[PATCH] x86_64 ia32 vDSO: use install_special_mapping

This patch uses install_special_mapping for the ia32 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>

2 files changed, 13 insertions, 47 deletions

diff --git a/arch/x86_64/ia32/syscall32.c b/arch/x86_64/ia32/syscall32.c
index 59f1fa155915..568ff0df89e7 100644
--- a/arch/x86_64/ia32/syscall32.c
+++ b/arch/x86_64/ia32/syscall32.c
@@ -18,68 +18,34 @@ extern unsigned char syscall32_syscall[], syscall32_syscall_end[];
 extern unsigned char syscall32_sysenter[], syscall32_sysenter_end[];
 extern int sysctl_vsyscall32;
 
-char *syscall32_page; 
+static struct page *syscall32_pages[1];
 static int use_sysenter = -1;
 
-static struct page *
-syscall32_nopage(struct vm_area_struct *vma, unsigned long adr, int *type)
-{
-        struct page *p = virt_to_page(adr - vma->vm_start + syscall32_page);
-        get_page(p);
-        return p;
-}
-
-/* Prevent VMA merging */
-static void syscall32_vma_close(struct vm_area_struct *vma)
-{
-}
-
-static struct vm_operations_struct syscall32_vm_ops = {
-        .close = syscall32_vma_close,
-        .nopage = syscall32_nopage,
-};
-
 struct linux_binprm;
 
 /* Setup a VMA at program startup for the vsyscall page */
 int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
 {
-        int npages = (VSYSCALL32_END - VSYSCALL32_BASE) >> PAGE_SHIFT;
-        struct vm_area_struct *vma;
         struct mm_struct *mm = current->mm;
         int ret;
 
-        vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
-        if (!vma)
-                return -ENOMEM;
-
-        memset(vma, 0, sizeof(struct vm_area_struct));
-        /* Could randomize here */
-        vma->vm_start = VSYSCALL32_BASE;
-        vma->vm_end = VSYSCALL32_END;
-        /* MAYWRITE to allow gdb to COW and set breakpoints */
-        vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYWRITE;
+        down_write(&mm->mmap_sem);
         /*
+         * MAYWRITE to allow gdb to COW and set breakpoints
+         *
          * 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 & 7];
-        vma->vm_ops = &syscall32_vm_ops;
-        vma->vm_mm = mm;
-
-        down_write(&mm->mmap_sem);
-        if ((ret = insert_vm_struct(mm, vma))) {
-                up_write(&mm->mmap_sem);
-                kmem_cache_free(vm_area_cachep, vma);
-                return ret;
-        }
-        mm->total_vm += npages;
+        /* Could randomize here */
+        ret = install_special_mapping(mm, VSYSCALL32_BASE, PAGE_SIZE,
+                                      VM_READ|VM_EXEC|
+                                      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
+                                      VM_ALWAYSDUMP,
+                                      syscall32_pages);
         up_write(&mm->mmap_sem);
-        return 0;
+        return ret;
 }
 
 const char *arch_vma_name(struct vm_area_struct *vma)
@@ -92,9 +58,10 @@ const char *arch_vma_name(struct vm_area_struct *vma)
 
 static int __init init_syscall32(void)
 { 
-        syscall32_page = (void *)get_zeroed_page(GFP_KERNEL); 
+        char *syscall32_page = (void *)get_zeroed_page(GFP_KERNEL);
         if (!syscall32_page) 
                 panic("Cannot allocate syscall32 page"); 
+        syscall32_pages[0] = virt_to_page(syscall32_page);
         if (use_sysenter > 0) {
                 memcpy(syscall32_page, syscall32_sysenter,
                        syscall32_sysenter_end - syscall32_sysenter);
diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h
index 6d324b838972..a6d2ff5c69b7 100644
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -81,7 +81,6 @@ extern void swap_low_mappings(void);
 extern void __show_regs(struct pt_regs * regs);
 extern void show_regs(struct pt_regs * regs);
 
-extern char *syscall32_page;
 extern void syscall32_cpu_init(void);
 
 extern void setup_node_bootmem(int nodeid, unsigned long start, unsigned long end);