The patch titled
fully honor vdso_enabled [i386, sh; x86_64?]
has been removed from the -mm tree. Its filename was
fully-honor-vdso_enabled.patch
This patch was dropped because I am hopelessly confused - please resend
------------------------------------------------------
Subject: fully honor vdso_enabled [i386, sh; x86_64?]
From: John Reiser <jreiser@xxxxxxxxxxxx>
Architectures such as i386, sh, x86_64 have a flag
/proc/sys/vm/vdso_enabled to choose whether the kernel should setup a
process to use vdso after execve(). Informing the user code via
AT_SYSINFO* is controlled by macro ARCH_DLINFO in fs/binfmt_elf.c and
include/asm-$ARCH/elf.h, but the vdso page is established always via
arch_setup_additonal_pages() called from load_elf_binary(). If
vdso_enabled is off, then current code wastes kernel time during execve()
and fragments the address space unnecessarily.
This patch changes arch_setup_additonal_pages() to honor vdso_enabled. For
i386 it also allows the option of a fixed addresss to avoid fragmenting the
address space. Compiles and runs on i386. x86_64 [IA32 support] and sh
maintainers also please comment.
For some related history, including interaction with exec-shield, see:
http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=229304
and also 207020 and 162797.
Signed-off-by: John Reiser <jreiser@xxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxx>
Acked-by: Paul Mundt <lethal@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/i386/kernel/sysenter.c | 19 ++++++++++++++++++-
arch/sh/kernel/vsyscall/vsyscall.c | 3 +++
include/asm-i386/a.out.h | 2 +-
3 files changed, 22 insertions(+), 2 deletions(-)
diff -puN arch/i386/kernel/sysenter.c~fully-honor-vdso_enabled arch/i386/kernel/sysenter.c
--- a/arch/i386/kernel/sysenter.c~fully-honor-vdso_enabled
+++ a/arch/i386/kernel/sysenter.c
@@ -22,6 +22,8 @@
#include <asm/msr.h>
#include <asm/pgtable.h>
#include <asm/unistd.h>
+#include <asm/a.out.h>
+#include <asm/mman.h>
/*
* Should the kernel map a VDSO page into processes and pass its
@@ -105,10 +107,25 @@ int arch_setup_additional_pages(struct l
{
struct mm_struct *mm = current->mm;
unsigned long addr;
+ unsigned long flags;
int ret;
+ switch (vdso_enabled) {
+ case 0: /* none */
+ return 0;
+ default:
+ case 1: /* vdso in random available page */
+ addr = 0ul;
+ flags = 0ul;
+ break;
+ case 2: /* out of user's way */
+ addr = STACK_TOP;
+ flags = MAP_FIXED;
+ break;
+ }
+
down_write(&mm->mmap_sem);
- addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
+ addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, flags);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
diff -puN arch/sh/kernel/vsyscall/vsyscall.c~fully-honor-vdso_enabled arch/sh/kernel/vsyscall/vsyscall.c
--- a/arch/sh/kernel/vsyscall/vsyscall.c~fully-honor-vdso_enabled
+++ a/arch/sh/kernel/vsyscall/vsyscall.c
@@ -64,6 +64,9 @@ int arch_setup_additional_pages(struct l
unsigned long addr;
int ret;
+ if (!vdso_enabled)
+ return 0;
+
down_write(&mm->mmap_sem);
addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
if (IS_ERR_VALUE(addr)) {
diff -puN include/asm-i386/a.out.h~fully-honor-vdso_enabled include/asm-i386/a.out.h
--- a/include/asm-i386/a.out.h~fully-honor-vdso_enabled
+++ a/include/asm-i386/a.out.h
@@ -19,7 +19,7 @@ struct exec
#ifdef __KERNEL__
-#define STACK_TOP TASK_SIZE
+#define STACK_TOP (TASK_SIZE - PAGE_SIZE) /* 1 page optional for vdso */
#endif
_
Patches currently in -mm which might be from jreiser@xxxxxxxxxxxx are
fully-honor-vdso_enabled.patch
-
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