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/switch_to.h>
  41 #include <asm/runtime_instr.h>
  42 #include "entry.h"
  43
  44 asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  45
  46 extern void kernel_thread_starter(void);
  47
  48 void flush_thread(void)
  49 {
  50 }
  51
  52 void arch_setup_new_exec(void)
  53 {
  54         if (S390_lowcore.current_pid != current->pid) {
  55                 S390_lowcore.current_pid = current->pid;
  56                 if (test_facility(40))
  57                         lpp(&S390_lowcore.lpp);
  58         }
  59 }
  60
  61 void arch_release_task_struct(struct task_struct *tsk)
  62 {
  63         runtime_instr_release(tsk);
  64         guarded_storage_release(tsk);
  65 }
  66
  67 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  68 {
  69         /*
  70          * Save the floating-point or vector register state of the current
  71          * task and set the CIF_FPU flag to lazy restore the FPU register
  72          * state when returning to user space.
  73          */
  74         save_fpu_regs();
  75
  76         memcpy(dst, src, arch_task_struct_size);
  77         dst->thread.fpu.regs = dst->thread.fpu.fprs;
  78         return 0;
  79 }
  80
  81 int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp,
  82                     unsigned long arg, struct task_struct *p, unsigned long tls)
  83 {
  84         struct fake_frame
  85         {
  86                 struct stack_frame sf;
  87                 struct pt_regs childregs;
  88         } *frame;
  89
  90         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
  91         p->thread.ksp = (unsigned long) frame;
  92         /* Save access registers to new thread structure. */
  93         save_access_regs(&p->thread.acrs[0]);
  94         /* start new process with ar4 pointing to the correct address space */
  95         p->thread.mm_segment = get_fs();
  96         /* Don't copy debug registers */
  97         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
  98         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
  99         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 100         p->thread.per_flags = 0;
 101         /* Initialize per thread user and system timer values */
 102         p->thread.user_timer = 0;
 103         p->thread.guest_timer = 0;
 104         p->thread.system_timer = 0;
 105         p->thread.hardirq_timer = 0;
 106         p->thread.softirq_timer = 0;
 107
 108         frame->sf.back_chain = 0;
 109         /* new return point is ret_from_fork */
 110         frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 111         /* fake return stack for resume(), don't go back to schedule */
 112         frame->sf.gprs[9] = (unsigned long) frame;
 113
 114         /* Store access registers to kernel stack of new process. */
 115         if (unlikely(p->flags & PF_KTHREAD)) {
 116                 /* kernel thread */
 117                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 118                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 119                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 120                 frame->childregs.psw.addr =
 121                                 (unsigned long) kernel_thread_starter;
 122                 frame->childregs.gprs[9] = new_stackp; /* function */
 123                 frame->childregs.gprs[10] = arg;
 124                 frame->childregs.gprs[11] = (unsigned long) do_exit;
 125                 frame->childregs.orig_gpr2 = -1;
 126
 127                 return 0;
 128         }
 129         frame->childregs = *current_pt_regs();
 130         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 131         frame->childregs.flags = 0;
 132         if (new_stackp)
 133                 frame->childregs.gprs[15] = new_stackp;
 134
 135         /* Don't copy runtime instrumentation info */
 136         p->thread.ri_cb = NULL;
 137         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 138         /* Don't copy guarded storage control block */
 139         p->thread.gs_cb = NULL;
 140         p->thread.gs_bc_cb = NULL;
 141
 142         /* Set a new TLS ?  */
 143         if (clone_flags & CLONE_SETTLS) {
 144                 if (is_compat_task()) {
 145                         p->thread.acrs[0] = (unsigned int)tls;
 146                 } else {
 147                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 148                         p->thread.acrs[1] = (unsigned int)tls;
 149                 }
 150         }
 151         return 0;
 152 }
 153
 154 asmlinkage void execve_tail(void)
 155 {
 156         current->thread.fpu.fpc = 0;
 157         asm volatile("sfpc %0" : : "d" (0));
 158 }
 159
 160 /*
 161  * fill in the FPU structure for a core dump.
 162  */
 163 int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 164 {
 165         save_fpu_regs();
 166         fpregs->fpc = current->thread.fpu.fpc;
 167         fpregs->pad = 0;
 168         if (MACHINE_HAS_VX)
 169                 convert_vx_to_fp((freg_t *)&fpregs->fprs,
 170                                  current->thread.fpu.vxrs);
 171         else
 172                 memcpy(&fpregs->fprs, current->thread.fpu.fprs,
 173                        sizeof(fpregs->fprs));
 174         return 1;
 175 }
 176 EXPORT_SYMBOL(dump_fpu);
 177
 178 unsigned long get_wchan(struct task_struct *p)
 179 {
 180         struct stack_frame *sf, *low, *high;
 181         unsigned long return_address;
 182         int count;
 183
 184         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 185                 return 0;
 186
 187         if (!try_get_task_stack(p))
 188                 return 0;
 189
 190         low = task_stack_page(p);
 191         high = (struct stack_frame *) task_pt_regs(p);
 192         sf = (struct stack_frame *) p->thread.ksp;
 193         if (sf <= low || sf > high) {
 194                 return_address = 0;
 195                 goto out;
 196         }
 197         for (count = 0; count < 16; count++) {
 198                 sf = (struct stack_frame *) sf->back_chain;
 199                 if (sf <= low || sf > high) {
 200                         return_address = 0;
 201                         goto out;
 202                 }
 203                 return_address = sf->gprs[8];
 204                 if (!in_sched_functions(return_address))
 205                         goto out;
 206         }
 207 out:
 208         put_task_stack(p);
 209         return return_address;
 210 }
 211
 212 unsigned long arch_align_stack(unsigned long sp)
 213 {
 214         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 215                 sp -= get_random_int() & ~PAGE_MASK;
 216         return sp & ~0xf;
 217 }
 218
 219 static inline unsigned long brk_rnd(void)
 220 {
 221         return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
 222 }
 223
 224 unsigned long arch_randomize_brk(struct mm_struct *mm)
 225 {
 226         unsigned long ret;
 227
 228         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 229         return (ret > mm->brk) ? ret : mm->brk;
 230 }
 231
 232 void set_fs_fixup(void)
 233 {
 234         struct pt_regs *regs = current_pt_regs();
 235         static bool warned;
 236
 237         set_fs(USER_DS);
 238         if (warned)
 239                 return;
 240         WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code);
 241         show_registers(regs);
 242         warned = true;
 243 }