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Commit 13585fa0 authored by Nadav Amit's avatar Nadav Amit Committed by Ingo Molnar
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fork: Provide a function for copying init_mm 



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

Tested-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarNadav Amit <namit@vmware.com>
Signed-off-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: <akpm@linux-foundation.org>
Cc: <ard.biesheuvel@linaro.org>
Cc: <deneen.t.dock@intel.com>
Cc: <kernel-hardening@lists.openwall.com>
Cc: <kristen@linux.intel.com>
Cc: <linux_dti@icloud.com>
Cc: <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-6-namit@vmware.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent aad42dd4

include/linux/sched/task.h

+1 −0
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ 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 *);

kernel/fork.c

+18 −6
Original line number Diff line number Diff line
@@ -1299,13 +1299,20 @@ 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 duplicates the provided @oldmm structure

 * content into it.

 *

 * 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();
@@ -1372,7 +1379,7 @@ 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;
@@ -2187,6 +2194,11 @@ 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.

 *