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