MIPS: Limit fixrange_init() to the FIXMAP region

fixrange_init() allocates page tables for all addresses higher than
FIXADDR_TOP.  On processors that override the default FIXADDR_TOP
address of 0xfffe_0000, this can consume up to 4 pages (1 page per 4MB)
for pgd's that are never used.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1980/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 5 insertions, 5 deletions

diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 11689e1a2924..b7ebc4fa89bc 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -277,11 +277,11 @@ void __init fixrange_init(unsigned long start, unsigned long end,
         k = __pmd_offset(vaddr);
         pgd = pgd_base + i;
 
-        for ( ; (i < PTRS_PER_PGD) && (vaddr != end); pgd++, i++) {
+        for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
                 pud = (pud_t *)pgd;
-                for ( ; (j < PTRS_PER_PUD) && (vaddr != end); pud++, j++) {
+                for ( ; (j < PTRS_PER_PUD) && (vaddr < end); pud++, j++) {
                         pmd = (pmd_t *)pud;
-                        for (; (k < PTRS_PER_PMD) && (vaddr != end); pmd++, k++) {
+                        for (; (k < PTRS_PER_PMD) && (vaddr < end); pmd++, k++) {
                                 if (pmd_none(*pmd)) {
                                         pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
                                         set_pmd(pmd, __pmd((unsigned long)pte));
diff --git a/arch/mips/mm/pgtable-32.c b/arch/mips/mm/pgtable-32.c
index 575e4019227b..adc6911ba748 100644
--- a/arch/mips/mm/pgtable-32.c
+++ b/arch/mips/mm/pgtable-32.c
@@ -52,7 +52,7 @@ void __init pagetable_init(void)
          * Fixed mappings:
          */
         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
-        fixrange_init(vaddr, 0, pgd_base);
+        fixrange_init(vaddr, vaddr + FIXADDR_SIZE, pgd_base);
 
 #ifdef CONFIG_HIGHMEM
         /*
diff --git a/arch/mips/mm/pgtable-64.c b/arch/mips/mm/pgtable-64.c
index 78eaa4f0b0ec..cda4e300eb0a 100644
--- a/arch/mips/mm/pgtable-64.c
+++ b/arch/mips/mm/pgtable-64.c
@@ -76,5 +76,5 @@ void __init pagetable_init(void)
          * Fixed mappings:
          */
         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
-        fixrange_init(vaddr, 0, pgd_base);
+        fixrange_init(vaddr, vaddr + FIXADDR_SIZE, pgd_base);
 }