Merge tag 'dt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

[sfrench/cifs-2.6.git] / arch / arm / kernel / process.c

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index a35f6ebbd2c2bddecf8f5b63a04e612ad5d38c75..a0a691d1cbeee0e675e3d18674b15fc1f1224342 100644 (file)
--- 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();
 }
@@ -474,19 +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();
@@ -494,18 +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);