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