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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: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Masami 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: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.2
Nadav Amit 2019-04-25 17:11:25 -07:00 committed by Ingo Molnar
parent aad42dd44d
commit 13585fa066
2 changed files with 19 additions and 6 deletions
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1
include/linux/sched/task.h
View File

@ -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 *);

24
kernel/fork.c
View File

@ -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.
*