Commit 079a96ae authored by Will Deacon's avatar Will Deacon Committed by Linus Torvalds
Browse files

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: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 63dca8d5

arch/sparc/kernel/sys_sparc_64.c

+1 −1
Original line number Diff line number Diff line
@@ -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))

arch/xtensa/kernel/syscall.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

include/linux/shm.h

+4 −2
Original line number Diff line number Diff line
@@ -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;

}

ipc/compat.c

+6 −2
Original line number Diff line number Diff line
@@ -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();

ipc/shm.c

+5 −4
Original line number Diff line number Diff line
@@ -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();

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