x86-64, vdso: Do not allocate memory for the vDSO

We can map the vDSO straight from kernel data, saving a few page
allocations.  As an added bonus, the deleted code contained a memory
leak.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/2c4ed5c2c2e93603790229e0c3403ae506ccc0cb.1311277573.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

2 files changed, 19 insertions, 21 deletions

diff --git a/arch/x86/vdso/vdso.S b/arch/x86/vdso/vdso.S
index 1d3aa6b87181..1b979c12ba85 100644
--- a/arch/x86/vdso/vdso.S
+++ b/arch/x86/vdso/vdso.S
@@ -1,10 +1,21 @@
+#include <asm/page_types.h>
+#include <linux/linkage.h>
 #include <linux/init.h>
 
-__INITDATA
+__PAGE_ALIGNED_DATA
 
         .globl vdso_start, vdso_end
+        .align PAGE_SIZE
 vdso_start:
         .incbin "arch/x86/vdso/vdso.so"
 vdso_end:
 
-__FINIT
+.previous
+
+        .globl vdso_pages
+        .bss
+        .align 8
+        .type vdso_pages, @object
+vdso_pages:
+        .zero (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE * 8
+        .size vdso_pages, .-vdso_pages
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index c39938d1332f..316fbca3490e 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -14,13 +14,14 @@
 #include <asm/vgtod.h>
 #include <asm/proto.h>
 #include <asm/vdso.h>
+#include <asm/page.h>
 
 unsigned int __read_mostly vdso_enabled = 1;
 
 extern char vdso_start[], vdso_end[];
 extern unsigned short vdso_sync_cpuid;
 
-static struct page **vdso_pages;
+extern struct page *vdso_pages[];
 static unsigned vdso_size;
 
 static void __init patch_vdso(void *vdso, size_t len)
@@ -54,7 +55,7 @@ found:
         apply_alternatives(alt_data, alt_data + alt_sec->sh_size);
 }
 
-static int __init init_vdso_vars(void)
+static int __init init_vdso(void)
 {
         int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE;
         int i;
@@ -62,26 +63,12 @@ static int __init init_vdso_vars(void)
         patch_vdso(vdso_start, vdso_end - vdso_start);
 
         vdso_size = npages << PAGE_SHIFT;
-        vdso_pages = kmalloc(sizeof(struct page *) * npages, GFP_KERNEL);
-        if (!vdso_pages)
-                goto oom;
-        for (i = 0; i < npages; i++) {
-                struct page *p;
-                p = alloc_page(GFP_KERNEL);
-                if (!p)
-                        goto oom;
-                vdso_pages[i] = p;
-                copy_page(page_address(p), vdso_start + i*PAGE_SIZE);
-        }
+        for (i = 0; i < npages; i++)
+                vdso_pages[i] = virt_to_page(vdso_start + i*PAGE_SIZE);
 
         return 0;
-
- oom:
-        printk("Cannot allocate vdso\n");
-        vdso_enabled = 0;
-        return -ENOMEM;
 }
-subsys_initcall(init_vdso_vars);
+subsys_initcall(init_vdso);
 
 struct linux_binprm;