[PATCH] powerpc vdso updates

This patch cleans up some locking & error handling in the ppc vdso and
moves the vdso base pointer from the thread struct to the mm context
where it more logically belongs. It brings the powerpc implementation
closer to Ingo's new x86 one and also adds an arch_vma_name() function
allowing to print [vsdo] in /proc/<pid>/maps if Ingo's x86 vdso patch is
also applied.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 36 insertions, 21 deletions

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 573afb68d69e..bc3e15be3087 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -223,6 +223,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
         struct vm_area_struct *vma;
         unsigned long vdso_pages;
         unsigned long vdso_base;
+        int rc;
 
 #ifdef CONFIG_PPC64
         if (test_thread_flag(TIF_32BIT)) {
@@ -237,20 +238,13 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
         vdso_base = VDSO32_MBASE;
 #endif
 
-        current->thread.vdso_base = 0;
+        current->mm->context.vdso_base = 0;
 
         /* vDSO has a problem and was disabled, just don't "enable" it for the
          * process
          */
         if (vdso_pages == 0)
                 return 0;
-
-        vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
-        if (vma == NULL)
-                return -ENOMEM;
-
-        memset(vma, 0, sizeof(*vma));
-
         /* Add a page to the vdso size for the data page */
         vdso_pages ++;
 
@@ -259,17 +253,23 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
          * at vdso_base which is the "natural" base for it, but we might fail
          * and end up putting it elsewhere.
          */
+        down_write(&mm->mmap_sem);
         vdso_base = get_unmapped_area(NULL, vdso_base,
                                       vdso_pages << PAGE_SHIFT, 0, 0);
-        if (vdso_base & ~PAGE_MASK) {
-                kmem_cache_free(vm_area_cachep, vma);
-                return (int)vdso_base;
+        if (IS_ERR_VALUE(vdso_base)) {
+                rc = vdso_base;
+                goto fail_mmapsem;
         }
 
-        current->thread.vdso_base = vdso_base;
 
+        /* Allocate a VMA structure and fill it up */
+        vma = kmem_cache_zalloc(vm_area_cachep, SLAB_KERNEL);
+        if (vma == NULL) {
+                rc = -ENOMEM;
+                goto fail_mmapsem;
+        }
         vma->vm_mm = mm;
-        vma->vm_start = current->thread.vdso_base;
+        vma->vm_start = vdso_base;
         vma->vm_end = vma->vm_start + (vdso_pages << PAGE_SHIFT);
 
         /*
@@ -282,23 +282,38 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
          * 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;
+        vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC;
         vma->vm_flags |= mm->def_flags;
         vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
         vma->vm_ops = &vdso_vmops;
 
-        down_write(&mm->mmap_sem);
-        if (insert_vm_struct(mm, vma)) {
-                up_write(&mm->mmap_sem);
-                kmem_cache_free(vm_area_cachep, vma);
-                return -ENOMEM;
-        }
+        /* Insert new VMA */
+        rc = insert_vm_struct(mm, vma);
+        if (rc)
+                goto fail_vma;
+
+        /* Put vDSO base into mm struct and account for memory usage */
+        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;
+}
+
+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 void * __init find_section32(Elf32_Ehdr *ehdr, const char *secname,
                                   unsigned long *size)
 {