s390/vdso: use _install_special_mapping to establish vdso

Switch to the improved _install_special_mapping function to install
the vdso mapping. This has two advantages, the arch_vma_name function
is not needed anymore and the vdso vma still has its name after its
memory location has been changed with mremap.

Tested-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 10516ae..b89d19f 100644 (file)
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -50,6 +50,56 @@ static struct page **vdso64_pagelist;
  */
 unsigned int __read_mostly vdso_enabled = 1;
 
+static int vdso_fault(const struct vm_special_mapping *sm,
+                     struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+       struct page **vdso_pagelist;
+       unsigned long vdso_pages;
+
+       vdso_pagelist = vdso64_pagelist;
+       vdso_pages = vdso64_pages;
+#ifdef CONFIG_COMPAT
+       if (is_compat_task()) {
+               vdso_pagelist = vdso32_pagelist;
+               vdso_pages = vdso32_pages;
+       }
+#endif
+
+       if (vmf->pgoff >= vdso_pages)
+               return VM_FAULT_SIGBUS;
+
+       vmf->page = vdso_pagelist[vmf->pgoff];
+       get_page(vmf->page);
+       return 0;
+}
+
+static int vdso_mremap(const struct vm_special_mapping *sm,
+                      struct vm_area_struct *vma)
+{
+       unsigned long vdso_pages;
+
+       vdso_pages = vdso64_pages;
+#ifdef CONFIG_COMPAT
+       if (is_compat_task())
+               vdso_pages = vdso32_pages;
+#endif
+
+       if ((vdso_pages << PAGE_SHIFT) != vma->vm_end - vma->vm_start)
+               return -EINVAL;
+
+       if (WARN_ON_ONCE(current->mm != vma->vm_mm))
+               return -EFAULT;
+
+       current->mm->context.vdso_base = vma->vm_start;
+       return 0;
+}
+
+static const struct vm_special_mapping vdso_mapping = {
+       .name = "[vdso]",
+       .fault = vdso_fault,
+       .mremap = vdso_mremap,
+};
+
 static int __init vdso_setup(char *s)
 {
        unsigned long val;
@@ -181,7 +231,7 @@ static void vdso_init_cr5(void)
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
        struct mm_struct *mm = current->mm;
-       struct page **vdso_pagelist;
+       struct vm_area_struct *vma;
        unsigned long vdso_pages;
        unsigned long vdso_base;
        int rc;
@@ -194,13 +244,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
        if (!uses_interp)
                return 0;
 
-       vdso_pagelist = vdso64_pagelist;
        vdso_pages = vdso64_pages;
 #ifdef CONFIG_COMPAT
-       if (is_compat_task()) {
-               vdso_pagelist = vdso32_pagelist;
+       if (is_compat_task())
                vdso_pages = vdso32_pages;
-       }
 #endif
        /*
         * vDSO has a problem and was disabled, just don't "enable" it for
@@ -209,8 +256,6 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
        if (vdso_pages == 0)
                return 0;
 
-       current->mm->context.vdso_base = 0;
-
        /*
         * pick a base address for the vDSO in process space. We try to put
         * it at vdso_base which is the "natural" base for it, but we might
@@ -225,13 +270,6 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
        }
 
        /*
-        * Put vDSO base into mm struct. We need to do this before calling
-        * install_special_mapping or the perf counter mmap tracking code
-        * will fail to recognise it as a vDSO (since arch_vma_name fails).
-        */
-       current->mm->context.vdso_base = vdso_base;
-
-       /*
         * our vma flags don't have VM_WRITE so by default, the process
         * isn't allowed to write those pages.
         * gdb can break that with ptrace interface, and thus trigger COW
@@ -241,24 +279,23 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
         * It's fine to use that for setting breakpoints in the vDSO code
         * pages though.
         */
-       rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
-                                    VM_READ|VM_EXEC|
-                                    VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
-                                    vdso_pagelist);
-       if (rc)
-               current->mm->context.vdso_base = 0;
+       vma = _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
+                                      VM_READ|VM_EXEC|
+                                      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+                                      &vdso_mapping);
+       if (IS_ERR(vma)) {
+               rc = PTR_ERR(vma);
+               goto out_up;
+       }
+
+       current->mm->context.vdso_base = vdso_base;
+       rc = 0;
+
 out_up:
        up_write(&mm->mmap_sem);
        return rc;
 }
 
-const char *arch_vma_name(struct vm_area_struct *vma)
-{
-       if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)
-               return "[vdso]";
-       return NULL;
-}
-
 static int __init vdso_init(void)
 {
        int i;