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 <linux/init_task.h>
  27 #include <asm/io.h>
  28 #include <asm/processor.h>
  29 #include <asm/vtimer.h>
  30 #include <asm/exec.h>
  31 #include <asm/irq.h>
  32 #include <asm/nmi.h>
  33 #include <asm/smp.h>
  34 #include <asm/switch_to.h>
  35 #include <asm/runtime_instr.h>
  36 #include "entry.h"
  37
  38 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  39
  40 /* FPU save area for the init task */
  41 __vector128 init_task_fpu_regs[__NUM_VXRS] __init_task_data;
  42
  43 /*
  44  * Return saved PC of a blocked thread. used in kernel/sched.
  45  * resume in entry.S does not create a new stack frame, it
  46  * just stores the registers %r6-%r15 to the frame given by
  47  * schedule. We want to return the address of the caller of
  48  * schedule, so we have to walk the backchain one time to
  49  * find the frame schedule() store its return address.
  50  */
  51 unsigned long thread_saved_pc(struct task_struct *tsk)
  52 {
  53         struct stack_frame *sf, *low, *high;
  54
  55         if (!tsk || !task_stack_page(tsk))
  56                 return 0;
  57         low = task_stack_page(tsk);
  58         high = (struct stack_frame *) task_pt_regs(tsk);
  59         sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
  60         if (sf <= low || sf > high)
  61                 return 0;
  62         sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
  63         if (sf <= low || sf > high)
  64                 return 0;
  65         return sf->gprs[8];
  66 }
  67
  68 extern void kernel_thread_starter(void);
  69
  70 /*
  71  * Free current thread data structures etc..
  72  */
  73 void exit_thread(void)
  74 {
  75         exit_thread_runtime_instr();
  76 }
  77
  78 void flush_thread(void)
  79 {
  80 }
  81
  82 void release_thread(struct task_struct *dead_task)
  83 {
  84 }
  85
  86 void arch_release_task_struct(struct task_struct *tsk)
  87 {
  88         /* Free either the floating-point or the vector register save area */
  89         kfree(tsk->thread.fpu.regs);
  90 }
  91
  92 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  93 {
  94         size_t fpu_regs_size;
  95
  96         *dst = *src;
  97
  98         /*
  99          * If the vector extension is available, it is enabled for all tasks,
 100          * and, thus, the FPU register save area must be allocated accordingly.
 101          */
 102         fpu_regs_size = MACHINE_HAS_VX ? sizeof(__vector128) * __NUM_VXRS
 103                                        : sizeof(freg_t) * __NUM_FPRS;
 104         dst->thread.fpu.regs = kzalloc(fpu_regs_size, GFP_KERNEL|__GFP_REPEAT);
 105         if (!dst->thread.fpu.regs)
 106                 return -ENOMEM;
 107
 108         /*
 109          * Save the floating-point or vector register state of the current
 110          * task and set the CIF_FPU flag to lazy restore the FPU register
 111          * state when returning to user space.
 112          */
 113         save_fpu_regs();
 114         dst->thread.fpu.fpc = current->thread.fpu.fpc;
 115         memcpy(dst->thread.fpu.regs, current->thread.fpu.regs, fpu_regs_size);
 116
 117         return 0;
 118 }
 119
 120 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 121                 unsigned long arg, struct task_struct *p)
 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         /* Initialize per thread user and system timer values */
 141         ti = task_thread_info(p);
 142         ti->user_timer = 0;
 143         ti->system_timer = 0;
 144
 145         frame->sf.back_chain = 0;
 146         /* new return point is ret_from_fork */
 147         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 148         /* fake return stack for resume(), don't go back to schedule */
 149         frame->sf.gprs[9] = (unsigned long) frame;
 150
 151         /* Store access registers to kernel stack of new process. */
 152         if (unlikely(p->flags & PF_KTHREAD)) {
 153                 /* kernel thread */
 154                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 155                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 156                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 157                 frame->childregs.psw.addr = PSW_ADDR_AMODE |
 158                                 (unsigned long) kernel_thread_starter;
 159                 frame->childregs.gprs[9] = new_stackp; /* function */
 160                 frame->childregs.gprs[10] = arg;
 161                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 162                 frame->childregs.orig_gpr2 = -1;
 163
 164                 return 0;
 165         }
 166         frame->childregs = *current_pt_regs();
 167         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 168         frame->childregs.flags = 0;
 169         if (new_stackp)
 170                 frame->childregs.gprs[15] = new_stackp;
 171
 172         /* Don't copy runtime instrumentation info */
 173         p->thread.ri_cb = NULL;
 174         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 175
 176         /* Set a new TLS ?  */
 177         if (clone_flags & CLONE_SETTLS) {
 178                 unsigned long tls = frame->childregs.gprs[6];
 179                 if (is_compat_task()) {
 180                         p->thread.acrs[0] = (unsigned int)tls;
 181                 } else {
 182                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 183                         p->thread.acrs[1] = (unsigned int)tls;
 184                 }
 185         }
 186         return 0;
 187 }
 188
 189 asmlinkage void execve_tail(void)
 190 {
 191         current->thread.fpu.fpc = 0;
 192         asm volatile("sfpc %0" : : "d" (0));
 193 }
 194
 195 /*
 196  * fill in the FPU structure for a core dump.
 197  */
 198 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 199 {
 200         save_fpu_regs();
 201         fpregs->fpc = current->thread.fpu.fpc;
 202         fpregs->pad = 0;
 203         if (MACHINE_HAS_VX)
 204                 convert_vx_to_fp((freg_t *)&fpregs->fprs,
 205                                  current->thread.fpu.vxrs);
 206         else
 207                 memcpy(&fpregs->fprs, current->thread.fpu.fprs,
 208                        sizeof(fpregs->fprs));
 209         return 1;
 210 }
 211 EXPORT_SYMBOL(dump_fpu);
 212
 213 unsigned long get_wchan(struct task_struct *p)
 214 {
 215         struct stack_frame *sf, *low, *high;
 216         unsigned long return_address;
 217         int count;
 218
 219         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 220                 return 0;
 221         low = task_stack_page(p);
 222         high = (struct stack_frame *) task_pt_regs(p);
 223         sf = (struct stack_frame *) (p->thread.ksp & PSW_ADDR_INSN);
 224         if (sf <= low || sf > high)
 225                 return 0;
 226         for (count = 0; count < 16; count++) {
 227                 sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
 228                 if (sf <= low || sf > high)
 229                         return 0;
 230                 return_address = sf->gprs[8] & PSW_ADDR_INSN;
 231                 if (!in_sched_functions(return_address))
 232                         return return_address;
 233         }
 234         return 0;
 235 }
 236
 237 unsigned long arch_align_stack(unsigned long sp)
 238 {
 239         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 240                 sp -= get_random_int() & ~PAGE_MASK;
 241         return sp & ~0xf;
 242 }
 243
 244 static inline unsigned long brk_rnd(void)
 245 {
 246         return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
 247 }
 248
 249 unsigned long arch_randomize_brk(struct mm_struct *mm)
 250 {
 251         unsigned long ret;
 252
 253         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 254         return (ret > mm->brk) ? ret : mm->brk;
 255 }