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, 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 to_mm->stub_pages = NULL; 96 97 return 0; 98 99 out_free: 100 if (to_mm->id.stack != 0) 101 free_page(to_mm->id.stack); 102 out: 103 return ret; 104 } 105 106 void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) 107 { 108 struct page **pages; 109 int err, ret; 110 111 if (!skas_needs_stub) 112 return; 113 114 ret = init_stub_pte(mm, STUB_CODE, 115 (unsigned long) &__syscall_stub_start); 116 if (ret) 117 goto out; 118 119 ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack); 120 if (ret) 121 goto out; 122 123 pages = kmalloc(2 * sizeof(struct page *), GFP_KERNEL); 124 if (pages == NULL) { 125 printk(KERN_ERR "arch_dup_mmap failed to allocate 2 page " 126 "pointers\n"); 127 goto out; 128 } 129 130 pages[0] = virt_to_page(&__syscall_stub_start); 131 pages[1] = virt_to_page(mm->context.id.stack); 132 mm->context.stub_pages = pages; 133 134 /* dup_mmap already holds mmap_sem */ 135 err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START, 136 VM_READ | VM_MAYREAD | VM_EXEC | 137 VM_MAYEXEC | VM_DONTCOPY, pages); 138 if (err) { 139 printk(KERN_ERR "install_special_mapping returned %d\n", err); 140 goto out_free; 141 } 142 return; 143 144 out_free: 145 kfree(pages); 146 out: 147 force_sigsegv(SIGSEGV, current); 148 } 149 150 void arch_exit_mmap(struct mm_struct *mm) 151 { 152 pte_t *pte; 153 154 if (mm->context.stub_pages != NULL) 155 kfree(mm->context.stub_pages); 156 pte = virt_to_pte(mm, STUB_CODE); 157 if (pte != NULL) 158 pte_clear(mm, STUB_CODE, pte); 159 160 pte = virt_to_pte(mm, STUB_DATA); 161 if (pte == NULL) 162 return; 163 164 pte_clear(mm, STUB_DATA, pte); 165 } 166 167 void destroy_context(struct mm_struct *mm) 168 { 169 struct mm_context *mmu = &mm->context; 170 171 if (proc_mm) 172 os_close_file(mmu->id.u.mm_fd); 173 else { 174 /* 175 * If init_new_context wasn't called, this will be 176 * zero, resulting in a kill(0), which will result in the 177 * whole UML suddenly dying. Also, cover negative and 178 * 1 cases, since they shouldn't happen either. 179 */ 180 if (mmu->id.u.pid < 2) { 181 printk(KERN_ERR "corrupt mm_context - pid = %d\n", 182 mmu->id.u.pid); 183 return; 184 } 185 os_kill_ptraced_process(mmu->id.u.pid, 1); 186 } 187 188 if (skas_needs_stub) 189 free_page(mmu->id.stack); 190 191 free_ldt(mmu); 192 } 193