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/sched/debug.h>
  15 #include <linux/sched/task.h>
  16 #include <linux/sched/task_stack.h>
  17 #include <linux/kernel.h>
  18 #include <linux/mm.h>
  19 #include <linux/elfcore.h>
  20 #include <linux/smp.h>
  21 #include <linux/slab.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/tick.h>
  24 #include <linux/personality.h>
  25 #include <linux/syscalls.h>
  26 #include <linux/compat.h>
  27 #include <linux/kprobes.h>
  28 #include <linux/random.h>
  29 #include <linux/export.h>
  30 #include <linux/init_task.h>
  31 #include <asm/io.h>
  32 #include <asm/processor.h>
  33 #include <asm/vtimer.h>
  34 #include <asm/exec.h>
  35 #include <asm/irq.h>
  36 #include <asm/nmi.h>
  37 #include <asm/smp.h>
  38 #include <asm/switch_to.h>
  39 #include <asm/runtime_instr.h>
  40 #include "entry.h"
  41
  42 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  43
  44 /*
  45  * Return saved PC of a blocked thread. used in kernel/sched.
  46  * resume in entry.S does not create a new stack frame, it
  47  * just stores the registers %r6-%r15 to the frame given by
  48  * schedule. We want to return the address of the caller of
  49  * schedule, so we have to walk the backchain one time to
  50  * find the frame schedule() store its return address.
  51  */
  52 unsigned long thread_saved_pc(struct task_struct *tsk)
  53 {
  54         struct stack_frame *sf, *low, *high;
  55
  56         if (!tsk || !task_stack_page(tsk))
  57                 return 0;
  58         low = task_stack_page(tsk);
  59         high = (struct stack_frame *) task_pt_regs(tsk);
  60         sf = (struct stack_frame *) tsk->thread.ksp;
  61         if (sf <= low || sf > high)
  62                 return 0;
  63         sf = (struct stack_frame *) sf->back_chain;
  64         if (sf <= low || sf > high)
  65                 return 0;
  66         return sf->gprs[8];
  67 }
  68
  69 extern void kernel_thread_starter(void);
  70
  71 /*
  72  * Free current thread data structures etc..
  73  */
  74 void exit_thread(struct task_struct *tsk)
  75 {
  76         if (tsk == current)
  77                 exit_thread_runtime_instr();
  78 }
  79
  80 void flush_thread(void)
  81 {
  82 }
  83
  84 void release_thread(struct task_struct *dead_task)
  85 {
  86 }
  87
  88 void arch_release_task_struct(struct task_struct *tsk)
  89 {
  90 }
  91
  92 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  93 {
  94         /*
  95          * Save the floating-point or vector register state of the current
  96          * task and set the CIF_FPU flag to lazy restore the FPU register
  97          * state when returning to user space.
  98          */
  99         save_fpu_regs();
 100
 101         memcpy(dst, src, arch_task_struct_size);
 102         dst->thread.fpu.regs = dst->thread.fpu.fprs;
 103         return 0;
 104 }
 105
 106 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp,
 107                     unsigned long arg, struct task_struct *p, unsigned long tls)
 108 {
 109         struct fake_frame
 110         {
 111                 struct stack_frame sf;
 112                 struct pt_regs childregs;
 113         } *frame;
 114
 115         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 116         p->thread.ksp = (unsigned long) frame;
 117         /* Save access registers to new thread structure. */
 118         save_access_regs(&p->thread.acrs[0]);
 119         /* start new process with ar4 pointing to the correct address space */
 120         p->thread.mm_segment = get_fs();
 121         /* Don't copy debug registers */
 122         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 123         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 124         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 125         /* Initialize per thread user and system timer values */
 126         p->thread.user_timer = 0;
 127         p->thread.system_timer = 0;
 128
 129         frame->sf.back_chain = 0;
 130         /* new return point is ret_from_fork */
 131         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 132         /* fake return stack for resume(), don't go back to schedule */
 133         frame->sf.gprs[9] = (unsigned long) frame;
 134
 135         /* Store access registers to kernel stack of new process. */
 136         if (unlikely(p->flags & PF_KTHREAD)) {
 137                 /* kernel thread */
 138                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 139                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 140                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 141                 frame->childregs.psw.addr =
 142                                 (unsigned long) kernel_thread_starter;
 143                 frame->childregs.gprs[9] = new_stackp; /* function */
 144                 frame->childregs.gprs[10] = arg;
 145                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 146                 frame->childregs.orig_gpr2 = -1;
 147
 148                 return 0;
 149         }
 150         frame->childregs = *current_pt_regs();
 151         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 152         frame->childregs.flags = 0;
 153         if (new_stackp)
 154                 frame->childregs.gprs[15] = new_stackp;
 155
 156         /* Don't copy runtime instrumentation info */
 157         p->thread.ri_cb = NULL;
 158         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 159
 160         /* Set a new TLS ?  */
 161         if (clone_flags & CLONE_SETTLS) {
 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 }
 239
 240 void set_fs_fixup(void)
 241 {
 242         struct pt_regs *regs = current_pt_regs();
 243         static bool warned;
 244
 245         set_fs(USER_DS);
 246         if (warned)
 247                 return;
 248         WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code);
 249         show_registers(regs);
 250         warned = true;
 251 }