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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: Dominik Brodowski <linux@dominikbrodowski.net>
This commit is contained in:
Dominik Brodowski 2018-03-17 16:00:25 +01:00
parent 7d4dd4f159
commit b6e9b0babb
2 changed files with 44 additions and 37 deletions
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33
kernel/compat.c
View File

@ -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
/*

48
mm/mempolicy.c
View File

@ -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)