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 <asm/mmu_context.h> 14 #include <as-layout.h> 15 #include <os.h> 16 #include <skas.h> 17 18 int init_new_context(struct task_struct *task, struct mm_struct *mm) 19 { 20 struct mm_context *from_mm = NULL; 21 struct mm_context *to_mm = &mm->context; 22 unsigned long stack = 0; 23 int ret = -ENOMEM; 24 25 stack = __get_free_pages(GFP_KERNEL | __GFP_ZERO, ilog2(STUB_DATA_PAGES)); 26 if (stack == 0) 27 goto out; 28 29 to_mm->id.stack = stack; 30 if (current->mm != NULL && current->mm != &init_mm) 31 from_mm = ¤t->mm->context; 32 33 block_signals_trace(); 34 if (from_mm) 35 to_mm->id.u.pid = copy_context_skas0(stack, 36 from_mm->id.u.pid); 37 else to_mm->id.u.pid = start_userspace(stack); 38 unblock_signals_trace(); 39 40 if (to_mm->id.u.pid < 0) { 41 ret = to_mm->id.u.pid; 42 goto out_free; 43 } 44 45 ret = init_new_ldt(to_mm, from_mm); 46 if (ret < 0) { 47 printk(KERN_ERR "init_new_context_skas - init_ldt" 48 " failed, errno = %d\n", ret); 49 goto out_free; 50 } 51 52 return 0; 53 54 out_free: 55 if (to_mm->id.stack != 0) 56 free_pages(to_mm->id.stack, ilog2(STUB_DATA_PAGES)); 57 out: 58 return ret; 59 } 60 61 void destroy_context(struct mm_struct *mm) 62 { 63 struct mm_context *mmu = &mm->context; 64 65 /* 66 * If init_new_context wasn't called, this will be 67 * zero, resulting in a kill(0), which will result in the 68 * whole UML suddenly dying. Also, cover negative and 69 * 1 cases, since they shouldn't happen either. 70 */ 71 if (mmu->id.u.pid < 2) { 72 printk(KERN_ERR "corrupt mm_context - pid = %d\n", 73 mmu->id.u.pid); 74 return; 75 } 76 os_kill_ptraced_process(mmu->id.u.pid, 1); 77 78 free_pages(mmu->id.stack, ilog2(STUB_DATA_PAGES)); 79 free_ldt(mmu); 80 } 81