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/elf-randomize.h>
  11 #include <linux/compiler.h>
  12 #include <linux/cpu.h>
  13 #include <linux/sched.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mm.h>
  16 #include <linux/elfcore.h>
  17 #include <linux/smp.h>
  18 #include <linux/slab.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/tick.h>
  21 #include <linux/personality.h>
  22 #include <linux/syscalls.h>
  23 #include <linux/compat.h>
  24 #include <linux/kprobes.h>
  25 #include <linux/random.h>
  26 #include <linux/module.h>
  27 #include <linux/init_task.h>
  28 #include <asm/io.h>
  29 #include <asm/processor.h>
  30 #include <asm/vtimer.h>
  31 #include <asm/exec.h>
  32 #include <asm/irq.h>
  33 #include <asm/nmi.h>
  34 #include <asm/smp.h>
  35 #include <asm/switch_to.h>
  36 #include <asm/runtime_instr.h>
  37 #include "entry.h"
  38
  39 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  40
  41 /*
  42  * Return saved PC of a blocked thread. used in kernel/sched.
  43  * resume in entry.S does not create a new stack frame, it
  44  * just stores the registers %r6-%r15 to the frame given by
  45  * schedule. We want to return the address of the caller of
  46  * schedule, so we have to walk the backchain one time to
  47  * find the frame schedule() store its return address.
  48  */
  49 unsigned long thread_saved_pc(struct task_struct *tsk)
  50 {
  51         struct stack_frame *sf, *low, *high;
  52
  53         if (!tsk || !task_stack_page(tsk))
  54                 return 0;
  55         low = task_stack_page(tsk);
  56         high = (struct stack_frame *) task_pt_regs(tsk);
  57         sf = (struct stack_frame *) tsk->thread.ksp;
  58         if (sf <= low || sf > high)
  59                 return 0;
  60         sf = (struct stack_frame *) sf->back_chain;
  61         if (sf <= low || sf > high)
  62                 return 0;
  63         return sf->gprs[8];
  64 }
  65
  66 extern void kernel_thread_starter(void);
  67
  68 /*
  69  * Free current thread data structures etc..
  70  */
  71 void exit_thread(struct task_struct *tsk)
  72 {
  73         if (tsk == current)
  74                 exit_thread_runtime_instr();
  75 }
  76
  77 void flush_thread(void)
  78 {
  79 }
  80
  81 void release_thread(struct task_struct *dead_task)
  82 {
  83 }
  84
  85 void arch_release_task_struct(struct task_struct *tsk)
  86 {
  87 }
  88
  89 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  90 {
  91         /*
  92          * Save the floating-point or vector register state of the current
  93          * task and set the CIF_FPU flag to lazy restore the FPU register
  94          * state when returning to user space.
  95          */
  96         save_fpu_regs();
  97
  98         memcpy(dst, src, arch_task_struct_size);
  99         dst->thread.fpu.regs = dst->thread.fpu.fprs;
 100         return 0;
 101 }
 102
 103 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 104                 unsigned long arg, struct task_struct *p)
 105 {
 106         struct thread_info *ti;
 107         struct fake_frame
 108         {
 109                 struct stack_frame sf;
 110                 struct pt_regs childregs;
 111         } *frame;
 112
 113         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 114         p->thread.ksp = (unsigned long) frame;
 115         /* Save access registers to new thread structure. */
 116         save_access_regs(&p->thread.acrs[0]);
 117         /* start new process with ar4 pointing to the correct address space */
 118         p->thread.mm_segment = get_fs();
 119         /* Don't copy debug registers */
 120         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 121         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 122         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 123         /* Initialize per thread user and system timer values */
 124         ti = task_thread_info(p);
 125         ti->user_timer = 0;
 126         ti->system_timer = 0;
 127
 128         frame->sf.back_chain = 0;
 129         /* new return point is ret_from_fork */
 130         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 131         /* fake return stack for resume(), don't go back to schedule */
 132         frame->sf.gprs[9] = (unsigned long) frame;
 133
 134         /* Store access registers to kernel stack of new process. */
 135         if (unlikely(p->flags & PF_KTHREAD)) {
 136                 /* kernel thread */
 137                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 138                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 139                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 140                 frame->childregs.psw.addr =
 141                                 (unsigned long) kernel_thread_starter;
 142                 frame->childregs.gprs[9] = new_stackp; /* function */
 143                 frame->childregs.gprs[10] = arg;
 144                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 145                 frame->childregs.orig_gpr2 = -1;
 146
 147                 return 0;
 148         }
 149         frame->childregs = *current_pt_regs();
 150         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 151         frame->childregs.flags = 0;
 152         if (new_stackp)
 153                 frame->childregs.gprs[15] = new_stackp;
 154
 155         /* Don't copy runtime instrumentation info */
 156         p->thread.ri_cb = NULL;
 157         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 158
 159         /* Set a new TLS ?  */
 160         if (clone_flags & CLONE_SETTLS) {
 161                 unsigned long tls = frame->childregs.gprs[6];
 162                 if (is_compat_task()) {
 163                         p->thread.acrs[0] = (unsigned int)tls;
 164                 } else {
 165                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 166                         p->thread.acrs[1] = (unsigned int)tls;
 167                 }
 168         }
 169         return 0;
 170 }
 171
 172 asmlinkage void execve_tail(void)
 173 {
 174         current->thread.fpu.fpc = 0;
 175         asm volatile("sfpc %0" : : "d" (0));
 176 }
 177
 178 /*
 179  * fill in the FPU structure for a core dump.
 180  */
 181 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 182 {
 183         save_fpu_regs();
 184         fpregs->fpc = current->thread.fpu.fpc;
 185         fpregs->pad = 0;
 186         if (MACHINE_HAS_VX)
 187                 convert_vx_to_fp((freg_t *)&fpregs->fprs,
 188                                  current->thread.fpu.vxrs);
 189         else
 190                 memcpy(&fpregs->fprs, current->thread.fpu.fprs,
 191                        sizeof(fpregs->fprs));
 192         return 1;
 193 }
 194 EXPORT_SYMBOL(dump_fpu);
 195
 196 unsigned long get_wchan(struct task_struct *p)
 197 {
 198         struct stack_frame *sf, *low, *high;
 199         unsigned long return_address;
 200         int count;
 201
 202         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 203                 return 0;
 204         low = task_stack_page(p);
 205         high = (struct stack_frame *) task_pt_regs(p);
 206         sf = (struct stack_frame *) p->thread.ksp;
 207         if (sf <= low || sf > high)
 208                 return 0;
 209         for (count = 0; count < 16; count++) {
 210                 sf = (struct stack_frame *) sf->back_chain;
 211                 if (sf <= low || sf > high)
 212                         return 0;
 213                 return_address = sf->gprs[8];
 214                 if (!in_sched_functions(return_address))
 215                         return return_address;
 216         }
 217         return 0;
 218 }
 219
 220 unsigned long arch_align_stack(unsigned long sp)
 221 {
 222         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 223                 sp -= get_random_int() & ~PAGE_MASK;
 224         return sp & ~0xf;
 225 }
 226
 227 static inline unsigned long brk_rnd(void)
 228 {
 229         return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
 230 }
 231
 232 unsigned long arch_randomize_brk(struct mm_struct *mm)
 233 {
 234         unsigned long ret;
 235
 236         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 237         return (ret > mm->brk) ? ret : mm->brk;
 238 }