On Thu, Feb 21, 2013 at 06:46:39PM +1100, Amnon Shiloh wrote:
> Cyrill Gorcunov wrote:
>
> >> Another possibility is to have a dual #if:
> >>
> >> #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(CONFIG_MM_FIELDS_SETTING)
> >
> > Thus this approach looks preferred. And MM_FIELDS_SETTING will be y by
> > default.
> > Mind to cook a patch and lets see if community accept it? Don't forget to
> > CC Andrew Morton.
>
> Very well, patch attached.
Wouldn't the below do the same trick but eliminate OR in preproc code?
---
From: Amnon Shiloh <u3...@miso.sublimeip.com>
Subject: prctl: Make PR_SET_MM being depend on own CONFIG_MM_FIELDS_SETTING
...
Signed-off-by: Amnon Shiloh <u3...@miso.sublimeip.com>
---
init/Kconfig | 17 +++++++++++++++++
kernel/sys.c | 16 ++++++++--------
2 files changed, 25 insertions(+), 8 deletions(-)
Index: linux-2.6.git/init/Kconfig
===================================================================
--- linux-2.6.git.orig/init/Kconfig
+++ linux-2.6.git/init/Kconfig
@@ -991,6 +991,7 @@ endif # CGROUPS
config CHECKPOINT_RESTORE
bool "Checkpoint/restore support" if EXPERT
default n
+ select MM_FIELDS_SETTING
help
Enables additional kernel features in a sake of checkpoint/restore.
In particular it adds auxiliary prctl codes to setup process text,
@@ -999,6 +1000,22 @@ config CHECKPOINT_RESTORE
If unsure, say N here.
+config MM_FIELDS_SETTING
+ bool "Allow modifying per-process memory-region fields"
+ default y
+ help
+ Support "prctl(PR_SET_MM)" which allows applications to modify
+ the following in their "mm_struct":
+
+ start_code, end_code, start_data, end_data, start_brk, brk,
+ start_stack, arg_start, arg_end, env_start, env_end.
+
+ Also to modify their executable file ("/proc/self/exe").
+
+ This option is needed for reconstructing processes (such as when
+ restoring a process from a checkpoint; duplicating a process;
+ or migrating it to another computer).
+
menuconfig NAMESPACES
bool "Namespaces support" if EXPERT
default !EXPERT
Index: linux-2.6.git/kernel/sys.c
===================================================================
--- linux-2.6.git.orig/kernel/sys.c
+++ linux-2.6.git/kernel/sys.c
@@ -1788,7 +1788,7 @@ SYSCALL_DEFINE1(umask, int, mask)
return mask;
}
-#ifdef CONFIG_CHECKPOINT_RESTORE
+#ifdef CONFIG_MM_FIELDS_SETTING
static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
{
struct fd exe;
@@ -1981,23 +1981,23 @@ out:
up_read(&mm->mmap_sem);
return error;
}
+#else /* CONFIG_MM_FIELDS_SETTING */
-static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
-{
- return put_user(me->clear_child_tid, tid_addr);
-}
-
-#else /* CONFIG_CHECKPOINT_RESTORE */
static int prctl_set_mm(int opt, unsigned long addr,
unsigned long arg4, unsigned long arg5)
{
return -EINVAL;
}
+#endif
+
static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
{
+#ifdef CONFIG_CHECKPOINT_RESTORE
+ return put_user(me->clear_child_tid, tid_addr);
+#else
return -EINVAL;
-}
#endif
+}
SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
unsigned long, arg4, unsigned long, arg5)
--
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