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 "entry.h"
  44
  45 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  46
  47 extern void kernel_thread_starter(void);
  48
  49 void flush_thread(void)
  50 {
  51 }
  52
  53 void arch_setup_new_exec(void)
  54 {
  55         if (S390_lowcore.current_pid != current->pid) {
  56                 S390_lowcore.current_pid = current->pid;
  57                 if (test_facility(40))
  58                         lpp(&S390_lowcore.lpp);
  59         }
  60 }
  61
  62 void arch_release_task_struct(struct task_struct *tsk)
  63 {
  64         runtime_instr_release(tsk);
  65         guarded_storage_release(tsk);
  66 }
  67
  68 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  69 {
  70         /*
  71          * Save the floating-point or vector register state of the current
  72          * task and set the CIF_FPU flag to lazy restore the FPU register
  73          * state when returning to user space.
  74          */
  75         save_fpu_regs();
  76
  77         memcpy(dst, src, arch_task_struct_size);
  78         dst->thread.fpu.regs = dst->thread.fpu.fprs;
  79         return 0;
  80 }
  81
  82 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp,
  83                     unsigned long arg, struct task_struct *p, unsigned long tls)
  84 {
  85         struct fake_frame
  86         {
  87                 struct stack_frame sf;
  88                 struct pt_regs childregs;
  89         } *frame;
  90
  91         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
  92         p->thread.ksp = (unsigned long) frame;
  93         /* Save access registers to new thread structure. */
  94         save_access_regs(&p->thread.acrs[0]);
  95         /* start new process with ar4 pointing to the correct address space */
  96         p->thread.mm_segment = get_fs();
  97         /* Don't copy debug registers */
  98         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
  99         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 100         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 101         p->thread.per_flags = 0;
 102         /* Initialize per thread user and system timer values */
 103         p->thread.user_timer = 0;
 104         p->thread.guest_timer = 0;
 105         p->thread.system_timer = 0;
 106         p->thread.hardirq_timer = 0;
 107         p->thread.softirq_timer = 0;
 108         p->thread.last_break = 1;
 109
 110         frame->sf.back_chain = 0;
 111         /* new return point is ret_from_fork */
 112         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 113         /* fake return stack for resume(), don't go back to schedule */
 114         frame->sf.gprs[9] = (unsigned long) frame;
 115
 116         /* Store access registers to kernel stack of new process. */
 117         if (unlikely(p->flags & PF_KTHREAD)) {
 118                 /* kernel thread */
 119                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 120                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 121                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 122                 frame->childregs.psw.addr =
 123                                 (unsigned long) kernel_thread_starter;
 124                 frame->childregs.gprs[9] = new_stackp; /* function */
 125                 frame->childregs.gprs[10] = arg;
 126                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 127                 frame->childregs.orig_gpr2 = -1;
 128
 129                 return 0;
 130         }
 131         frame->childregs = *current_pt_regs();
 132         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 133         frame->childregs.flags = 0;
 134         if (new_stackp)
 135                 frame->childregs.gprs[15] = new_stackp;
 136
 137         /* Don't copy runtime instrumentation info */
 138         p->thread.ri_cb = NULL;
 139         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 140         /* Don't copy guarded storage control block */
 141         p->thread.gs_cb = NULL;
 142         p->thread.gs_bc_cb = NULL;
 143
 144         /* Set a new TLS ?  */
 145         if (clone_flags & CLONE_SETTLS) {
 146                 if (is_compat_task()) {
 147                         p->thread.acrs[0] = (unsigned int)tls;
 148                 } else {
 149                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 150                         p->thread.acrs[1] = (unsigned int)tls;
 151                 }
 152         }
 153         return 0;
 154 }
 155
 156 asmlinkage void execve_tail(void)
 157 {
 158         current->thread.fpu.fpc = 0;
 159         asm volatile("sfpc %0" : : "d" (0));
 160 }
 161
 162 /*
 163  * fill in the FPU structure for a core dump.
 164  */
 165 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 166 {
 167         save_fpu_regs();
 168         fpregs->fpc = current->thread.fpu.fpc;
 169         fpregs->pad = 0;
 170         if (MACHINE_HAS_VX)
 171                 convert_vx_to_fp((freg_t *)&fpregs->fprs,
 172                                  current->thread.fpu.vxrs);
 173         else
 174                 memcpy(&fpregs->fprs, current->thread.fpu.fprs,
 175                        sizeof(fpregs->fprs));
 176         return 1;
 177 }
 178 EXPORT_SYMBOL(dump_fpu);
 179
 180 unsigned long get_wchan(struct task_struct *p)
 181 {
 182         struct stack_frame *sf, *low, *high;
 183         unsigned long return_address;
 184         int count;
 185
 186         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 187                 return 0;
 188
 189         if (!try_get_task_stack(p))
 190                 return 0;
 191
 192         low = task_stack_page(p);
 193         high = (struct stack_frame *) task_pt_regs(p);
 194         sf = (struct stack_frame *) p->thread.ksp;
 195         if (sf <= low || sf > high) {
 196                 return_address = 0;
 197                 goto out;
 198         }
 199         for (count = 0; count < 16; count++) {
 200                 sf = (struct stack_frame *)READ_ONCE_NOCHECK(sf->back_chain);
 201                 if (sf <= low || sf > high) {
 202                         return_address = 0;
 203                         goto out;
 204                 }
 205                 return_address = READ_ONCE_NOCHECK(sf->gprs[8]);
 206                 if (!in_sched_functions(return_address))
 207                         goto out;
 208         }
 209 out:
 210         put_task_stack(p);
 211         return return_address;
 212 }
 213
 214 unsigned long arch_align_stack(unsigned long sp)
 215 {
 216         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 217                 sp -= get_random_int() & ~PAGE_MASK;
 218         return sp & ~0xf;
 219 }
 220
 221 static inline unsigned long brk_rnd(void)
 222 {
 223         return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
 224 }
 225
 226 unsigned long arch_randomize_brk(struct mm_struct *mm)
 227 {
 228         unsigned long ret;
 229
 230         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 231         return (ret > mm->brk) ? ret : mm->brk;
 232 }
 233
 234 void set_fs_fixup(void)
 235 {
 236         struct pt_regs *regs = current_pt_regs();
 237         static bool warned;
 238
 239         set_fs(USER_DS);
 240         if (warned)
 241                 return;
 242         WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code);
 243         show_registers(regs);
 244         warned = true;
 245 }