1 /* 2 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 3 * Licensed under the GPL 4 */ 5 6 #include "linux/mm.h" 7 #include "linux/sched.h" 8 #include "linux/slab.h" 9 #include "asm/pgalloc.h" 10 #include "asm/pgtable.h" 11 #include "as-layout.h" 12 #include "os.h" 13 #include "skas.h" 14 15 extern int __syscall_stub_start; 16 17 static int init_stub_pte(struct mm_struct *mm, unsigned long proc, 18 unsigned long kernel) 19 { 20 pgd_t *pgd; 21 pud_t *pud; 22 pmd_t *pmd; 23 pte_t *pte; 24 25 pgd = pgd_offset(mm, proc); 26 pud = pud_alloc(mm, pgd, proc); 27 if (!pud) 28 goto out; 29 30 pmd = pmd_alloc(mm, pud, proc); 31 if (!pmd) 32 goto out_pmd; 33 34 pte = pte_alloc_map(mm, NULL, pmd, proc); 35 if (!pte) 36 goto out_pte; 37 38 *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT)); 39 *pte = pte_mkread(*pte); 40 return 0; 41 42 out_pte: 43 pmd_free(mm, pmd); 44 out_pmd: 45 pud_free(mm, pud); 46 out: 47 return -ENOMEM; 48 } 49 50 int init_new_context(struct task_struct *task, struct mm_struct *mm) 51 { 52 struct mm_context *from_mm = NULL; 53 struct mm_context *to_mm = &mm->context; 54 unsigned long stack = 0; 55 int ret = -ENOMEM; 56 57 if (skas_needs_stub) { 58 stack = get_zeroed_page(GFP_KERNEL); 59 if (stack == 0) 60 goto out; 61 } 62 63 to_mm->id.stack = stack; 64 if (current->mm != NULL && current->mm != &init_mm) 65 from_mm = ¤t->mm->context; 66 67 if (proc_mm) { 68 ret = new_mm(stack); 69 if (ret < 0) { 70 printk(KERN_ERR "init_new_context_skas - " 71 "new_mm failed, errno = %d\n", ret); 72 goto out_free; 73 } 74 to_mm->id.u.mm_fd = ret; 75 } 76 else { 77 if (from_mm) 78 to_mm->id.u.pid = copy_context_skas0(stack, 79 from_mm->id.u.pid); 80 else to_mm->id.u.pid = start_userspace(stack); 81 82 if (to_mm->id.u.pid < 0) { 83 ret = to_mm->id.u.pid; 84 goto out_free; 85 } 86 } 87 88 ret = init_new_ldt(to_mm, from_mm); 89 if (ret < 0) { 90 printk(KERN_ERR "init_new_context_skas - init_ldt" 91 " failed, errno = %d\n", ret); 92 goto out_free; 93 } 94 95 return 0; 96 97 out_free: 98 if (to_mm->id.stack != 0) 99 free_page(to_mm->id.stack); 100 out: 101 return ret; 102 } 103 104 void uml_setup_stubs(struct mm_struct *mm) 105 { 106 int err, ret; 107 108 if (!skas_needs_stub) 109 return; 110 111 ret = init_stub_pte(mm, STUB_CODE, 112 (unsigned long) &__syscall_stub_start); 113 if (ret) 114 goto out; 115 116 ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack); 117 if (ret) 118 goto out; 119 120 mm->context.stub_pages[0] = virt_to_page(&__syscall_stub_start); 121 mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack); 122 123 /* dup_mmap already holds mmap_sem */ 124 err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START, 125 VM_READ | VM_MAYREAD | VM_EXEC | 126 VM_MAYEXEC | VM_DONTCOPY, 127 mm->context.stub_pages); 128 if (err) { 129 printk(KERN_ERR "install_special_mapping returned %d\n", err); 130 goto out; 131 } 132 return; 133 134 out: 135 force_sigsegv(SIGSEGV, current); 136 } 137 138 void arch_exit_mmap(struct mm_struct *mm) 139 { 140 pte_t *pte; 141 142 pte = virt_to_pte(mm, STUB_CODE); 143 if (pte != NULL) 144 pte_clear(mm, STUB_CODE, pte); 145 146 pte = virt_to_pte(mm, STUB_DATA); 147 if (pte == NULL) 148 return; 149 150 pte_clear(mm, STUB_DATA, pte); 151 } 152 153 void destroy_context(struct mm_struct *mm) 154 { 155 struct mm_context *mmu = &mm->context; 156 157 if (proc_mm) 158 os_close_file(mmu->id.u.mm_fd); 159 else { 160 /* 161 * If init_new_context wasn't called, this will be 162 * zero, resulting in a kill(0), which will result in the 163 * whole UML suddenly dying. Also, cover negative and 164 * 1 cases, since they shouldn't happen either. 165 */ 166 if (mmu->id.u.pid < 2) { 167 printk(KERN_ERR "corrupt mm_context - pid = %d\n", 168 mmu->id.u.pid); 169 return; 170 } 171 os_kill_ptraced_process(mmu->id.u.pid, 1); 172 } 173 174 if (skas_needs_stub) 175 free_page(mmu->id.stack); 176 177 free_ldt(mmu); 178 } 179