2 * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
3 * Licensed under the GPL
6 #include "linux/config.h"
7 #include "linux/sched.h"
8 #include "linux/list.h"
9 #include "linux/spinlock.h"
10 #include "linux/slab.h"
11 #include "linux/errno.h"
13 #include "asm/current.h"
14 #include "asm/segment.h"
16 #include "asm/pgalloc.h"
17 #include "asm/pgtable.h"
21 extern int __syscall_stub_start
;
23 static int init_stub_pte(struct mm_struct
*mm
, unsigned long proc
,
31 pgd
= pgd_offset(mm
, proc
);
32 pud
= pud_alloc(mm
, pgd
, proc
);
36 pmd
= pmd_alloc(mm
, pud
, proc
);
40 pte
= pte_alloc_map(mm
, pmd
, proc
);
44 /* There's an interaction between the skas0 stub pages, stack
45 * randomization, and the BUG at the end of exit_mmap. exit_mmap
46 * checks that the number of page tables freed is the same as had
47 * been allocated. If the stack is on the last page table page,
48 * then the stack pte page will be freed, and if not, it won't. To
49 * avoid having to know where the stack is, or if the process mapped
50 * something at the top of its address space for some other reason,
51 * we set TASK_SIZE to end at the start of the last page table.
52 * This keeps exit_mmap off the last page, but introduces a leak
53 * of that page. So, we hang onto it here and free it in
54 * destroy_context_skas.
57 mm
->context
.skas
.last_page_table
= pmd_page_kernel(*pmd
);
58 #ifdef CONFIG_3_LEVEL_PGTABLES
59 mm
->context
.skas
.last_pmd
= (unsigned long) __va(pud_val(*pud
));
62 *pte
= mk_pte(virt_to_page(kernel
), __pgprot(_PAGE_PRESENT
));
63 *pte
= pte_mkexec(*pte
);
64 *pte
= pte_wrprotect(*pte
);
75 int init_new_context_skas(struct task_struct
*task
, struct mm_struct
*mm
)
77 struct mm_struct
*cur_mm
= current
->mm
;
78 struct mm_id
*cur_mm_id
= &cur_mm
->context
.skas
.id
;
79 struct mm_id
*mm_id
= &mm
->context
.skas
.id
;
80 unsigned long stack
= 0;
81 int from
, ret
= -ENOMEM
;
83 if(!proc_mm
|| !ptrace_faultinfo
){
84 stack
= get_zeroed_page(GFP_KERNEL
);
88 /* This zeros the entry that pgd_alloc didn't, needed since
89 * we are about to reinitialize it, and want mm.nr_ptes to
92 mm
->pgd
[USER_PTRS_PER_PGD
] = __pgd(0);
94 ret
= init_stub_pte(mm
, CONFIG_STUB_CODE
,
95 (unsigned long) &__syscall_stub_start
);
99 ret
= init_stub_pte(mm
, CONFIG_STUB_DATA
, stack
);
105 mm_id
->stack
= stack
;
108 if((cur_mm
!= NULL
) && (cur_mm
!= &init_mm
))
109 from
= cur_mm_id
->u
.mm_fd
;
112 ret
= new_mm(from
, stack
);
114 printk("init_new_context_skas - new_mm failed, "
115 "errno = %d\n", ret
);
118 mm_id
->u
.mm_fd
= ret
;
121 if((cur_mm
!= NULL
) && (cur_mm
!= &init_mm
))
122 mm_id
->u
.pid
= copy_context_skas0(stack
,
124 else mm_id
->u
.pid
= start_userspace(stack
);
130 if(mm_id
->stack
!= 0)
131 free_page(mm_id
->stack
);
136 void destroy_context_skas(struct mm_struct
*mm
)
138 struct mmu_context_skas
*mmu
= &mm
->context
.skas
;
141 os_close_file(mmu
->id
.u
.mm_fd
);
143 os_kill_ptraced_process(mmu
->id
.u
.pid
, 1);
145 if(!proc_mm
|| !ptrace_faultinfo
){
146 free_page(mmu
->id
.stack
);
147 pte_lock_deinit(virt_to_page(mmu
->last_page_table
));
148 pte_free_kernel((pte_t
*) mmu
->last_page_table
);
149 dec_page_state(nr_page_table_pages
);
150 #ifdef CONFIG_3_LEVEL_PGTABLES
151 pmd_free((pmd_t
*) mmu
->last_pmd
);
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