1 files changed, 18 insertions, 10 deletions

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 532e7933d606..6f2a6b6deb6b 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -255,6 +255,7 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
                                    unsigned long pfn)
 {
         pgprot_t forbidden = __pgprot(0);
+        pgprot_t required = __pgprot(0);
 
         /*
          * The BIOS area between 640k and 1Mb needs to be executable for
@@ -278,6 +279,12 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
         if (within(pfn, __pa((unsigned long)__start_rodata) >> PAGE_SHIFT,
                    __pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
                 pgprot_val(forbidden) |= _PAGE_RW;
+        /*
+         * .data and .bss should always be writable.
+         */
+        if (within(address, (unsigned long)_sdata, (unsigned long)_edata) ||
+            within(address, (unsigned long)__bss_start, (unsigned long)__bss_stop))
+                pgprot_val(required) |= _PAGE_RW;
 
 #if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
         /*
@@ -317,6 +324,7 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 #endif
 
         prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
+        prot = __pgprot(pgprot_val(prot) | pgprot_val(required));
 
         return prot;
 }
@@ -393,7 +401,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
 {
         unsigned long nextpage_addr, numpages, pmask, psize, flags, addr, pfn;
         pte_t new_pte, old_pte, *tmp;
-        pgprot_t old_prot, new_prot;
+        pgprot_t old_prot, new_prot, req_prot;
         int i, do_split = 1;
         unsigned int level;
 
@@ -438,10 +446,10 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
          * We are safe now. Check whether the new pgprot is the same:
          */
         old_pte = *kpte;
-        old_prot = new_prot = pte_pgprot(old_pte);
+        old_prot = new_prot = req_prot = pte_pgprot(old_pte);
 
-        pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
-        pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);
+        pgprot_val(req_prot) &= ~pgprot_val(cpa->mask_clr);
+        pgprot_val(req_prot) |= pgprot_val(cpa->mask_set);
 
         /*
          * old_pte points to the large page base address. So we need
@@ -450,17 +458,17 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
         pfn = pte_pfn(old_pte) + ((address & (psize - 1)) >> PAGE_SHIFT);
         cpa->pfn = pfn;
 
-        new_prot = static_protections(new_prot, address, pfn);
+        new_prot = static_protections(req_prot, address, pfn);
 
         /*
          * We need to check the full range, whether
          * static_protection() requires a different pgprot for one of
          * the pages in the range we try to preserve:
          */
-        addr = address + PAGE_SIZE;
-        pfn++;
-        for (i = 1; i < cpa->numpages; i++, addr += PAGE_SIZE, pfn++) {
-                pgprot_t chk_prot = static_protections(new_prot, addr, pfn);
+        addr = address & pmask;
+        pfn = pte_pfn(old_pte);
+        for (i = 0; i < (psize >> PAGE_SHIFT); i++, addr += PAGE_SIZE, pfn++) {
+                pgprot_t chk_prot = static_protections(req_prot, addr, pfn);
 
                 if (pgprot_val(chk_prot) != pgprot_val(new_prot))
                         goto out_unlock;
@@ -483,7 +491,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
          * that we limited the number of possible pages already to
          * the number of pages in the large page.
          */
-        if (address == (nextpage_addr - psize) && cpa->numpages == numpages) {
+        if (address == (address & pmask) && cpa->numpages == (psize >> PAGE_SHIFT)) {
                 /*
                  * The address is aligned and the number of pages
                  * covers the full page.