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