ARM: 8154/1: use _install_special_mapping for sigpage

_install_special_mapping allows the VMA to be identifed in
/proc/pid/maps without the use of arch_vma_name, providing a
slight net reduction in object size:

  text    data     bss     dec     hex filename
  2996      96     144    3236     ca4 arch/arm/kernel/process.o (before)
  2956     104     144    3204     c84 arch/arm/kernel/process.o (after)

Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 16 insertions, 8 deletions

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 81ef686a91ca..46fbbb3701a0 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -472,19 +472,23 @@ int in_gate_area_no_mm(unsigned long addr)
 
 const char *arch_vma_name(struct vm_area_struct *vma)
 {
-        return is_gate_vma(vma) ? "[vectors]" :
-                (vma->vm_mm && vma->vm_start == vma->vm_mm->context.sigpage) ?
-                 "[sigpage]" : NULL;
+        return is_gate_vma(vma) ? "[vectors]" : NULL;
 }
 
 static struct page *signal_page;
 extern struct page *get_signal_page(void);
 
+static const struct vm_special_mapping sigpage_mapping = {
+        .name = "[sigpage]",
+        .pages = &signal_page,
+};
+
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
         struct mm_struct *mm = current->mm;
+        struct vm_area_struct *vma;
         unsigned long addr;
-        int ret;
+        int ret = 0;
 
         if (!signal_page)
                 signal_page = get_signal_page();
@@ -498,12 +502,16 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
                 goto up_fail;
         }
 
-        ret = install_special_mapping(mm, addr, PAGE_SIZE,
+        vma = _install_special_mapping(mm, addr, PAGE_SIZE,
                 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
-                &signal_page);
+                &sigpage_mapping);
+
+        if (IS_ERR(vma)) {
+                ret = PTR_ERR(vma);
+                goto up_fail;
+        }
 
-        if (ret == 0)
-                mm->context.sigpage = addr;
+        mm->context.sigpage = addr;
 
  up_fail:
         up_write(&mm->mmap_sem);