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Message-ID: <tip-13585fa0668c724efab9635aaeef6ec390217415@git.kernel.org>
Date: Tue, 30 Apr 2019 04:18:40 -0700
From: tip-bot for Nadav Amit <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: peterz@...radead.org, luto@...nel.org, mhiramat@...nel.org,
kristen@...ux.intel.com, linux-kernel@...r.kernel.org, hpa@...or.com,
deneen.t.dock@...el.com, namit@...are.com, tglx@...utronix.de,
torvalds@...ux-foundation.org, dave.hansen@...el.com, mingo@...nel.org,
linux_dti@...oud.com, kernel-hardening@...ts.openwall.com,
will.deacon@....com, rick.p.edgecombe@...el.com, riel@...riel.com,
keescook@...omium.org, akpm@...ux-foundation.org, bp@...en8.de,
ard.biesheuvel@...aro.org
Subject: [tip:x86/mm] fork: Provide a function for copying init_mm
Commit-ID: 13585fa0668c724efab9635aaeef6ec390217415
Gitweb: https://git.kernel.org/tip/13585fa0668c724efab9635aaeef6ec390217415
Author: Nadav Amit <namit@...are.com>
AuthorDate: Thu, 25 Apr 2019 17:11:25 -0700
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 30 Apr 2019 12:37:51 +0200
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@...nel.org>
Signed-off-by: Nadav Amit <namit@...are.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Masami Hiramatsu <mhiramat@...nel.org>
Cc: <akpm@...ux-foundation.org>
Cc: <ard.biesheuvel@...aro.org>
Cc: <deneen.t.dock@...el.com>
Cc: <kernel-hardening@...ts.openwall.com>
Cc: <kristen@...ux.intel.com>
Cc: <linux_dti@...oud.com>
Cc: <will.deacon@....com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Rik van Riel <riel@...riel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-6-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
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 2e97a2227045..f1227f2c38a4 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -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 *);
diff --git a/kernel/fork.c b/kernel/fork.c
index 44fba5e5e916..fbe9dfcd8680 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -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.
*
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