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