On Wed, 29 Aug 2018 01:11:44 -0700
Nadav Amit <namit@xxxxxxxxxx> 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@xxxxxxxxxx>
Thanks!
>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Nadav Amit <namit@xxxxxxxxxx>
> ---
> 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
>
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>
