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 void arch_cpu_idle(void)
  65 {
  66         local_mcck_disable();
  67         if (test_cpu_flag(CIF_MCCK_PENDING)) {
  68                 local_mcck_enable();
  69                 local_irq_enable();
  70                 return;
  71         }
  72         /* Halt the cpu and keep track of cpu time accounting. */
  73         vtime_stop_cpu();
  74         local_irq_enable();
  75 }
  76
  77 void arch_cpu_idle_exit(void)
  78 {
  79         if (test_cpu_flag(CIF_MCCK_PENDING))
  80                 s390_handle_mcck();
  81 }
  82
  83 void arch_cpu_idle_dead(void)
  84 {
  85         cpu_die();
  86 }
  87
  88 extern void __kprobes kernel_thread_starter(void);
  89
  90 /*
  91  * Free current thread data structures etc..
  92  */
  93 void exit_thread(void)
  94 {
  95         exit_thread_runtime_instr();
  96 }
  97
  98 void flush_thread(void)
  99 {
 100 }
 101
 102 void release_thread(struct task_struct *dead_task)
 103 {
 104 }
 105
 106 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 107                 unsigned long arg, struct task_struct *p)
 108 {
 109         struct thread_info *ti;
 110         struct fake_frame
 111         {
 112                 struct stack_frame sf;
 113                 struct pt_regs childregs;
 114         } *frame;
 115
 116         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 117         p->thread.ksp = (unsigned long) frame;
 118         /* Save access registers to new thread structure. */
 119         save_access_regs(&p->thread.acrs[0]);
 120         /* start new process with ar4 pointing to the correct address space */
 121         p->thread.mm_segment = get_fs();
 122         /* Don't copy debug registers */
 123         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 124         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 125         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 126         /* Initialize per thread user and system timer values */
 127         ti = task_thread_info(p);
 128         ti->user_timer = 0;
 129         ti->system_timer = 0;
 130
 131         frame->sf.back_chain = 0;
 132         /* new return point is ret_from_fork */
 133         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 134         /* fake return stack for resume(), don't go back to schedule */
 135         frame->sf.gprs[9] = (unsigned long) frame;
 136
 137         /* Store access registers to kernel stack of new process. */
 138         if (unlikely(p->flags & PF_KTHREAD)) {
 139                 /* kernel thread */
 140                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 141                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 142                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 143                 frame->childregs.psw.addr = PSW_ADDR_AMODE |
 144                                 (unsigned long) kernel_thread_starter;
 145                 frame->childregs.gprs[9] = new_stackp; /* function */
 146                 frame->childregs.gprs[10] = arg;
 147                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 148                 frame->childregs.orig_gpr2 = -1;
 149
 150                 return 0;
 151         }
 152         frame->childregs = *current_pt_regs();
 153         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 154         frame->childregs.flags = 0;
 155         if (new_stackp)
 156                 frame->childregs.gprs[15] = new_stackp;
 157
 158         /* Don't copy runtime instrumentation info */
 159         p->thread.ri_cb = NULL;
 160         p->thread.ri_signum = 0;
 161         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 162
 163 #ifndef CONFIG_64BIT
 164         /*
 165          * save fprs to current->thread.fp_regs to merge them with
 166          * the emulated registers and then copy the result to the child.
 167          */
 168         save_fp_ctl(&current->thread.fp_regs.fpc);
 169         save_fp_regs(current->thread.fp_regs.fprs);
 170         memcpy(&p->thread.fp_regs, &current->thread.fp_regs,
 171                sizeof(s390_fp_regs));
 172         /* Set a new TLS ?  */
 173         if (clone_flags & CLONE_SETTLS)
 174                 p->thread.acrs[0] = frame->childregs.gprs[6];
 175 #else /* CONFIG_64BIT */
 176         /* Save the fpu registers to new thread structure. */
 177         save_fp_ctl(&p->thread.fp_regs.fpc);
 178         save_fp_regs(p->thread.fp_regs.fprs);
 179         p->thread.fp_regs.pad = 0;
 180         /* Set a new TLS ?  */
 181         if (clone_flags & CLONE_SETTLS) {
 182                 unsigned long tls = frame->childregs.gprs[6];
 183                 if (is_compat_task()) {
 184                         p->thread.acrs[0] = (unsigned int)tls;
 185                 } else {
 186                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 187                         p->thread.acrs[1] = (unsigned int)tls;
 188                 }
 189         }
 190 #endif /* CONFIG_64BIT */
 191         return 0;
 192 }
 193
 194 asmlinkage void execve_tail(void)
 195 {
 196         current->thread.fp_regs.fpc = 0;
 197         if (MACHINE_HAS_IEEE)
 198                 asm volatile("sfpc %0,%0" : : "d" (0));
 199 }
 200
 201 /*
 202  * fill in the FPU structure for a core dump.
 203  */
 204 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 205 {
 206 #ifndef CONFIG_64BIT
 207         /*
 208          * save fprs to current->thread.fp_regs to merge them with
 209          * the emulated registers and then copy the result to the dump.
 210          */
 211         save_fp_ctl(&current->thread.fp_regs.fpc);
 212         save_fp_regs(current->thread.fp_regs.fprs);
 213         memcpy(fpregs, &current->thread.fp_regs, sizeof(s390_fp_regs));
 214 #else /* CONFIG_64BIT */
 215         save_fp_ctl(&fpregs->fpc);
 216         save_fp_regs(fpregs->fprs);
 217 #endif /* CONFIG_64BIT */
 218         return 1;
 219 }
 220 EXPORT_SYMBOL(dump_fpu);
 221
 222 unsigned long get_wchan(struct task_struct *p)
 223 {
 224         struct stack_frame *sf, *low, *high;
 225         unsigned long return_address;
 226         int count;
 227
 228         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 229                 return 0;
 230         low = task_stack_page(p);
 231         high = (struct stack_frame *) task_pt_regs(p);
 232         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 233         if (sf <= low || sf > high)
 234                 return 0;
 235         for (count = 0; count < 16; count++) {
 236                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 237                 if (sf <= low || sf > high)
 238                         return 0;
 239                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 240                 if (!in_sched_functions(return_address))
 241                         return return_address;
 242         }
 243         return 0;
 244 }
 245
 246 unsigned long arch_align_stack(unsigned long sp)
 247 {
 248         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 249                 sp -= get_random_int() & ~PAGE_MASK;
 250         return sp & ~0xf;
 251 }
 252
 253 static inline unsigned long brk_rnd(void)
 254 {
 255         /* 8MB for 32bit, 1GB for 64bit */
 256         if (is_32bit_task())
 257                 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
 258         else
 259                 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
 260 }
 261
 262 unsigned long arch_randomize_brk(struct mm_struct *mm)
 263 {
 264         unsigned long ret;
 265
 266         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 267         return (ret > mm->brk) ? ret : mm->brk;
 268 }
 269
 270 unsigned long randomize_et_dyn(unsigned long base)
 271 {
 272         unsigned long ret;
 273
 274         if (!(current->flags & PF_RANDOMIZE))
 275                 return base;
 276         ret = PAGE_ALIGN(base + brk_rnd());
 277         return (ret > base) ? ret : base;
 278 }