Introduce fixed sys_sync_file_range2() syscall, implement on PowerPC and ARM

Not all the world is an i386.  Many architectures need 64-bit arguments to be
aligned in suitable pairs of registers, and the original
sys_sync_file_range(int, loff_t, loff_t, int) was therefore wasting an
argument register for padding after the first integer.  Since we don't
normally have more than 6 arguments for system calls, that left no room for
the final argument on some architectures.

Fix this by introducing sys_sync_file_range2(int, int, loff_t, loff_t) which
all fits nicely.  In fact, ARM already had that, but called it
sys_arm_sync_file_range.  Move it to fs/sync.c and rename it, then implement
the needed compatibility routine.  And stop the missing syscall check from
bitching about the absence of sys_sync_file_range() if we've implemented
sys_sync_file_range2() instead.

Tested on PPC32 and with 32-bit and 64-bit userspace on PPC64.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

9 files changed, 29 insertions, 15 deletions

diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index 19326d7cdeb3..a98d0c933db0 100644
--- a/arch/arm/kernel/calls.S
+++ b/arch/arm/kernel/calls.S
@@ -350,7 +350,7 @@
                 CALL(sys_set_robust_list)
                 CALL(sys_get_robust_list)
 /* 340 */       CALL(sys_splice)
-                CALL(sys_arm_sync_file_range)
+                CALL(sys_sync_file_range2)
                 CALL(sys_tee)
                 CALL(sys_vmsplice)
                 CALL(sys_move_pages)
diff --git a/arch/arm/kernel/sys_arm.c b/arch/arm/kernel/sys_arm.c
index 1ca2d5174fcb..4d25e49a14f7 100644
--- a/arch/arm/kernel/sys_arm.c
+++ b/arch/arm/kernel/sys_arm.c
@@ -328,16 +328,3 @@ asmlinkage long sys_arm_fadvise64_64(int fd, int advice,
 {
         return sys_fadvise64_64(fd, offset, len, advice);
 }
-
-/*
- * Yet more syscall fsckage - we can't fit sys_sync_file_range's
- * arguments into the available registers with EABI.  So, let's
- * create an ARM specific syscall for this which has _sane_
- * arguments.  (This incidentally also has an ABI-independent
- * argument layout.)
- */
-asmlinkage long sys_arm_sync_file_range(int fd, unsigned int flags,
-                                        loff_t offset, loff_t nbytes)
-{
-        return sys_sync_file_range(fd, offset, nbytes, flags);
-}
diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
index 047246ad4f65..b42cbf1e2d7d 100644
--- a/arch/powerpc/kernel/sys_ppc32.c
+++ b/arch/powerpc/kernel/sys_ppc32.c
@@ -810,3 +810,12 @@ asmlinkage long compat_sys_request_key(const char __user *_type,
         return sys_request_key(_type, _description, _callout_info, destringid);
 }
 
+asmlinkage long compat_sys_sync_file_range2(int fd, unsigned int flags,
+                                   unsigned offset_hi, unsigned offset_lo,
+                                   unsigned nbytes_hi, unsigned nbytes_lo)
+{
+        loff_t offset = ((loff_t)offset_hi << 32) | offset_lo;
+        loff_t nbytes = ((loff_t)nbytes_hi << 32) | nbytes_lo;
+
+        return sys_sync_file_range(fd, offset, nbytes, flags);
+}
diff --git a/fs/sync.c b/fs/sync.c
index 2f97576355b8..7cd005ea7639 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -236,6 +236,14 @@ out:
         return ret;
 }
 
+/* It would be nice if people remember that not all the world's an i386
+   when they introduce new system calls */
+asmlinkage long sys_sync_file_range2(int fd, unsigned int flags,
+                                     loff_t offset, loff_t nbytes)
+{
+        return sys_sync_file_range(fd, offset, nbytes, flags);
+}
+
 /*
  * `endbyte' is inclusive
  */
diff --git a/include/asm-arm/unistd.h b/include/asm-arm/unistd.h
index 250d7f145aca..bfdbebebdc1b 100644
--- a/include/asm-arm/unistd.h
+++ b/include/asm-arm/unistd.h
@@ -367,6 +367,7 @@
 #define __NR_get_robust_list            (__NR_SYSCALL_BASE+339)
 #define __NR_splice                     (__NR_SYSCALL_BASE+340)
 #define __NR_arm_sync_file_range        (__NR_SYSCALL_BASE+341)
+#define __NR_sync_file_range2           __NR_arm_sync_file_range
 #define __NR_tee                        (__NR_SYSCALL_BASE+342)
 #define __NR_vmsplice                   (__NR_SYSCALL_BASE+343)
 #define __NR_move_pages                 (__NR_SYSCALL_BASE+344)
diff --git a/include/asm-powerpc/systbl.h b/include/asm-powerpc/systbl.h
index 700ca5928741..1cc3f9cb6f4e 100644
--- a/include/asm-powerpc/systbl.h
+++ b/include/asm-powerpc/systbl.h
@@ -311,3 +311,4 @@ COMPAT_SYS_SPU(utimensat)
 COMPAT_SYS_SPU(signalfd)
 COMPAT_SYS_SPU(timerfd)
 SYSCALL_SPU(eventfd)
+COMPAT_SYS_SPU(sync_file_range2)
diff --git a/include/asm-powerpc/unistd.h b/include/asm-powerpc/unistd.h
index e3c28dc31abf..f71c6061f1ec 100644
--- a/include/asm-powerpc/unistd.h
+++ b/include/asm-powerpc/unistd.h
@@ -330,10 +330,11 @@
 #define __NR_signalfd           305
 #define __NR_timerfd            306
 #define __NR_eventfd            307
+#define __NR_sync_file_range2   308
 
 #ifdef __KERNEL__
 
-#define __NR_syscalls           308
+#define __NR_syscalls           309
 
 #define __NR__exit __NR_exit
 #define NR_syscalls     __NR_syscalls
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index b02070eac422..83d0ec11235e 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -598,6 +598,8 @@ asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags);
 
 asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
                                         unsigned int flags);
+asmlinkage long sys_sync_file_range2(int fd, unsigned int flags,
+                                     loff_t offset, loff_t nbytes);
 asmlinkage long sys_get_robust_list(int pid,
                                     struct robust_list_head __user * __user *head_ptr,
                                     size_t __user *len_ptr);
diff --git a/scripts/checksyscalls.sh b/scripts/checksyscalls.sh
index f98171f5a3df..0dcc01ce45a6 100755
--- a/scripts/checksyscalls.sh
+++ b/scripts/checksyscalls.sh
@@ -99,6 +99,11 @@ cat << EOF
 #define __IGNORE_setfsuid32
 #define __IGNORE_setfsgid32
 
+/* sync_file_range had a stupid ABI. Allow sync_file_range2 instead */
+#ifdef __NR_sync_file_range2
+#define __IGNORE_sync_file_range
+#endif
+
 /* Unmerged syscalls for AFS, STREAMS, etc. */
 #define __IGNORE_afs_syscall
 #define __IGNORE_getpmsg