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 <linux/entry-common.h>
  33 #include <asm/cpu_mf.h>
  34 #include <asm/io.h>
  35 #include <asm/processor.h>
  36 #include <asm/vtimer.h>
  37 #include <asm/exec.h>
  38 #include <asm/irq.h>
  39 #include <asm/nmi.h>
  40 #include <asm/smp.h>
  41 #include <asm/stacktrace.h>
  42 #include <asm/switch_to.h>
  43 #include <asm/runtime_instr.h>
  44 #include <asm/unwind.h>
  45 #include "entry.h"
  46
  47 void ret_from_fork(void) asm("ret_from_fork");
  48
  49 void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs)
  50 {
  51         void (*func)(void *arg);
  52
  53         schedule_tail(prev);
  54
  55         if (!user_mode(regs)) {
  56                 /* Kernel thread */
  57                 func = (void *)regs->gprs[9];
  58                 func((void *)regs->gprs[10]);
  59         }
  60         clear_pt_regs_flag(regs, PIF_SYSCALL);
  61         syscall_exit_to_user_mode(regs);
  62 }
  63
  64 void flush_thread(void)
  65 {
  66 }
  67
  68 void arch_setup_new_exec(void)
  69 {
  70         if (S390_lowcore.current_pid != current->pid) {
  71                 S390_lowcore.current_pid = current->pid;
  72                 if (test_facility(40))
  73                         lpp(&S390_lowcore.lpp);
  74         }
  75 }
  76
  77 void arch_release_task_struct(struct task_struct *tsk)
  78 {
  79         runtime_instr_release(tsk);
  80         guarded_storage_release(tsk);
  81 }
  82
  83 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  84 {
  85         /*
  86          * Save the floating-point or vector register state of the current
  87          * task and set the CIF_FPU flag to lazy restore the FPU register
  88          * state when returning to user space.
  89          */
  90         save_fpu_regs();
  91
  92         memcpy(dst, src, arch_task_struct_size);
  93         dst->thread.fpu.regs = dst->thread.fpu.fprs;
  94         return 0;
  95 }
  96
  97 int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
  98                 unsigned long arg, struct task_struct *p, unsigned long tls)
  99 {
 100         struct fake_frame
 101         {
 102                 struct stack_frame sf;
 103                 struct pt_regs childregs;
 104         } *frame;
 105
 106         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 107         p->thread.ksp = (unsigned long) frame;
 108         /* Save access registers to new thread structure. */
 109         save_access_regs(&p->thread.acrs[0]);
 110         /* start new process with ar4 pointing to the correct address space */
 111         /* Don't copy debug registers */
 112         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 113         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 114         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 115         p->thread.per_flags = 0;
 116         /* Initialize per thread user and system timer values */
 117         p->thread.user_timer = 0;
 118         p->thread.guest_timer = 0;
 119         p->thread.system_timer = 0;
 120         p->thread.hardirq_timer = 0;
 121         p->thread.softirq_timer = 0;
 122         p->thread.last_break = 1;
 123
 124         frame->sf.back_chain = 0;
 125         frame->sf.gprs[5] = (unsigned long)frame + sizeof(struct stack_frame);
 126         frame->sf.gprs[6] = (unsigned long)p;
 127         /* new return point is ret_from_fork */
 128         frame->sf.gprs[8] = (unsigned long)ret_from_fork;
 129         /* fake return stack for resume(), don't go back to schedule */
 130         frame->sf.gprs[9] = (unsigned long)frame;
 131
 132         /* Store access registers to kernel stack of new process. */
 133         if (unlikely(p->flags & PF_KTHREAD)) {
 134                 /* kernel thread */
 135                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 136                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 137                                 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 138                 frame->childregs.psw.addr =
 139                                 (unsigned long)__ret_from_fork;
 140                 frame->childregs.gprs[9] = new_stackp; /* function */
 141                 frame->childregs.gprs[10] = arg;
 142                 frame->childregs.gprs[11] = (unsigned long)do_exit;
 143                 frame->childregs.orig_gpr2 = -1;
 144
 145                 return 0;
 146         }
 147         frame->childregs = *current_pt_regs();
 148         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 149         frame->childregs.flags = 0;
 150         if (new_stackp)
 151                 frame->childregs.gprs[15] = new_stackp;
 152
 153         /* Don't copy runtime instrumentation info */
 154         p->thread.ri_cb = NULL;
 155         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 156         /* Don't copy guarded storage control block */
 157         p->thread.gs_cb = NULL;
 158         p->thread.gs_bc_cb = NULL;
 159
 160         /* Set a new TLS ?  */
 161         if (clone_flags & CLONE_SETTLS) {
 162                 if (is_compat_task()) {
 163                         p->thread.acrs[0] = (unsigned int)tls;
 164                 } else {
 165                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 166                         p->thread.acrs[1] = (unsigned int)tls;
 167                 }
 168         }
 169         return 0;
 170 }
 171
 172 void execve_tail(void)
 173 {
 174         current->thread.fpu.fpc = 0;
 175         asm volatile("sfpc %0" : : "d" (0));
 176 }
 177
 178 unsigned long get_wchan(struct task_struct *p)
 179 {
 180         struct unwind_state state;
 181         unsigned long ip = 0;
 182
 183         if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 184                 return 0;
 185
 186         if (!try_get_task_stack(p))
 187                 return 0;
 188
 189         unwind_for_each_frame(&state, p, NULL, 0) {
 190                 if (state.stack_info.type != STACK_TYPE_TASK) {
 191                         ip = 0;
 192                         break;
 193                 }
 194
 195                 ip = unwind_get_return_address(&state);
 196                 if (!ip)
 197                         break;
 198
 199                 if (!in_sched_functions(ip))
 200                         break;
 201         }
 202
 203         put_task_stack(p);
 204         return ip;
 205 }
 206
 207 unsigned long arch_align_stack(unsigned long sp)
 208 {
 209         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 210                 sp -= get_random_int() & ~PAGE_MASK;
 211         return sp & ~0xf;
 212 }
 213
 214 static inline unsigned long brk_rnd(void)
 215 {
 216         return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
 217 }
 218
 219 unsigned long arch_randomize_brk(struct mm_struct *mm)
 220 {
 221         unsigned long ret;
 222
 223         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 224         return (ret > mm->brk) ? ret : mm->brk;
 225 }