ARM: fix booting low-vectors machines

commit d8aa712c30148ba26fd89a5dc14de95d4c375184 upstream.

Commit f6f91b0d9fd9 (ARM: allow kuser helpers to be removed from the
vector page) required two pages for the vectors code.  Although the
code setting up the initial page tables was updated, the code which
allocates page tables for new processes wasn't, neither was the code
which tears down the mappings.  Fix this.

Fixes: f6f91b0d9fd9 ("ARM: allow kuser helpers to be removed from the vector page")
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 4 insertions, 3 deletions

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 9bcd262a9008..5aac06fcc97e 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -58,7 +58,7 @@ extern void __pgd_error(const char *file, int line, pgd_t);
  * mapping to be mapped at.  This is particularly important for
  * non-high vector CPUs.
  */
-#define FIRST_USER_ADDRESS      PAGE_SIZE
+#define FIRST_USER_ADDRESS      (PAGE_SIZE * 2)
 
 /*
  * Use TASK_SIZE as the ceiling argument for free_pgtables() and
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 10062ceadd1c..f0ef2f7d4ad7 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -146,7 +146,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 
         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
         info.length = len;
-        info.low_limit = PAGE_SIZE;
+        info.low_limit = FIRST_USER_ADDRESS;
         info.high_limit = mm->mmap_base;
         info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
         info.align_offset = pgoff << PAGE_SHIFT;
diff --git a/arch/arm/mm/pgd.c b/arch/arm/mm/pgd.c
index 0acb089d0f70..1046b373d1ae 100644
--- a/arch/arm/mm/pgd.c
+++ b/arch/arm/mm/pgd.c
@@ -87,7 +87,8 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
                 init_pud = pud_offset(init_pgd, 0);
                 init_pmd = pmd_offset(init_pud, 0);
                 init_pte = pte_offset_map(init_pmd, 0);
-                set_pte_ext(new_pte, *init_pte, 0);
+                set_pte_ext(new_pte + 0, init_pte[0], 0);
+                set_pte_ext(new_pte + 1, init_pte[1], 0);
                 pte_unmap(init_pte);
                 pte_unmap(new_pte);
         }