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>

3 files changed, 10 insertions, 14 deletions

diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index 19326d7..a98d0c9 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 1ca2d51..4d25e49 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 047246a..b42cbf1 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);
+}