Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=9a4029fd3409eb224eb62c32d9792071382694ec
Commit: 9a4029fd3409eb224eb62c32d9792071382694ec
Parent: f4f97b3ea90130520afb478cbc2918be2b6587b8
Author: Jeremy Fitzhardinge <[EMAIL PROTECTED]>
AuthorDate: Tue Jul 17 18:37:05 2007 -0700
Committer: Jeremy Fitzhardinge <[EMAIL PROTECTED]>
CommitDate: Wed Jul 18 08:47:43 2007 -0700
xen: ignore RW mapping of RO pages in pagetable_init
When setting up the initial pagetable, which includes mappings of all
low physical memory, ignore a mapping which tries to set the RW bit on
an RO pte. An RO pte indicates a page which is part of the current
pagetable, and so it cannot be allowed to become RW.
Once xen_pagetable_setup_done is called, set_pte reverts to its normal
behaviour.
Signed-off-by: Jeremy Fitzhardinge <[EMAIL PROTECTED]>
Acked-by: Chris Wright <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED] (Eric W. Biederman)
---
arch/i386/xen/enlighten.c | 27 +++++++++++++++++++++++++--
1 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/arch/i386/xen/enlighten.c b/arch/i386/xen/enlighten.c
index 86e68e6..9550ae3 100644
--- a/arch/i386/xen/enlighten.c
+++ b/arch/i386/xen/enlighten.c
@@ -505,7 +505,7 @@ static void xen_write_cr3(unsigned long cr3)
/* Early in boot, while setting up the initial pagetable, assume
everything is pinned. */
-static void xen_alloc_pt_init(struct mm_struct *mm, u32 pfn)
+static __init void xen_alloc_pt_init(struct mm_struct *mm, u32 pfn)
{
BUG_ON(mem_map); /* should only be used early */
make_lowmem_page_readonly(__va(PFN_PHYS(pfn)));
@@ -557,10 +557,32 @@ static void *xen_kmap_atomic_pte(struct page *page, enum
km_type type)
}
#endif
+static __init pte_t mask_rw_pte(pte_t *ptep, pte_t pte)
+{
+ /* If there's an existing pte, then don't allow _PAGE_RW to be set */
+ if (pte_val_ma(*ptep) & _PAGE_PRESENT)
+ pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) &
+ pte_val_ma(pte));
+
+ return pte;
+}
+
+/* Init-time set_pte while constructing initial pagetables, which
+ doesn't allow RO pagetable pages to be remapped RW */
+static __init void xen_set_pte_init(pte_t *ptep, pte_t pte)
+{
+ pte = mask_rw_pte(ptep, pte);
+
+ xen_set_pte(ptep, pte);
+}
+
static __init void xen_pagetable_setup_start(pgd_t *base)
{
pgd_t *xen_pgd = (pgd_t *)xen_start_info->pt_base;
+ /* special set_pte for pagetable initialization */
+ paravirt_ops.set_pte = xen_set_pte_init;
+
init_mm.pgd = base;
/*
* copy top-level of Xen-supplied pagetable into place. For
@@ -607,6 +629,7 @@ static __init void xen_pagetable_setup_done(pgd_t *base)
/* This will work as long as patching hasn't happened yet
(which it hasn't) */
paravirt_ops.alloc_pt = xen_alloc_pt;
+ paravirt_ops.set_pte = xen_set_pte;
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
/*
@@ -745,7 +768,7 @@ static const struct paravirt_ops xen_paravirt_ops
__initdata = {
.kmap_atomic_pte = xen_kmap_atomic_pte,
#endif
- .set_pte = xen_set_pte,
+ .set_pte = NULL, /* see xen_pagetable_setup_* */
.set_pte_at = xen_set_pte_at,
.set_pmd = xen_set_pmd,
-
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
