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 "asm/pgalloc.h" 9 #include "asm/pgtable.h" 10 #include "as-layout.h" 11 #include "os.h" 12 #include "skas.h" 13 14 extern int __syscall_stub_start; 15 16 static int init_stub_pte(struct mm_struct *mm, unsigned long proc, 17 unsigned long kernel) 18 { 19 pgd_t *pgd; 20 pud_t *pud; 21 pmd_t *pmd; 22 pte_t *pte; 23 24 pgd = pgd_offset(mm, proc); 25 pud = pud_alloc(mm, pgd, proc); 26 if (!pud) 27 goto out; 28 29 pmd = pmd_alloc(mm, pud, proc); 30 if (!pmd) 31 goto out_pmd; 32 33 pte = pte_alloc_map(mm, pmd, proc); 34 if (!pte) 35 goto out_pte; 36 37 *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT)); 38 *pte = pte_mkread(*pte); 39 return 0; 40 41 out_pte: 42 pmd_free(mm, pmd); 43 out_pmd: 44 pud_free(mm, pud); 45 out: 46 return -ENOMEM; 47 } 48 49 int init_new_context(struct task_struct *task, struct mm_struct *mm) 50 { 51 struct mm_context *from_mm = NULL; 52 struct mm_context *to_mm = &mm->context; 53 unsigned long stack = 0; 54 int ret = -ENOMEM; 55 56 if (skas_needs_stub) { 57 stack = get_zeroed_page(GFP_KERNEL); 58 if (stack == 0) 59 goto out; 60 } 61 62 to_mm->id.stack = stack; 63 if (current->mm != NULL && current->mm != &init_mm) 64 from_mm = ¤t->mm->context; 65 66 if (proc_mm) { 67 ret = new_mm(stack); 68 if (ret < 0) { 69 printk(KERN_ERR "init_new_context_skas - " 70 "new_mm failed, errno = %d\n", ret); 71 goto out_free; 72 } 73 to_mm->id.u.mm_fd = ret; 74 } 75 else { 76 if (from_mm) 77 to_mm->id.u.pid = copy_context_skas0(stack, 78 from_mm->id.u.pid); 79 else to_mm->id.u.pid = start_userspace(stack); 80 81 if (to_mm->id.u.pid < 0) { 82 ret = to_mm->id.u.pid; 83 goto out_free; 84 } 85 } 86 87 ret = init_new_ldt(to_mm, from_mm); 88 if (ret < 0) { 89 printk(KERN_ERR "init_new_context_skas - init_ldt" 90 " failed, errno = %d\n", ret); 91 goto out_free; 92 } 93 94 to_mm->stub_pages = NULL; 95 96 return 0; 97 98 out_free: 99 if (to_mm->id.stack != 0) 100 free_page(to_mm->id.stack); 101 out: 102 return ret; 103 } 104 105 void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) 106 { 107 struct page **pages; 108 int err, ret; 109 110 if (!skas_needs_stub) 111 return; 112 113 ret = init_stub_pte(mm, STUB_CODE, 114 (unsigned long) &__syscall_stub_start); 115 if (ret) 116 goto out; 117 118 ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack); 119 if (ret) 120 goto out; 121 122 pages = kmalloc(2 * sizeof(struct page *), GFP_KERNEL); 123 if (pages == NULL) { 124 printk(KERN_ERR "arch_dup_mmap failed to allocate 2 page " 125 "pointers\n"); 126 goto out; 127 } 128 129 pages[0] = virt_to_page(&__syscall_stub_start); 130 pages[1] = virt_to_page(mm->context.id.stack); 131 mm->context.stub_pages = pages; 132 133 /* dup_mmap already holds mmap_sem */ 134 err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START, 135 VM_READ | VM_MAYREAD | VM_EXEC | 136 VM_MAYEXEC | VM_DONTCOPY, pages); 137 if (err) { 138 printk(KERN_ERR "install_special_mapping returned %d\n", err); 139 goto out_free; 140 } 141 return; 142 143 out_free: 144 kfree(pages); 145 out: 146 force_sigsegv(SIGSEGV, current); 147 } 148 149 void arch_exit_mmap(struct mm_struct *mm) 150 { 151 pte_t *pte; 152 153 if (mm->context.stub_pages != NULL) 154 kfree(mm->context.stub_pages); 155 pte = virt_to_pte(mm, STUB_CODE); 156 if (pte != NULL) 157 pte_clear(mm, STUB_CODE, pte); 158 159 pte = virt_to_pte(mm, STUB_DATA); 160 if (pte == NULL) 161 return; 162 163 pte_clear(mm, STUB_DATA, pte); 164 } 165 166 void destroy_context(struct mm_struct *mm) 167 { 168 struct mm_context *mmu = &mm->context; 169 170 if (proc_mm) 171 os_close_file(mmu->id.u.mm_fd); 172 else { 173 /* 174 * If init_new_context wasn't called, this will be 175 * zero, resulting in a kill(0), which will result in the 176 * whole UML suddenly dying. Also, cover negative and 177 * 1 cases, since they shouldn't happen either. 178 */ 179 if (mmu->id.u.pid < 2) { 180 printk(KERN_ERR "corrupt mm_context - pid = %d\n", 181 mmu->id.u.pid); 182 return; 183 } 184 os_kill_ptraced_process(mmu->id.u.pid, 1); 185 } 186 187 if (skas_needs_stub) 188 free_page(mmu->id.stack); 189 190 free_ldt(mmu); 191 } 192