[PATCH 047/109] mm: add kernel_[sg]et_mempolicy() helpers; remove in-kernel calls to syscalls

From: Dominik Brodowski
Date: Thu Mar 29 2018 - 07:50:02 EST


Using the mm-internal kernel_[sg]et_mempolicy() helper allows us to get
rid of the mm-internal calls to the sys_[sg]et_mempolicy() syscalls.

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@xxxxxxxxxxxxxxxxxxxxxxxxxx

Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
---
mm/mempolicy.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e4d7d4c0b253..ca817e768d0e 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1365,8 +1365,8 @@ SYSCALL_DEFINE6(mbind, unsigned long, start, unsigned long, len,
}

/* Set the process memory policy */
-SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
- unsigned long, maxnode)
+static long kernel_set_mempolicy(int mode, const unsigned long __user *nmask,
+ unsigned long maxnode)
{
int err;
nodemask_t nodes;
@@ -1384,6 +1384,12 @@ SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
return do_set_mempolicy(mode, flags, &nodes);
}

+SYSCALL_DEFINE3(set_mempolicy, int, mode, const unsigned long __user *, nmask,
+ unsigned long, maxnode)
+{
+ return kernel_set_mempolicy(mode, nmask, maxnode);
+}
+
static int kernel_migrate_pages(pid_t pid, unsigned long maxnode,
const unsigned long __user *old_nodes,
const unsigned long __user *new_nodes)
@@ -1485,9 +1491,11 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,


/* Retrieve NUMA policy */
-SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
- unsigned long __user *, nmask, unsigned long, maxnode,
- unsigned long, addr, unsigned long, flags)
+static int kernel_get_mempolicy(int __user *policy,
+ unsigned long __user *nmask,
+ unsigned long maxnode,
+ unsigned long addr,
+ unsigned long flags)
{
int err;
int uninitialized_var(pval);
@@ -1510,6 +1518,13 @@ SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
return err;
}

+SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
+ unsigned long __user *, nmask, unsigned long, maxnode,
+ unsigned long, addr, unsigned long, flags)
+{
+ return kernel_get_mempolicy(policy, nmask, maxnode, addr, flags);
+}
+
#ifdef CONFIG_COMPAT

COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
@@ -1528,7 +1543,7 @@ COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
if (nmask)
nm = compat_alloc_user_space(alloc_size);

- err = sys_get_mempolicy(policy, nm, nr_bits+1, addr, flags);
+ err = kernel_get_mempolicy(policy, nm, nr_bits+1, addr, flags);

if (!err && nmask) {
unsigned long copy_size;
@@ -1560,7 +1575,7 @@ COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask,
return -EFAULT;
}

- return sys_set_mempolicy(mode, nm, nr_bits+1);
+ return kernel_set_mempolicy(mode, nm, nr_bits+1);
}

COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len,
--
2.16.3