[PATCH 3.14 03/23] x86, pageattr: Export page unmapping interface

Greg Kroah-Hartman
2014-04-11T16:21:58Z

From: Borislav Petkov <bp@suse.de>

commit 42a5477251f0e0f33ad5f6a95c48d685ec03191e upstream.

We will use it in efi so expose it.

Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/include/asm/pgtable_types.h | 2 +
arch/x86/mm/pageattr.c | 44 ++++++++++++++++++++++++-----------
2 files changed, 33 insertions(+), 13 deletions(-)

--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -385,6 +385,8 @@ extern pte_t *lookup_address(unsigned lo
extern phys_addr_t slow_virt_to_phys(void *__address);
extern int kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,
unsigned numpages, unsigned long page_flags);
+void kernel_unmap_pages_in_pgd(pgd_t *root, unsigned long address,
+ unsigned numpages);
#endif /* !__ASSEMBLY__ */

#endif /* _ASM_X86_PGTABLE_DEFS_H */
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -692,6 +692,18 @@ static bool try_to_free_pmd_page(pmd_t *
return true;
}

+static bool try_to_free_pud_page(pud_t *pud)
+{
+ int i;
+
+ for (i = 0; i < PTRS_PER_PUD; i++)
+ if (!pud_none(pud[i]))
+ return false;
+
+ free_page((unsigned long)pud);
+ return true;
+}
+
static bool unmap_pte_range(pmd_t *pmd, unsigned long start, unsigned long end)
{
pte_t *pte = pte_offset_kernel(pmd, start);
@@ -805,6 +817,16 @@ static void unmap_pud_range(pgd_t *pgd,
*/
}

+static void unmap_pgd_range(pgd_t *root, unsigned long addr, unsigned long end)
+{
+ pgd_t *pgd_entry = root + pgd_index(addr);
+
+ unmap_pud_range(pgd_entry, addr, end);
+
+ if (try_to_free_pud_page((pud_t *)pgd_page_vaddr(*pgd_entry)))
+ pgd_clear(pgd_entry);
+}
+
static int alloc_pte_page(pmd_t *pmd)
{
pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL | __GFP_NOTRACK);
@@ -999,9 +1021,8 @@ static int populate_pud(struct cpa_data
static int populate_pgd(struct cpa_data *cpa, unsigned long addr)
{
pgprot_t pgprot = __pgprot(_KERNPG_TABLE);
- bool allocd_pgd = false;
- pgd_t *pgd_entry;
pud_t *pud = NULL; /* shut up gcc */
+ pgd_t *pgd_entry;
int ret;

pgd_entry = cpa->pgd + pgd_index(addr);
@@ -1015,7 +1036,6 @@ static int populate_pgd(struct cpa_data
return -1;

set_pgd(pgd_entry, __pgd(__pa(pud) | _KERNPG_TABLE));
- allocd_pgd = true;
}

pgprot_val(pgprot) &= ~pgprot_val(cpa->mask_clr);
@@ -1023,19 +1043,11 @@ static int populate_pgd(struct cpa_data

ret = populate_pud(cpa, addr, pgd_entry, pgprot);
if (ret < 0) {
- unmap_pud_range(pgd_entry, addr,
+ unmap_pgd_range(cpa->pgd, addr,
addr + (cpa->numpages << PAGE_SHIFT));
-
- if (allocd_pgd) {
- /*
- * If I allocated this PUD page, I can just as well
- * free it in this error path.
- */
- pgd_clear(pgd_entry);
- free_page((unsigned long)pud);
- }
return ret;
}
+
cpa->numpages = ret;
return 0;
}
@@ -1861,6 +1873,12 @@ out:
return retval;
}

+void kernel_unmap_pages_in_pgd(pgd_t *root, unsigned long address,
+ unsigned numpages)
+{
+ unmap_pgd_range(root, address, address + (numpages << PAGE_SHIFT));
+}
+
/*
* The testcases use internal knowledge of the implementation that shouldn't
* be exposed to the rest of the kernel. Include these directly here.