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/slab.h>
  20 #include <linux/unistd.h>
  21 #include <linux/ptrace.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/tick.h>
  31 #include <linux/elfcore.h>
  32 #include <linux/kernel_stat.h>
  33 #include <linux/syscalls.h>
  34 #include <linux/compat.h>
  35 #include <linux/kprobes.h>
  36 #include <asm/compat.h>
  37 #include <asm/uaccess.h>
  38 #include <asm/pgtable.h>
  39 #include <asm/system.h>
  40 #include <asm/io.h>
  41 #include <asm/processor.h>
  42 #include <asm/irq.h>
  43 #include <asm/timer.h>
  44 #include <asm/nmi.h>
  45 #include <asm/smp.h>
  46 #include "entry.h"
  47
  48 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  49
  50 /*
  51  * Return saved PC of a blocked thread. used in kernel/sched.
  52  * resume in entry.S does not create a new stack frame, it
  53  * just stores the registers %r6-%r15 to the frame given by
  54  * schedule. We want to return the address of the caller of
  55  * schedule, so we have to walk the backchain one time to
  56  * find the frame schedule() store its return address.
  57  */
  58 unsigned long thread_saved_pc(struct task_struct *tsk)
  59 {
  60         struct stack_frame *sf, *low, *high;
  61
  62         if (!tsk || !task_stack_page(tsk))
  63                 return 0;
  64         low = task_stack_page(tsk);
  65         high = (struct stack_frame *) task_pt_regs(tsk);
  66         sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  67         if (sf <= low || sf > high)
  68                 return 0;
  69         sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  70         if (sf <= low || sf > high)
  71                 return 0;
  72         return sf->gprs[8];
  73 }
  74
  75 /*
  76  * The idle loop on a S390...
  77  */
  78 static void default_idle(void)
  79 {
  80         if (cpu_is_offline(smp_processor_id()))
  81                 cpu_die();
  82         local_irq_disable();
  83         if (need_resched()) {
  84                 local_irq_enable();
  85                 return;
  86         }
  87         local_mcck_disable();
  88         if (test_thread_flag(TIF_MCCK_PENDING)) {
  89                 local_mcck_enable();
  90                 local_irq_enable();
  91                 s390_handle_mcck();
  92                 return;
  93         }
  94         trace_hardirqs_on();
  95         /* Don't trace preempt off for idle. */
  96         stop_critical_timings();
  97         /* Stop virtual timer and halt the cpu. */
  98         vtime_stop_cpu();
  99         /* Reenable preemption tracer. */
 100         start_critical_timings();
 101 }
 102
 103 void cpu_idle(void)
 104 {
 105         for (;;) {
 106                 tick_nohz_stop_sched_tick(1);
 107                 while (!need_resched())
 108                         default_idle();
 109                 tick_nohz_restart_sched_tick();
 110                 preempt_enable_no_resched();
 111                 schedule();
 112                 preempt_disable();
 113         }
 114 }
 115
 116 extern void __kprobes kernel_thread_starter(void);
 117
 118 asm(
 119         ".section .kprobes.text, \"ax\"\n"
 120         ".global kernel_thread_starter\n"
 121         "kernel_thread_starter:\n"
 122         "    la    2,0(10)\n"
 123         "    basr  14,9\n"
 124         "    la    2,0\n"
 125         "    br    11\n"
 126         ".previous\n");
 127
 128 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 129 {
 130         struct pt_regs regs;
 131
 132         memset(&regs, 0, sizeof(regs));
 133         regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
 134         regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 135         regs.gprs[9] = (unsigned long) fn;
 136         regs.gprs[10] = (unsigned long) arg;
 137         regs.gprs[11] = (unsigned long) do_exit;
 138         regs.orig_gpr2 = -1;
 139
 140         /* Ok, create the new process.. */
 141         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 142                        0, &regs, 0, NULL, NULL);
 143 }
 144 EXPORT_SYMBOL(kernel_thread);
 145
 146 /*
 147  * Free current thread data structures etc..
 148  */
 149 void exit_thread(void)
 150 {
 151 }
 152
 153 void flush_thread(void)
 154 {
 155 }
 156
 157 void release_thread(struct task_struct *dead_task)
 158 {
 159 }
 160
 161 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 162                 unsigned long unused,
 163                 struct task_struct *p, struct pt_regs *regs)
 164 {
 165         struct thread_info *ti;
 166         struct fake_frame
 167         {
 168                 struct stack_frame sf;
 169                 struct pt_regs childregs;
 170         } *frame;
 171
 172         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 173         p->thread.ksp = (unsigned long) frame;
 174         /* Store access registers to kernel stack of new process. */
 175         frame->childregs = *regs;
 176         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 177         frame->childregs.gprs[15] = new_stackp;
 178         frame->sf.back_chain = 0;
 179
 180         /* new return point is ret_from_fork */
 181         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 182
 183         /* fake return stack for resume(), don't go back to schedule */
 184         frame->sf.gprs[9] = (unsigned long) frame;
 185
 186         /* Save access registers to new thread structure. */
 187         save_access_regs(&p->thread.acrs[0]);
 188
 189 #ifndef CONFIG_64BIT
 190         /*
 191          * save fprs to current->thread.fp_regs to merge them with
 192          * the emulated registers and then copy the result to the child.
 193          */
 194         save_fp_regs(&current->thread.fp_regs);
 195         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 196                sizeof(s390_fp_regs));
 197         /* Set a new TLS ?  */
 198         if (clone_flags & CLONE_SETTLS)
 199                 p->thread.acrs[0] = regs->gprs[6];
 200 #else /* CONFIG_64BIT */
 201         /* Save the fpu registers to new thread structure. */
 202         save_fp_regs(&p->thread.fp_regs);
 203         /* Set a new TLS ?  */
 204         if (clone_flags & CLONE_SETTLS) {
 205                 if (is_compat_task()) {
 206                         p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 207                 } else {
 208                         p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 209                         p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 210                 }
 211         }
 212 #endif /* CONFIG_64BIT */
 213         /* start new process with ar4 pointing to the correct address space */
 214         p->thread.mm_segment = get_fs();
 215         /* Don't copy debug registers */
 216         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 217         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 218         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 219         clear_tsk_thread_flag(p, TIF_PER_TRAP);
 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_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags,
 234                 int __user *, parent_tidptr, int __user *, child_tidptr)
 235 {
 236         struct pt_regs *regs = task_pt_regs(current);
 237
 238         if (!newsp)
 239                 newsp = regs->gprs[15];
 240         return do_fork(clone_flags, newsp, regs, 0,
 241                        parent_tidptr, child_tidptr);
 242 }
 243
 244 /*
 245  * This is trivial, and on the face of it looks like it
 246  * could equally well be done in user mode.
 247  *
 248  * Not so, for quite unobvious reasons - register pressure.
 249  * In user mode vfork() cannot have a stack frame, and if
 250  * done by calling the "clone()" system call directly, you
 251  * do not have enough call-clobbered registers to hold all
 252  * the information you need.
 253  */
 254 SYSCALL_DEFINE0(vfork)
 255 {
 256         struct pt_regs *regs = task_pt_regs(current);
 257         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 258                        regs->gprs[15], regs, 0, NULL, NULL);
 259 }
 260
 261 asmlinkage void execve_tail(void)
 262 {
 263         current->thread.fp_regs.fpc = 0;
 264         if (MACHINE_HAS_IEEE)
 265                 asm volatile("sfpc %0,%0" : : "d" (0));
 266 }
 267
 268 /*
 269  * sys_execve() executes a new program.
 270  */
 271 SYSCALL_DEFINE3(execve, const char __user *, name,
 272                 const char __user *const __user *, argv,
 273                 const char __user *const __user *, envp)
 274 {
 275         struct pt_regs *regs = task_pt_regs(current);
 276         char *filename;
 277         long rc;
 278
 279         filename = getname(name);
 280         rc = PTR_ERR(filename);
 281         if (IS_ERR(filename))
 282                 return rc;
 283         rc = do_execve(filename, argv, envp, regs);
 284         if (rc)
 285                 goto out;
 286         execve_tail();
 287         rc = regs->gprs[2];
 288 out:
 289         putname(filename);
 290         return rc;
 291 }
 292
 293 /*
 294  * fill in the FPU structure for a core dump.
 295  */
 296 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 297 {
 298 #ifndef CONFIG_64BIT
 299         /*
 300          * save fprs to current->thread.fp_regs to merge them with
 301          * the emulated registers and then copy the result to the dump.
 302          */
 303         save_fp_regs(&current->thread.fp_regs);
 304         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 305 #else /* CONFIG_64BIT */
 306         save_fp_regs(fpregs);
 307 #endif /* CONFIG_64BIT */
 308         return 1;
 309 }
 310 EXPORT_SYMBOL(dump_fpu);
 311
 312 unsigned long get_wchan(struct task_struct *p)
 313 {
 314         struct stack_frame *sf, *low, *high;
 315         unsigned long return_address;
 316         int count;
 317
 318         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 319                 return 0;
 320         low = task_stack_page(p);
 321         high = (struct stack_frame *) task_pt_regs(p);
 322         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 323         if (sf <= low || sf > high)
 324                 return 0;
 325         for (count = 0; count < 16; count++) {
 326                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 327                 if (sf <= low || sf > high)
 328                         return 0;
 329                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 330                 if (!in_sched_functions(return_address))
 331                         return return_address;
 332         }
 333         return 0;
 334 }