[PATCH] freepgt: arm26 FIRST_USER_ADDRESS PAGE_SIZE

ARM26 define FIRST_USER_ADDRESS as PAGE_SIZE (beyond the machine vectors when
they are mapped low), and use that definition in place of locally defined
MIN_MAP_ADDR.  Previously, ARM26 permitted user mappings at 0 if the machine
vectors were mapped high; but that's inconsistent with ARM, and
FIRST_USER_ADDRESS would then have to be determined at runtime.  Let's fix it
at PAGE_SIZE throughout the architecture.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 11 insertions, 5 deletions

diff --git a/arch/arm26/kernel/sys_arm.c b/arch/arm26/kernel/sys_arm.c
index e7edd201579a..85457897b8a9 100644
--- a/arch/arm26/kernel/sys_arm.c
+++ b/arch/arm26/kernel/sys_arm.c
@@ -64,10 +64,10 @@ inline long do_mmap2(
         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
 
         /*
-         * If we are doing a fixed mapping, and address < PAGE_SIZE,
+         * If we are doing a fixed mapping, and address < FIRST_USER_ADDRESS,
          * then deny it.
          */
-        if (flags & MAP_FIXED && addr < PAGE_SIZE && vectors_base() == 0)
+        if (flags & MAP_FIXED && addr < FIRST_USER_ADDRESS)
                 goto out;
 
         error = -EBADF;
@@ -121,11 +121,10 @@ sys_arm_mremap(unsigned long addr, unsigned long old_len,
         unsigned long ret = -EINVAL;
 
         /*
-         * If we are doing a fixed mapping, and address < PAGE_SIZE,
+         * If we are doing a fixed mapping, and address < FIRST_USER_ADDRESS,
          * then deny it.
          */
-        if (flags & MREMAP_FIXED && new_addr < PAGE_SIZE &&
-            vectors_base() == 0)
+        if (flags & MREMAP_FIXED && new_addr < FIRST_USER_ADDRESS)
                 goto out;
 
         down_write(&current->mm->mmap_sem);
diff --git a/include/asm-arm26/pgtable.h b/include/asm-arm26/pgtable.h
index af0b8907dc14..4a0a00da425f 100644
--- a/include/asm-arm26/pgtable.h
+++ b/include/asm-arm26/pgtable.h
@@ -62,6 +62,13 @@
 #define PTRS_PER_PMD            1
 #define PTRS_PER_PTE            32
 
+/*
+ * This is the lowest virtual address we can permit any user space
+ * mapping to be mapped at.  This is particularly important for
+ * non-high vector CPUs.
+ */
+#define FIRST_USER_ADDRESS      PAGE_SIZE
+
 #define FIRST_USER_PGD_NR       1
 #define USER_PTRS_PER_PGD       ((TASK_SIZE/PGD_SIZE) - FIRST_USER_PGD_NR)