 303 /*
 304  * fill in the FPU structure for a core dump.
 305  */
 306 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 307 {
 308 #ifndef CONFIG_64BIT
 309         /*
 310          * save fprs to current->thread.fp_regs to merge them with
 311          * the emulated registers and then copy the result to the dump.
 312          */
 313         save_fp_regs(&current->thread.fp_regs);
 314         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 315 #else /* CONFIG_64BIT */
 316         save_fp_regs(fpregs);
 317 #endif /* CONFIG_64BIT */
 318         return 1;
 319 }
 320 EXPORT_SYMBOL(dump_fpu);
 321
 322 unsigned long get_wchan(struct task_struct *p)
 323 {
 324         struct stack_frame *sf, *low, *high;
 325         unsigned long return_address;
 326         int count;
 327
 328         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 329                 return 0;
 330         low = task_stack_page(p);
 331         high = (struct stack_frame *) task_pt_regs(p);
 332         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 333         if (sf <= low || sf > high)
 334                 return 0;
 335         for (count = 0; count < 16; count++) {
 336                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 337                 if (sf <= low || sf > high)
 338                         return 0;
 339                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 340                 if (!in_sched_functions(return_address))
 341                         return return_address;
 342         }
 343         return 0;
 344 }