Commit b6e9b0ba authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

mm: add kernel_migrate_pages() helper, move compat syscall to mm/mempolicy.c 

Move compat_sys_migrate_pages() to mm/mempolicy.c and make it call a newly
introduced helper -- kernel_migrate_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 7d4dd4f1

kernel/compat.c

+0 −33
Original line number Diff line number Diff line
@@ -508,39 +508,6 @@ COMPAT_SYSCALL_DEFINE6(move_pages, pid_t, pid, compat_ulong_t, nr_pages, 
	}

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

}



COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid,

		       compat_ulong_t, maxnode,

		       const compat_ulong_t __user *, old_nodes,

		       const compat_ulong_t __user *, new_nodes)

{

	unsigned long __user *old = NULL;

	unsigned long __user *new = NULL;

	nodemask_t tmp_mask;

	unsigned long nr_bits;

	unsigned long size;



	nr_bits = min_t(unsigned long, maxnode - 1, MAX_NUMNODES);

	size = ALIGN(nr_bits, BITS_PER_LONG) / 8;

	if (old_nodes) {

		if (compat_get_bitmap(nodes_addr(tmp_mask), old_nodes, nr_bits))

			return -EFAULT;

		old = compat_alloc_user_space(new_nodes ? size * 2 : size);

		if (new_nodes)

			new = old + size / sizeof(unsigned long);

		if (copy_to_user(old, nodes_addr(tmp_mask), size))

			return -EFAULT;

	}

	if (new_nodes) {

		if (compat_get_bitmap(nodes_addr(tmp_mask), new_nodes, nr_bits))

			return -EFAULT;

		if (new == NULL)

			new = compat_alloc_user_space(size);

		if (copy_to_user(new, nodes_addr(tmp_mask), size))

			return -EFAULT;

	}

	return sys_migrate_pages(pid, nr_bits + 1, old, new);

}

#endif



/*

mm/mempolicy.c

+44 −4
Original line number Diff line number Diff line
@@ -1377,9 +1377,9 @@ SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask, 
	return do_set_mempolicy(mode, flags, &nodes);

}



SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,

		const unsigned long __user *, old_nodes,

		const unsigned long __user *, new_nodes)

static int kernel_migrate_pages(pid_t pid, unsigned long maxnode,

				const unsigned long __user *old_nodes,

				const unsigned long __user *new_nodes)

{

	struct mm_struct *mm = NULL;

	struct task_struct *task;
@@ -1469,6 +1469,13 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode, 


}



SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,

		const unsigned long __user *, old_nodes,

		const unsigned long __user *, new_nodes)

{

	return kernel_migrate_pages(pid, maxnode, old_nodes, new_nodes);

}





/* Retrieve NUMA policy */

SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
@@ -1571,7 +1578,40 @@ COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len, 
	return sys_mbind(start, len, mode, nm, nr_bits+1, flags);

}



#endif

COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid,

		       compat_ulong_t, maxnode,

		       const compat_ulong_t __user *, old_nodes,

		       const compat_ulong_t __user *, new_nodes)

{

	unsigned long __user *old = NULL;

	unsigned long __user *new = NULL;

	nodemask_t tmp_mask;

	unsigned long nr_bits;

	unsigned long size;



	nr_bits = min_t(unsigned long, maxnode - 1, MAX_NUMNODES);

	size = ALIGN(nr_bits, BITS_PER_LONG) / 8;

	if (old_nodes) {

		if (compat_get_bitmap(nodes_addr(tmp_mask), old_nodes, nr_bits))

			return -EFAULT;

		old = compat_alloc_user_space(new_nodes ? size * 2 : size);

		if (new_nodes)

			new = old + size / sizeof(unsigned long);

		if (copy_to_user(old, nodes_addr(tmp_mask), size))

			return -EFAULT;

	}

	if (new_nodes) {

		if (compat_get_bitmap(nodes_addr(tmp_mask), new_nodes, nr_bits))

			return -EFAULT;

		if (new == NULL)

			new = compat_alloc_user_space(size);

		if (copy_to_user(new, nodes_addr(tmp_mask), size))

			return -EFAULT;

	}

	return kernel_migrate_pages(pid, nr_bits + 1, old, new);

}



#endif /* CONFIG_COMPAT */



struct mempolicy *__get_vma_policy(struct vm_area_struct *vma,

						unsigned long addr)