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 <linux/io.h>
  34 #include <asm/guarded_storage.h>
  35 #include <asm/access-regs.h>
  36 #include <asm/switch_to.h>
  37 #include <asm/cpu_mf.h>
  38 #include <asm/processor.h>
  39 #include <asm/ptrace.h>
  40 #include <asm/vtimer.h>
  41 #include <asm/exec.h>
  42 #include <asm/fpu.h>
  43 #include <asm/irq.h>
  44 #include <asm/nmi.h>
  45 #include <asm/smp.h>
  46 #include <asm/stacktrace.h>
  47 #include <asm/runtime_instr.h>
  48 #include <asm/unwind.h>
  49 #include "entry.h"
  50
  51 void ret_from_fork(void) asm("ret_from_fork");
  52
  53 void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs)
  54 {
  55         void (*func)(void *arg);
  56
  57         schedule_tail(prev);
  58
  59         if (!user_mode(regs)) {
  60                 /* Kernel thread */
  61                 func = (void *)regs->gprs[9];
  62                 func((void *)regs->gprs[10]);
  63         }
  64         clear_pt_regs_flag(regs, PIF_SYSCALL);
  65         syscall_exit_to_user_mode(regs);
  66 }
  67
  68 void flush_thread(void)
  69 {
  70 }
  71
  72 void arch_setup_new_exec(void)
  73 {
  74         if (S390_lowcore.current_pid != current->pid) {
  75                 S390_lowcore.current_pid = current->pid;
  76                 if (test_facility(40))
  77                         lpp(&S390_lowcore.lpp);
  78         }
  79 }
  80
  81 void arch_release_task_struct(struct task_struct *tsk)
  82 {
  83         runtime_instr_release(tsk);
  84         guarded_storage_release(tsk);
  85 }
  86
  87 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  88 {
  89         /*
  90          * Save the floating-point or vector register state of the current
  91          * task and set the TIF_FPU flag to lazy restore the FPU register
  92          * state when returning to user space.
  93          */
  94         save_user_fpu_regs();
  95
  96         *dst = *src;
  97         dst->thread.kfpu_flags = 0;
  98
  99         /*
 100          * Don't transfer over the runtime instrumentation or the guarded
 101          * storage control block pointers. These fields are cleared here instead
 102          * of in copy_thread() to avoid premature freeing of associated memory
 103          * on fork() failure. Wait to clear the RI flag because ->stack still
 104          * refers to the source thread.
 105          */
 106         dst->thread.ri_cb = NULL;
 107         dst->thread.gs_cb = NULL;
 108         dst->thread.gs_bc_cb = NULL;
 109
 110         return 0;
 111 }
 112
 113 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 114 {
 115         unsigned long clone_flags = args->flags;
 116         unsigned long new_stackp = args->stack;
 117         unsigned long tls = args->tls;
 118         struct fake_frame
 119         {
 120                 struct stack_frame sf;
 121                 struct pt_regs childregs;
 122         } *frame;
 123
 124         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 125         p->thread.ksp = (unsigned long) frame;
 126         /* Save access registers to new thread structure. */
 127         save_access_regs(&p->thread.acrs[0]);
 128         /* start new process with ar4 pointing to the correct address space */
 129         /* Don't copy debug registers */
 130         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 131         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 132         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 133         p->thread.per_flags = 0;
 134         /* Initialize per thread user and system timer values */
 135         p->thread.user_timer = 0;
 136         p->thread.guest_timer = 0;
 137         p->thread.system_timer = 0;
 138         p->thread.hardirq_timer = 0;
 139         p->thread.softirq_timer = 0;
 140         p->thread.last_break = 1;
 141
 142         frame->sf.back_chain = 0;
 143         frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs;
 144         frame->sf.gprs[12 - 6] = (unsigned long)p;
 145         /* new return point is ret_from_fork */
 146         frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork;
 147         /* fake return stack for resume(), don't go back to schedule */
 148         frame->sf.gprs[15 - 6] = (unsigned long)frame;
 149
 150         /* Store access registers to kernel stack of new process. */
 151         if (unlikely(args->fn)) {
 152                 /* kernel thread */
 153                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 154                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO |
 155                                             PSW_MASK_EXT | PSW_MASK_MCHECK;
 156                 frame->childregs.gprs[9] = (unsigned long)args->fn;
 157                 frame->childregs.gprs[10] = (unsigned long)args->fn_arg;
 158                 frame->childregs.orig_gpr2 = -1;
 159                 frame->childregs.last_break = 1;
 160                 return 0;
 161         }
 162         frame->childregs = *current_pt_regs();
 163         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 164         frame->childregs.flags = 0;
 165         if (new_stackp)
 166                 frame->childregs.gprs[15] = new_stackp;
 167         /*
 168          * Clear the runtime instrumentation flag after the above childregs
 169          * copy. The CB pointer was already cleared in arch_dup_task_struct().
 170          */
 171         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 172
 173         /* Set a new TLS ?  */
 174         if (clone_flags & CLONE_SETTLS) {
 175                 if (is_compat_task()) {
 176                         p->thread.acrs[0] = (unsigned int)tls;
 177                 } else {
 178                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 179                         p->thread.acrs[1] = (unsigned int)tls;
 180                 }
 181         }
 182         /*
 183          * s390 stores the svc return address in arch_data when calling
 184          * sigreturn()/restart_syscall() via vdso. 1 means no valid address
 185          * stored.
 186          */
 187         p->restart_block.arch_data = 1;
 188         return 0;
 189 }
 190
 191 void execve_tail(void)
 192 {
 193         current->thread.ufpu.fpc = 0;
 194         fpu_sfpc(0);
 195 }
 196
 197 struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next)
 198 {
 199         save_user_fpu_regs();
 200         save_kernel_fpu_regs(&prev->thread);
 201         save_access_regs(&prev->thread.acrs[0]);
 202         save_ri_cb(prev->thread.ri_cb);
 203         save_gs_cb(prev->thread.gs_cb);
 204         update_cr_regs(next);
 205         restore_kernel_fpu_regs(&next->thread);
 206         restore_access_regs(&next->thread.acrs[0]);
 207         restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb);
 208         restore_gs_cb(next->thread.gs_cb);
 209         return __switch_to_asm(prev, next);
 210 }
 211
 212 unsigned long __get_wchan(struct task_struct *p)
 213 {
 214         struct unwind_state state;
 215         unsigned long ip = 0;
 216
 217         if (!task_stack_page(p))
 218                 return 0;
 219
 220         if (!try_get_task_stack(p))
 221                 return 0;
 222
 223         unwind_for_each_frame(&state, p, NULL, 0) {
 224                 if (state.stack_info.type != STACK_TYPE_TASK) {
 225                         ip = 0;
 226                         break;
 227                 }
 228
 229                 ip = unwind_get_return_address(&state);
 230                 if (!ip)
 231                         break;
 232
 233                 if (!in_sched_functions(ip))
 234                         break;
 235         }
 236
 237         put_task_stack(p);
 238         return ip;
 239 }
 240
 241 unsigned long arch_align_stack(unsigned long sp)
 242 {
 243         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 244                 sp -= get_random_u32_below(PAGE_SIZE);
 245         return sp & ~0xf;
 246 }
 247
 248 static inline unsigned long brk_rnd(void)
 249 {
 250         return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT;
 251 }
 252
 253 unsigned long arch_randomize_brk(struct mm_struct *mm)
 254 {
 255         unsigned long ret;
 256
 257         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 258         return (ret > mm->brk) ? ret : mm->brk;
 259 }