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