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Subject[PATCH 26/45] mm: add kernel_move_pages() helper, move compat syscall to mm/migrate.c
Date
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 tries to remove in-kernel calls to
syscalls. On this basis, the syscall entry path can be streamlined.

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>
---
kernel/compat.c | 22 ----------------------
mm/migrate.c | 39 +++++++++++++++++++++++++++++++++++----
2 files changed, 35 insertions(+), 26 deletions(-)

diff --git a/kernel/compat.c b/kernel/compat.c
index 51bdf1808943..6d21894806b4 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -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.
diff --git a/mm/migrate.c b/mm/migrate.c
index 1e5525a25691..003886606a22 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -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
--
2.16.2
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