[PATCH] powerpc vDSO: use install_special_mapping

This patch uses install_special_mapping for the powerpc vDSO setup,
consolidating duplicated code.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 27 insertions, 77 deletions

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index ae0ede19879d..50149ec6efa4 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -49,9 +49,13 @@
 /* Max supported size for symbol names */
 #define MAX_SYMNAME     64
 
+#define VDSO32_MAXPAGES (((0x3000 + PAGE_MASK) >> PAGE_SHIFT) + 2)
+#define VDSO64_MAXPAGES (((0x3000 + PAGE_MASK) >> PAGE_SHIFT) + 2)
+
 extern char vdso32_start, vdso32_end;
 static void *vdso32_kbase = &vdso32_start;
 unsigned int vdso32_pages;
+static struct page *vdso32_pagelist[VDSO32_MAXPAGES];
 unsigned long vdso32_sigtramp;
 unsigned long vdso32_rt_sigtramp;
 
@@ -59,6 +63,7 @@ unsigned long vdso32_rt_sigtramp;
 extern char vdso64_start, vdso64_end;
 static void *vdso64_kbase = &vdso64_start;
 unsigned int vdso64_pages;
+static struct page *vdso64_pagelist[VDSO64_MAXPAGES];
 unsigned long vdso64_rt_sigtramp;
 #endif /* CONFIG_PPC64 */
 
@@ -165,55 +170,6 @@ static void dump_vdso_pages(struct vm_area_struct * vma)
 #endif /* DEBUG */
 
 /*
- * Keep a dummy vma_close for now, it will prevent VMA merging.
- */
-static void vdso_vma_close(struct vm_area_struct * vma)
-{
-}
-
-/*
- * Our nopage() function, maps in the actual vDSO kernel pages, they will
- * be mapped read-only by do_no_page(), and eventually COW'ed, either
- * right away for an initial write access, or by do_wp_page().
- */
-static struct page * vdso_vma_nopage(struct vm_area_struct * vma,
-                                     unsigned long address, int *type)
-{
-        unsigned long offset = address - vma->vm_start;
-        struct page *pg;
-#ifdef CONFIG_PPC64
-        void *vbase = (vma->vm_mm->task_size > TASK_SIZE_USER32) ?
-                vdso64_kbase : vdso32_kbase;
-#else
-        void *vbase = vdso32_kbase;
-#endif
-
-        DBG("vdso_vma_nopage(current: %s, address: %016lx, off: %lx)\n",
-            current->comm, address, offset);
-
-        if (address < vma->vm_start || address > vma->vm_end)
-                return NOPAGE_SIGBUS;
-
-        /*
-         * Last page is systemcfg.
-         */
-        if ((vma->vm_end - address) <= PAGE_SIZE)
-                pg = virt_to_page(vdso_data);
-        else
-                pg = virt_to_page(vbase + offset);
-
-        get_page(pg);
-        DBG(" ->page count: %d\n", page_count(pg));
-
-        return pg;
-}
-
-static struct vm_operations_struct vdso_vmops = {
-        .close  = vdso_vma_close,
-        .nopage = vdso_vma_nopage,
-};
-
-/*
  * This is called from binfmt_elf, we create the special vma for the
  * vDSO and insert it into the mm struct tree
  */
@@ -221,20 +177,23 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
                                 int executable_stack)
 {
         struct mm_struct *mm = current->mm;
-        struct vm_area_struct *vma;
+        struct page **vdso_pagelist;
         unsigned long vdso_pages;
         unsigned long vdso_base;
         int rc;
 
 #ifdef CONFIG_PPC64
         if (test_thread_flag(TIF_32BIT)) {
+                vdso_pagelist = vdso32_pagelist;
                 vdso_pages = vdso32_pages;
                 vdso_base = VDSO32_MBASE;
         } else {
+                vdso_pagelist = vdso64_pagelist;
                 vdso_pages = vdso64_pages;
                 vdso_base = VDSO64_MBASE;
         }
 #else
+        vdso_pagelist = vdso32_pagelist;
         vdso_pages = vdso32_pages;
         vdso_base = VDSO32_MBASE;
 #endif
@@ -262,17 +221,6 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
                 goto fail_mmapsem;
         }
 
-
-        /* Allocate a VMA structure and fill it up */
-        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
-        if (vma == NULL) {
-                rc = -ENOMEM;
-                goto fail_mmapsem;
-        }
-        vma->vm_mm = mm;
-        vma->vm_start = vdso_base;
-        vma->vm_end = vma->vm_start + (vdso_pages << PAGE_SHIFT);
-
         /*
          * our vma flags don't have VM_WRITE so by default, the process isn't
          * allowed to write those pages.
@@ -282,32 +230,26 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
          * and your nice userland gettimeofday will be totally dead.
          * It's fine to use that for setting breakpoints in the vDSO code
          * pages though
-         */
-        vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC;
-        /*
+         *
          * Make sure the vDSO gets into every core dump.
          * Dumping its contents makes post-mortem fully interpretable later
          * without matching up the same kernel and hardware config to see
          * what PC values meant.
          */
-        vma->vm_flags |= VM_ALWAYSDUMP;
-        vma->vm_flags |= mm->def_flags;
-        vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
-        vma->vm_ops = &vdso_vmops;
-
-        /* Insert new VMA */
-        rc = insert_vm_struct(mm, vma);
+        rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
+                                     VM_READ|VM_EXEC|
+                                     VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
+                                     VM_ALWAYSDUMP,
+                                     vdso_pagelist);
         if (rc)
-                goto fail_vma;
+                goto fail_mmapsem;
 
-        /* Put vDSO base into mm struct and account for memory usage */
+        /* Put vDSO base into mm struct */
         current->mm->context.vdso_base = vdso_base;
-        mm->total_vm += (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+
         up_write(&mm->mmap_sem);
         return 0;
 
- fail_vma:
-        kmem_cache_free(vm_area_cachep, vma);
  fail_mmapsem:
         up_write(&mm->mmap_sem);
         return rc;
@@ -778,18 +720,26 @@ void __init vdso_init(void)
         }
 
         /* Make sure pages are in the correct state */
+        BUG_ON(vdso32_pages + 2 > VDSO32_MAXPAGES);
         for (i = 0; i < vdso32_pages; i++) {
                 struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
                 ClearPageReserved(pg);
                 get_page(pg);
-
+                vdso32_pagelist[i] = pg;
         }
+        vdso32_pagelist[i++] = virt_to_page(vdso_data);
+        vdso32_pagelist[i] = NULL;
+
 #ifdef CONFIG_PPC64
+        BUG_ON(vdso64_pages + 2 > VDSO64_MAXPAGES);
         for (i = 0; i < vdso64_pages; i++) {
                 struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
                 ClearPageReserved(pg);
                 get_page(pg);
+                vdso64_pagelist[i] = pg;
         }
+        vdso64_pagelist[i++] = virt_to_page(vdso_data);
+        vdso64_pagelist[i] = NULL;
 #endif /* CONFIG_PPC64 */
 
         get_page(virt_to_page(vdso_data));