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                 exit_thread_gs();
  79         }
  80 }
  81
  82 void flush_thread(void)
  83 {
  84 }
  85
  86 void release_thread(struct task_struct *dead_task)
  87 {
  88 }
  89
  90 void arch_release_task_struct(struct task_struct *tsk)
  91 {
  92 }
  93
  94 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  95 {
  96         /*
  97          * Save the floating-point or vector register state of the current
  98          * task and set the CIF_FPU flag to lazy restore the FPU register
  99          * state when returning to user space.
 100          */
 101         save_fpu_regs();
 102
 103         memcpy(dst, src, arch_task_struct_size);
 104         dst->thread.fpu.regs = dst->thread.fpu.fprs;
 105         return 0;
 106 }
 107
 108 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp,
 109                     unsigned long arg, struct task_struct *p, unsigned long tls)
 110 {
 111         struct fake_frame
 112         {
 113                 struct stack_frame sf;
 114                 struct pt_regs childregs;
 115         } *frame;
 116
 117         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 118         p->thread.ksp = (unsigned long) frame;
 119         /* Save access registers to new thread structure. */
 120         save_access_regs(&p->thread.acrs[0]);
 121         /* start new process with ar4 pointing to the correct address space */
 122         p->thread.mm_segment = get_fs();
 123         /* Don't copy debug registers */
 124         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 125         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 126         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 127         /* Initialize per thread user and system timer values */
 128         p->thread.user_timer = 0;
 129         p->thread.guest_timer = 0;
 130         p->thread.system_timer = 0;
 131         p->thread.hardirq_timer = 0;
 132         p->thread.softirq_timer = 0;
 133
 134         frame->sf.back_chain = 0;
 135         /* new return point is ret_from_fork */
 136         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 137         /* fake return stack for resume(), don't go back to schedule */
 138         frame->sf.gprs[9] = (unsigned long) frame;
 139
 140         /* Store access registers to kernel stack of new process. */
 141         if (unlikely(p->flags & PF_KTHREAD)) {
 142                 /* kernel thread */
 143                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 144                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 145                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 146                 frame->childregs.psw.addr =
 147                                 (unsigned long) kernel_thread_starter;
 148                 frame->childregs.gprs[9] = new_stackp; /* function */
 149                 frame->childregs.gprs[10] = arg;
 150                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 151                 frame->childregs.orig_gpr2 = -1;
 152
 153                 return 0;
 154         }
 155         frame->childregs = *current_pt_regs();
 156         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 157         frame->childregs.flags = 0;
 158         if (new_stackp)
 159                 frame->childregs.gprs[15] = new_stackp;
 160
 161         /* Don't copy runtime instrumentation info */
 162         p->thread.ri_cb = NULL;
 163         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 164         /* Don't copy guarded storage control block */
 165         p->thread.gs_cb = NULL;
 166         p->thread.gs_bc_cb = NULL;
 167
 168         /* Set a new TLS ?  */
 169         if (clone_flags & CLONE_SETTLS) {
 170                 if (is_compat_task()) {
 171                         p->thread.acrs[0] = (unsigned int)tls;
 172                 } else {
 173                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 174                         p->thread.acrs[1] = (unsigned int)tls;
 175                 }
 176         }
 177         return 0;
 178 }
 179
 180 asmlinkage void execve_tail(void)
 181 {
 182         current->thread.fpu.fpc = 0;
 183         asm volatile("sfpc %0" : : "d" (0));
 184 }
 185
 186 /*
 187  * fill in the FPU structure for a core dump.
 188  */
 189 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 190 {
 191         save_fpu_regs();
 192         fpregs->fpc = current->thread.fpu.fpc;
 193         fpregs->pad = 0;
 194         if (MACHINE_HAS_VX)
 195                 convert_vx_to_fp((freg_t *)&fpregs->fprs,
 196                                  current->thread.fpu.vxrs);
 197         else
 198                 memcpy(&fpregs->fprs, current->thread.fpu.fprs,
 199                        sizeof(fpregs->fprs));
 200         return 1;
 201 }
 202 EXPORT_SYMBOL(dump_fpu);
 203
 204 unsigned long get_wchan(struct task_struct *p)
 205 {
 206         struct stack_frame *sf, *low, *high;
 207         unsigned long return_address;
 208         int count;
 209
 210         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 211                 return 0;
 212         low = task_stack_page(p);
 213         high = (struct stack_frame *) task_pt_regs(p);
 214         sf = (struct stack_frame *) p->thread.ksp;
 215         if (sf <= low || sf > high)
 216                 return 0;
 217         for (count = 0; count < 16; count++) {
 218                 sf = (struct stack_frame *) sf->back_chain;
 219                 if (sf <= low || sf > high)
 220                         return 0;
 221                 return_address = sf->gprs[8];
 222                 if (!in_sched_functions(return_address))
 223                         return return_address;
 224         }
 225         return 0;
 226 }
 227
 228 unsigned long arch_align_stack(unsigned long sp)
 229 {
 230         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 231                 sp -= get_random_int() & ~PAGE_MASK;
 232         return sp & ~0xf;
 233 }
 234
 235 static inline unsigned long brk_rnd(void)
 236 {
 237         return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
 238 }
 239
 240 unsigned long arch_randomize_brk(struct mm_struct *mm)
 241 {
 242         unsigned long ret;
 243
 244         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 245         return (ret > mm->brk) ? ret : mm->brk;
 246 }
 247
 248 void set_fs_fixup(void)
 249 {
 250         struct pt_regs *regs = current_pt_regs();
 251         static bool warned;
 252
 253         set_fs(USER_DS);
 254         if (warned)
 255                 return;
 256         WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code);
 257         show_registers(regs);
 258         warned = true;
 259 }