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ipc: add COMPAT_SHMLBA support 

If the SHMLBA definition for a native task differs from the definition for
a compat task, the do_shmat() function would need to handle both.

This patch introduces COMPAT_SHMLBA, which is used by the compat shmat
syscall when calling the ipc code and allows architectures such as AArch64
(where the native SHMLBA is 64k but the compat (AArch32) definition is
16k) to provide the correct semantics for compat IPC system calls.

Cc: David S. Miller <davem@davemloft.net>
Cc: Chris Zankel <chris@zankel.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Will Deacon 2012-07-30 14:42:38 -07:00 committed by Linus Torvalds
parent 63dca8d5b5
commit 079a96ae38
6 changed files with 18 additions and 11 deletions
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2
arch/sparc/kernel/sys_sparc_64.c
View File

@ -470,7 +470,7 @@ SYSCALL_DEFINE6(sparc_ipc, unsigned int, call, int, first, unsigned long, second
switch (call) {
case SHMAT: {
ulong raddr;
err = do_shmat(first, ptr, (int)second, &raddr);
err = do_shmat(first, ptr, (int)second, &raddr, SHMLBA);
if (!err) {
if (put_user(raddr,
(ulong __user *) third))

2
arch/xtensa/kernel/syscall.c
View File

@ -44,7 +44,7 @@ asmlinkage long xtensa_shmat(int shmid, char __user *shmaddr, int shmflg)
unsigned long ret;
long err;
err = do_shmat(shmid, shmaddr, shmflg, &ret);
err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
if (err)
return err;
return (long)ret;

6
include/linux/shm.h
View File

@ -107,12 +107,14 @@ struct shmid_kernel /* private to the kernel */
#define SHM_NORESERVE 010000 /* don't check for reservations */
#ifdef CONFIG_SYSVIPC
long do_shmat(int shmid, char __user *shmaddr, int shmflg, unsigned long *addr);
long do_shmat(int shmid, char __user *shmaddr, int shmflg, unsigned long *addr,
unsigned long shmlba);
extern int is_file_shm_hugepages(struct file *file);
extern void exit_shm(struct task_struct *task);
#else
static inline long do_shmat(int shmid, char __user *shmaddr,
int shmflg, unsigned long *addr)
int shmflg, unsigned long *addr,
unsigned long shmlba)
{
return -ENOSYS;
}

8
ipc/compat.c
View File

@ -514,6 +514,10 @@ long compat_sys_msgctl(int first, int second, void __user *uptr)
return err;
}
#ifndef COMPAT_SHMLBA
#define COMPAT_SHMLBA SHMLBA
#endif
#ifdef CONFIG_ARCH_WANT_OLD_COMPAT_IPC
long compat_sys_shmat(int first, int second, compat_uptr_t third, int version,
void __user *uptr)
@ -524,7 +528,7 @@ long compat_sys_shmat(int first, int second, compat_uptr_t third, int version,
if (version == 1)
return -EINVAL;
err = do_shmat(first, uptr, second, &raddr);
err = do_shmat(first, uptr, second, &raddr, COMPAT_SHMLBA);
if (err < 0)
return err;
uaddr = compat_ptr(third);
@ -536,7 +540,7 @@ long compat_sys_shmat(int shmid, compat_uptr_t shmaddr, int shmflg)
unsigned long ret;
long err;
err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret);
err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
if (err)
return err;
force_successful_syscall_return();

9
ipc/shm.c
View File

@ -953,7 +953,8 @@ out:
* "raddr" thing points to kernel space, and there has to be a wrapper around
* this.
*/
long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
unsigned long shmlba)
{
struct shmid_kernel *shp;
unsigned long addr;
@ -973,9 +974,9 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
if (shmid < 0)
goto out;
else if ((addr = (ulong)shmaddr)) {
if (addr & (SHMLBA-1)) {
if (addr & (shmlba - 1)) {
if (shmflg & SHM_RND)
addr &= ~(SHMLBA-1); /* round down */
addr &= ~(shmlba - 1); /* round down */
else
#ifndef __ARCH_FORCE_SHMLBA
if (addr & ~PAGE_MASK)
@ -1107,7 +1108,7 @@ SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
unsigned long ret;
long err;
err = do_shmat(shmid, shmaddr, shmflg, &ret);
err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
if (err)
return err;
force_successful_syscall_return();

2
ipc/syscall.c
View File

@ -73,7 +73,7 @@ SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
default: {
unsigned long raddr;
ret = do_shmat(first, (char __user *)ptr,
second, &raddr);
second, &raddr, SHMLBA);
if (ret)
return ret;
return put_user(raddr, (unsigned long __user *) third);