linux/arch/s390/kernel/process.c
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   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/switch_to.h>
  41#include <asm/runtime_instr.h>
  42#include "entry.h"
  43
  44asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
  45
  46extern void kernel_thread_starter(void);
  47
  48void flush_thread(void)
  49{
  50}
  51
  52void arch_setup_new_exec(void)
  53{
  54        if (S390_lowcore.current_pid != current->pid) {
  55                S390_lowcore.current_pid = current->pid;
  56                if (test_facility(40))
  57                        lpp(&S390_lowcore.lpp);
  58        }
  59}
  60
  61void arch_release_task_struct(struct task_struct *tsk)
  62{
  63        runtime_instr_release(tsk);
  64        guarded_storage_release(tsk);
  65}
  66
  67int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  68{
  69        /*
  70         * Save the floating-point or vector register state of the current
  71         * task and set the CIF_FPU flag to lazy restore the FPU register
  72         * state when returning to user space.
  73         */
  74        save_fpu_regs();
  75
  76        memcpy(dst, src, arch_task_struct_size);
  77        dst->thread.fpu.regs = dst->thread.fpu.fprs;
  78        return 0;
  79}
  80
  81int copy_thread_tls(unsigned long clone_flags, unsigned long new_stackp,
  82                    unsigned long arg, struct task_struct *p, unsigned long tls)
  83{
  84        struct fake_frame
  85        {
  86                struct stack_frame sf;
  87                struct pt_regs childregs;
  88        } *frame;
  89
  90        frame = container_of(task_pt_regs(p), struct fake_frame, childregs);
  91        p->thread.ksp = (unsigned long) frame;
  92        /* Save access registers to new thread structure. */
  93        save_access_regs(&p->thread.acrs[0]);
  94        /* start new process with ar4 pointing to the correct address space */
  95        p->thread.mm_segment = get_fs();
  96        /* Don't copy debug registers */
  97        memset(&p->thread.per_user, 0, sizeof(p->thread.per_user));
  98        memset(&p->thread.per_event, 0, sizeof(p->thread.per_event));
  99        clear_tsk_thread_flag(p, TIF_SINGLE_STEP);
 100        p->thread.per_flags = 0;
 101        /* Initialize per thread user and system timer values */
 102        p->thread.user_timer = 0;
 103        p->thread.guest_timer = 0;
 104        p->thread.system_timer = 0;
 105        p->thread.hardirq_timer = 0;
 106        p->thread.softirq_timer = 0;
 107        p->thread.last_break = 1;
 108
 109        frame->sf.back_chain = 0;
 110        /* new return point is ret_from_fork */
 111        frame->sf.gprs[8] = (unsigned long) ret_from_fork;
 112        /* fake return stack for resume(), don't go back to schedule */
 113        frame->sf.gprs[9] = (unsigned long) frame;
 114
 115        /* Store access registers to kernel stack of new process. */
 116        if (unlikely(p->flags & PF_KTHREAD)) {
 117                /* kernel thread */
 118                memset(&frame->childregs, 0, sizeof(struct pt_regs));
 119                frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 120                                PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 121                frame->childregs.psw.addr =
 122                                (unsigned long) kernel_thread_starter;
 123                frame->childregs.gprs[9] = new_stackp; /* function */
 124                frame->childregs.gprs[10] = arg;
 125                frame->childregs.gprs[11] = (unsigned long) do_exit;
 126                frame->childregs.orig_gpr2 = -1;
 127
 128                return 0;
 129        }
 130        frame->childregs = *current_pt_regs();
 131        frame->childregs.gprs[2] = 0;   /* child returns 0 on fork. */
 132        frame->childregs.flags = 0;
 133        if (new_stackp)
 134                frame->childregs.gprs[15] = new_stackp;
 135
 136        /* Don't copy runtime instrumentation info */
 137        p->thread.ri_cb = NULL;
 138        frame->childregs.psw.mask &= ~PSW_MASK_RI;
 139        /* Don't copy guarded storage control block */
 140        p->thread.gs_cb = NULL;
 141        p->thread.gs_bc_cb = NULL;
 142
 143        /* Set a new TLS ?  */
 144        if (clone_flags & CLONE_SETTLS) {
 145                if (is_compat_task()) {
 146                        p->thread.acrs[0] = (unsigned int)tls;
 147                } else {
 148                        p->thread.acrs[0] = (unsigned int)(tls >> 32);
 149                        p->thread.acrs[1] = (unsigned int)tls;
 150                }
 151        }
 152        return 0;
 153}
 154
 155asmlinkage void execve_tail(void)
 156{
 157        current->thread.fpu.fpc = 0;
 158        asm volatile("sfpc %0" : : "d" (0));
 159}
 160
 161/*
 162 * fill in the FPU structure for a core dump.
 163 */
 164int dump_fpu (struct pt_regs * regs, s390_fp_regs *fpregs)
 165{
 166        save_fpu_regs();
 167        fpregs->fpc = current->thread.fpu.fpc;
 168        fpregs->pad = 0;
 169        if (MACHINE_HAS_VX)
 170                convert_vx_to_fp((freg_t *)&fpregs->fprs,
 171                                 current->thread.fpu.vxrs);
 172        else
 173                memcpy(&fpregs->fprs, current->thread.fpu.fprs,
 174                       sizeof(fpregs->fprs));
 175        return 1;
 176}
 177EXPORT_SYMBOL(dump_fpu);
 178
 179unsigned long get_wchan(struct task_struct *p)
 180{
 181        struct stack_frame *sf, *low, *high;
 182        unsigned long return_address;
 183        int count;
 184
 185        if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))
 186                return 0;
 187
 188        if (!try_get_task_stack(p))
 189                return 0;
 190
 191        low = task_stack_page(p);
 192        high = (struct stack_frame *) task_pt_regs(p);
 193        sf = (struct stack_frame *) p->thread.ksp;
 194        if (sf <= low || sf > high) {
 195                return_address = 0;
 196                goto out;
 197        }
 198        for (count = 0; count < 16; count++) {
 199                sf = (struct stack_frame *)READ_ONCE_NOCHECK(sf->back_chain);
 200                if (sf <= low || sf > high) {
 201                        return_address = 0;
 202                        goto out;
 203                }
 204                return_address = READ_ONCE_NOCHECK(sf->gprs[8]);
 205                if (!in_sched_functions(return_address))
 206                        goto out;
 207        }
 208out:
 209        put_task_stack(p);
 210        return return_address;
 211}
 212
 213unsigned long arch_align_stack(unsigned long sp)
 214{
 215        if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 216                sp -= get_random_int() & ~PAGE_MASK;
 217        return sp & ~0xf;
 218}
 219
 220static inline unsigned long brk_rnd(void)
 221{
 222        return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
 223}
 224
 225unsigned long arch_randomize_brk(struct mm_struct *mm)
 226{
 227        unsigned long ret;
 228
 229        ret = PAGE_ALIGN(mm->brk + brk_rnd());
 230        return (ret > mm->brk) ? ret : mm->brk;
 231}
 232
 233void set_fs_fixup(void)
 234{
 235        struct pt_regs *regs = current_pt_regs();
 236        static bool warned;
 237
 238        set_fs(USER_DS);
 239        if (warned)
 240                return;
 241        WARN(1, "Unbalanced set_fs - int code: 0x%x\n", regs->int_code);
 242        show_registers(regs);
 243        warned = true;
 244}
 245