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From: Nadav Amit <namit@vmware.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@redhat.com>,
	<x86@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	<linux-arch@vger.kernel.org>, Nadav Amit <namit@vmware.com>,
	Andy Lutomirski <luto@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: [RFC PATCH 3/6] fork: provide a function for copying init_mm
Date: Wed, 29 Aug 2018 01:11:44 -0700	[thread overview]
Message-ID: <20180829081147.184610-4-namit@vmware.com> (raw)
In-Reply-To: <20180829081147.184610-1-namit@vmware.com>

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(-)

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


  parent reply	other threads:[~2018-08-29  8:13 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-29  8:11 [RFC PATCH 0/6] x86: text_poke() fixes Nadav Amit
2018-08-29  8:11 ` [RFC PATCH 1/6] x86/alternative: assert text_mutex is taken Nadav Amit
2018-08-29  8:59   ` Masami Hiramatsu
2018-08-29 17:11     ` Nadav Amit
2018-08-29 19:36       ` Nadav Amit
2018-08-29 20:13         ` Sean Christopherson
2018-08-29 20:44           ` Nadav Amit
2018-08-29 21:00             ` Sean Christopherson
2018-08-29 22:56               ` Nadav Amit
2018-08-30  2:26               ` Masami Hiramatsu
2018-08-30  5:23                 ` Nadav Amit
2018-08-29  8:11 ` [RFC PATCH 2/6] x86/mm: temporary mm struct Nadav Amit
2018-08-29  9:49   ` Masami Hiramatsu
2018-08-29 15:41     ` Andy Lutomirski
2018-08-29 16:54       ` Nadav Amit
2018-08-29 21:38         ` Andy Lutomirski
2018-08-30  1:38       ` Masami Hiramatsu
2018-08-30  1:59         ` Andy Lutomirski
2018-08-31  4:42           ` Masami Hiramatsu
2018-08-29 15:46   ` Andy Lutomirski
2018-08-29  8:11 ` Nadav Amit [this message]
2018-08-29  9:54   ` [RFC PATCH 3/6] fork: provide a function for copying init_mm Masami Hiramatsu
2018-08-29  8:11 ` [RFC PATCH 4/6] x86/alternatives: initializing temporary mm for patching Nadav Amit
2018-08-29 13:21   ` Masami Hiramatsu
2018-08-29 17:45     ` Nadav Amit
2018-08-29  8:11 ` [RFC PATCH 5/6] x86/alternatives: use temporary mm for text poking Nadav Amit
2018-08-29  9:28   ` Peter Zijlstra
2018-08-29 15:46     ` Andy Lutomirski
2018-08-29 16:14       ` Peter Zijlstra
2018-08-29 16:32         ` Andy Lutomirski
2018-08-29 16:37           ` Dave Hansen
2018-08-29  8:11 ` [RFC PATCH 6/6] x86/alternatives: remove text_poke() return value Nadav Amit
2018-08-29  9:52   ` Masami Hiramatsu
2018-08-29 17:15     ` Nadav Amit

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