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 17 int 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 = ¤t->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 60 void 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