1 files changed, 54 insertions, 10 deletions

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 81ef686a91ca..a0a691d1cbee 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -306,7 +306,6 @@ void __show_regs(struct pt_regs *regs)
 
 void show_regs(struct pt_regs * regs)
 {
-        printk("\n");
         __show_regs(regs);
         dump_stack();
 }
@@ -334,6 +333,8 @@ void flush_thread(void)
         memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
         memset(&thread->fpstate, 0, sizeof(union fp_state));
 
+        flush_tls();
+
         thread_notify(THREAD_NOTIFY_FLUSH, thread);
 }
 
@@ -472,19 +473,57 @@ 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;
+}
+
+/* If possible, provide a placement hint at a random offset from the
+ * stack for the signal page.
+ */
+static unsigned long sigpage_addr(const struct mm_struct *mm,
+                                  unsigned int npages)
+{
+        unsigned long offset;
+        unsigned long first;
+        unsigned long last;
+        unsigned long addr;
+        unsigned int slots;
+
+        first = PAGE_ALIGN(mm->start_stack);
+
+        last = TASK_SIZE - (npages << PAGE_SHIFT);
+
+        /* No room after stack? */
+        if (first > last)
+                return 0;
+
+        /* Just enough room? */
+        if (first == last)
+                return first;
+
+        slots = ((last - first) >> PAGE_SHIFT) + 1;
+
+        offset = get_random_int() % slots;
+
+        addr = first + (offset << PAGE_SHIFT);
+
+        return addr;
 }
 
 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;
+        unsigned long hint;
+        int ret = 0;
 
         if (!signal_page)
                 signal_page = get_signal_page();
@@ -492,18 +531,23 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
                 return -ENOMEM;
 
         down_write(&mm->mmap_sem);
-        addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
+        hint = sigpage_addr(mm, 1);
+        addr = get_unmapped_area(NULL, hint, PAGE_SIZE, 0, 0);
         if (IS_ERR_VALUE(addr)) {
                 ret = addr;
                 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);