x86, pageattr: Export page unmapping interface

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>

1 files changed, 31 insertions, 13 deletions

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index b3b19f46c016..a3488689e301 100644
--- 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 *pmd)
         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, unsigned long start, unsigned long end)
          */
 }
 
+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 *cpa, unsigned long start, pgd_t *pgd,
 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 *cpa, unsigned long addr)
                         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 *cpa, unsigned long addr)
 
         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.