[RFC,3/6] fork: provide a function for copying init_mm
diff mbox series

Message ID 20180829081147.184610-4-namit@vmware.com
State New
Headers show
Series
  • x86: text_poke() fixes
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Commit Message

Nadav Amit Aug. 29, 2018, 8:11 a.m. UTC
Provide a function for copying init_mm. This function will be later used
for setting a temporary mm.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 include/linux/sched/task.h |  1 +
 kernel/fork.c              | 24 ++++++++++++++++++------
 2 files changed, 19 insertions(+), 6 deletions(-)

Comments

Masami Hiramatsu Aug. 29, 2018, 9:54 a.m. UTC | #1
On Wed, 29 Aug 2018 01:11:44 -0700
Nadav Amit <namit@vmware.com> wrote:

> Provide a function for copying init_mm. This function will be later used
> for setting a temporary mm.

This looks good to me :)

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thanks!

> 
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Nadav Amit <namit@vmware.com>
> ---
>  include/linux/sched/task.h |  1 +
>  kernel/fork.c              | 24 ++++++++++++++++++------
>  2 files changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
> index 108ede99e533..ac0a675678f5 100644
> --- a/include/linux/sched/task.h
> +++ b/include/linux/sched/task.h
> @@ -74,6 +74,7 @@ extern void exit_itimers(struct signal_struct *);
>  extern long _do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *, unsigned long);
>  extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
>  struct task_struct *fork_idle(int);
> +struct mm_struct *copy_init_mm(void);
>  extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
>  extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
>  
> diff --git a/kernel/fork.c b/kernel/fork.c
> index d896e9ca38b0..a1c637b903c1 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1254,13 +1254,20 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
>  		complete_vfork_done(tsk);
>  }
>  
> -/*
> - * Allocate a new mm structure and copy contents from the
> - * mm structure of the passed in task structure.
> +/**
> + * dup_mm() - duplicates an existing mm structure
> + * @tsk: the task_struct with which the new mm will be associated.
> + * @oldmm: the mm to duplicate.
> + *
> + * Allocates a new mm structure and copy contents from the provided
> + * @oldmm structure.
> + *
> + * Return: the duplicated mm or NULL on failure.
>   */
> -static struct mm_struct *dup_mm(struct task_struct *tsk)
> +static struct mm_struct *dup_mm(struct task_struct *tsk,
> +				struct mm_struct *oldmm)
>  {
> -	struct mm_struct *mm, *oldmm = current->mm;
> +	struct mm_struct *mm;
>  	int err;
>  
>  	mm = allocate_mm();
> @@ -1327,7 +1334,7 @@ static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
>  	}
>  
>  	retval = -ENOMEM;
> -	mm = dup_mm(tsk);
> +	mm = dup_mm(tsk, current->mm);
>  	if (!mm)
>  		goto fail_nomem;
>  
> @@ -2127,6 +2134,11 @@ struct task_struct *fork_idle(int cpu)
>  	return task;
>  }
>  
> +struct mm_struct *copy_init_mm(void)
> +{
> +	return dup_mm(NULL, &init_mm);
> +}
> +
>  /*
>   *  Ok, this is the main fork-routine.
>   *
> -- 
> 2.17.1
>

Patch
diff mbox series

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 108ede99e533..ac0a675678f5 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -74,6 +74,7 @@  extern void exit_itimers(struct signal_struct *);
 extern long _do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *, unsigned long);
 extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
 struct task_struct *fork_idle(int);
+struct mm_struct *copy_init_mm(void);
 extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
 
diff --git a/kernel/fork.c b/kernel/fork.c
index d896e9ca38b0..a1c637b903c1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1254,13 +1254,20 @@  void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 		complete_vfork_done(tsk);
 }
 
-/*
- * Allocate a new mm structure and copy contents from the
- * mm structure of the passed in task structure.
+/**
+ * dup_mm() - duplicates an existing mm structure
+ * @tsk: the task_struct with which the new mm will be associated.
+ * @oldmm: the mm to duplicate.
+ *
+ * Allocates a new mm structure and copy contents from the provided
+ * @oldmm structure.
+ *
+ * Return: the duplicated mm or NULL on failure.
  */
-static struct mm_struct *dup_mm(struct task_struct *tsk)
+static struct mm_struct *dup_mm(struct task_struct *tsk,
+				struct mm_struct *oldmm)
 {
-	struct mm_struct *mm, *oldmm = current->mm;
+	struct mm_struct *mm;
 	int err;
 
 	mm = allocate_mm();
@@ -1327,7 +1334,7 @@  static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
 	}
 
 	retval = -ENOMEM;
-	mm = dup_mm(tsk);
+	mm = dup_mm(tsk, current->mm);
 	if (!mm)
 		goto fail_nomem;
 
@@ -2127,6 +2134,11 @@  struct task_struct *fork_idle(int cpu)
 	return task;
 }
 
+struct mm_struct *copy_init_mm(void)
+{
+	return dup_mm(NULL, &init_mm);
+}
+
 /*
  *  Ok, this is the main fork-routine.
  *