Commit 7addf443 authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

mm: add kernel_move_pages() helper, move compat syscall to mm/migrate.c 

Move compat_sys_move_pages() to mm/migrate.c and make it call a newly
introduced helper -- kernel_move_pages() -- instead of the syscall.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net



Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent b6e9b0ba

kernel/compat.c

+0 −22
Original line number Diff line number Diff line
@@ -488,28 +488,6 @@ get_compat_sigset(sigset_t *set, const compat_sigset_t __user *compat) 
}

EXPORT_SYMBOL_GPL(get_compat_sigset);



#ifdef CONFIG_NUMA

COMPAT_SYSCALL_DEFINE6(move_pages, pid_t, pid, compat_ulong_t, nr_pages,

		       compat_uptr_t __user *, pages32,

		       const int __user *, nodes,

		       int __user *, status,

		       int, flags)

{

	const void __user * __user *pages;

	int i;



	pages = compat_alloc_user_space(nr_pages * sizeof(void *));

	for (i = 0; i < nr_pages; i++) {

		compat_uptr_t p;



		if (get_user(p, pages32 + i) ||

			put_user(compat_ptr(p), pages + i))

			return -EFAULT;

	}

	return sys_move_pages(pid, nr_pages, pages, nodes, status, flags);

}

#endif



/*

 * Allocate user-space memory for the duration of a single system call,

 * in order to marshall parameters inside a compat thunk.

mm/migrate.c

+35 −4
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <linux/backing-dev.h>

#include <linux/compaction.h>

#include <linux/syscalls.h>

#include <linux/compat.h>

#include <linux/hugetlb.h>

#include <linux/hugetlb_cgroup.h>

#include <linux/gfp.h>
@@ -1745,10 +1746,10 @@ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, 
 * Move a list of pages in the address space of the currently executing

 * process.

 */

SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,

		const void __user * __user *, pages,

		const int __user *, nodes,

		int __user *, status, int, flags)

static int kernel_move_pages(pid_t pid, unsigned long nr_pages,

			     const void __user * __user *pages,

			     const int __user *nodes,

			     int __user *status, int flags)

{

	struct task_struct *task;

	struct mm_struct *mm;
@@ -1807,6 +1808,36 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, 
	return err;

}



SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,

		const void __user * __user *, pages,

		const int __user *, nodes,

		int __user *, status, int, flags)

{

	return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags);

}



#ifdef CONFIG_COMPAT

COMPAT_SYSCALL_DEFINE6(move_pages, pid_t, pid, compat_ulong_t, nr_pages,

		       compat_uptr_t __user *, pages32,

		       const int __user *, nodes,

		       int __user *, status,

		       int, flags)

{

	const void __user * __user *pages;

	int i;



	pages = compat_alloc_user_space(nr_pages * sizeof(void *));

	for (i = 0; i < nr_pages; i++) {

		compat_uptr_t p;



		if (get_user(p, pages32 + i) ||

			put_user(compat_ptr(p), pages + i))

			return -EFAULT;

	}

	return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags);

}

#endif /* CONFIG_COMPAT */



#ifdef CONFIG_NUMA_BALANCING

/*

 * Returns true if this is a safe migration target node for misplaced NUMA