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 <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         save_user_fpu_regs();
  90
  91         *dst = *src;
  92         dst->thread.kfpu_flags = 0;
  93
  94         /*
  95          * Don't transfer over the runtime instrumentation or the guarded
  96          * storage control block pointers. These fields are cleared here instead
  97          * of in copy_thread() to avoid premature freeing of associated memory
  98          * on fork() failure. Wait to clear the RI flag because ->stack still
  99          * refers to the source thread.
 100          */
 101         dst->thread.ri_cb = NULL;
 102         dst->thread.gs_cb = NULL;
 103         dst->thread.gs_bc_cb = NULL;
 104
 105         return 0;
 106 }
 107
 108 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 109 {
 110         unsigned long clone_flags = args->flags;
 111         unsigned long new_stackp = args->stack;
 112         unsigned long tls = args->tls;
 113         struct fake_frame
 114         {
 115                 struct stack_frame sf;
 116                 struct pt_regs childregs;
 117         } *frame;
 118
 119         frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
 120         p->thread.ksp = (unsigned long) frame;
 121         /* Save access registers to new thread structure. */
 122         save_access_regs(&p->thread.acrs[0]);
 123         /* start new process with ar4 pointing to the correct address space */
 124         /* Don't copy debug registers */
 125         memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
 126         memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
 127         clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 128         p->thread.per_flags = 0;
 129         /* Initialize per thread user and system timer values */
 130         p->thread.user_timer = 0;
 131         p->thread.guest_timer = 0;
 132         p->thread.system_timer = 0;
 133         p->thread.hardirq_timer = 0;
 134         p->thread.softirq_timer = 0;
 135         p->thread.last_break = 1;
 136
 137         frame->sf.back_chain = 0;
 138         frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs;
 139         frame->sf.gprs[12 - 6] = (unsigned long)p;
 140         /* new return point is ret_from_fork */
 141         frame->sf.gprs[14 - 6] = (unsigned long)ret_from_fork;
 142         /* fake return stack for resume(), don't go back to schedule */
 143         frame->sf.gprs[15 - 6] = (unsigned long)frame;
 144
 145         /* Store access registers to kernel stack of new process. */
 146         if (unlikely(args->fn)) {
 147                 /* kernel thread */
 148                 memset(&frame->childregs, 0, sizeof(struct pt_regs));
 149                 frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_IO |
 150                                             PSW_MASK_EXT | PSW_MASK_MCHECK;
 151                 frame->childregs.gprs[9] = (unsigned long)args->fn;
 152                 frame->childregs.gprs[10] = (unsigned long)args->fn_arg;
 153                 frame->childregs.orig_gpr2 = -1;
 154                 frame->childregs.last_break = 1;
 155                 return 0;
 156         }
 157         frame->childregs = *current_pt_regs();
 158         frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 159         frame->childregs.flags = 0;
 160         if (new_stackp)
 161                 frame->childregs.gprs[15] = new_stackp;
 162         /*
 163          * Clear the runtime instrumentation flag after the above childregs
 164          * copy. The CB pointer was already cleared in arch_dup_task_struct().
 165          */
 166         frame->childregs.psw.mask &= ~PSW_MASK_RI;
 167
 168         /* Set a new TLS ?  */
 169         if (clone_flags & CLONE_SETTLS) {
 170                 if (is_compat_task()) {
 171                         p->thread.acrs[0] = (unsigned int)tls;
 172                 } else {
 173                         p->thread.acrs[0] = (unsigned int)(tls >> 32);
 174                         p->thread.acrs[1] = (unsigned int)tls;
 175                 }
 176         }
 177         /*
 178          * s390 stores the svc return address in arch_data when calling
 179          * sigreturn()/restart_syscall() via vdso. 1 means no valid address
 180          * stored.
 181          */
 182         p->restart_block.arch_data = 1;
 183         return 0;
 184 }
 185
 186 void execve_tail(void)
 187 {
 188         current->thread.ufpu.fpc = 0;
 189         fpu_sfpc(0);
 190 }
 191
 192 struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next)
 193 {
 194         save_user_fpu_regs();
 195         save_kernel_fpu_regs(&prev->thread);
 196         save_access_regs(&prev->thread.acrs[0]);
 197         save_ri_cb(prev->thread.ri_cb);
 198         save_gs_cb(prev->thread.gs_cb);
 199         update_cr_regs(next);
 200         restore_kernel_fpu_regs(&next->thread);
 201         restore_access_regs(&next->thread.acrs[0]);
 202         restore_ri_cb(next->thread.ri_cb, prev->thread.ri_cb);
 203         restore_gs_cb(next->thread.gs_cb);
 204         return __switch_to_asm(prev, next);
 205 }
 206
 207 unsigned long __get_wchan(struct task_struct *p)
 208 {
 209         struct unwind_state state;
 210         unsigned long ip = 0;
 211
 212         if (!task_stack_page(p))
 213                 return 0;
 214
 215         if (!try_get_task_stack(p))
 216                 return 0;
 217
 218         unwind_for_each_frame(&state, p, NULL, 0) {
 219                 if (state.stack_info.type != STACK_TYPE_TASK) {
 220                         ip = 0;
 221                         break;
 222                 }
 223
 224                 ip = unwind_get_return_address(&state);
 225                 if (!ip)
 226                         break;
 227
 228                 if (!in_sched_functions(ip))
 229                         break;
 230         }
 231
 232         put_task_stack(p);
 233         return ip;
 234 }
 235
 236 unsigned long arch_align_stack(unsigned long sp)
 237 {
 238         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 239                 sp -= get_random_u32_below(PAGE_SIZE);
 240         return sp & ~0xf;
 241 }
 242
 243 static inline unsigned long brk_rnd(void)
 244 {
 245         return (get_random_u16() & BRK_RND_MASK) << PAGE_SHIFT;
 246 }
 247
 248 unsigned long arch_randomize_brk(struct mm_struct *mm)
 249 {
 250         unsigned long ret;
 251
 252         ret = PAGE_ALIGN(mm->brk + brk_rnd());
 253         return (ret > mm->brk) ? ret : mm->brk;
 254 }