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Subject[PATCH 34/45] ipc: add shmget syscall wrapper
Date
Provide ksys_shmget() wrapper to avoid in-kernel calls to this syscall.
The ksys_ prefix denotes that this function is meant as a drop-in
replacement for the syscall. In particular, it uses the same calling
convention as sys_shmget().

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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
---
ipc/shm.c | 7 ++++++-
ipc/syscall.c | 4 ++--
ipc/util.h | 1 +
3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/ipc/shm.c b/ipc/shm.c
index 4643865e9171..9f3cdb259a51 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -656,7 +656,7 @@ static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
return 0;
}

-SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
+long ksys_shmget(key_t key, size_t size, int shmflg)
{
struct ipc_namespace *ns;
static const struct ipc_ops shm_ops = {
@@ -675,6 +675,11 @@ SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
}

+SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
+{
+ return ksys_shmget(key, size, shmflg);
+}
+
static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
{
switch (version) {
diff --git a/ipc/syscall.c b/ipc/syscall.c
index 355c4a644bbf..60bceb19b6f0 100644
--- a/ipc/syscall.c
+++ b/ipc/syscall.c
@@ -92,7 +92,7 @@ SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
case SHMDT:
return sys_shmdt((char __user *)ptr);
case SHMGET:
- return sys_shmget(first, second, third);
+ return ksys_shmget(first, second, third);
case SHMCTL:
return sys_shmctl(first, second,
(struct shmid_ds __user *) ptr);
@@ -180,7 +180,7 @@ COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second,
case SHMDT:
return sys_shmdt(compat_ptr(ptr));
case SHMGET:
- return sys_shmget(first, (unsigned)second, third);
+ return ksys_shmget(first, (unsigned int)second, third);
case SHMCTL:
return compat_sys_shmctl(first, second, compat_ptr(ptr));
}
diff --git a/ipc/util.h b/ipc/util.h
index b35c0dfe3bc3..51002c0b2a21 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -243,6 +243,7 @@ long ksys_semtimedop(int semid, struct sembuf __user *tsops,
long ksys_semget(key_t key, int nsems, int semflg);
long ksys_semctl(int semid, int semnum, int cmd, unsigned long arg);
long ksys_msgget(key_t key, int msgflg);
+long ksys_shmget(key_t key, size_t size, int shmflg);

/* for CONFIG_ARCH_WANT_OLD_COMPAT_IPC */
#ifdef CONFIG_COMPAT
--
2.16.2
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