LXR linux/arch/um/kernel/skas/mmu.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
   4 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   5 */
   6
   7#include <linux/mm.h>
   8#include <linux/sched/signal.h>
   9#include <linux/slab.h>
  10
  11#include <asm/pgalloc.h>
  12#include <asm/sections.h>
  13#include <as-layout.h>
  14#include <os.h>
  15#include <skas.h>
  16
  17int init_new_context(struct task_struct *task, struct mm_struct *mm)
  18{
  19        struct mm_context *from_mm = NULL;
  20        struct mm_context *to_mm = &mm->context;
  21        unsigned long stack = 0;
  22        int ret = -ENOMEM;
  23
  24        stack = get_zeroed_page(GFP_KERNEL);
  25        if (stack == 0)
  26                goto out;
  27
  28        to_mm->id.stack = stack;
  29        if (current->mm != NULL && current->mm != &init_mm)
  30                from_mm = &current->mm->context;
  31
  32        block_signals_trace();
  33        if (from_mm)
  34                to_mm->id.u.pid = copy_context_skas0(stack,
  35                                                     from_mm->id.u.pid);
  36        else to_mm->id.u.pid = start_userspace(stack);
  37        unblock_signals_trace();
  38
  39        if (to_mm->id.u.pid < 0) {
  40                ret = to_mm->id.u.pid;
  41                goto out_free;
  42        }
  43
  44        ret = init_new_ldt(to_mm, from_mm);
  45        if (ret < 0) {
  46                printk(KERN_ERR "init_new_context_skas - init_ldt"
  47                       " failed, errno = %d\n", ret);
  48                goto out_free;
  49        }
  50
  51        return 0;
  52
  53 out_free:
  54        if (to_mm->id.stack != 0)
  55                free_page(to_mm->id.stack);
  56 out:
  57        return ret;
  58}
  59
  60void destroy_context(struct mm_struct *mm)
  61{
  62        struct mm_context *mmu = &mm->context;
  63
  64        /*
  65         * If init_new_context wasn't called, this will be
  66         * zero, resulting in a kill(0), which will result in the
  67         * whole UML suddenly dying.  Also, cover negative and
  68         * 1 cases, since they shouldn't happen either.
  69         */
  70        if (mmu->id.u.pid < 2) {
  71                printk(KERN_ERR "corrupt mm_context - pid = %d\n",
  72                       mmu->id.u.pid);
  73                return;
  74        }
  75        os_kill_ptraced_process(mmu->id.u.pid, 1);
  76
  77        free_page(mmu->id.stack);
  78        free_ldt(mmu);
  79}
  80