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 stack = get_zeroed_page(GFP_KERNEL); 58 if (stack == 0) 59 goto out; 60 61 to_mm->id.stack = stack; 62 if (current->mm != NULL && current->mm != &init_mm) 63 from_mm = ¤t->mm->context; 64 65 if (from_mm) 66 to_mm->id.u.pid = copy_context_skas0(stack, 67 from_mm->id.u.pid); 68 else to_mm->id.u.pid = start_userspace(stack); 69 70 if (to_mm->id.u.pid < 0) { 71 ret = to_mm->id.u.pid; 72 goto out_free; 73 } 74 75 ret = init_new_ldt(to_mm, from_mm); 76 if (ret < 0) { 77 printk(KERN_ERR "init_new_context_skas - init_ldt" 78 " failed, errno = %d\n", ret); 79 goto out_free; 80 } 81 82 return 0; 83 84 out_free: 85 if (to_mm->id.stack != 0) 86 free_page(to_mm->id.stack); 87 out: 88 return ret; 89 } 90 91 void uml_setup_stubs(struct mm_struct *mm) 92 { 93 int err, ret; 94 95 ret = init_stub_pte(mm, STUB_CODE, 96 (unsigned long) &__syscall_stub_start); 97 if (ret) 98 goto out; 99 100 ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack); 101 if (ret) 102 goto out; 103 104 mm->context.stub_pages[0] = virt_to_page(&__syscall_stub_start); 105 mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack); 106 107 /* dup_mmap already holds mmap_sem */ 108 err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START, 109 VM_READ | VM_MAYREAD | VM_EXEC | 110 VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP, 111 mm->context.stub_pages); 112 if (err) { 113 printk(KERN_ERR "install_special_mapping returned %d\n", err); 114 goto out; 115 } 116 return; 117 118 out: 119 force_sigsegv(SIGSEGV, current); 120 } 121 122 void arch_exit_mmap(struct mm_struct *mm) 123 { 124 pte_t *pte; 125 126 pte = virt_to_pte(mm, STUB_CODE); 127 if (pte != NULL) 128 pte_clear(mm, STUB_CODE, pte); 129 130 pte = virt_to_pte(mm, STUB_DATA); 131 if (pte == NULL) 132 return; 133 134 pte_clear(mm, STUB_DATA, pte); 135 } 136 137 void destroy_context(struct mm_struct *mm) 138 { 139 struct mm_context *mmu = &mm->context; 140 141 /* 142 * If init_new_context wasn't called, this will be 143 * zero, resulting in a kill(0), which will result in the 144 * whole UML suddenly dying. Also, cover negative and 145 * 1 cases, since they shouldn't happen either. 146 */ 147 if (mmu->id.u.pid < 2) { 148 printk(KERN_ERR "corrupt mm_context - pid = %d\n", 149 mmu->id.u.pid); 150 return; 151 } 152 os_kill_ptraced_process(mmu->id.u.pid, 1); 153 154 free_page(mmu->id.stack); 155 free_ldt(mmu); 156 } 157