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    Contents of /trunk/kernel26-xen/patches-2.6.25-r1/1069-2.6.25-xen-Try-to-make-pagetables-read-only.patch

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    Revision 606 - (show annotations) (download)
    Thu May 22 23:13:13 2008 UTC (16 years ago) by niro
    File size: 3534 byte(s) 
    -ver bump to 2.6.25-magellan-r1:
- linux-2.6.25.4
- fbcondecor-0.9.4
- squashfs-3.3
- unionfs-2.3.3
- tuxonice-3.0-rc7
- linux-phc-0.3.0
- acpi-dstd-0.9a
- reiser4
- xen-3.2.0
. ipw3945-1.2.2
    1 From 856b9dd6237a7f7dacd949c8f0f50ec21fbf7368 Mon Sep 17 00:00:00 2001
    2 From: Eduardo Habkost <ehabkost@redhat.com>
    3 Date: Tue, 18 Dec 2007 10:21:45 -0200
    4 Subject: [PATCH] Try to make pagetables read-only
    5
    6 Not working yet. :(
    7
    8 Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
    9 ---
    10 arch/x86/mm/init_64.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++
    11 1 files changed, 81 insertions(+), 0 deletions(-)
    12
    13 diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
    14 index a6f2051..cf1453b 100644
    15 --- a/arch/x86/mm/init_64.c
    16 +++ b/arch/x86/mm/init_64.c
    17 @@ -70,6 +70,85 @@ static unsigned long dma_reserve __initdata;
    18
    19 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
    20
    21 +#ifdef CONFIG_XEN
    22 +
    23 +static void __make_page_readonly(void *va)
    24 +{
    25 + pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t pte, *ptep;
    26 + unsigned long addr = (unsigned long) va;
    27 +
    28 + xprintk("%s(%p)\n", __func__, va);
    29 +
    30 + pgd = pgd_offset_k(addr);
    31 + pud = pud_offset(pgd, addr);
    32 + pmd = pmd_offset(pud, addr);
    33 + ptep = pte_offset_kernel(pmd, addr);
    34 +
    35 + pte.pte = ptep->pte & ~_PAGE_RW;
    36 + xprintk("update_va_mapping: %lx, %lx\n", addr, pte);
    37 +
    38 + if (HYPERVISOR_update_va_mapping(addr, pte, 0))
    39 + BUG(); //xen_l1_entry_update(ptep, pte); /* fallback */
    40 +
    41 + if ((addr >= VMALLOC_START) && (addr < VMALLOC_END))
    42 + __make_page_readonly(__va(pte_pfn(pte) << PAGE_SHIFT));
    43 +}
    44 +
    45 +static void __make_page_writable(void *va)
    46 +{
    47 + pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t pte, *ptep;
    48 + unsigned long addr = (unsigned long) va;
    49 +
    50 + pgd = pgd_offset_k(addr);
    51 + pud = pud_offset(pgd, addr);
    52 + pmd = pmd_offset(pud, addr);
    53 + ptep = pte_offset_kernel(pmd, addr);
    54 +
    55 + pte.pte = ptep->pte | _PAGE_RW;
    56 + if (HYPERVISOR_update_va_mapping(addr, pte, 0))
    57 + BUG();//xen_l1_entry_update(ptep, pte); /* fallback */
    58 +
    59 + if ((addr >= VMALLOC_START) && (addr < VMALLOC_END))
    60 + __make_page_writable(__va(pte_pfn(pte) << PAGE_SHIFT));
    61 +}
    62 +
    63 +void make_page_readonly(void *va, unsigned int feature)
    64 +{
    65 + if (!xen_feature(feature))
    66 + __make_page_readonly(va);
    67 +}
    68 +
    69 +void make_page_writable(void *va, unsigned int feature)
    70 +{
    71 + if (!xen_feature(feature))
    72 + __make_page_writable(va);
    73 +}
    74 +
    75 +void make_pages_readonly(void *va, unsigned nr, unsigned int feature)
    76 +{
    77 + if (xen_feature(feature))
    78 + return;
    79 +
    80 + while (nr-- != 0) {
    81 + __make_page_readonly(va);
    82 + va = (void*)((unsigned long)va + PAGE_SIZE);
    83 + }
    84 +}
    85 +
    86 +void make_pages_writable(void *va, unsigned nr, unsigned int feature)
    87 +{
    88 + if (xen_feature(feature))
    89 + return;
    90 +
    91 + while (nr-- != 0) {
    92 + __make_page_writable(va);
    93 + va = (void*)((unsigned long)va + PAGE_SIZE);
    94 + }
    95 +}
    96 +
    97 +
    98 +#endif
    99 +
    100 /*
    101 * NOTE: pagetable_init alloc all the fixmap pagetables contiguous on the
    102 * physical space so we can cache the place of the first one and move
    103 @@ -150,6 +229,7 @@ set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t pteval)
    104 pud = pud_page + pud_index(vaddr);
    105 if (pud_none(*pud)) {
    106 pmd = (pmd_t *) spp_getpage();
    107 + make_page_readonly(pmd, XENFEAT_writable_page_tables);
    108 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE | _PAGE_USER));
    109 if (pmd != pmd_offset(pud, 0)) {
    110 printk(KERN_ERR "PAGETABLE BUG #01! %p <-> %p\n",
    111 @@ -160,6 +240,7 @@ set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t pteval)
    112 pmd = pmd_offset(pud, vaddr);
    113 if (pmd_none(*pmd)) {
    114 pte = (pte_t *) spp_getpage();
    115 + make_page_readonly(pte, XENFEAT_writable_page_tables);
    116 set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE | _PAGE_USER));
    117 if (pte != pte_offset_kernel(pmd, 0)) {
    118 printk(KERN_ERR "PAGETABLE BUG #02!\n");
    119 --
    120 1.5.4.1
    121