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 <[email protected]>,
   7  *               Hartmut Penner <[email protected]>,
   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
  95         /*
  96          * Don't transfer over the runtime instrumentation or the guarded
  97          * storage control block pointers. These fields are cleared here instead
  98          * of in copy_thread() to avoid premature freeing of associated memory
  99          * on fork() failure. Wait to clear the RI flag because ->stack still
 100          * refers to the source thread.
 101          */
 102         dst->thread.ri_cb = NULL;
 103         dst->thread.gs_cb = NULL;
 104         dst->thread.gs_bc_cb = NULL;
 105
 106         return 0;
 107 }
 108
 109 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 110 {
 111         unsigned long clone_flags = args->flags;
 112         unsigned long new_stackp = args->stack;
 113         unsigned long tls = args->tls;
 114         struct fake_frame
 115         {
 116                 struct stack_frame sf;
 117                 struct pt_regs childregs;
 118         } *frame;
 119
 120         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 121         p->thread.ksp = (unsigned long) frame;
 122         /* Save access registers to new thread structure. */
 123         save_access_regs(&p->thread.acrs[0]);
 124         /* start new process with ar4 pointing to the correct address space */
 125         /* Don't copy debug registers */
 126         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 127         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 128         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 129         p->thread.per_flags = 0;
 130         /* Initialize per thread user and system timer values */
 131         p->thread.user_timer = 0;
 132         p->thread.guest_timer = 0;
 133         p->thread.system_timer = 0;
 134         p->thread.hardirq_timer = 0;
 135         p->thread.softirq_timer = 0;
 136         p->thread.last_break = 1;
 137
 138         frame->sf.back_chain = 0;
 139         frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs;
 140         frame->sf.gprs[12 - 6] = (unsigned long)p;
 141         /* new return point is ret_from_fork */
 142         frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork;
 143         /* fake return stack for resume(), don't go back to schedule */
 144         frame->sf.gprs[15 - 6] = (unsigned long)frame;
 145
 146         /* Store access registers to kernel stack of new process. */
 147         if (unlikely(args->fn)) {
 148                 /* kernel thread */
 149                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 150                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO |
 151                                             PSW_MASK_EXT | PSW_MASK_MCHECK;
 152                 frame->childregs.gprs[9] = (unsigned long)args->fn;
 153                 frame->childregs.gprs[10] = (unsigned long)args->fn_arg;
 154                 frame->childregs.orig_gpr2 = -1;
 155                 frame->childregs.last_break = 1;
 156                 return 0;
 157         }
 158         frame->childregs = *current_pt_regs();
 159         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 160         frame->childregs.flags = 0;
 161         if (new_stackp)
 162                 frame->childregs.gprs[15] = new_stackp;
 163         /*
 164          * Clear the runtime instrumentation flag after the above childregs
 165          * copy. The CB pointer was already cleared in arch_dup_task_struct().
 166          */
 167         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 168
 169         /* Set a new TLS ?  */
 170         if (clone_flags & CLONE_SETTLS) {
 171                 if (is_compat_task()) {
 172                         p->thread.acrs[0] = (unsigned int)tls;
 173                 } else {
 174                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 175                         p->thread.acrs[1] = (unsigned int)tls;
 176                 }
 177         }
 178         /*
 179          * s390 stores the svc return address in arch_data when calling
 180          * sigreturn()/restart_syscall() via vdso. 1 means no valid address
 181          * stored.
 182          */
 183         p->restart_block.arch_data = 1;
 184         return 0;
 185 }
 186
 187 void execve_tail(void)
 188 {
 189         current->thread.fpu.fpc = 0;
 190         asm volatile("sfpc %0" : : "d" (0));
 191 }
 192
 193 unsigned long __get_wchan(struct task_struct *p)
 194 {
 195         struct unwind_state state;
 196         unsigned long ip = 0;
 197
 198         if (!task_stack_page(p))
 199                 return 0;
 200
 201         if (!try_get_task_stack(p))
 202                 return 0;
 203
 204         unwind_for_each_frame(&state, p, NULL, 0) {
 205                 if (state.stack_info.type != STACK_TYPE_TASK) {
 206                         ip = 0;
 207                         break;
 208                 }
 209
 210                 ip = unwind_get_return_address(&state);
 211                 if (!ip)
 212                         break;
 213
 214                 if (!in_sched_functions(ip))
 215                         break;
 216         }
 217
 218         put_task_stack(p);
 219         return ip;
 220 }
 221
 222 unsigned long arch_align_stack(unsigned long sp)
 223 {
 224         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 225                 sp -= get_random_u32_below(PAGE_SIZE);
 226         return sp & ~0xf;
 227 }
 228
 229 static inline unsigned long brk_rnd(void)
 230 {
 231         return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT;
 232 }
 233
 234 unsigned long arch_randomize_brk(struct mm_struct *mm)
 235 {
 236         unsigned long ret;
 237
 238         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 239         return (ret > mm->brk) ? ret : mm->brk;
 240 }