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_context *from_mm = NULL; 25 struct mm_context *to_mm = &mm->context; 26 unsigned long stack = 0; 27 int ret = -ENOMEM; 28 29 stack = __get_free_pages(GFP_KERNEL | __GFP_ZERO, ilog2(STUB_DATA_PAGES)); 30 if (stack == 0) 31 goto out; 32 33 to_mm->id.stack = stack; 34 if (current->mm != NULL && current->mm != &init_mm) 35 from_mm = ¤t->mm->context; 36 37 block_signals_trace(); 38 if (from_mm) 39 to_mm->id.u.pid = copy_context_skas0(stack, 40 from_mm->id.u.pid); 41 else to_mm->id.u.pid = start_userspace(stack); 42 unblock_signals_trace(); 43 44 if (to_mm->id.u.pid < 0) { 45 ret = to_mm->id.u.pid; 46 goto out_free; 47 } 48 49 ret = init_new_ldt(to_mm, from_mm); 50 if (ret < 0) { 51 printk(KERN_ERR "init_new_context_skas - init_ldt" 52 " failed, errno = %d\n", ret); 53 goto out_free; 54 } 55 56 return 0; 57 58 out_free: 59 if (to_mm->id.stack != 0) 60 free_pages(to_mm->id.stack, ilog2(STUB_DATA_PAGES)); 61 out: 62 return ret; 63 } 64 65 void destroy_context(struct mm_struct *mm) 66 { 67 struct mm_context *mmu = &mm->context; 68 69 /* 70 * If init_new_context wasn't called, this will be 71 * zero, resulting in a kill(0), which will result in the 72 * whole UML suddenly dying. Also, cover negative and 73 * 1 cases, since they shouldn't happen either. 74 */ 75 if (mmu->id.u.pid < 2) { 76 printk(KERN_ERR "corrupt mm_context - pid = %d\n", 77 mmu->id.u.pid); 78 return; 79 } 80 os_kill_ptraced_process(mmu->id.u.pid, 1); 81 82 free_pages(mmu->id.stack, ilog2(STUB_DATA_PAGES)); 83 free_ldt(mmu); 84 } 85