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 #include <stub-data.h> 18 19 /* Ensure the stub_data struct covers the allocated area */ 20 static_assert(sizeof(struct stub_data) == STUB_DATA_PAGES * UM_KERN_PAGE_SIZE); 21 22 int init_new_context(struct task_struct *task, struct mm_struct *mm) 23 { 24 struct mm_id *new_id = &mm->context.id; 25 unsigned long stack = 0; 26 int ret = -ENOMEM; 27 28 stack = __get_free_pages(GFP_KERNEL | __GFP_ZERO, ilog2(STUB_DATA_PAGES)); 29 if (stack == 0) 30 goto out; 31 32 new_id->stack = stack; 33 34 block_signals_trace(); 35 new_id->pid = start_userspace(stack); 36 unblock_signals_trace(); 37 38 if (new_id->pid < 0) { 39 ret = new_id->pid; 40 goto out_free; 41 } 42 43 /* Ensure the new MM is clean and nothing unwanted is mapped */ 44 unmap(new_id, 0, STUB_START); 45 46 return 0; 47 48 out_free: 49 free_pages(new_id->stack, ilog2(STUB_DATA_PAGES)); 50 out: 51 return ret; 52 } 53 54 void destroy_context(struct mm_struct *mm) 55 { 56 struct mm_context *mmu = &mm->context; 57 58 /* 59 * If init_new_context wasn't called, this will be 60 * zero, resulting in a kill(0), which will result in the 61 * whole UML suddenly dying. Also, cover negative and 62 * 1 cases, since they shouldn't happen either. 63 */ 64 if (mmu->id.pid < 2) { 65 printk(KERN_ERR "corrupt mm_context - pid = %d\n", 66 mmu->id.pid); 67 return; 68 } 69 os_kill_ptraced_process(mmu->id.pid, 1); 70 71 free_pages(mmu->id.stack, ilog2(STUB_DATA_PAGES)); 72 } 73