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

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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>
This commit is contained in:
Andy Lutomirski
2011-07-21 15:47:10 -04:00
committed by H. Peter Anvin
parent ae7bd11b47
commit aafade242f
2 changed files with 19 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
arch/x86/vdso/vdso.S
View File

@@ -1,10 +1,21 @@
#include <asm/page_types.h>
#include <linux/linkage.h>
#include <linux/init.h> #include <linux/init.h>
__INITDATA __PAGE_ALIGNED_DATA
.globl vdso_start, vdso_end .globl vdso_start, vdso_end
.align PAGE_SIZE
vdso_start: vdso_start:
.incbin "arch/x86/vdso/vdso.so" .incbin "arch/x86/vdso/vdso.so"
vdso_end: 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

25
arch/x86/vdso/vma.c
View File

@@ -14,13 +14,14 @@
#include <asm/vgtod.h> #include <asm/vgtod.h>
#include <asm/proto.h> #include <asm/proto.h>
#include <asm/vdso.h> #include <asm/vdso.h>
#include <asm/page.h>
unsigned int __read_mostly vdso_enabled = 1; unsigned int __read_mostly vdso_enabled = 1;
extern char vdso_start[], vdso_end[]; extern char vdso_start[], vdso_end[];
extern unsigned short vdso_sync_cpuid; extern unsigned short vdso_sync_cpuid;
static struct page **vdso_pages; extern struct page *vdso_pages[];
static unsigned vdso_size; static unsigned vdso_size;
static void __init patch_vdso(void *vdso, size_t len) 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); 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 npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE;
int i; int i;
@@ -62,26 +63,12 @@ static int __init init_vdso_vars(void)
patch_vdso(vdso_start, vdso_end - vdso_start); patch_vdso(vdso_start, vdso_end - vdso_start);
vdso_size = npages << PAGE_SHIFT; vdso_size = npages << PAGE_SHIFT;
vdso_pages = kmalloc(sizeof(struct page *) * npages, GFP_KERNEL); for (i = 0; i < npages; i++)
if (!vdso_pages) vdso_pages[i] = virt_to_page(vdso_start + i*PAGE_SIZE);
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);
}
return 0; 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; struct linux_binprm;