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/io.h>
  33 #include <asm/processor.h>
  34 #include <asm/vtimer.h>
  35 #include <asm/exec.h>
  36 #include <asm/irq.h>
  37 #include <asm/nmi.h>
  38 #include <asm/smp.h>
  39 #include <asm/switch_to.h>
  40 #include <asm/runtime_instr.h>
  41 #include "entry.h"
  42
  43 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  44
  45 extern void kernel_thread_starter(void);
  46
  47 void flush_thread(void)
  48 {
  49 }
  50
  51 void arch_release_task_struct(struct task_struct *tsk)
  52 {
  53         runtime_instr_release(tsk);
  54         guarded_storage_release(tsk);
  55 }
  56
  57 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  58 {
  59         /*
  60          * Save the floating-point or vector register state of the current
  61          * task and set the CIF_FPU flag to lazy restore the FPU register
  62          * state when returning to user space.
  63          */
  64         save_fpu_regs();
  65
  66         memcpy(dst, src, arch_task_struct_size);
  67         dst->thread.fpu.regs = dst->thread.fpu.fprs;
  68         return 0;
  69 }
  70
  71 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp,
  72                     unsigned long arg, struct task_struct *p, unsigned long tls)
  73 {
  74         struct fake_frame
  75         {
  76                 struct stack_frame sf;
  77                 struct pt_regs childregs;
  78         } *frame;
  79
  80         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
  81         p->thread.ksp = (unsigned long) frame;
  82         /* Save access registers to new thread structure. */
  83         save_access_regs(&p->thread.acrs[0]);
  84         /* start new process with ar4 pointing to the correct address space */
  85         p->thread.mm_segment = get_fs();
  86         /* Don't copy debug registers */
  87         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
  88         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
  89         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
  90         p->thread.per_flags = 0;
  91         /* Initialize per thread user and system timer values */
  92         p->thread.user_timer = 0;
  93         p->thread.guest_timer = 0;
  94         p->thread.system_timer = 0;
  95         p->thread.hardirq_timer = 0;
  96         p->thread.softirq_timer = 0;
  97
  98         frame->sf.back_chain = 0;
  99         /* new return point is ret_from_fork */
 100         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 101         /* fake return stack for resume(), don't go back to schedule */
 102         frame->sf.gprs[9] = (unsigned long) frame;
 103
 104         /* Store access registers to kernel stack of new process. */
 105         if (unlikely(p->flags & PF_KTHREAD)) {
 106                 /* kernel thread */
 107                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 108                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 109                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 110                 frame->childregs.psw.addr =
 111                                 (unsigned long) kernel_thread_starter;
 112                 frame->childregs.gprs[9] = new_stackp; /* function */
 113                 frame->childregs.gprs[10] = arg;
 114                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 115                 frame->childregs.orig_gpr2 = -1;
 116
 117                 return 0;
 118         }
 119         frame->childregs = *current_pt_regs();
 120         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 121         frame->childregs.flags = 0;
 122         if (new_stackp)
 123                 frame->childregs.gprs[15] = new_stackp;
 124
 125         /* Don't copy runtime instrumentation info */
 126         p->thread.ri_cb = NULL;
 127         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 128         /* Don't copy guarded storage control block */
 129         p->thread.gs_cb = NULL;
 130         p->thread.gs_bc_cb = NULL;
 131
 132         /* Set a new TLS ?  */
 133         if (clone_flags & CLONE_SETTLS) {
 134                 if (is_compat_task()) {
 135                         p->thread.acrs[0] = (unsigned int)tls;
 136                 } else {
 137                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 138                         p->thread.acrs[1] = (unsigned int)tls;
 139                 }
 140         }
 141         return 0;
 142 }
 143
 144 asmlinkage void execve_tail(void)
 145 {
 146         current->thread.fpu.fpc = 0;
 147         asm volatile("sfpc %0" : : "d" (0));
 148 }
 149
 150 /*
 151  * fill in the FPU structure for a core dump.
 152  */
 153 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 154 {
 155         save_fpu_regs();
 156         fpregs->fpc = current->thread.fpu.fpc;
 157         fpregs->pad = 0;
 158         if (MACHINE_HAS_VX)
 159                 convert_vx_to_fp((freg_t *)&fpregs->fprs,
 160                                  current->thread.fpu.vxrs);
 161         else
 162                 memcpy(&fpregs->fprs, current->thread.fpu.fprs,
 163                        sizeof(fpregs->fprs));
 164         return 1;
 165 }
 166 EXPORT_SYMBOL(dump_fpu);
 167
 168 unsigned long get_wchan(struct task_struct *p)
 169 {
 170         struct stack_frame *sf, *low, *high;
 171         unsigned long return_address;
 172         int count;
 173
 174         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 175                 return 0;
 176         low = task_stack_page(p);
 177         high = (struct stack_frame *) task_pt_regs(p);
 178         sf = (struct stack_frame *) p->thread.ksp;
 179         if (sf <= low || sf > high)
 180                 return 0;
 181         for (count = 0; count < 16; count++) {
 182                 sf = (struct stack_frame *) sf->back_chain;
 183                 if (sf <= low || sf > high)
 184                         return 0;
 185                 return_address = sf->gprs[8];
 186                 if (!in_sched_functions(return_address))
 187                         return return_address;
 188         }
 189         return 0;
 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 }