161 lines
3.8 KiB
C
161 lines
3.8 KiB
C
/*
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* Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
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* Licensed under the GPL
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*/
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#include "linux/config.h"
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#include "linux/sched.h"
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#include "linux/list.h"
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#include "linux/spinlock.h"
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#include "linux/slab.h"
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#include "linux/errno.h"
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#include "linux/mm.h"
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#include "asm/current.h"
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#include "asm/segment.h"
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#include "asm/mmu.h"
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#include "asm/pgalloc.h"
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#include "asm/pgtable.h"
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#include "asm/ldt.h"
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#include "os.h"
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#include "skas.h"
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extern int __syscall_stub_start;
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static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
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unsigned long kernel)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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pgd = pgd_offset(mm, proc);
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pud = pud_alloc(mm, pgd, proc);
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if (!pud)
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goto out;
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pmd = pmd_alloc(mm, pud, proc);
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if (!pmd)
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goto out_pmd;
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pte = pte_alloc_map(mm, pmd, proc);
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if (!pte)
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goto out_pte;
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/* There's an interaction between the skas0 stub pages, stack
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* randomization, and the BUG at the end of exit_mmap. exit_mmap
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* checks that the number of page tables freed is the same as had
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* been allocated. If the stack is on the last page table page,
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* then the stack pte page will be freed, and if not, it won't. To
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* avoid having to know where the stack is, or if the process mapped
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* something at the top of its address space for some other reason,
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* we set TASK_SIZE to end at the start of the last page table.
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* This keeps exit_mmap off the last page, but introduces a leak
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* of that page. So, we hang onto it here and free it in
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* destroy_context_skas.
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*/
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mm->context.skas.last_page_table = pmd_page_kernel(*pmd);
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#ifdef CONFIG_3_LEVEL_PGTABLES
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mm->context.skas.last_pmd = (unsigned long) __va(pud_val(*pud));
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#endif
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*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
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*pte = pte_mkexec(*pte);
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*pte = pte_wrprotect(*pte);
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return(0);
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out_pmd:
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pud_free(pud);
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out_pte:
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pmd_free(pmd);
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out:
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return(-ENOMEM);
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}
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int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
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{
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struct mmu_context_skas *from_mm = NULL;
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struct mmu_context_skas *to_mm = &mm->context.skas;
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unsigned long stack = 0;
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int ret = -ENOMEM;
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if(skas_needs_stub){
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stack = get_zeroed_page(GFP_KERNEL);
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if(stack == 0)
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goto out;
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/* This zeros the entry that pgd_alloc didn't, needed since
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* we are about to reinitialize it, and want mm.nr_ptes to
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* be accurate.
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*/
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mm->pgd[USER_PTRS_PER_PGD] = __pgd(0);
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ret = init_stub_pte(mm, CONFIG_STUB_CODE,
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(unsigned long) &__syscall_stub_start);
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if(ret)
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goto out_free;
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ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack);
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if(ret)
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goto out_free;
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mm->nr_ptes--;
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}
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to_mm->id.stack = stack;
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if(current->mm != NULL && current->mm != &init_mm)
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from_mm = ¤t->mm->context.skas;
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if(proc_mm){
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ret = new_mm(stack);
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if(ret < 0){
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printk("init_new_context_skas - new_mm failed, "
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"errno = %d\n", ret);
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goto out_free;
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}
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to_mm->id.u.mm_fd = ret;
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}
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else {
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if(from_mm)
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to_mm->id.u.pid = copy_context_skas0(stack,
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from_mm->id.u.pid);
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else to_mm->id.u.pid = start_userspace(stack);
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}
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ret = init_new_ldt(to_mm, from_mm);
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if(ret < 0){
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printk("init_new_context_skas - init_ldt"
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" failed, errno = %d\n", ret);
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goto out_free;
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}
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return 0;
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out_free:
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if(to_mm->id.stack != 0)
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free_page(to_mm->id.stack);
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out:
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return ret;
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}
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void destroy_context_skas(struct mm_struct *mm)
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{
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struct mmu_context_skas *mmu = &mm->context.skas;
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if(proc_mm)
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os_close_file(mmu->id.u.mm_fd);
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else
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os_kill_ptraced_process(mmu->id.u.pid, 1);
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if(!proc_mm || !ptrace_faultinfo){
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free_page(mmu->id.stack);
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pte_lock_deinit(virt_to_page(mmu->last_page_table));
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pte_free_kernel((pte_t *) mmu->last_page_table);
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dec_page_state(nr_page_table_pages);
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#ifdef CONFIG_3_LEVEL_PGTABLES
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pmd_free((pmd_t *) mmu->last_pmd);
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#endif
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}
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}
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