2 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
7 #include "linux/sched.h"
8 #include "asm/pgalloc.h"
9 #include "asm/pgtable.h"
10 #include "as-layout.h"
14 extern int __syscall_stub_start;
16 static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
24 pgd = pgd_offset(mm, proc);
25 pud = pud_alloc(mm, pgd, proc);
29 pmd = pmd_alloc(mm, pud, proc);
33 pte = pte_alloc_map(mm, pmd, proc);
38 * There's an interaction between the skas0 stub pages, stack
39 * randomization, and the BUG at the end of exit_mmap. exit_mmap
40 * checks that the number of page tables freed is the same as had
41 * been allocated. If the stack is on the last page table page,
42 * then the stack pte page will be freed, and if not, it won't. To
43 * avoid having to know where the stack is, or if the process mapped
44 * something at the top of its address space for some other reason,
45 * we set TASK_SIZE to end at the start of the last page table.
46 * This keeps exit_mmap off the last page, but introduces a leak
47 * of that page. So, we hang onto it here and free it in
48 * destroy_context_skas.
51 mm->context.last_page_table = pmd_page_vaddr(*pmd);
52 #ifdef CONFIG_3_LEVEL_PGTABLES
53 mm->context.last_pmd = (unsigned long) __va(pud_val(*pud));
56 *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
57 *pte = pte_mkread(*pte);
68 int init_new_context(struct task_struct *task, struct mm_struct *mm)
70 struct mm_context *from_mm = NULL;
71 struct mm_context *to_mm = &mm->context;
72 unsigned long stack = 0;
75 if (skas_needs_stub) {
76 stack = get_zeroed_page(GFP_KERNEL);
81 * This zeros the entry that pgd_alloc didn't, needed since
82 * we are about to reinitialize it, and want mm.nr_ptes to
85 mm->pgd[USER_PTRS_PER_PGD] = __pgd(0);
87 ret = init_stub_pte(mm, STUB_CODE,
88 (unsigned long) &__syscall_stub_start);
92 ret = init_stub_pte(mm, STUB_DATA, stack);
99 to_mm->id.stack = stack;
100 if (current->mm != NULL && current->mm != &init_mm)
101 from_mm = ¤t->mm->context;
106 printk(KERN_ERR "init_new_context_skas - "
107 "new_mm failed, errno = %d\n", ret);
110 to_mm->id.u.mm_fd = ret;
114 to_mm->id.u.pid = copy_context_skas0(stack,
116 else to_mm->id.u.pid = start_userspace(stack);
119 ret = init_new_ldt(to_mm, from_mm);
121 printk(KERN_ERR "init_new_context_skas - init_ldt"
122 " failed, errno = %d\n", ret);
129 if (to_mm->id.stack != 0)
130 free_page(to_mm->id.stack);
135 void destroy_context(struct mm_struct *mm)
137 struct mm_context *mmu = &mm->context;
140 os_close_file(mmu->id.u.mm_fd);
142 os_kill_ptraced_process(mmu->id.u.pid, 1);
144 if (!proc_mm || !ptrace_faultinfo) {
145 free_page(mmu->id.stack);
146 pte_lock_deinit(virt_to_page(mmu->last_page_table));
147 pte_free_kernel((pte_t *) mmu->last_page_table);
148 dec_zone_page_state(virt_to_page(mmu->last_page_table), NR_PAGETABLE);
149 #ifdef CONFIG_3_LEVEL_PGTABLES
150 pmd_free((pmd_t *) mmu->last_pmd);