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         /* Free either the floating-point or the vector register save area */
  85         kfree(tsk->thread.fpu.regs);
  86 }
  87
  88 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  89 {
  90         *dst = *src;
  91
  92         /* Set up a new floating-point register save area */
  93         dst->thread.fpu.fpc = 0;
  94         dst->thread.fpu.flags = 0;      /* Always start with VX disabled */
  95         dst->thread.fpu.fprs = kzalloc(sizeof(freg_t) * __NUM_FPRS,
  96                                        GFP_KERNEL|__GFP_REPEAT);
  97         if (!dst->thread.fpu.fprs)
  98                 return -ENOMEM;
  99
 100         /*
 101          * Save the floating-point or vector register state of the current
 102          * task.  The state is not saved for early kernel threads, for example,
 103          * the init_task, which do not have an allocated save area.
 104          * The CIF_FPU flag is set in any case to lazy clear or restore a saved
 105          * state when switching to a different task or returning to user space.
 106          */
 107         save_fpu_regs();
 108         dst->thread.fpu.fpc = current->thread.fpu.fpc;
 109         if (is_vx_task(current))
 110                 convert_vx_to_fp(dst->thread.fpu.fprs,
 111                                  current->thread.fpu.vxrs);
 112         else
 113                 memcpy(dst->thread.fpu.fprs, current->thread.fpu.fprs,
 114                        sizeof(freg_t) * __NUM_FPRS);
 115         return 0;
 116 }
 117
 118 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 119                 unsigned long arg, struct task_struct *p)
 120 {
 121         struct thread_info *ti;
 122         struct fake_frame
 123         {
 124                 struct stack_frame sf;
 125                 struct pt_regs childregs;
 126         } *frame;
 127
 128         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 129         p->thread.ksp = (unsigned long) frame;
 130         /* Save access registers to new thread structure. */
 131         save_access_regs(&p->thread.acrs[0]);
 132         /* start new process with ar4 pointing to the correct address space */
 133         p->thread.mm_segment = get_fs();
 134         /* Don't copy debug registers */
 135         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 136         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 137         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 138         /* Initialize per thread user and system timer values */
 139         ti = task_thread_info(p);
 140         ti->user_timer = 0;
 141         ti->system_timer = 0;
 142
 143         frame->sf.back_chain = 0;
 144         /* new return point is ret_from_fork */
 145         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 146         /* fake return stack for resume(), don't go back to schedule */
 147         frame->sf.gprs[9] = (unsigned long) frame;
 148
 149         /* Store access registers to kernel stack of new process. */
 150         if (unlikely(p->flags & PF_KTHREAD)) {
 151                 /* kernel thread */
 152                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 153                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 154                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 155                 frame->childregs.psw.addr = PSW_ADDR_AMODE |
 156                                 (unsigned long) kernel_thread_starter;
 157                 frame->childregs.gprs[9] = new_stackp; /* function */
 158                 frame->childregs.gprs[10] = arg;
 159                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 160                 frame->childregs.orig_gpr2 = -1;
 161
 162                 return 0;
 163         }
 164         frame->childregs = *current_pt_regs();
 165         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 166         frame->childregs.flags = 0;
 167         if (new_stackp)
 168                 frame->childregs.gprs[15] = new_stackp;
 169
 170         /* Don't copy runtime instrumentation info */
 171         p->thread.ri_cb = NULL;
 172         p->thread.ri_signum = 0;
 173         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 174
 175         /* Set a new TLS ?  */
 176         if (clone_flags & CLONE_SETTLS) {
 177                 unsigned long tls = frame->childregs.gprs[6];
 178                 if (is_compat_task()) {
 179                         p->thread.acrs[0] = (unsigned int)tls;
 180                 } else {
 181                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 182                         p->thread.acrs[1] = (unsigned int)tls;
 183                 }
 184         }
 185         return 0;
 186 }
 187
 188 asmlinkage void execve_tail(void)
 189 {
 190         current->thread.fpu.fpc = 0;
 191         asm volatile("sfpc %0" : : "d" (0));
 192 }
 193
 194 /*
 195  * fill in the FPU structure for a core dump.
 196  */
 197 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 198 {
 199         save_fpu_regs();
 200         fpregs->fpc = current->thread.fpu.fpc;
 201         fpregs->pad = 0;
 202         if (is_vx_task(current))
 203                 convert_vx_to_fp((freg_t *)&fpregs->fprs,
 204                                  current->thread.fpu.vxrs);
 205         else
 206                 memcpy(&fpregs->fprs, current->thread.fpu.fprs,
 207                        sizeof(fpregs->fprs));
 208         return 1;
 209 }
 210 EXPORT_SYMBOL(dump_fpu);
 211
 212 unsigned long get_wchan(struct task_struct *p)
 213 {
 214         struct stack_frame *sf, *low, *high;
 215         unsigned long return_address;
 216         int count;
 217
 218         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 219                 return 0;
 220         low = task_stack_page(p);
 221         high = (struct stack_frame *) task_pt_regs(p);
 222         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 223         if (sf <= low || sf > high)
 224                 return 0;
 225         for (count = 0; count < 16; count++) {
 226                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 227                 if (sf <= low || sf > high)
 228                         return 0;
 229                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 230                 if (!in_sched_functions(return_address))
 231                         return return_address;
 232         }
 233         return 0;
 234 }
 235
 236 unsigned long arch_align_stack(unsigned long sp)
 237 {
 238         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 239                 sp -= get_random_int() & ~PAGE_MASK;
 240         return sp & ~0xf;
 241 }
 242
 243 static inline unsigned long brk_rnd(void)
 244 {
 245         /* 8MB for 32bit, 1GB for 64bit */
 246         if (is_32bit_task())
 247                 return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
 248         else
 249                 return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
 250 }
 251
 252 unsigned long arch_randomize_brk(struct mm_struct *mm)
 253 {
 254         unsigned long ret;
 255
 256         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 257         return (ret > mm->brk) ? ret : mm->brk;
 258 }