* Andrew Morton <akpm@xxxxxxxx> wrote:
> > arch/i386/kernel/sysenter.c | 21 +++++++++++++++++++++
> > include/linux/sysctl.h | 1 +
> > kernel/sysctl.c | 16 ++++++++++++++++
> > 3 files changed, 38 insertions(+)
>
> Documentation/kernel-parameters.txt, please.
grumble. I had this done but quilt didnt pick it up.
> > +unsigned int vdso_enabled = 1;
>
> __read_mostly.
done. New patch attached.
------
Subject: i386, vdso=[0|1] boot option and /proc/sys/vm/vdso_enabled
From: Ingo Molnar <mingo@xxxxxxx>
add the vdso=0 boot option and the /proc/sys/vm/vdso_enabled
sysctl, on i386. VDSO defaults to enabled.
# cat /proc/self/maps | grep vdso
b7f42000-b7f43000 r-xp b7f42000 00:00 0 [vdso]
# echo 0 > /proc/sys/vm/vdso_enabled
# cat /proc/self/maps | grep vdso
# echo 1 > /proc/sys/vm/vdso_enabled
# cat /proc/self/maps | grep vdso
b7f05000-b7f06000 r-xp b7f05000 00:00 0 [vdso]
#
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
Documentation/kernel-parameters.txt | 4 ++++
arch/i386/kernel/sysenter.c | 21 +++++++++++++++++++++
include/linux/sysctl.h | 1 +
kernel/sysctl.c | 16 ++++++++++++++++
4 files changed, 42 insertions(+)
Index: linux-vdso-rand.q/Documentation/kernel-parameters.txt
===================================================================
--- linux-vdso-rand.q.orig/Documentation/kernel-parameters.txt
+++ linux-vdso-rand.q/Documentation/kernel-parameters.txt
@@ -1646,6 +1646,10 @@ running once the system is up.
usbhid.mousepoll=
[USBHID] The interval which mice are to be polled at.
+ vdso= [IA-32]
+ vdso=1: enable VDSO (default)
+ vdso=0: disable VDSO mapping
+
video= [FB] Frame buffer configuration
See Documentation/fb/modedb.txt.
Index: linux-vdso-rand.q/arch/i386/kernel/sysenter.c
===================================================================
--- linux-vdso-rand.q.orig/arch/i386/kernel/sysenter.c
+++ linux-vdso-rand.q/arch/i386/kernel/sysenter.c
@@ -22,6 +22,21 @@
#include <asm/pgtable.h>
#include <asm/unistd.h>
+/*
+ * Should the kernel map a VDSO page into processes and pass its
+ * address down to glibc upon exec()?
+ */
+unsigned int __read_mostly vdso_enabled = 1;
+
+static int __init vdso_setup(char *s)
+{
+ vdso_enabled = simple_strtoul(s, NULL, 0);
+
+ return 1;
+}
+
+__setup("vdso=", vdso_setup);
+
extern asmlinkage void sysenter_entry(void);
void enable_sep_cpu(void)
@@ -97,6 +112,9 @@ int arch_setup_additional_pages(struct l
unsigned long addr;
int ret;
+ if (unlikely(!vdso_enabled))
+ return 0;
+
down_write(&mm->mmap_sem);
addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
if (IS_ERR_VALUE(addr)) {
@@ -122,16 +140,19 @@ int arch_setup_additional_pages(struct l
ret = insert_vm_struct(mm, vma);
if (ret)
goto free_vma;
+
current->mm->context.vdso = (void *)addr;
current_thread_info()->sysenter_return = SYSENTER_RETURN_OFFSET + addr;
mm->total_vm++;
up_write(&mm->mmap_sem);
+
return 0;
free_vma:
kmem_cache_free(vm_area_cachep, vma);
up_fail:
up_write(&mm->mmap_sem);
+
return ret;
}
Index: linux-vdso-rand.q/include/linux/sysctl.h
===================================================================
--- linux-vdso-rand.q.orig/include/linux/sysctl.h
+++ linux-vdso-rand.q/include/linux/sysctl.h
@@ -186,6 +186,7 @@ enum
VM_PERCPU_PAGELIST_FRACTION=30,/* int: fraction of pages in each percpu_pagelist */
VM_ZONE_RECLAIM_MODE=31, /* reclaim local zone memory before going off node */
VM_ZONE_RECLAIM_INTERVAL=32, /* time period to wait after reclaim failure */
+ VM_VDSO_ENABLED=33, /* map VDSO into new processes? */
};
Index: linux-vdso-rand.q/kernel/sysctl.c
===================================================================
--- linux-vdso-rand.q.orig/kernel/sysctl.c
+++ linux-vdso-rand.q/kernel/sysctl.c
@@ -158,6 +158,10 @@ extern ctl_table inotify_table[];
int sysctl_legacy_va_layout;
#endif
+#ifdef CONFIG_X86_32
+extern int vdso_enabled;
+#endif
+
/* /proc declarations: */
#ifdef CONFIG_PROC_FS
@@ -915,6 +919,18 @@ static ctl_table vm_table[] = {
.strategy = &sysctl_jiffies,
},
#endif
+#ifdef CONFIG_X86_32
+ {
+ .ctl_name = VM_VDSO_ENABLED,
+ .procname = "vdso_enabled",
+ .data = &vdso_enabled,
+ .maxlen = sizeof(vdso_enabled),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ .strategy = &sysctl_intvec,
+ .extra1 = &zero,
+ },
+#endif
{ .ctl_name = 0 }
};
