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/sched.h>
  13 #include <linux/kernel.h>
  14 #include <linux/mm.h>
  15 #include <linux/elfcore.h>
  16 #include <linux/smp.h>
  17 #include <linux/slab.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/tick.h>
  20 #include <linux/personality.h>
  21 #include <linux/syscalls.h>
  22 #include <linux/compat.h>
  23 #include <linux/kprobes.h>
  24 #include <linux/random.h>
  25 #include <linux/module.h>
  26 #include <asm/system.h>
  27 #include <asm/io.h>
  28 #include <asm/processor.h>
  29 #include <asm/irq.h>
  30 #include <asm/timer.h>
  31 #include <asm/nmi.h>
  32 #include <asm/compat.h>
  33 #include <asm/smp.h>
  34 #include "entry.h"
  35
  36 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  37
  38 /*
  39  * Return saved PC of a blocked thread. used in kernel/sched.
  40  * resume in entry.S does not create a new stack frame, it
  41  * just stores the registers %r6-%r15 to the frame given by
  42  * schedule. We want to return the address of the caller of
  43  * schedule, so we have to walk the backchain one time to
  44  * find the frame schedule() store its return address.
  45  */
  46 unsigned long thread_saved_pc(struct task_struct *tsk)
  47 {
  48         struct stack_frame *sf, *low, *high;
  49
  50         if (!tsk || !task_stack_page(tsk))
  51                 return 0;
  52         low = task_stack_page(tsk);
  53         high = (struct stack_frame *) task_pt_regs(tsk);
  54         sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  55         if (sf <= low || sf > high)
  56                 return 0;
  57         sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  58         if (sf <= low || sf > high)
  59                 return 0;
  60         return sf->gprs[8];
  61 }
  62
  63 /*
  64  * The idle loop on a S390...
  65  */
  66 static void default_idle(void)
  67 {
  68         if (cpu_is_offline(smp_processor_id()))
  69                 cpu_die();
  70         local_irq_disable();
  71         if (need_resched()) {
  72                 local_irq_enable();
  73                 return;
  74         }
  75         local_mcck_disable();
  76         if (test_thread_flag(TIF_MCCK_PENDING)) {
  77                 local_mcck_enable();
  78                 local_irq_enable();
  79                 s390_handle_mcck();
  80                 return;
  81         }
  82         trace_hardirqs_on();
  83         /* Don't trace preempt off for idle. */
  84         stop_critical_timings();
  85         /* Stop virtual timer and halt the cpu. */
  86         vtime_stop_cpu();
  87         /* Reenable preemption tracer. */
  88         start_critical_timings();
  89 }
  90
  91 void cpu_idle(void)
  92 {
  93         for (;;) {
  94                 tick_nohz_stop_sched_tick(1);
  95                 while (!need_resched())
  96                         default_idle();
  97                 tick_nohz_restart_sched_tick();
  98                 preempt_enable_no_resched();
  99                 schedule();
 100                 preempt_disable();
 101         }
 102 }
 103
 104 extern void __kprobes kernel_thread_starter(void);
 105
 106 asm(
 107         ".section .kprobes.text, \"ax\"\n"
 108         ".global kernel_thread_starter\n"
 109         "kernel_thread_starter:\n"
 110         "    la    2,0(10)\n"
 111         "    basr  14,9\n"
 112         "    la    2,0\n"
 113         "    br    11\n"
 114         ".previous\n");
 115
 116 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 117 {
 118         struct pt_regs regs;
 119
 120         memset(&regs, 0, sizeof(regs));
 121         regs.psw.mask = psw_kernel_bits |
 122                 PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 123         regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 124         regs.gprs[9] = (unsigned long) fn;
 125         regs.gprs[10] = (unsigned long) arg;
 126         regs.gprs[11] = (unsigned long) do_exit;
 127         regs.orig_gpr2 = -1;
 128
 129         /* Ok, create the new process.. */
 130         return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
 131                        0, &regs, 0, NULL, NULL);
 132 }
 133 EXPORT_SYMBOL(kernel_thread);
 134
 135 /*
 136  * Free current thread data structures etc..
 137  */
 138 void exit_thread(void)
 139 {
 140 }
 141
 142 void flush_thread(void)
 143 {
 144 }
 145
 146 void release_thread(struct task_struct *dead_task)
 147 {
 148 }
 149
 150 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 151                 unsigned long unused,
 152                 struct task_struct *p, struct pt_regs *regs)
 153 {
 154         struct thread_info *ti;
 155         struct fake_frame
 156         {
 157                 struct stack_frame sf;
 158                 struct pt_regs childregs;
 159         } *frame;
 160
 161         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 162         p->thread.ksp = (unsigned long) frame;
 163         /* Store access registers to kernel stack of new process. */
 164         frame->childregs = *regs;
 165         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 166         frame->childregs.gprs[15] = new_stackp;
 167         frame->sf.back_chain = 0;
 168
 169         /* new return point is ret_from_fork */
 170         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 171
 172         /* fake return stack for resume(), don't go back to schedule */
 173         frame->sf.gprs[9] = (unsigned long) frame;
 174
 175         /* Save access registers to new thread structure. */
 176         save_access_regs(&p->thread.acrs[0]);
 177
 178 #ifndef CONFIG_64BIT
 179         /*
 180          * save fprs to current->thread.fp_regs to merge them with
 181          * the emulated registers and then copy the result to the child.
 182          */
 183         save_fp_regs(&current->thread.fp_regs);
 184         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 185                sizeof(s390_fp_regs));
 186         /* Set a new TLS ?  */
 187         if (clone_flags & CLONE_SETTLS)
 188                 p->thread.acrs[0] = regs->gprs[6];
 189 #else /* CONFIG_64BIT */
 190         /* Save the fpu registers to new thread structure. */
 191         save_fp_regs(&p->thread.fp_regs);
 192         /* Set a new TLS ?  */
 193         if (clone_flags & CLONE_SETTLS) {
 194                 if (is_compat_task()) {
 195                         p->thread.acrs[0] = (unsigned int) regs->gprs[6];
 196                 } else {
 197                         p->thread.acrs[0] = (unsigned int)(regs->gprs[6] >> 32);
 198                         p->thread.acrs[1] = (unsigned int) regs->gprs[6];
 199                 }
 200         }
 201 #endif /* CONFIG_64BIT */
 202         /* start new process with ar4 pointing to the correct address space */
 203         p->thread.mm_segment = get_fs();
 204         /* Don't copy debug registers */
 205         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 206         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 207         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 208         clear_tsk_thread_flag(p, TIF_PER_TRAP);
 209         /* Initialize per thread user and system timer values */
 210         ti = task_thread_info(p);
 211         ti->user_timer = 0;
 212         ti->system_timer = 0;
 213         return 0;
 214 }
 215
 216 SYSCALL_DEFINE0(fork)
 217 {
 218         struct pt_regs *regs = task_pt_regs(current);
 219         return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 220 }
 221
 222 SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags,
 223                 int __user *, parent_tidptr, int __user *, child_tidptr)
 224 {
 225         struct pt_regs *regs = task_pt_regs(current);
 226
 227         if (!newsp)
 228                 newsp = regs->gprs[15];
 229         return do_fork(clone_flags, newsp, regs, 0,
 230                        parent_tidptr, child_tidptr);
 231 }
 232
 233 /*
 234  * This is trivial, and on the face of it looks like it
 235  * could equally well be done in user mode.
 236  *
 237  * Not so, for quite unobvious reasons - register pressure.
 238  * In user mode vfork() cannot have a stack frame, and if
 239  * done by calling the "clone()" system call directly, you
 240  * do not have enough call-clobbered registers to hold all
 241  * the information you need.
 242  */
 243 SYSCALL_DEFINE0(vfork)
 244 {
 245         struct pt_regs *regs = task_pt_regs(current);
 246         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
 247                        regs->gprs[15], regs, 0, NULL, NULL);
 248 }
 249
 250 asmlinkage void execve_tail(void)
 251 {
 252         current->thread.fp_regs.fpc = 0;
 253         if (MACHINE_HAS_IEEE)
 254                 asm volatile("sfpc %0,%0" : : "d" (0));
 255 }
 256
 257 /*
 258  * sys_execve() executes a new program.
 259  */
 260 SYSCALL_DEFINE3(execve, const char __user *, name,
 261                 const char __user *const __user *, argv,
 262                 const char __user *const __user *, envp)
 263 {
 264         struct pt_regs *regs = task_pt_regs(current);
 265         char *filename;
 266         long rc;
 267
 268         filename = getname(name);
 269         rc = PTR_ERR(filename);
 270         if (IS_ERR(filename))
 271                 return rc;
 272         rc = do_execve(filename, argv, envp, regs);
 273         if (rc)
 274                 goto out;
 275         execve_tail();
 276         rc = regs->gprs[2];
 277 out:
 278         putname(filename);
 279         return rc;
 280 }
 281
 282 /*
 283  * fill in the FPU structure for a core dump.
 284  */
 285 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 286 {
 287 #ifndef CONFIG_64BIT
 288         /*
 289          * save fprs to current->thread.fp_regs to merge them with
 290          * the emulated registers and then copy the result to the dump.
 291          */
 292         save_fp_regs(&current->thread.fp_regs);
 293         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 294 #else /* CONFIG_64BIT */
 295         save_fp_regs(fpregs);
 296 #endif /* CONFIG_64BIT */
 297         return 1;
 298 }
 299 EXPORT_SYMBOL(dump_fpu);
 300
 301 unsigned long get_wchan(struct task_struct *p)
 302 {
 303         struct stack_frame *sf, *low, *high;
 304         unsigned long return_address;
 305         int count;
 306
 307         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 308                 return 0;
 309         low = task_stack_page(p);
 310         high = (struct stack_frame *) task_pt_regs(p);
 311         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 312         if (sf <= low || sf > high)
 313                 return 0;
 314         for (count = 0; count < 16; count++) {
 315                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 316                 if (sf <= low || sf > high)
 317                         return 0;
 318                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 319                 if (!in_sched_functions(return_address))
 320                         return return_address;
 321         }
 322         return 0;
 323 }
 324
 325 unsigned long arch_align_stack(unsigned long sp)
 326 {
 327         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 328                 sp -= get_random_int() & ~PAGE_MASK;
 329         return sp & ~0xf;
 330 }
 331
 332 static inline unsigned long brk_rnd(void)
 333 {
 334         /* 8MB for 32bit, 1GB for 64bit */
 335         if (is_32bit_task())
 336                 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
 337         else
 338                 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
 339 }
 340
 341 unsigned long arch_randomize_brk(struct mm_struct *mm)
 342 {
 343         unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd());
 344
 345         if (ret < mm->brk)
 346                 return mm->brk;
 347         return ret;
 348 }
 349
 350 unsigned long randomize_et_dyn(unsigned long base)
 351 {
 352         unsigned long ret = PAGE_ALIGN(base + brk_rnd());
 353
 354         if (!(current->flags & PF_RANDOMIZE))
 355                 return base;
 356         if (ret < base)
 357                 return base;
 358         return ret;
 359 }