[PATCH 2/4] x86, cpa: Map in an arbitrary pgd

Borislav Petkov
2013-06-02T12:56:08Z

From: Borislav Petkov <bp-l3A5Bk7waGM@public.gmane.org>

Add the ability to map pages in an arbitrary pgd.

Signed-off-by: Borislav Petkov <bp-l3A5Bk7waGM@public.gmane.org>
---
arch/x86/include/asm/pgtable_types.h | 3 +-
arch/x86/mm/pageattr.c | 80 ++++++++++++++++++++++++++++--------
2 files changed, 65 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index e6423002c10b..0613e147f083 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -352,7 +352,8 @@ static inline void update_page_count(int level, unsigned long pages) { }
*/
extern pte_t *lookup_address(unsigned long address, unsigned int *level);
extern phys_addr_t slow_virt_to_phys(void *__address);
-
+extern void kernel_map_pages_in_pgd(pgd_t *pgd, unsigned long address,
+ unsigned numpages, unsigned long page_flags);
#endif /* !__ASSEMBLY__ */

#endif /* _ASM_X86_PGTABLE_DEFS_H */
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index bb32480c2d71..3d64e5fc2adc 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -30,6 +30,7 @@
*/
struct cpa_data {
unsigned long *vaddr;
+ pgd_t *pgd;
pgprot_t mask_set;
pgprot_t mask_clr;
int numpages;
@@ -322,17 +323,9 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
return prot;
}

-/*
- * Lookup the page table entry for a virtual address. Return a pointer
- * to the entry and the level of the mapping.
- *
- * Note: We return pud and pmd either when the entry is marked large
- * or when the present bit is not set. Otherwise we would return a
- * pointer to a nonexisting mapping.
- */
-pte_t *lookup_address(unsigned long address, unsigned int *level)
+static pte_t *
+__lookup_address_in_pgd(pgd_t *pgd, unsigned long address, unsigned int *level)
{
- pgd_t *pgd = pgd_offset_k(address);
pud_t *pud;
pmd_t *pmd;

@@ -361,8 +354,30 @@ pte_t *lookup_address(unsigned long address, unsigned int *level)

return pte_offset_kernel(pmd, address);
}
+
+/*
+ * Lookup the page table entry for a virtual address. Return a pointer
+ * to the entry and the level of the mapping.
+ *
+ * Note: We return pud and pmd either when the entry is marked large
+ * or when the present bit is not set. Otherwise we would return a
+ * pointer to a nonexisting mapping.
+ */
+pte_t *lookup_address(unsigned long address, unsigned int *level)
+{
+ return __lookup_address_in_pgd(pgd_offset_k(address), address, level);
+}
EXPORT_SYMBOL_GPL(lookup_address);

+pte_t *_lookup_address_cpa(struct cpa_data *cpa, unsigned long address,
+ unsigned int *level)
+{
+ if (cpa->pgd)
+ return __lookup_address_in_pgd(cpa->pgd, address, level);
+
+ return lookup_address(address, level);
+}
+
/*
* This is necessary because __pa() does not work on some
* kinds of memory, like vmalloc() or the alloc_remap()
@@ -437,7 +452,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
* Check for races, another CPU might have split this page
* up already:
*/
- tmp = lookup_address(address, &level);
+ tmp = _lookup_address_cpa(cpa, address, &level);
if (tmp != kpte)
goto out_unlock;

@@ -543,7 +558,8 @@ out_unlock:
}

static int
-__split_large_page(pte_t *kpte, unsigned long address, struct page *base)
+__split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
+ struct page *base)
{
pte_t *pbase = (pte_t *)page_address(base);
unsigned long pfn, pfninc = 1;
@@ -556,7 +572,7 @@ __split_large_page(pte_t *kpte, unsigned long address, struct page *base)
* Check for races, another CPU might have split this page
* up for us already:
*/
- tmp = lookup_address(address, &level);
+ tmp = _lookup_address_cpa(cpa, address, &level);
if (tmp != kpte) {
spin_unlock(&pgd_lock);
return 1;
@@ -632,7 +648,8 @@ __split_large_page(pte_t *kpte, unsigned long address, struct page *base)
return 0;
}

-static int split_large_page(pte_t *kpte, unsigned long address)
+static int split_large_page(struct cpa_data *cpa, pte_t *kpte,
+ unsigned long address)
{
struct page *base;

@@ -644,7 +661,7 @@ static int split_large_page(pte_t *kpte, unsigned long address)
if (!base)
return -ENOMEM;

- if (__split_large_page(kpte, address, base))
+ if (__split_large_page(cpa, kpte, address, base))
__free_page(base);

return 0;
@@ -697,7 +714,10 @@ static int __change_page_attr(struct cpa_data *cpa, int primary)
else
address = *cpa->vaddr;
repeat:
- kpte = lookup_address(address, &level);
+ if (cpa->pgd)
+ kpte = __lookup_address_in_pgd(cpa->pgd, address, &level);
+ else
+ kpte = _lookup_address_cpa(cpa, address, &level);
if (!kpte)
return __cpa_process_fault(cpa, address, primary);

@@ -761,7 +781,7 @@ repeat:
/*
* We have to split the large page:
*/
- err = split_large_page(kpte, address);
+ err = split_large_page(cpa, kpte, address);
if (!err) {
/*
* Do a global flush tlb after splitting the large page
@@ -910,6 +930,8 @@ static int change_page_attr_set_clr(unsigned long *addr, int numpages,
int ret, cache, checkalias;
unsigned long baddr = 0;

+ memset(&cpa, 0, sizeof(cpa));
+
/*
* Check, if we are requested to change a not supported
* feature:
@@ -1434,6 +1456,30 @@ bool kernel_page_present(struct page *page)

#endif /* CONFIG_DEBUG_PAGEALLOC */

+void kernel_map_pages_in_pgd(pgd_t *pgd, unsigned long address,
+ unsigned numpages, unsigned long page_flags)
+{
+ struct cpa_data cpa = {
+ .vaddr = &address,
+ .pgd = pgd,
+ .numpages = numpages,
+ .mask_set = __pgprot(0),
+ .mask_clr = __pgprot(0),
+ .flags = 0
+ };
+
+ if (!(__supported_pte_mask & _PAGE_NX))
+ return;
+
+ if (!(page_flags & _PAGE_NX))
+ cpa.mask_clr = __pgprot(_PAGE_NX);
+
+ cpa.mask_set = __pgprot(_PAGE_PRESENT | page_flags);
+
+ __change_page_attr_set_clr(&cpa, 0);
+ __flush_tlb_all();
+}
+
/*
* The testcases use internal knowledge of the implementation that shouldn't
* be exposed to the rest of the kernel. Include these directly here.
--
1.8.3.rc1.25.g423ecb0