arch/s390/kernel/process.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * This file handles the architecture dependent parts of process handling.
   4  *
   5  *    Copyright IBM Corp. 1999, 2009
   6  *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
   7  *               Hartmut Penner <hp@de.ibm.com>,
   8  *               Denis Joseph Barrow,
   9  */
  10
  11 #include <linux/elf-randomize.h>
  12 #include <linux/compiler.h>
  13 #include <linux/cpu.h>
  14 #include <linux/sched.h>
  15 #include <linux/sched/debug.h>
  16 #include <linux/sched/task.h>
  17 #include <linux/sched/task_stack.h>
  18 #include <linux/kernel.h>
  19 #include <linux/mm.h>
  20 #include <linux/elfcore.h>
  21 #include <linux/smp.h>
  22 #include <linux/slab.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/tick.h>
  25 #include <linux/personality.h>
  26 #include <linux/syscalls.h>
  27 #include <linux/compat.h>
  28 #include <linux/kprobes.h>
  29 #include <linux/random.h>
  30 #include <linux/export.h>
  31 #include <linux/init_task.h>
  32 #include <asm/cpu_mf.h>
  33 #include <asm/io.h>
  34 #include <asm/processor.h>
  35 #include <asm/vtimer.h>
  36 #include <asm/exec.h>
  37 #include <asm/irq.h>
  38 #include <asm/nmi.h>
  39 #include <asm/smp.h>
  40 #include <asm/stacktrace.h>
  41 #include <asm/switch_to.h>
  42 #include <asm/runtime_instr.h>
  43 #include <asm/unwind.h>
  44 #include "entry.h"
  45
  46 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  47
  48 extern void kernel_thread_starter(void);
  49
  50 void flush_thread(void)
  51 {
  52 }
  53
  54 void arch_setup_new_exec(void)
  55 {
  56         if (S390_lowcore.current_pid != current->pid) {
  57                 S390_lowcore.current_pid = current->pid;
  58                 if (test_facility(40))
  59                         lpp(&S390_lowcore.lpp);
  60         }
  61 }
  62
  63 void arch_release_task_struct(struct task_struct *tsk)
  64 {
  65         runtime_instr_release(tsk);
  66         guarded_storage_release(tsk);
  67 }
  68
  69 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  70 {
  71         /*
  72          * Save the floating-point or vector register state of the current
  73          * task and set the CIF_FPU flag to lazy restore the FPU register
  74          * state when returning to user space.
  75          */
  76         save_fpu_regs();
  77
  78         memcpy(dst, src, arch_task_struct_size);
  79         dst->thread.fpu.regs = dst->thread.fpu.fprs;
  80         return 0;
  81 }
  82
  83 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
  84                 unsigned long arg, struct task_struct *p, unsigned long tls)
  85 {
  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         p->thread.per_flags = 0;
 103         /* Initialize per thread user and system timer values */
 104         p->thread.user_timer = 0;
 105         p->thread.guest_timer = 0;
 106         p->thread.system_timer = 0;
 107         p->thread.hardirq_timer = 0;
 108         p->thread.softirq_timer = 0;
 109         p->thread.last_break = 1;
 110
 111         frame->sf.back_chain = 0;
 112         /* new return point is ret_from_fork */
 113         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 114         /* fake return stack for resume(), don't go back to schedule */
 115         frame->sf.gprs[9] = (unsigned long) frame;
 116
 117         /* Store access registers to kernel stack of new process. */
 118         if (unlikely(p->flags & PF_KTHREAD)) {
 119                 /* kernel thread */
 120                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 121                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 122                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 123                 frame->childregs.psw.addr =
 124                                 (unsigned long) kernel_thread_starter;
 125                 frame->childregs.gprs[9] = new_stackp; /* function */
 126                 frame->childregs.gprs[10] = arg;
 127                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 128                 frame->childregs.orig_gpr2 = -1;
 129
 130                 return 0;
 131         }
 132         frame->childregs = *current_pt_regs();
 133         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 134         frame->childregs.flags = 0;
 135         if (new_stackp)
 136                 frame->childregs.gprs[15] = new_stackp;
 137
 138         /* Don't copy runtime instrumentation info */
 139         p->thread.ri_cb = NULL;
 140         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 141         /* Don't copy guarded storage control block */
 142         p->thread.gs_cb = NULL;
 143         p->thread.gs_bc_cb = NULL;
 144
 145         /* Set a new TLS ?  */
 146         if (clone_flags & CLONE_SETTLS) {
 147                 if (is_compat_task()) {
 148                         p->thread.acrs[0] = (unsigned int)tls;
 149                 } else {
 150                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 151                         p->thread.acrs[1] = (unsigned int)tls;
 152                 }
 153         }
 154         return 0;
 155 }
 156
 157 asmlinkage void execve_tail(void)
 158 {
 159         current->thread.fpu.fpc = 0;
 160         asm volatile("sfpc %0" : : "d" (0));
 161 }
 162
 163 unsigned long get_wchan(struct task_struct *p)
 164 {
 165         struct unwind_state state;
 166         unsigned long ip = 0;
 167
 168         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 169                 return 0;
 170
 171         if (!try_get_task_stack(p))
 172                 return 0;
 173
 174         unwind_for_each_frame(&state, p, NULL, 0) {
 175                 if (state.stack_info.type != STACK_TYPE_TASK) {
 176                         ip = 0;
 177                         break;
 178                 }
 179
 180                 ip = unwind_get_return_address(&state);
 181                 if (!ip)
 182                         break;
 183
 184                 if (!in_sched_functions(ip))
 185                         break;
 186         }
 187
 188         put_task_stack(p);
 189         return ip;
 190 }
 191
 192 unsigned long arch_align_stack(unsigned long sp)
 193 {
 194         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 195                 sp -= get_random_int() & ~PAGE_MASK;
 196         return sp & ~0xf;
 197 }
 198
 199 static inline unsigned long brk_rnd(void)
 200 {
 201         return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
 202 }
 203
 204 unsigned long arch_randomize_brk(struct mm_struct *mm)
 205 {
 206         unsigned long ret;
 207
 208         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 209         return (ret > mm->brk) ? ret : mm->brk;
 210 }
 211
 212 void set_fs_fixup(void)
 213 {
 214         struct pt_regs *regs = current_pt_regs();
 215         static bool warned;
 216
 217         set_fs(USER_DS);
 218         if (warned)
 219                 return;
 220         WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code);
 221         show_registers(regs);
 222         warned = true;
 223 }